//! The Relm4 view: one component whose widgets mirror the model. The
//! `Component` impl is a thin adapter — `handle` and `handle_result` in
//! `app.rs` own the state machine; background work runs through
//! `spawn_command` on the blocking pool and reports back as `OpResult`.
//!
//! Every visual decision is delegated to libadwaita: the widgets below are
//! the stylesheet's own rows, groups, dialogs and status pages, and the
//! only styling is its documented class names. Nothing here picks a colour,
//! a font or a size, so carrier follows the user's theme and accent.

use std::sync::atomic::Ordering;
use std::time::Duration;

use fumi_core::crypto::{b32, fingerprint, KEY_LEN};
use gtk::prelude::*;
use gtk::{Align, Orientation, WrapMode};
use relm4::adw;
use relm4::adw::prelude::*;
use relm4::ComponentSender;
use relm4::{Component, ComponentParts};

use crate::app::{Carrier, Dialog, Message, OnboardMode, OpResult, Page, PendingOp};
use crate::ops::{self, Contact, Folder, Row};
use relm4::RelmApp;

/// A label, the unit every line is built from. The class argument is a
/// space-separated set of Adwaita's own typography classes, so weight and
/// size come from the stylesheet rather than from markup or a hardcoded
/// font: `heading` and `title` for hierarchy, `dim` and `caption` for
/// metadata, `mono` wherever a key or address must stay column-aligned.
fn label(text: &str, classes: &str) -> gtk::Label {
    let label = gtk::Label::new(Some(text));
    for class in classes.split_whitespace() {
        match class {
            "dim" => label.add_css_class("dim-label"),
            "caption" => {
                label.add_css_class("caption");
                label.add_css_class("dim-label");
            }
            "heading" => label.add_css_class("heading"),
            "title" => label.add_css_class("title-1"),
            "subtitle" => label.add_css_class("title-4"),
            "mono" => label.add_css_class("monospace"),
            "numeric" => label.add_css_class("numeric"),
            other => label.add_css_class(other),
        }
    }
    label.set_xalign(0.0);
    label
}

fn escape(text: &str) -> String {
    gtk::glib::markup_escape_text(text).to_string()
}

/// Buttons map onto the stylesheet's built-in classes: "accent" is the
/// suggested action, "danger" the destructive one, "pill" the wide call to
/// action a welcome screen wants, everything else flat.
fn button(text: &str, class: &str) -> gtk::Button {
    let button = gtk::Button::with_label(text);
    match class {
        "accent" => button.add_css_class("suggested-action"),
        "danger" => button.add_css_class("destructive-action"),
        "quiet" => button.add_css_class("flat"),
        "pill" => {
            button.add_css_class("pill");
            button.add_css_class("suggested-action");
        }
        "pill-quiet" => button.add_css_class("pill"),
        _ => {}
    }
    button
}

/// The same, with a symbolic icon beside the label. `ButtonContent` does
/// the icon-to-label spacing the stylesheet expects.
fn icon_label_button(icon: &str, text: &str, class: &str) -> gtk::Button {
    let button = button("", class);
    button.set_child(Some(
        &adw::ButtonContent::builder()
            .icon_name(icon)
            .label(text)
            .build(),
    ));
    button
}

/// A flat round icon button: the Adwaita form for a secondary affordance
/// that sits inside a row rather than in a toolbar.
fn icon_button(icon: &str, tooltip: &str) -> gtk::Button {
    let button = gtk::Button::from_icon_name(icon);
    button.add_css_class("flat");
    button.add_css_class("circular");
    button.set_tooltip_text(Some(tooltip));
    button.set_valign(Align::Center);
    button
}

/// One sidebar destination: icon, name, and a count that stays hidden
/// until it is non-zero. The row carries no class of its own — the list's
/// `navigation-sidebar` paints hover and selection.
fn nav_row(icon: &str, text: &str) -> (gtk::ListBoxRow, gtk::Label) {
    let row = gtk::ListBoxRow::new();
    let line = gtk::Box::new(Orientation::Horizontal, 12);
    line.set_margin_top(6);
    line.set_margin_bottom(6);
    line.set_margin_start(6);
    line.set_margin_end(6);
    line.append(&gtk::Image::from_icon_name(icon));
    let name = gtk::Label::new(Some(text));
    name.set_xalign(0.0);
    name.set_hexpand(true);
    line.append(&name);
    let count = label("", "caption numeric");
    count.set_visible(false);
    line.append(&count);
    row.set_child(Some(&line));
    (row, count)
}

/// A list that paints itself as one rounded group: the Adwaita form for a
/// short, fixed set of rows, as opposed to a long scrolling one.
fn boxed_list() -> gtk::ListBox {
    let list = gtk::ListBox::new();
    list.add_css_class("boxed-list");
    list.set_selection_mode(gtk::SelectionMode::None);
    list
}

/// Removes every child of a box, the coarse re-render primitive.
fn clear(boxed: &gtk::Box) {
    while let Some(child) = boxed.first_child() {
        boxed.remove(&child);
    }
}

/// The same for lists.
fn clear_list(list: &gtk::ListBox) {
    while let Some(child) = list.first_child() {
        list.remove(&child);
    }
}

pub fn run(dir: std::path::PathBuf) {
    let app: RelmApp<_> = RelmApp::new("com.randogoth.carrier");
    app.run::<Carrier>(dir);
}

fn truncate(text: &str, max: usize) -> String {
    if text.chars().count() <= max {
        text.to_string()
    } else {
        let cut: String = text.chars().take(max - 1).collect();
        format!("{cut}…")
    }
}

fn buffer_text(buffer: &gtk::TextBuffer) -> String {
    buffer
        .text(&buffer.start_iter(), &buffer.end_iter(), false)
        .to_string()
}

/// The contact's trust state as one word, the same vocabulary the sidebar,
/// the detail pane and the contacts page all label it with.
fn contact_state(contact: &Contact) -> &'static str {
    match contact.accepted {
        Some(true) => "accepted",
        Some(false) => "blocked",
        None if contact.verified => "verified",
        None => "trust on first use",
    }
}

#[derive(Debug, Clone)]
pub struct CarrierWidgets {
    /// `AlertDialog::present` needs a parent, and only the window is one.
    window: gtk::Window,
    window_title: adw::WindowTitle,
    // sidebar top: actions and destinations
    folders: gtk::ListBox,
    folder_counts: Vec<gtk::Label>,
    /// The Drafts row, hidden until the folder holds one.
    drafts_nav: gtk::ListBoxRow,
    settings_nav: gtk::ListBox,
    fetch_button: gtk::Button,
    write_button: gtk::Button,

    stack: gtk::Stack,

    // mail page
    list_stack: gtk::Stack,
    mail_list: gtk::ListBox,
    list_empty: adw::StatusPage,
    list_empty_fetch: gtk::Button,
    article_stack: gtk::Stack,
    article_subject: gtk::Label,
    article_meta: gtk::Label,
    article_headers: gtk::Label,
    article_view: gtk::TextView,
    article_body: gtk::TextBuffer,
    actions: gtk::Box,

    // compose page
    compose_to: adw::EntryRow,
    compose_headers: gtk::ListBox,
    compose_subject: adw::EntryRow,
    compose_body: gtk::TextBuffer,
    compose_send: adw::ButtonContent,

    // sidebar bottom: own identity and the contact list
    sidebar_own: gtk::Label,
    sidebar_contacts: gtk::ListBox,

    // the QR-only share popover on the detail view's header
    detail_share: gtk::MenuButton,
    detail_copy: gtk::Button,
    detail_qr: gtk::Image,

    // settings page
    identity_values: Vec<gtk::Label>,
    offer_group: adw::PreferencesGroup,
    offer_row: adw::ActionRow,
    pins_group: adw::PreferencesGroup,
    pin_rows: Vec<adw::ActionRow>,
    timeout_row: adw::SpinRow,
    backup_label: gtk::Label,

    // onboarding
    onboard_seed_label: gtk::Label,

    // signup
    signup_back: gtk::Button,
    signup_offer_list: gtk::ListBox,
    signup_offer_row: adw::ActionRow,

    // status bar and dialogs
    spinner: gtk::Spinner,
    status_label: gtk::Label,
    cancel_button: gtk::Button,
    /// The dialog currently on screen, so `render` presents it once on the
    /// None -> Some edge instead of stacking a copy on every message.
    dialog: Option<adw::AlertDialog>,
}

impl CarrierWidgets {
    fn new(root: &gtk::Window, sender: &ComponentSender<Carrier>) -> Self {
        // One helper per widget parameter type: a single closure would
        // have its signature unified across every call site.
        let input = |msg: Message| {
            let sender = sender.clone();
            move |_: &gtk::Button| sender.input(msg.clone())
        };

        // An Adwaita headerbar carrying the app name over the account
        // address, so the window reads like every other GNOME app and the
        // identity in use is never more than a glance away.
        let window_title = adw::WindowTitle::new("carrier", "");
        let header = adw::HeaderBar::new();
        header.set_title_widget(Some(&window_title));
        root.set_titlebar(Some(&header));

        // The sidebar column, left of the main box, split on the same
        // line as the main box's list/article split. The top panel stacks
        // the actions and the destinations; the bottom panel leads with
        // our own identity, carded apart from the contact list.
        let sidebar = gtk::Paned::new(Orientation::Vertical);
        // Position 1 is below any child's minimum, so both columns open
        // with the top pane at its smallest height.
        sidebar.set_position(1);
        // Refuse to shrink the top panel past its own minimum: otherwise
        // dragging the divider up clips it from the top and the actions
        // are the first thing to go. The filler below the folders has no
        // minimum of its own, so that space collapses first instead.
        sidebar.set_shrink_start_child(false);
        let sidebar_top = gtk::Box::new(Orientation::Vertical, 12);
        sidebar_top.set_margin_top(6);
        sidebar_top.set_margin_start(6);
        sidebar_top.set_margin_end(6);
        let sidebar_bottom = gtk::Box::new(Orientation::Vertical, 6);
        sidebar_bottom.set_margin_start(6);
        sidebar_bottom.set_margin_end(6);
        sidebar_bottom.set_margin_bottom(6);
        sidebar.set_start_child(Some(&sidebar_top));
        sidebar.set_end_child(Some(&sidebar_bottom));

        // Fetch and Write lead the top panel, each an equal half. Only
        // Fetch is suggested: two suggested actions side by side would
        // leave neither of them reading as the primary one.
        let sidebar_actions = gtk::Box::new(Orientation::Horizontal, 6);
        sidebar_actions.set_homogeneous(true);
        let fetch_button = icon_label_button("mail-send-receive-symbolic", "Fetch", "accent");
        let write_button = icon_label_button("mail-message-new-symbolic", "Write", "");
        sidebar_actions.append(&fetch_button);
        sidebar_actions.append(&write_button);
        sidebar_top.append(&sidebar_actions);

        // The destinations follow, as the sidebar list every GNOME app
        // uses: icon, name, and the unread count on the right.
        let folders = gtk::ListBox::new();
        folders.add_css_class("navigation-sidebar");
        folders.set_selection_mode(gtk::SelectionMode::Single);
        let folder_rows = [
            nav_row("folder-download-symbolic", "Inbox"),
            nav_row("contact-new-symbolic", "Requests"),
            nav_row("mail-send-symbolic", "Sent"),
            nav_row("document-edit-symbolic", "Drafts"),
        ];
        let mut folder_counts = Vec::new();
        let mut drafts_nav = None;
        for (index, (row, count)) in folder_rows.into_iter().enumerate() {
            // The drafts folder is carrier's own: it stays out of the
            // sidebar until a compose has been set aside into it.
            if index == 3 {
                row.set_visible(false);
                drafts_nav = Some(row.clone());
            }
            folders.append(&row);
            folder_counts.push(count);
        }
        let drafts_nav = drafts_nav.expect("four folder rows");
        sidebar_top.append(&folders);

        // Settings closes the top panel, pinned to its bottom. It is its
        // own list so that it highlights like a destination without
        // joining the folders' selection, the way GNOME Settings splits
        // its own sidebar.
        let filler = gtk::Label::new(None);
        filler.set_vexpand(true);
        sidebar_top.append(&filler);
        let settings_nav = gtk::ListBox::new();
        settings_nav.add_css_class("navigation-sidebar");
        settings_nav.set_selection_mode(gtk::SelectionMode::Single);
        let (settings_row, _) = nav_row("preferences-system-symbolic", "Settings");
        settings_nav.append(&settings_row);
        sidebar_top.append(&settings_nav);

        // Our own identity heads the bottom panel, carded so it reads
        // apart from the contacts below. Tapping it opens the detail
        // view the contacts get, with our own key lines in it.
        let own_text = gtk::Box::new(Orientation::Vertical, 0);
        own_text.set_hexpand(true);
        own_text.set_margin_top(8);
        own_text.set_margin_bottom(8);
        own_text.set_margin_start(12);
        let own_caption = label("you", "caption");
        let sidebar_own = label("", "mono heading");
        // Not selectable: a selectable label eats clicks on the text with
        // its selection gesture, and the address is already copyable from
        // the detail view's URI line.
        sidebar_own.set_ellipsize(gtk::pango::EllipsizeMode::End);
        own_text.append(&own_caption);
        own_text.append(&sidebar_own);
        let own_row = gtk::Button::new();
        own_row.add_css_class("card");
        own_row.set_halign(Align::Fill);
        own_row.set_margin_top(6);
        own_row.set_child(Some(&own_text));
        sidebar_bottom.append(&own_row);

        // The list's header carries its one action: importing a
        // smol:// address, in a popover off a plain add button.
        let contacts_head = gtk::Box::new(Orientation::Horizontal, 6);
        let contacts_caption = label("contacts", "caption");
        contacts_caption.set_hexpand(true);
        contacts_caption.set_valign(Align::Center);
        contacts_caption.set_margin_start(12);
        let contact_import = adw::EntryRow::builder()
            .title("Import a smol:// address")
            .build();
        let import_button = icon_label_button("document-open-symbolic", "Import", "accent");
        import_button.set_valign(Align::Center);
        contact_import.add_suffix(&import_button);
        let import_list = boxed_list();
        import_list.set_width_request(320);
        import_list.set_margin_top(6);
        import_list.set_margin_bottom(6);
        import_list.set_margin_start(6);
        import_list.set_margin_end(6);
        import_list.append(&contact_import);
        let import_popover = gtk::Popover::new();
        import_popover.set_child(Some(&import_list));
        let add_contact = gtk::MenuButton::new();
        add_contact.set_icon_name("list-add-symbolic");
        add_contact.add_css_class("flat");
        add_contact.add_css_class("circular");
        add_contact.set_tooltip_text(Some("Import a smol:// address"));
        add_contact.set_popover(Some(&import_popover));
        contacts_head.append(&contacts_caption);
        contacts_head.append(&add_contact);
        sidebar_bottom.append(&contacts_head);

        let contacts_scroll = gtk::ScrolledWindow::new();
        contacts_scroll.set_vexpand(true);
        let contacts_list = gtk::ListBox::new();
        contacts_list.add_css_class("navigation-sidebar");
        contacts_list.set_selection_mode(gtk::SelectionMode::Single);
        contacts_scroll.set_child(Some(&contacts_list));
        sidebar_bottom.append(&contacts_scroll);

        // --- pages ------------------------------------------------------
        let stack = gtk::Stack::new();
        stack.set_vexpand(true);

        // mail: the split — list above, article below
        let paned = gtk::Paned::new(Orientation::Vertical);
        paned.set_position(1);
        let list_scroll = gtk::ScrolledWindow::new();
        let mail_list = gtk::ListBox::new();
        mail_list.set_selection_mode(gtk::SelectionMode::Single);
        list_scroll.set_child(Some(&mail_list));
        // An empty folder gets a status page rather than a stray line of
        // dim text, so the pane says what to do about it.
        let list_empty = adw::StatusPage::new();
        let list_empty_fetch = icon_label_button("mail-send-receive-symbolic", "Fetch", "pill");
        list_empty_fetch.set_halign(Align::Center);
        list_empty.set_child(Some(&list_empty_fetch));
        let list_stack = gtk::Stack::new();
        list_stack.set_hhomogeneous(false);
        list_stack.set_vhomogeneous(false);
        list_stack.add_named(&list_scroll, Some("list"));
        list_stack.add_named(&list_empty, Some("empty"));
        paned.set_start_child(Some(&list_stack));
        paned.set_resize_start_child(true);
        paned.set_shrink_start_child(false);

        let article = gtk::Box::new(Orientation::Vertical, 0);
        let article_head = gtk::Box::new(Orientation::Vertical, 10);
        article_head.set_margin_top(12);
        article_head.set_margin_bottom(12);
        article_head.set_margin_start(12);
        article_head.set_margin_end(12);
        let article_subject = label("", "subtitle");
        article_subject.set_wrap(true);
        article_subject.set_hexpand(true);
        // The detail view's header bar: the address on the left, the QR
        // share on the right. The popover holds the code and nothing
        // else — the URI sits in the body below.
        let detail_qr = gtk::Image::new();
        detail_qr.set_margin_top(12);
        detail_qr.set_margin_bottom(12);
        detail_qr.set_margin_start(12);
        detail_qr.set_margin_end(12);
        let detail_popover = gtk::Popover::new();
        detail_popover.set_child(Some(&detail_qr));
        let detail_share = gtk::MenuButton::new();
        detail_share.set_icon_name("send-to-symbolic");
        detail_share.add_css_class("flat");
        detail_share.add_css_class("circular");
        detail_share.set_tooltip_text(Some("Show the address as a QR code"));
        detail_share.set_popover(Some(&detail_popover));
        detail_share.set_valign(Align::Start);
        detail_share.set_visible(false);
        // Copies the address the header shows, so it serves the contact
        // and the own-identity detail alike.
        let detail_copy = icon_button("edit-copy-symbolic", "Copy the address");
        detail_copy.set_valign(Align::Start);
        detail_copy.set_visible(false);
        let copy_source = article_subject.clone();
        detail_copy.connect_clicked(move |_| {
            let address = copy_source.text().to_string();
            if let Some(display) = gtk::gdk::Display::default() {
                display.clipboard().set_text(&address);
            }
        });
        let subject_row = gtk::Box::new(Orientation::Horizontal, 6);
        subject_row.append(&article_subject);
        subject_row.append(&detail_copy);
        subject_row.append(&detail_share);
        let article_meta = label("", "caption");
        article_meta.set_wrap(true);
        article_head.append(&subject_row);
        article_head.append(&article_meta);
        // The sender's own frontmatter fields, when a mail carries any:
        // envelope data, so it reads like the contact detail's key block
        // rather than like body prose.
        let article_headers = label("", "caption mono");
        article_headers.set_wrap(true);
        article_headers.set_wrap_mode(gtk::pango::WrapMode::WordChar);
        article_headers.set_selectable(true);
        article_headers.set_visible(false);
        article_head.append(&article_headers);
        article.append(&article_head);
        article.append(&gtk::Separator::new(Orientation::Horizontal));
        let article_view = gtk::TextView::new();
        article_view.set_wrap_mode(WrapMode::WordChar);
        article_view.set_editable(false);
        article_view.set_cursor_visible(false);
        article_view.set_top_margin(12);
        article_view.set_bottom_margin(12);
        article_view.set_left_margin(12);
        article_view.set_right_margin(12);
        let article_body = article_view.buffer();
        let article_scroll = gtk::ScrolledWindow::new();
        article_scroll.set_vexpand(true);
        article_scroll.set_child(Some(&article_view));
        article.append(&article_scroll);
        // The action bar carries the stylesheet's `toolbar` class, which
        // supplies its own padding and ground, so no separator is needed
        // to tell it apart from the body above.
        let actions = gtk::Box::new(Orientation::Horizontal, 6);
        actions.add_css_class("toolbar");
        article.append(&actions);

        // No icon: the pane sits directly under the list's own empty page,
        // and two envelopes stacked up the window say nothing twice.
        let article_empty = adw::StatusPage::builder()
            .title("No message selected")
            .description("Pick a message from the list above to read it.")
            .build();
        let article_stack = gtk::Stack::new();
        article_stack.set_hhomogeneous(false);
        article_stack.set_vhomogeneous(false);
        article_stack.add_named(&article, Some("detail"));
        article_stack.add_named(&article_empty, Some("empty"));
        paned.set_end_child(Some(&article_stack));
        // The sidebar's divider follows this one and vice versa, so both
        // columns always split on the same line.
        let sidebar_sync = sidebar.clone();
        paned.connect_position_notify(move |p| {
            if sidebar_sync.position() != p.position() {
                sidebar_sync.set_position(p.position());
            }
        });
        let main_sync = paned.clone();
        sidebar.connect_position_notify(move |p| {
            if main_sync.position() != p.position() {
                main_sync.set_position(p.position());
            }
        });
        stack.add_named(&paned, Some("mail"));

        // compose
        let compose = gtk::Box::new(Orientation::Vertical, 12);
        compose.set_margin_top(12);
        compose.set_margin_bottom(12);
        compose.set_margin_start(12);
        compose.set_margin_end(12);
        let compose_fields = boxed_list();
        let compose_to = adw::EntryRow::builder().title("To").build();
        let compose_subject = adw::EntryRow::builder().title("Subject").build();
        compose_fields.append(&compose_to);
        compose_fields.append(&compose_subject);
        compose.append(&compose_fields);
        // Frontmatter rows: one `Key: value` entry each, plus a flat
        // add button below. Rows are rebuilt in render on structural
        // changes only, so the entries never lose focus while typing.
        let compose_headers = boxed_list();
        compose.append(&compose_headers);
        let add_header = button("+ header", "quiet");
        add_header.set_halign(Align::Start);
        compose.append(&add_header);
        let compose_view = gtk::TextView::new();
        compose_view.set_wrap_mode(WrapMode::WordChar);
        compose_view.set_top_margin(8);
        compose_view.set_bottom_margin(8);
        compose_view.set_left_margin(8);
        compose_view.set_right_margin(8);
        let compose_body = compose_view.buffer();
        let compose_scroll = gtk::ScrolledWindow::new();
        compose_scroll.add_css_class("card");
        compose_scroll.set_vexpand(true);
        compose_scroll.set_child(Some(&compose_view));
        compose.append(&compose_scroll);
        let compose_send_button = button("", "accent");
        let compose_send = adw::ButtonContent::builder()
            .icon_name("mail-send-symbolic")
            .label("Send")
            .build();
        compose_send_button.set_child(Some(&compose_send));
        let compose_cancel = button("Cancel", "quiet");
        let compose_actions = gtk::Box::new(Orientation::Horizontal, 6);
        compose_actions.set_halign(Align::End);
        compose_actions.append(&compose_cancel);
        compose_actions.append(&compose_send_button);
        compose.append(&compose_actions);
        stack.add_named(&compose, Some("compose"));

        // settings: the preferences page every GNOME app shows, one group
        // per concern, so scrolling, width and margins come for free.
        let settings = adw::PreferencesPage::new();

        let identity_group = adw::PreferencesGroup::builder().title("Identity").build();
        let identity_actions = gtk::Box::new(Orientation::Horizontal, 6);
        let rotate_button = icon_label_button("view-refresh-symbolic", "Rotate", "");
        let learn_button = button("Learn key", "");
        identity_actions.append(&learn_button);
        identity_actions.append(&rotate_button);
        identity_group.set_header_suffix(Some(&identity_actions));
        let mut identity_values = Vec::new();
        for title in ["Address", "Key", "Fingerprint", "Rotations"] {
            let row = adw::ActionRow::builder().title(title).build();
            let value = label("", "mono dim");
            value.set_selectable(true);
            value.set_ellipsize(gtk::pango::EllipsizeMode::End);
            value.set_max_width_chars(48);
            value.set_valign(Align::Center);
            row.add_suffix(&value);
            identity_group.add(&row);
            identity_values.push(value);
        }
        settings.add(&identity_group);

        // The pin offer is a group that appears in place rather than a
        // dialog: pinning is a decision about this host, taken next to the
        // identity it belongs to.
        let offer_group = adw::PreferencesGroup::builder()
            .title("Server key offered")
            .visible(false)
            .build();
        let offer_row = adw::ActionRow::builder().title("").build();
        offer_row.add_css_class("monospace");
        offer_row.set_subtitle_lines(2);
        let offer_pin = button("Pin", "accent");
        offer_pin.set_valign(Align::Center);
        let offer_discard = button("Discard", "");
        offer_discard.set_valign(Align::Center);
        offer_row.add_suffix(&offer_discard);
        offer_row.add_suffix(&offer_pin);
        offer_group.add(&offer_row);
        settings.add(&offer_group);

        let pins_group = adw::PreferencesGroup::builder()
            .title("Server keys")
            .build();
        settings.add(&pins_group);

        let network_group = adw::PreferencesGroup::builder().title("Network").build();
        let timeout_row = adw::SpinRow::with_range(1.0, 600.0, 1.0);
        timeout_row.set_title("Timeout");
        timeout_row.set_subtitle("Seconds before a network call gives up");
        network_group.add(&timeout_row);
        settings.add(&network_group);

        let backup_group = adw::PreferencesGroup::builder()
            .title("Backup")
            .description(
                "Sealed to a key derived from the seed, so it restores only where this\n                 identity already lives. The seed itself is never in the file.",
            )
            .build();
        let backup_actions = gtk::Box::new(Orientation::Horizontal, 6);
        let export_button = icon_label_button("document-save-symbolic", "Export", "");
        let copy_export = icon_button("edit-copy-symbolic", "Copy the backup");
        backup_actions.append(&copy_export);
        backup_actions.append(&export_button);
        backup_group.set_header_suffix(Some(&backup_actions));
        let backup_label = label("", "mono caption");
        backup_label.set_wrap(true);
        backup_label.set_wrap_mode(gtk::pango::WrapMode::Char);
        backup_label.set_selectable(true);
        let backup_scroll = gtk::ScrolledWindow::new();
        backup_scroll.add_css_class("card");
        backup_scroll.set_height_request(72);
        backup_scroll.set_child(Some(&backup_label));
        backup_group.add(&backup_scroll);
        settings.add(&backup_group);

        let import_group = adw::PreferencesGroup::builder()
            .title("Restore")
            .description("Paste a gsmol backup to restore the contacts, pins and mail it carries.")
            .build();
        let import_view = gtk::TextView::new();
        import_view.set_wrap_mode(WrapMode::WordChar);
        import_view.set_top_margin(8);
        import_view.set_bottom_margin(8);
        import_view.set_left_margin(8);
        import_view.set_right_margin(8);
        import_view.add_css_class("monospace");
        let import_body = import_view.buffer();
        let import_scroll = gtk::ScrolledWindow::new();
        import_scroll.add_css_class("card");
        import_scroll.set_height_request(96);
        import_scroll.set_child(Some(&import_view));
        import_group.add(&import_scroll);
        let import_backup = icon_label_button("document-open-symbolic", "Restore", "");
        import_backup.set_halign(Align::End);
        import_backup.set_margin_top(6);
        import_group.add(&import_backup);
        settings.add(&import_group);

        stack.add_named(&settings, Some("settings"));

        // onboarding: three static modes, each a centred column
        let center = |child: &gtk::Box| {
            let outer = gtk::Box::new(Orientation::Vertical, 0);
            outer.set_hexpand(true);
            outer.set_vexpand(true);
            child.set_halign(Align::Center);
            child.set_valign(Align::Center);
            child.set_width_request(520);
            outer.append(child);
            outer
        };

        let onboard_start = gtk::Box::new(Orientation::Vertical, 12);
        let title = label("carrier", "title");
        title.set_halign(Align::Center);
        onboard_start.append(&title);
        let tagline = label("smolmail: one seed, sealed mail, five operations", "dim");
        tagline.set_halign(Align::Center);
        tagline.set_margin_bottom(12);
        onboard_start.append(&tagline);
        let create_button = button("Create an identity", "pill");
        let restore_button = button("Restore from a seed", "pill-quiet");
        onboard_start.append(&create_button);
        onboard_start.append(&restore_button);
        stack.add_named(&center(&onboard_start), Some("onboard"));

        let onboard_created = gtk::Box::new(Orientation::Vertical, 12);
        let created_title = label("Write this seed down", "subtitle");
        onboard_created.append(&created_title);
        onboard_created.append(&label(
            "It is the only secret, and it is shown once.",
            "dim",
        ));
        let onboard_seed_label = label("", "mono subtitle");
        onboard_seed_label.set_selectable(true);
        onboard_seed_label.set_wrap(true);
        onboard_seed_label.set_wrap_mode(gtk::pango::WrapMode::Char);
        onboard_seed_label.set_hexpand(true);
        onboard_seed_label.set_margin_top(12);
        onboard_seed_label.set_margin_bottom(12);
        onboard_seed_label.set_margin_start(12);
        onboard_seed_label.set_margin_end(12);
        let seed_card = gtk::Box::new(Orientation::Horizontal, 0);
        seed_card.add_css_class("card");
        seed_card.append(&onboard_seed_label);
        onboard_created.append(&seed_card);
        let saved_button = button("I saved it", "pill");
        let created_back = button("Back", "pill-quiet");
        onboard_created.append(&saved_button);
        onboard_created.append(&created_back);
        stack.add_named(&center(&onboard_created), Some("onboard-created"));

        let onboard_restore = gtk::Box::new(Orientation::Vertical, 12);
        onboard_restore.append(&label("Restore from a seed", "subtitle"));
        let restore_list = boxed_list();
        let onboard_seed_entry = adw::EntryRow::builder()
            .title("Seed — 32 bytes, base32 or hex")
            .build();
        restore_list.append(&onboard_seed_entry);
        onboard_restore.append(&restore_list);
        let restore_go = button("Restore", "pill");
        let restore_back = button("Back", "pill-quiet");
        onboard_restore.append(&restore_go);
        onboard_restore.append(&restore_back);
        stack.add_named(&center(&onboard_restore), Some("onboard-restore"));

        // signup
        let signup = gtk::Box::new(Orientation::Vertical, 12);
        signup.append(&label("Set up the address", "subtitle"));
        let signup_group = adw::PreferencesGroup::builder()
            .description(
                "The invite token and server key are only needed when the operator published them.",
            )
            .build();
        let signup_user = adw::EntryRow::builder().title("User").build();
        let signup_host = adw::EntryRow::builder().title("Host").build();
        let signup_invite = adw::EntryRow::builder().title("Invite token").build();
        let signup_key = adw::EntryRow::builder().title("Server key").build();
        for row in [&signup_user, &signup_host, &signup_invite, &signup_key] {
            signup_group.add(row);
        }
        signup.append(&signup_group);
        let signup_learn = button("Learn the server key and pin what it presents", "");
        signup.append(&signup_learn);
        let signup_offer_list = boxed_list();
        signup_offer_list.set_visible(false);
        let signup_offer_row = adw::ActionRow::builder()
            .title("Server key offered")
            .build();
        signup_offer_row.set_subtitle_lines(2);
        let signup_offer_pin = button("Pin", "accent");
        signup_offer_pin.set_valign(Align::Center);
        let signup_offer_discard = button("Discard", "");
        signup_offer_discard.set_valign(Align::Center);
        signup_offer_row.add_suffix(&signup_offer_discard);
        signup_offer_row.add_suffix(&signup_offer_pin);
        signup_offer_list.append(&signup_offer_row);
        signup.append(&signup_offer_list);
        let register_button = button("Register", "pill");
        let recall_button = button("I already have this address", "pill-quiet");
        signup.append(&register_button);
        signup.append(&recall_button);
        let signup_back = button("Back", "quiet");
        signup_back.set_visible(false);
        signup.append(&signup_back);
        stack.add_named(&center(&signup), Some("signup"));

        // --- status bar -------------------------------------------------
        // One fixed line at the bottom: the spinner and the running
        // operation while something is busy, the last finished note
        // afterwards — no transient chrome, nothing moving.
        let status_bar = gtk::Box::new(Orientation::Horizontal, 10);
        status_bar.add_css_class("toolbar");
        let spinner = gtk::Spinner::new();
        spinner.set_visible(false);
        let status_label = label("", "caption");
        status_label.set_hexpand(true);
        let cancel_button = button("Cancel", "");
        cancel_button.set_visible(false);
        status_bar.append(&spinner);
        status_bar.append(&status_label);
        status_bar.append(&cancel_button);

        let toolbar = adw::ToolbarView::new();
        toolbar.set_content(Some(&stack));
        toolbar.add_bottom_bar(&status_bar);

        // The columns split is a paned too: the divider between sidebar
        // and main box drags, extra space goes to the main box.
        let columns = gtk::Paned::new(Orientation::Horizontal);
        columns.set_start_child(Some(&sidebar));
        columns.set_end_child(Some(&toolbar));
        columns.set_resize_start_child(false);
        columns.set_position(1);
        // The sidebar opens as wide as the top-left pane is tall — a
        // value only the first layout knows, so the divider moves once
        // measurement lands.
        let list_default = list_stack.clone();
        let columns_default = columns.clone();
        gtk::glib::timeout_add_local(Duration::from_millis(50), move || {
            let height = list_default.height();
            if height == 0 {
                gtk::glib::ControlFlow::Continue
            } else {
                columns_default.set_position(height);
                gtk::glib::ControlFlow::Break
            }
        });
        // A window resize (fullscreen, maximize, tiling) makes the paned
        // re-derive its dividers, and the position sync between the two
        // columns then feeds those transient values to each other. Every
        // height change re-asserts the default layout: the top panes back
        // at their smallest, the sidebar back at the top pane's height.
        let watch_root = root.clone();
        let watch_paned = paned.clone();
        let watch_sidebar = sidebar.clone();
        let watch_list = list_stack.clone();
        let watch_columns = columns.clone();
        let last_height = std::cell::Cell::new(0);
        gtk::glib::timeout_add_local(Duration::from_millis(250), move || {
            let height = watch_root.height();
            let was = last_height.replace(height);
            if was != 0 && was != height {
                watch_paned.set_position(1);
                watch_sidebar.set_position(1);
                let relist = watch_list.clone();
                let recolumns = watch_columns.clone();
                gtk::glib::timeout_add_local(Duration::from_millis(200), move || {
                    let measured = relist.height();
                    if measured > 0 {
                        recolumns.set_position(measured);
                    }
                    gtk::glib::ControlFlow::Break
                });
            }
            gtk::glib::ControlFlow::Continue
        });
        root.set_child(Some(&columns));

        // --- signal wiring ---------------------------------------------
        // Both sidebar lists route through row-activated, which fires only
        // on a click or Enter: the programmatic `select_row` in `render`
        // would otherwise feed its own selection straight back as input.
        let folder_sender = sender.clone();
        folders.connect_row_activated(move |_, row| {
            let folder = match row.index() {
                0 => Folder::Inbox,
                1 => Folder::Requests,
                2 => Folder::Sent,
                3 => Folder::Drafts,
                _ => return,
            };
            folder_sender.input(Message::GotoMail(folder));
        });
        let settings_sender = sender.clone();
        settings_nav.connect_row_activated(move |_, _| {
            settings_sender.input(Message::Goto(Page::Settings));
        });
        fetch_button.connect_clicked(input(Message::FetchPressed));
        list_empty_fetch.connect_clicked(input(Message::FetchPressed));
        write_button.connect_clicked(input(Message::ComposePressed));
        cancel_button.connect_clicked(input(Message::FetchCancelled));

        // The mail and contact lists carry their target in the row's
        // widget name, which row-activated reads back.
        let mail_sender = sender.clone();
        mail_list.connect_row_activated(move |_, row| {
            if let Some((folder, id)) = row.widget_name().split_once('|') {
                let folder = match folder {
                    "0" => Folder::Inbox,
                    "1" => Folder::Requests,
                    "2" => Folder::Sent,
                    "3" => Folder::Drafts,
                    _ => return,
                };
                mail_sender.input(Message::MessageSelected(folder, id.to_string()));
            }
        });
        let contact_sender = sender.clone();
        contacts_list.connect_row_activated(move |_, row| {
            contact_sender.input(Message::ContactSelected(row.widget_name().to_string()));
        });

        let meta_link = sender.clone();
        article_meta.connect_activate_link(move |_, uri| {
            meta_link.input(Message::ContactSelected(uri.to_string()));
            gtk::glib::Propagation::Stop
        });

        add_header.connect_clicked(input(Message::ComposeHeaderAdded));

        compose_send_button.connect_clicked(input(Message::SendPressed));
        compose_cancel.connect_clicked(input(Message::ComposeClosed));
        let to_sender = sender.clone();
        compose_to.connect_changed(move |entry| {
            to_sender.input(Message::ComposeToChanged(entry.text().to_string()))
        });
        let subject_sender = sender.clone();
        compose_subject.connect_changed(move |entry| {
            subject_sender.input(Message::ComposeSubjectChanged(entry.text().to_string()))
        });
        let body_sender = sender.clone();
        compose_body.connect_changed(move |buffer| {
            body_sender.input(Message::ComposeBodyChanged(buffer_text(buffer)))
        });

        own_row.connect_clicked(input(Message::OwnSelected));
        copy_export.connect_clicked(input(Message::CopyExport));
        import_button.connect_clicked(input(Message::ContactImportPressed));
        let import_sender = sender.clone();
        contact_import.connect_changed(move |entry| {
            import_sender.input(Message::ContactImportChanged(entry.text().to_string()))
        });
        let import_entry_sender = sender.clone();
        contact_import.connect_entry_activated(move |_| {
            import_entry_sender.input(Message::ContactImportPressed)
        });

        rotate_button.connect_clicked(input(Message::RotatePressed));
        learn_button.connect_clicked(input(Message::SettingsLearnKey));
        offer_pin.connect_clicked(input(Message::PinAccept));
        signup_offer_pin.connect_clicked(input(Message::PinAccept));
        offer_discard.connect_clicked(input(Message::PinDiscard));
        signup_offer_discard.connect_clicked(input(Message::PinDiscard));
        export_button.connect_clicked(input(Message::ExportPressed));
        import_backup.connect_clicked(input(Message::ImportPressed));
        let timeout_sender = sender.clone();
        timeout_row.connect_value_notify(move |row| {
            timeout_sender.input(Message::TimeoutChanged((row.value() as u64).to_string()))
        });
        let import_body_sender = sender.clone();
        import_body.connect_changed(move |buffer| {
            import_body_sender.input(Message::ImportBodyChanged(buffer_text(buffer)))
        });

        create_button.connect_clicked(input(Message::OnboardCreate));
        restore_button.connect_clicked(input(Message::OnboardRestore));
        restore_back.connect_clicked(input(Message::OnboardBack));
        created_back.connect_clicked(input(Message::OnboardBack));
        saved_button.connect_clicked(input(Message::OnboardSeedSaved));
        let seed_sender = sender.clone();
        onboard_seed_entry.connect_changed(move |entry| {
            seed_sender.input(Message::OnboardSeedChanged(entry.text().to_string()))
        });
        let seed_go_sender = sender.clone();
        onboard_seed_entry.connect_entry_activated(move |_| {
            seed_go_sender.input(Message::OnboardRestoreFromSeed)
        });
        restore_go.connect_clicked(input(Message::OnboardRestoreFromSeed));

        let user_sender = sender.clone();
        signup_user.connect_changed(move |entry| {
            user_sender.input(Message::SignupUserChanged(entry.text().to_string()))
        });
        let host_sender = sender.clone();
        signup_host.connect_changed(move |entry| {
            host_sender.input(Message::SignupHostChanged(entry.text().to_string()))
        });
        let invite_sender = sender.clone();
        signup_invite.connect_changed(move |entry| {
            invite_sender.input(Message::SignupInviteChanged(entry.text().to_string()))
        });
        let key_sender = sender.clone();
        signup_key.connect_changed(move |entry| {
            key_sender.input(Message::SignupKeyChanged(entry.text().to_string()))
        });
        signup_learn.connect_clicked(input(Message::SignupLearnKey));
        register_button.connect_clicked(input(Message::SignupRegister));
        recall_button.connect_clicked(input(Message::SignupRecall));
        signup_back.connect_clicked(input(Message::SignupBack));

        CarrierWidgets {
            window: root.clone(),
            window_title,
            folders,
            folder_counts,
            drafts_nav,
            settings_nav,
            fetch_button,
            write_button,
            stack,
            list_stack,
            mail_list,
            list_empty,
            list_empty_fetch,
            article_stack,
            article_subject,
            article_meta,
            article_headers,
            article_view,
            article_body,
            actions,
            compose_to,
            compose_headers,
            compose_subject,
            compose_body,
            compose_send,
            sidebar_own,
            sidebar_contacts: contacts_list,
            detail_share,
            detail_copy,
            detail_qr,
            identity_values,
            offer_group,
            offer_row,
            pins_group,
            pin_rows: Vec::new(),
            timeout_row,
            backup_label,
            onboard_seed_label,
            signup_back,
            signup_offer_list,
            signup_offer_row,
            spinner,
            status_label,
            cancel_button,
            dialog: None,
        }
    }
}

impl Component for Carrier {
    type CommandOutput = OpResult;
    type Input = Message;
    type Output = ();
    type Init = std::path::PathBuf;
    type Root = gtk::Window;
    type Widgets = CarrierWidgets;

    fn init_root() -> Self::Root {
        let window = gtk::Window::new();
        window.set_title(Some("carrier"));
        window.set_default_size(1080, 640);
        window
    }

    fn init(
        init: Self::Init,
        root: Self::Root,
        sender: ComponentSender<Self>,
    ) -> ComponentParts<Self> {
        let (model, op) = Carrier::boot(init);
        let widgets = CarrierWidgets::new(&root, &sender);
        if let Some(op) = op {
            spawn_op(&model, op, &sender);
        }
        ComponentParts { model, widgets }
    }

    fn update(&mut self, message: Self::Input, sender: ComponentSender<Self>, _root: &Self::Root) {
        for op in self.handle(message) {
            spawn_op(self, op, &sender);
        }
    }

    fn update_cmd(
        &mut self,
        message: Self::CommandOutput,
        sender: ComponentSender<Self>,
        _root: &Self::Root,
    ) {
        if let Some(op) = self.handle_result(message) {
            spawn_op(self, op, &sender);
        }
    }

    fn update_view(&self, widgets: &mut Self::Widgets, sender: ComponentSender<Self>) {
        render(self, widgets, &sender);
    }
}

/// Runs one `PendingOp` on the blocking pool and reports back. The fetch
/// also gets a ticker: a thread that re-lists the store every 250 ms until
/// the model raises the cancel flag, giving the list live progress.
fn spawn_op(model: &Carrier, op: PendingOp, sender: &ComponentSender<Carrier>) {
    let store = model.store.clone();
    let master = model.master.unwrap_or([0u8; KEY_LEN]);
    let timeout = model.timeout;
    match op {
        PendingOp::Snapshot { read } => sender.spawn_command(move |out| {
            let _ = out.send(OpResult::SnapshotLoaded(ops::snapshot(
                &store, &master, &read,
            )));
        }),
        PendingOp::Register { addr, invite, key } => sender.spawn_command(move |out| {
            let res = if key.is_empty() {
                ops::register(&store, &master, &addr, invite.as_deref(), timeout)
            } else {
                ops::parse_key(&key).and_then(|key| {
                    ops::pin(&store, &addr, &key)?;
                    ops::register(&store, &master, &addr, invite.as_deref(), timeout)
                })
            };
            let _ = out.send(OpResult::Generic(res.map(|_| "registered".to_string())));
        }),
        PendingOp::Restore { addr } => sender.spawn_command(move |out| {
            let res = ops::restore(&store, &master, &addr, timeout)
                .map(|index| format!("restored at rotation {index}"));
            let _ = out.send(OpResult::Generic(res));
        }),
        PendingOp::LearnKey { addr } => sender.spawn_command(move |out| {
            let offered =
                ops::learn_key(&store, &addr, 30).map(|key| key.map(|key| (addr.clone(), key)));
            let _ = out.send(OpResult::PinOffered(offered));
        }),
        PendingOp::Pin { addr, key } => sender.spawn_command(move |out| {
            let _ = out.send(OpResult::Pinned(ops::pin(&store, &addr, &key)));
        }),
        PendingOp::Fetch { cancel } => {
            let ticker_cancel = cancel.clone();
            let input = sender.input_sender().clone();
            std::thread::spawn(move || {
                while !ticker_cancel.load(Ordering::Relaxed) {
                    std::thread::sleep(Duration::from_millis(250));
                    if ticker_cancel.load(Ordering::Relaxed) {
                        break;
                    }
                    let _ = input.send(Message::FetchTick);
                }
            });
            sender.spawn_command(move |out| {
                let _ = out.send(OpResult::Generic(ops::fetch(
                    &store, &master, cancel, timeout,
                )));
            });
        }
        PendingOp::Send {
            to,
            subject,
            body,
            reply_to,
            headers,
        } => sender.spawn_command(move |out| {
            let res = ops::send(
                &store,
                &master,
                &to,
                if subject.is_empty() {
                    None
                } else {
                    Some(subject.as_str())
                },
                &body,
                reply_to.as_deref(),
                &headers,
                timeout,
            );
            let _ = out.send(OpResult::Generic(res));
        }),
        PendingOp::Delete {
            id,
            folder,
            everywhere,
        } => sender.spawn_command(move |out| {
            let res = ops::delete(&store, &master, &id, folder, everywhere, timeout)
                .map(|_| "deleted".to_string());
            let _ = out.send(OpResult::Generic(res));
        }),
        PendingOp::Accept { address, identity } => sender.spawn_command(move |out| {
            let res = ops::accept_contact(&store, &master, &address, &identity, timeout)
                .map(|_| format!("accepted {address}"));
            let _ = out.send(OpResult::Generic(res));
        }),
        PendingOp::Block { address } => sender.spawn_command(move |out| {
            let res = ops::block_contact(&store, &master, &address, timeout).map(|blocked| {
                if blocked {
                    format!("blocked {address}")
                } else {
                    format!("{address} was not blocked")
                }
            });
            let _ = out.send(OpResult::Generic(res));
        }),
        PendingOp::ImportContact { uri } => sender.spawn_command(move |out| {
            let res = ops::import_contact(&store, &uri)
                .map(|(address, _)| format!("imported {address} (verified)"));
            let _ = out.send(OpResult::Generic(res));
        }),
        PendingOp::Rotate => sender.spawn_command(move |out| {
            let res = ops::rotate(&store, &master, timeout)
                .map(|(index, key)| format!("rotated to index {index}; new key {}…", &key[..12]));
            let _ = out.send(OpResult::Generic(res));
        }),
        PendingOp::Unpin { label } => sender.spawn_command(move |out| {
            let res = ops::unpin(&store, &label).map(|_| format!("unpinned {label}"));
            let _ = out.send(OpResult::Generic(res));
        }),
        PendingOp::Export { dir } => sender.spawn_command(move |out| {
            let exported = ops::export_backup(&store, &master, &dir)
                .map(|(path, text)| (format!("backup written to {}", path.display()), text));
            let _ = out.send(OpResult::Exported(exported));
        }),
        PendingOp::ImportBackup { text } => sender.spawn_command(move |out| {
            let _ = out.send(OpResult::Generic(ops::import_backup(
                &store, &master, &text,
            )));
        }),
    }
}
/// The coarse re-render: called after every input and result. Plain state
/// reads map onto widget updates; lists are rebuilt from scratch, which
/// a modest mailbox makes the honest option.
fn render(model: &Carrier, w: &mut CarrierWidgets, sender: &ComponentSender<Carrier>) {
    let input = |msg: Message| {
        let sender = sender.clone();
        move |_: &gtk::Button| sender.input(msg.clone())
    };

    // Prefill entries once after a reply, write or draft reopen;
    // afterwards typing flows entry -> model only, so the view never
    // fights the user. The fresh flag also rebuilds the header rows,
    // which otherwise sync on count changes alone.
    let mut compose_fresh = false;
    if model.compose_fresh.take() {
        compose_fresh = true;
        if let Some(compose) = &model.compose {
            w.compose_to.set_text(&compose.to);
            w.compose_subject.set_text(&compose.subject);
            w.compose_body.set_text(&compose.body);
        }
    }
    let rows = model.compose.as_ref().map_or(0, |c| c.headers.len());
    let mut current = 0;
    let mut child = w.compose_headers.first_child();
    while let Some(item) = child {
        current += 1;
        child = item.next_sibling();
    }
    if compose_fresh || current != rows {
        let added = rows > current;
        clear_list(&w.compose_headers);
        if let Some(compose) = &model.compose {
            let mut last_entry = None;
            for (index, text) in compose.headers.iter().enumerate() {
                let (row, entry) = compose_header_row(index, text, sender);
                last_entry = Some(entry);
                w.compose_headers.append(&row);
            }
            // A freshly appended row is the one being typed into.
            if added {
                if let Some(entry) = last_entry {
                    entry.grab_focus();
                }
            }
        }
    }

    // Header and sidebar identity.
    let address = model
        .snapshot
        .as_ref()
        .map(|s| s.who.address.clone())
        .unwrap_or_default();
    w.window_title.set_subtitle(&address);
    w.sidebar_own.set_text(&address);

    // Sidebar destinations: the active one carries the list selection, and
    // the list that does not own the current page clears its own.
    let unread = |folder: usize| {
        model
            .lists
            .get(folder)
            .map(|rows| rows.iter().filter(|r| r.unread).count())
            .unwrap_or(0)
    };
    let draft_count = model.drafts.len();
    w.drafts_nav.set_visible(draft_count > 0);
    for (count, value) in w
        .folder_counts
        .iter()
        .zip([unread(0), unread(1), 0, draft_count])
    {
        count.set_text(&value.to_string());
        count.set_visible(value > 0);
    }
    if model.page == Page::Mail {
        w.folders
            .select_row(w.folders.row_at_index(model.folder as i32).as_ref());
        w.settings_nav.unselect_all();
    } else if model.page == Page::Settings {
        w.folders.unselect_all();
        w.settings_nav
            .select_row(w.settings_nav.row_at_index(0).as_ref());
    } else {
        w.folders.unselect_all();
        w.settings_nav.unselect_all();
    }
    let fetching = model.busy.as_deref() == Some("fetching");
    w.fetch_button.set_sensitive(model.busy.is_none());
    w.write_button.set_sensitive(model.busy.is_none());

    // Page stack.
    let page = if model.compose.is_some() {
        "compose"
    } else {
        match model.page {
            Page::Onboard => match model.onboard.mode {
                OnboardMode::Start => "onboard",
                OnboardMode::Created => "onboard-created",
                OnboardMode::Restore => "onboard-restore",
            },
            Page::Signup => "signup",
            Page::Mail => "mail",
            Page::Settings => "settings",
        }
    };
    w.stack.set_visible_child_name(page);

    // Mail list.
    clear_list(&w.mail_list);
    let rows = model.rows();
    let (icon, title, description) = match model.folder {
        Folder::Inbox => (
            "mail-read-symbolic",
            "Inbox is empty",
            "Fetch to check the mailbox.",
        ),
        Folder::Requests => (
            "contact-new-symbolic",
            "No requests",
            "Mail from senders you have not accepted yet arrives here.",
        ),
        Folder::Sent => (
            "mail-send-symbolic",
            "Nothing sent yet",
            "Messages you send keep a sealed copy here.",
        ),
        Folder::Drafts => (
            "document-edit-symbolic",
            "No drafts",
            "A compose closed from the sidebar is kept here.",
        ),
    };
    w.list_empty.set_icon_name(Some(icon));
    w.list_empty.set_title(title);
    w.list_empty.set_description(Some(description));
    w.list_empty_fetch
        .set_visible(model.folder == Folder::Inbox);
    w.list_stack
        .set_visible_child_name(if rows.is_empty() { "empty" } else { "list" });
    let mut selected_row = None;
    for row in &rows {
        let item = mail_row(model.folder, row);
        let is_selected = model
            .open
            .as_ref()
            .is_some_and(|(folder, msg)| *folder == model.folder && msg.id == row.id);
        if is_selected {
            selected_row = Some(item.clone());
        }
        w.mail_list.append(&item);
    }
    w.mail_list.select_row(
        selected_row
            .as_ref()
            .map(|row| row.upcast_ref::<gtk::ListBoxRow>()),
    );

    // Article.
    let own_detail = model
        .selected_own
        .then(|| model.snapshot.as_ref().map(|s| &s.who))
        .flatten();
    let contact_detail = model.selected_contact.as_ref().and_then(|address| {
        model
            .snapshot
            .as_ref()?
            .contacts
            .iter()
            .find(|c| &c.address == address)
    });
    // The detail selections show over an open message, but the message
    // stays selected underneath: its list highlight holds, and picking
    // it again returns to it.
    match (&model.open, own_detail, contact_detail) {
        (_, Some(own), _) => {
            w.article_stack.set_visible_child_name("detail");
            w.article_view.add_css_class("monospace");
            w.article_subject.set_text(&own.address);
            w.article_meta
                .set_text(&format!("you · rotation {}", own.rotations));
            w.article_body
                .set_text(&detail_body(&own.address, &own.key, &own.fingerprint));
            set_qr(&w.detail_qr, &format!("smol://{}/{}", own.address, own.key));
            w.detail_share.set_visible(true);
            w.detail_copy.set_visible(true);
            clear(&w.actions);
        }
        (_, _, Some(contact)) => {
            w.article_stack.set_visible_child_name("detail");
            w.article_view.add_css_class("monospace");
            w.article_subject.set_text(&contact.address);
            w.article_meta.set_text(contact_state(contact));
            w.article_body.set_text(&detail_body(
                &contact.address,
                &contact.key,
                &contact.fingerprint,
            ));
            set_qr(
                &w.detail_qr,
                &format!("smol://{}/{}", contact.address, contact.key),
            );
            w.detail_share.set_visible(true);
            w.detail_copy.set_visible(true);

            clear(&w.actions);
            let write = icon_label_button("mail-message-new-symbolic", "Write", "");
            let write_msg = Message::ContactWrite(contact.address.clone());
            let write_sender = sender.clone();
            write.connect_clicked(move |_| write_sender.input(write_msg.clone()));
            w.actions.append(&write);
            let spacer = gtk::Label::new(None);
            spacer.set_hexpand(true);
            w.actions.append(&spacer);
            match contact.accepted {
                Some(true) => {
                    let block = icon_label_button("action-unavailable-symbolic", "Block", "danger");
                    let msg = Message::ContactBlock(contact.address.clone());
                    let block_sender = sender.clone();
                    block.connect_clicked(move |_| block_sender.input(msg.clone()));
                    w.actions.append(&block);
                }
                Some(false) => {
                    let unblock = icon_label_button("object-select-symbolic", "Unblock", "accent");
                    let msg = Message::ContactUnblock(contact.address.clone());
                    let unblock_sender = sender.clone();
                    unblock.connect_clicked(move |_| unblock_sender.input(msg.clone()));
                    w.actions.append(&unblock);
                }
                None => {
                    let accept = icon_label_button("object-select-symbolic", "Accept", "accent");
                    let msg = Message::ContactAccept(contact.address.clone(), contact.key.clone());
                    let accept_sender = sender.clone();
                    accept.connect_clicked(move |_| accept_sender.input(msg.clone()));
                    w.actions.append(&accept);
                }
            }
        }
        (Some((folder, msg)), _, _) => {
            w.article_stack.set_visible_child_name("detail");
            w.detail_share.set_visible(false);
            w.detail_copy.set_visible(false);
            // A message body is prose; only the detail below is a
            // column of keys that has to stay aligned.
            w.article_view.remove_css_class("monospace");
            let subject = if msg.subject.is_empty() {
                "(no subject)".to_string()
            } else {
                msg.subject.clone()
            };
            w.article_subject.set_text(&subject);
            let label = if *folder == Folder::Sent {
                "to"
            } else {
                "from"
            };
            // The address opens the sender's contact details when they
            // are a contact; an unknown or keyless sender stays text.
            let known = model
                .snapshot
                .as_ref()
                .is_some_and(|snap| snap.contacts.iter().any(|c| c.address == msg.from));
            let address = escape(&msg.from);
            let mut meta = if known {
                format!("{label} <a href='{address}'>{address}</a>")
            } else {
                format!("{label} {address}")
            };
            meta.push_str(&format!(" · {} UTC", escape(&ops::when(msg.time))));
            meta.push_str(&format!(" · id {}…", &msg.id[..msg.id.len().min(8)]));
            if msg.kept {
                meta.push_str(" · a server copy still exists");
            }
            w.article_meta.set_markup(&meta);
            let headers: Vec<String> = msg
                .headers
                .iter()
                .map(|(key, value)| format!("{key}: {value}"))
                .collect();
            w.article_headers.set_visible(!headers.is_empty());
            w.article_headers.set_text(&headers.join("\n"));
            w.article_body.set_text(&msg.body);

            clear(&w.actions);
            let reply = icon_label_button("mail-reply-sender-symbolic", "Reply", "");
            reply.connect_clicked(input(Message::ReplyPressed));
            w.actions.append(&reply);
            if *folder == Folder::Requests {
                if msg.reply_to.is_some() {
                    let accept = icon_label_button("object-select-symbolic", "Accept", "accent");
                    accept.connect_clicked(input(Message::AcceptPressed));
                    let block = icon_label_button("action-unavailable-symbolic", "Block", "danger");
                    block.connect_clicked(input(Message::BlockPressed));
                    w.actions.append(&accept);
                    w.actions.append(&block);
                } else {
                    w.actions.append(&crate::view::label(
                        "no reply address: cannot accept or block",
                        "caption",
                    ));
                }
            }
            let spacer = gtk::Label::new(None);
            spacer.set_hexpand(true);
            w.actions.append(&spacer);
            let delete = icon_label_button("user-trash-symbolic", "Delete", "danger");
            delete.connect_clicked(input(Message::DeletePressed));
            w.actions.append(&delete);
        }
        (None, None, None) => {
            w.article_stack.set_visible_child_name("empty");
            w.detail_share.set_visible(false);
            w.detail_copy.set_visible(false);
            clear(&w.actions);
        }
    }

    // Compose: a reply says so, on the button and in its icon.
    if let Some(compose) = &model.compose {
        let replying = compose.reply_to.is_some();
        w.compose_send
            .set_label(if replying { "Reply" } else { "Send" });
        w.compose_send.set_icon_name(if replying {
            "mail-reply-sender-symbolic"
        } else {
            "mail-send-symbolic"
        });
    }

    // Contacts: the sidebar's bottom panel lists them; the selected one
    // carries the list's selection so the detail view has a visible anchor.
    clear_list(&w.sidebar_contacts);
    if let Some(snap) = &model.snapshot {
        if snap.contacts.is_empty() {
            let empty = gtk::ListBoxRow::new();
            empty.set_activatable(false);
            let hint = label("no contacts", "caption");
            hint.set_margin_top(6);
            hint.set_margin_bottom(6);
            hint.set_margin_start(12);
            empty.set_child(Some(&hint));
            w.sidebar_contacts.append(&empty);
        }
        let mut selected_contact_row = None;
        for contact in &snap.contacts {
            let item = sidebar_contact_row(contact);
            if model.selected_contact.as_deref() == Some(contact.address.as_str()) {
                selected_contact_row = Some(item.clone());
            }
            w.sidebar_contacts.append(&item);
        }
        w.sidebar_contacts.select_row(
            selected_contact_row
                .as_ref()
                .map(|row| row.upcast_ref::<gtk::ListBoxRow>()),
        );
    }

    // Settings: the identity rows are fixed, so only their values change.
    if let Some(snap) = &model.snapshot {
        let values = [
            snap.who.address.clone(),
            snap.who.key.clone(),
            snap.who.fingerprint.clone(),
            snap.who.rotations.to_string(),
        ];
        for (value, text) in w.identity_values.iter().zip(values) {
            value.set_text(&text);
        }
    }
    if let Some((_, key)) = &model.pin_offer {
        w.offer_row.set_title(&escape(&fingerprint(key)));
        w.offer_row.set_subtitle(&escape(&b32(key)));
        w.offer_group.set_visible(true);
        w.signup_offer_row.set_subtitle(&escape(&fingerprint(key)));
        w.signup_offer_list.set_visible(true);
    } else {
        w.offer_group.set_visible(false);
        w.signup_offer_list.set_visible(false);
    }
    if w.timeout_row.value() as u64 != model.timeout {
        w.timeout_row.set_value(model.timeout as f64);
    }
    for row in std::mem::take(&mut w.pin_rows) {
        w.pins_group.remove(&row);
    }
    if let Some(snap) = &model.snapshot {
        if snap.pins.is_empty() {
            let empty = adw::ActionRow::builder()
                .title("No server keys pinned")
                .build();
            w.pins_group.add(&empty);
            w.pin_rows.push(empty);
        }
        for (pin_label, key) in &snap.pins {
            let row = adw::ActionRow::builder()
                .title(escape(pin_label))
                .subtitle(escape(&b32(key)))
                .build();
            row.set_subtitle_lines(1);
            let unpin = icon_button("user-trash-symbolic", "Unpin this server key");
            unpin.add_css_class("destructive-action");
            unpin.connect_clicked(input(Message::UnpinPressed(pin_label.clone())));
            row.add_suffix(&unpin);
            w.pins_group.add(&row);
            w.pin_rows.push(row);
        }
    }
    let backup_text = model
        .backup_text
        .as_ref()
        .map(|text| text.chars().take(2000).collect::<String>())
        .unwrap_or_default();
    w.backup_label.set_text(&backup_text);

    // Onboarding.
    if model.onboard.mode == OnboardMode::Created {
        w.onboard_seed_label.set_text(&model.onboard.seed_shown);
    }

    // Signup.
    w.signup_back.set_visible(model.signup.fresh);

    // Confirmations are presented once, on the None -> Some edge: `render`
    // runs after every message and an alert dialog is modal, so presenting
    // again would stack a second copy over the first.
    match (&model.dialog, w.dialog.is_some()) {
        (Some(dialog), false) => {
            let rotating = matches!(dialog, Dialog::Rotate);
            let replying = matches!(dialog, Dialog::Reply { .. });
            let alert = match dialog {
                Dialog::Delete { kept, .. } => {
                    let alert = adw::AlertDialog::new(
                        Some("Delete this message?"),
                        Some(if *kept {
                            "Deleting it here leaves the server's copy in place. Deleting it everywhere asks the server to drop that copy too."
                        } else {
                            "The sealed copy in the local store is removed."
                        }),
                    );
                    alert.add_response("cancel", "Cancel");
                    alert.add_response("here", "Delete");
                    alert.set_response_appearance("here", adw::ResponseAppearance::Destructive);
                    if *kept {
                        alert.add_response("everywhere", "Delete Everywhere");
                        alert.set_response_appearance(
                            "everywhere",
                            adw::ResponseAppearance::Destructive,
                        );
                    }
                    alert
                }
                Dialog::Rotate => {
                    let alert = adw::AlertDialog::new(
                        Some("Rotate the identity?"),
                        Some("The old key stays derivable from the seed, but the rotation index never moves back."),
                    );
                    alert.add_response("cancel", "Cancel");
                    alert.add_response("rotate", "Rotate");
                    alert.set_response_appearance("rotate", adw::ResponseAppearance::Destructive);
                    alert
                }
                Dialog::Reply { rows, .. } => {
                    let list = rows
                        .iter()
                        .map(String::as_str)
                        .collect::<Vec<_>>()
                        .join("\n");
                    let alert = adw::AlertDialog::new(
                        Some("Carry the sender's fields into the reply?"),
                        Some(&format!(
                            "This message carries its own frontmatter:\n\n{list}\n\nReply with copies of these fields, or start with none. The fields stay editable either way."
                        )),
                    );
                    alert.add_response("cancel", "Cancel Reply");
                    alert.add_response("without", "Reply Without");
                    alert.add_response("copy", "Copy Fields");
                    alert.set_response_appearance("copy", adw::ResponseAppearance::Suggested);
                    alert
                }
            };
            // The reply dialog carries its own default: Enter answers the
            // question instead of cancelling the reply the user asked for.
            let close_default = if replying { "without" } else { "cancel" };
            alert.set_close_response("cancel");
            alert.set_default_response(Some(close_default));
            let response_sender = sender.clone();
            alert.connect_response(None, move |_, response| {
                response_sender.input(match (rotating, replying, response) {
                    (true, _, "rotate") => Message::RotateConfirmed,
                    (true, _, _) => Message::RotateCancelled,
                    (_, true, "copy") => Message::ReplyConfirmed(true),
                    (_, true, "without") => Message::ReplyConfirmed(false),
                    (_, true, _) => Message::ReplyCancelled,
                    (false, _, "here") => Message::DeleteConfirmed(false),
                    (false, _, "everywhere") => Message::DeleteConfirmed(true),
                    (false, _, _) => Message::DeleteCancelled,
                });
            });
            alert.present(Some(&w.window));
            w.dialog = Some(alert);
        }
        (None, true) => {
            // Drop the handle before closing: `close` emits the close
            // response, which would otherwise arrive as a second cancel
            // and bring us straight back here.
            if let Some(alert) = w.dialog.take() {
                alert.close();
            }
        }
        _ => {}
    }

    // The fixed bottom line: work in progress while something runs, the
    // last note otherwise, errors tinted until the next note replaces them.
    w.spinner.set_visible(model.busy.is_some());
    if model.busy.is_some() {
        w.spinner.start();
    } else {
        w.spinner.stop();
    }
    w.status_label.set_text(&match (&model.busy, fetching) {
        (Some(_), true) => {
            let inbox = model.lists.first().map(|rows| rows.len()).unwrap_or(0);
            format!("fetching… {inbox} in inbox")
        }
        (Some(busy), false) => format!("{busy}…"),
        (None, _) => model.status.clone().unwrap_or_default(),
    });
    let errored = model.status_error && model.busy.is_none();
    if errored {
        w.status_label.add_css_class("error");
    } else {
        w.status_label.remove_css_class("error");
    }
    w.cancel_button.set_visible(fetching);
}

/// One list row, like a note title: the read flag and subject on the left,
/// sender and date muted on the right. An action row supplies the metrics
/// and the selection paint the stylesheet expects of a list.
fn mail_row(folder: Folder, row: &Row) -> adw::ActionRow {
    let item = adw::ActionRow::new();
    item.add_prefix(&gtk::Image::from_icon_name(if row.unread {
        "mail-unread-symbolic"
    } else {
        "mail-read-symbolic"
    }));
    let subject = if row.subject.is_empty() {
        "(no subject)".to_string()
    } else {
        row.subject.clone()
    };
    // Action row titles are markup, so unread weight goes in as a span
    // rather than a class, which would take the suffixes with it.
    item.set_title(&if row.unread {
        format!("<b>{}</b>", escape(&subject))
    } else {
        escape(&subject)
    });
    item.set_title_lines(1);
    if !row.unread {
        item.add_css_class("dim-label");
    }
    let from = label(&truncate(&row.from, 24), "caption");
    from.set_valign(Align::Center);
    let date = label(&ops::when(row.at), "caption numeric");
    date.set_valign(Align::Center);
    item.add_suffix(&from);
    item.add_suffix(&date);
    item.set_activatable(true);
    // The list's row-activated signal routes the click; the row carries
    // its folder and id in the widget name for the handler to read.
    item.set_widget_name(&format!("{}|{}", folder as usize, row.id));
    item
}

/// One compose header row: a `Key: value` entry plus a remove button.
/// The row carries its own validation state — anything the send would
/// reject is tinted and explained right where it is typed, and the
/// empty rows the send skips are left quiet.
fn compose_header_row<'a>(
    index: usize,
    text: &str,
    sender: &ComponentSender<Carrier>,
) -> (gtk::ListBoxRow, gtk::Entry) {
    let entry = gtk::Entry::new();
    entry.set_hexpand(true);
    entry.set_placeholder_text(Some("Key: value"));
    entry.set_text(text);
    let style = |entry: &gtk::Entry, text: &str| match crate::ops::header_row(text) {
        Err(reason) => {
            entry.add_css_class("error");
            entry.set_tooltip_text(Some(&reason));
        }
        Ok(_) => {
            entry.remove_css_class("error");
            entry.set_tooltip_text(None);
        }
    };
    style(&entry, text);
    let change_sender = sender.clone();
    let style_entry = entry.clone();
    entry.connect_changed(move |changed| {
        let text = changed.text().to_string();
        style(&style_entry, &text);
        change_sender.input(Message::ComposeHeaderChanged(index, text));
    });

    let remove = icon_button("user-trash-symbolic", "Remove this header");
    let remove_sender = sender.clone();
    remove.connect_clicked(move |_| {
        remove_sender.input(Message::ComposeHeaderRemoved(index));
    });

    let line = gtk::Box::new(Orientation::Horizontal, 6);
    line.set_margin_top(6);
    line.set_margin_bottom(6);
    line.set_margin_start(12);
    line.set_margin_end(6);
    line.append(&entry);
    line.append(&remove);

    let row = gtk::ListBoxRow::new();
    row.set_child(Some(&line));
    (row, entry)
}

/// One contact in the sidebar's bottom panel: the address over its trust
/// state; activating it opens the detail pane.
fn sidebar_contact_row(contact: &Contact) -> adw::ActionRow {
    let item = adw::ActionRow::builder()
        .title(escape(&contact.address))
        .subtitle(contact_state(contact))
        .activatable(true)
        .build();
    item.set_title_lines(1);
    item.set_subtitle_lines(1);
    item.set_widget_name(&contact.address);
    item
}

/// The detail view's body: the three lines an address is made of, in
/// the column-aligned form a key block wants.
fn detail_body(address: &str, key: &str, fingerprint: &str) -> String {
    format!("key           {key}\nfingerprint   {fingerprint}\nsmol://{address}/{key}")
}

/// Puts one URI's QR code into the detail header's share popover. A
/// GtkImage renders its paintable at the default icon size — a 16px
/// square, centered — unless pixel-size overrides it, and its widget
/// sizes like an icon slot unless a request overrides that. Both are
/// set to the texture's own dimensions, so the code paints 1:1.
fn set_qr(image: &gtk::Image, uri: &str) {
    let Some(texture) = qr_texture(uri) else {
        return;
    };
    let dim = texture.intrinsic_width();
    image.set_size_request(dim, dim);
    image.set_pixel_size(dim);
    image.set_paintable(Some(&texture));
}

/// The QR as an RGBA texture, black on white, taking no cues from the
/// theme. Each module is a whole number of pixels and the four quiet
/// modules the spec asks for are included, so nothing scales the texture
/// and no softening ever lands on an edge. The scale targets ~210px: a
/// popover that does not fit below its anchor is not placed at all.
fn qr_texture(uri: &str) -> Option<gtk::gdk::MemoryTexture> {
    const QUIET: i32 = 4;
    let code = qrcodegen::QrCode::encode_text(uri, qrcodegen::QrCodeEcc::Medium).ok()?;
    let size = code.size();
    let scale = (210 / (size + 2 * QUIET)).clamp(3, 6);
    let dim = (size + 2 * QUIET) * scale;
    let stride = dim as usize * 4;
    let mut pixels = vec![0xffu8; (dim * dim) as usize * 4];
    for y in 0..size {
        for x in 0..size {
            if code.get_module(x, y) {
                for dy in 0..scale {
                    for dx in 0..scale {
                        let px = (x + QUIET) * scale + dx;
                        let py = (y + QUIET) * scale + dy;
                        let i = (py * dim + px) as usize * 4;
                        pixels[i] = 0;
                        pixels[i + 1] = 0;
                        pixels[i + 2] = 0;
                    }
                }
            }
        }
    }
    Some(gtk::gdk::MemoryTexture::new(
        dim,
        dim,
        gtk::gdk::MemoryFormat::R8g8b8a8,
        &gtk::glib::Bytes::from_owned(pixels),
        stride,
    ))
}