//! The view: a compact horizontal split — a tab bar, the full-width list
//! above, the article below, and a status line at the bottom edge. Protocol
//! values (addresses, keys, ids, dates) are monospace; prose stays sans.

use iced::widget::text::Wrapping;
use iced::widget::{
    button, column, container, qr_code, row, rule, scrollable, text, text_editor, text_input, Space,
};
use iced::{Alignment, Element, Font, Length, Padding};

use fumi_core::crypto::{b32, fingerprint};

use crate::app::{Carrier, Dialog, Message, OnboardMode, Page};
use crate::ops::{self, Contact, Folder, Row};
use crate::theme::{self, ACCENT, MUTED, TEXT};

/// Column widths of the list, in pixels; monospace keeps them aligned.
const DATE_W: f32 = 104.0;
const FLAG_W: f32 = 24.0;
const FROM_W: f32 = 248.0;
const ADDR_W: f32 = 260.0;
const KEY_W: f32 = 248.0;
const STATE_W: f32 = 88.0;

pub fn view(app: &Carrier) -> Element<'_, Message> {
    let content: Element<'_, Message> = if app.compose.is_some() {
        compose(app)
    } else {
        match app.page {
            Page::Onboard => onboard(app),
            Page::Signup => signup(app),
            Page::Mail => mail(app),
            Page::Contacts => contacts(app),
            Page::Settings => settings(app),
        }
    };
    column![content, dialog_banner(app), status(app)]
        .spacing(0)
        .height(Length::Fill)
        .width(Length::Fill)
        .into()
}

// --- shared pieces ---------------------------------------------------------

/// One line of monospace UI text.
fn mono<'a>(content: impl std::fmt::Display) -> iced::widget::Text<'a> {
    text(content.to_string())
        .font(Font::MONOSPACE)
        .size(12)
        .color(TEXT)
}

fn muted<'a>(content: impl std::fmt::Display) -> iced::widget::Text<'a> {
    text(content.to_string())
        .font(Font::MONOSPACE)
        .size(12)
        .color(MUTED)
}

fn accent<'a>(content: impl std::fmt::Display) -> iced::widget::Text<'a> {
    text(content.to_string())
        .font(Font::MONOSPACE)
        .size(12)
        .color(ACCENT)
}

/// A fixed-width cell so every row lines up like a table column.
fn cell<'a>(content: iced::widget::Text<'a>, width: f32) -> Element<'a, Message> {
    container(content)
        .width(width)
        .align_x(Alignment::Start)
        .into()
}

fn action<'a>(label: &str, msg: Message) -> Element<'a, Message> {
    button(text(label.to_string()).size(12))
        .on_press(msg)
        .style(theme::accent())
        .padding([3, 10])
        .into()
}

fn action_disabled<'a>(label: &str) -> Element<'a, Message> {
    button(text(label.to_string()).size(12))
        .padding([3, 10])
        .style(theme::quiet())
        .into()
}

fn quiet_action<'a>(label: &str, msg: Message) -> Element<'a, Message> {
    button(text(label.to_string()).size(12))
        .on_press(msg)
        .style(theme::quiet())
        .padding([3, 10])
        .into()
}

fn danger_action<'a>(label: &str, msg: Message) -> Element<'a, Message> {
    button(text(label.to_string()).size(12))
        .on_press(msg)
        .style(theme::danger())
        .padding([3, 10])
        .into()
}

/// A tab entry: accent text when active, muted otherwise.
fn tab<'a>(label: impl std::fmt::Display, active: bool, msg: Message) -> Element<'a, Message> {
    let label = label.to_string();
    button(
        text(label)
            .font(Font::MONOSPACE)
            .size(12)
            .color(if active { ACCENT } else { MUTED }),
    )
    .on_press(msg)
    .padding([3, 6])
    .into()
}

/// The bar every main page shares: identity, folder tabs, page tabs, actions.
fn top_bar<'a>(app: &'a Carrier) -> Element<'a, Message> {
    let address = app
        .snapshot
        .as_ref()
        .map(|snap| snap.who.address.clone())
        .unwrap_or_default();
    let unread = |folder: usize| {
        app.lists
            .get(folder)
            .map(|rows| rows.iter().filter(|r| r.unread).count())
            .unwrap_or(0)
    };
    let fetching = app.busy.as_deref() == Some("fetching");
    let mut tabs = row![].spacing(2);
    for (folder, label) in [
        (Folder::Inbox, "Inbox"),
        (Folder::Requests, "Requests"),
        (Folder::Sent, "Sent"),
    ] {
        let count = unread(folder as usize);
        let label = if count > 0 {
            format!("{label} {count}")
        } else {
            label.to_string()
        };
        tabs = tabs.push(tab(
            label,
            app.folder == folder && app.page == Page::Mail,
            Message::GotoMail(folder),
        ));
    }
    tabs = tabs
        .push(tab(
            "Contacts",
            app.page == Page::Contacts,
            Message::Goto(Page::Contacts),
        ))
        .push(tab(
            "Settings",
            app.page == Page::Settings,
            Message::Goto(Page::Settings),
        ));
    let fetch = if fetching {
        action_disabled("Fetching…")
    } else if app.busy.is_some() {
        action_disabled("Fetch")
    } else {
        action("Fetch", Message::FetchPressed)
    };
    let write = if app.busy.is_some() {
        action_disabled("Write")
    } else {
        action("Write", Message::ComposePressed)
    };
    container(
        row![
            accent("carrier"),
            mono(address),
            Space::with_width(Length::Fill),
            tabs,
            Space::with_width(Length::Fill),
            fetch,
            write,
        ]
        .spacing(10)
        .align_y(Alignment::Center),
    )
    .style(theme::panel)
    .padding([6, 10])
    .width(Length::Fill)
    .into()
}

/// The one status line: the busy label with its cancel button while an
/// operation runs, otherwise the last result or error.
fn status<'a>(app: &'a Carrier) -> Element<'a, Message> {
    let mut line = row![].spacing(10).align_y(Alignment::Center);
    match (&app.busy, &app.status) {
        (Some(busy), _) => {
            if busy == "fetching" {
                let inbox = app.lists.first().map(|rows| rows.len()).unwrap_or(0);
                line = line.push(muted(format!("fetching… {inbox} in inbox")));
                line = line.push(quiet_action("Cancel", Message::FetchCancelled));
            } else {
                line = line.push(muted(format!("{busy}…")));
            }
        }
        (None, Some(status)) => {
            let piece = if app.status_error {
                text(status.clone()).font(Font::MONOSPACE).size(12)
            } else {
                muted(status.clone())
            };
            line = line.push(piece);
        }
        (None, None) => {}
    }
    container(line)
        .style(theme::status(app.status_error && app.busy.is_none()))
        .padding([4, 10])
        .width(Length::Fill)
        .into()
}

/// Inline confirmations: a slim banner between the content and the status.
fn dialog_banner<'a>(app: &'a Carrier) -> Element<'a, Message> {
    let Some(dialog) = &app.dialog else {
        return row![].into();
    };
    let mut line = row![].spacing(8).align_y(Alignment::Center);
    match dialog {
        Dialog::Delete { kept, .. } => {
            line = line.push(muted("delete this message:"));
            line = line.push(danger_action("here", Message::DeleteConfirmed(false)));
            if *kept {
                line = line.push(danger_action("everywhere", Message::DeleteConfirmed(true)));
            }
            line = line.push(quiet_action("cancel", Message::DeleteCancelled));
        }
        Dialog::Rotate => {
            line = line.push(muted(
                "rotate the identity? the old key stays derivable; the index never moves back",
            ));
            line = line.push(action("rotate", Message::RotateConfirmed));
            line = line.push(quiet_action("cancel", Message::RotateCancelled));
        }
    }
    container(line)
        .style(theme::status(false))
        .padding([4, 10])
        .width(Length::Fill)
        .into()
}

fn pin_offer_banner<'a>(app: &'a Carrier) -> Element<'a, Message> {
    let Some((_, key)) = &app.pin_offer else {
        return row![].into();
    };
    row![
        muted("server key offered:"),
        mono(fingerprint(key)),
        mono(short(&b32(key), 24)),
        action("pin", Message::PinAccept),
        quiet_action("discard", Message::PinDiscard),
    ]
    .spacing(8)
    .align_y(Alignment::Center)
    .into()
}

// --- mail ------------------------------------------------------------------

fn mail<'a>(app: &'a Carrier) -> Element<'a, Message> {
    column![
        top_bar(app),
        container(list_pane(app)).height(Length::FillPortion(38)),
        rule::Rule::horizontal(1.0),
        container(detail_pane(app)).height(Length::FillPortion(62)),
    ]
    .spacing(0)
    .height(Length::Fill)
    .into()
}

fn list_pane<'a>(app: &'a Carrier) -> Element<'a, Message> {
    let rows = app
        .lists
        .get(app.folder as usize)
        .cloned()
        .unwrap_or_default();
    let header = row![
        cell(muted("date"), DATE_W),
        cell(muted("f"), FLAG_W),
        cell(muted("from/to"), FROM_W),
        muted("subject"),
    ]
    .spacing(10)
    .padding(padding());
    let mut list = column![header].spacing(1);
    if rows.is_empty() {
        let hint = match app.folder {
            Folder::Inbox => "inbox is empty — fetch to check the mailbox",
            Folder::Requests => "no requests",
            Folder::Sent => "nothing sent yet",
        };
        list = list.push(container(muted(hint)).padding(Padding::new(10.0)));
    }
    for row in &rows {
        let selected = app
            .open
            .as_ref()
            .is_some_and(|(folder, msg)| *folder == app.folder && msg.id == row.id);
        list = list.push(list_row(app.folder, row, selected));
    }
    scrollable(list).height(Length::Fill).into()
}

/// One compact row: date, flags, from/to, subject — a flat button so the
/// whole line is clickable like a mu4e header.
fn list_row<'a>(folder: Folder, row: &Row, selected: bool) -> Element<'a, Message> {
    let flag = if row.unread {
        accent("●")
    } else {
        muted("·")
    };
    let date = ops::when(row.at);
    button(
        row![
            cell(mono(date), DATE_W),
            cell(flag, FLAG_W),
            cell(mono(truncate(&row.from, 32)), FROM_W),
            text(truncate(&row.subject, 64))
                .font(Font::MONOSPACE)
                .size(12)
                .color(if row.unread { TEXT } else { MUTED })
                .wrapping(Wrapping::None),
        ]
        .spacing(10)
        .align_y(Alignment::Center),
    )
    .on_press(Message::MessageSelected(folder, row.id.clone()))
    .style(theme::row_style(selected))
    .padding(padding())
    .width(Length::Fill)
    .into()
}

fn padding() -> Padding {
    Padding::new(3.0).right(10.0).left(10.0)
}

/// A `label: value` header line for the article view.
fn header_line<'a>(label: &str, value: impl std::fmt::Display) -> Element<'a, Message> {
    row![muted(format!("{label:<9}")), mono(value),]
        .spacing(4)
        .into()
}

fn detail_pane<'a>(app: &'a Carrier) -> Element<'a, Message> {
    let Some((folder, msg)) = &app.open else {
        return container(muted("select a message to read it"))
            .center(Length::Fill)
            .into();
    };
    let mut headers = column![].spacing(1);
    let to_label = if *folder == Folder::Sent {
        "to"
    } else {
        "from"
    };
    headers = headers.push(header_line(to_label, &msg.from));
    headers = headers.push(header_line(
        "subject",
        if msg.subject.is_empty() {
            "(no subject)".to_string()
        } else {
            msg.subject.clone()
        },
    ));
    headers = headers.push(header_line("date", format!("{} UTC", ops::when(msg.time))));
    headers = headers.push(header_line("id", short(&msg.id, 16)));
    if msg.kept {
        headers = headers.push(header_line("server", "a copy still exists there"));
    }
    let mut actions = row![].spacing(8);
    actions = actions.push(quiet_action("reply", Message::ReplyPressed));
    if *folder == Folder::Requests {
        if msg.reply_to.is_some() {
            actions = actions.push(action("accept", Message::AcceptPressed));
            actions = actions.push(danger_action("block", Message::BlockPressed));
        } else {
            actions = actions.push(muted("no reply address: cannot accept or block"));
        }
    }
    actions = actions.push(danger_action("delete", Message::DeletePressed));
    column![
        container(headers).padding([8, 10]),
        rule::Rule::horizontal(1.0),
        scrollable(column![container(
            text(msg.body.clone())
                .font(Font::MONOSPACE)
                .size(12)
                .color(TEXT)
        )
        .padding([8, 10])])
        .height(Length::Fill),
        rule::Rule::horizontal(1.0),
        container(actions).padding([6, 10]),
    ]
    .spacing(0)
    .height(Length::Fill)
    .into()
}

// --- compose ---------------------------------------------------------------

/// Compose takes the lower pane, keeping the list visible above — writing is
/// the article pane's other job, as in the layout it comes from.
fn compose<'a>(app: &'a Carrier) -> Element<'a, Message> {
    let Some(compose) = &app.compose else {
        unreachable!("compose view without a draft")
    };
    let label = if compose.reply_to.is_some() {
        "reply"
    } else {
        "write"
    };
    column![
        top_bar(app),
        container(
            column![
                row![
                    muted("to"),
                    text_input("alice@example.org or smol://…", &compose.to)
                        .on_input(Message::ComposeToEdited)
                        .size(12)
                        .width(Length::Fill),
                ]
                .spacing(8),
                row![
                    muted("subject"),
                    text_input("subject", &compose.subject)
                        .on_input(Message::ComposeSubjectEdited)
                        .size(12)
                        .width(Length::Fill),
                ]
                .spacing(8),
                text_editor(&compose.body)
                    .on_action(Message::ComposeBody)
                    .font(Font::MONOSPACE)
                    .size(12)
                    .height(Length::Fill),
                row![
                    action(label, Message::SendPressed),
                    quiet_action("cancel", Message::ComposeClosed),
                ]
                .spacing(8),
            ]
            .spacing(6)
        )
        .padding(10)
        .height(Length::Fill),
    ]
    .spacing(0)
    .height(Length::Fill)
    .into()
}

// --- contacts ---------------------------------------------------------------

fn contacts<'a>(app: &'a Carrier) -> Element<'a, Message> {
    let Some(snap) = &app.snapshot else {
        return column![top_bar(app)].into();
    };
    let own = format!("smol://{}/{}", snap.who.address, snap.who.key);
    let mut share = row![
        muted("you:"),
        mono(own),
        quiet_action("copy", Message::CopyOwnAddress),
    ]
    .spacing(8)
    .align_y(Alignment::Center);
    if let Some(data) = &app.share_qr {
        share = share.push(container(qr_code(data).cell_size(3)).padding(0));
    }
    let header = row![
        cell(muted("address"), ADDR_W),
        cell(muted("key"), KEY_W),
        cell(muted("state"), STATE_W),
        muted(""),
    ]
    .spacing(10)
    .padding(padding());
    let mut table = column![header].spacing(1);
    for contact in &snap.contacts {
        table = table.push(contact_row(contact));
    }
    if snap.contacts.is_empty() {
        table = table.push(
            container(muted("no contacts yet — import a smol:// address"))
                .padding(Padding::new(10.0)),
        );
    }
    column![
        top_bar(app),
        container(share).style(theme::panel).padding([6, 10]),
        container(
            row![
                text_input("paste a smol:// address to import", &app.contact_import)
                    .on_input(Message::ContactImportEdited)
                    .on_submit(Message::ContactImportPressed)
                    .size(12)
                    .width(Length::Fill),
                action("import", Message::ContactImportPressed),
            ]
            .spacing(8)
        )
        .padding([6, 10]),
        scrollable(table).height(Length::Fill),
    ]
    .spacing(0)
    .height(Length::Fill)
    .into()
}

fn contact_row<'a>(contact: &Contact) -> Element<'a, Message> {
    let state = match contact.accepted {
        Some(true) => "accepted",
        Some(false) => "blocked",
        None => {
            if contact.verified {
                "verified"
            } else {
                "tofu"
            }
        }
    };
    let mut actions = row![quiet_action(
        "write",
        Message::ContactWrite(contact.address.clone()),
    )]
    .spacing(6);
    match contact.accepted {
        Some(true) => {
            actions = actions.push(danger_action(
                "block",
                Message::ContactBlock(contact.address.clone()),
            ));
        }
        Some(false) => {
            actions = actions.push(action(
                "unblock",
                Message::ContactUnblock(contact.address.clone()),
            ));
        }
        None => {
            actions = actions.push(action(
                "accept",
                Message::ContactAccept(contact.address.clone(), contact.key.clone()),
            ));
        }
    }
    container(
        row![
            cell(accent(&contact.address), ADDR_W),
            cell(mono(short(&contact.key, 32)), KEY_W),
            cell(muted(state), STATE_W),
            actions,
        ]
        .spacing(10)
        .align_y(Alignment::Center),
    )
    .style(theme::card)
    .padding(padding())
    .width(Length::Fill)
    .into()
}

// --- settings ---------------------------------------------------------------

fn settings<'a>(app: &'a Carrier) -> Element<'a, Message> {
    let Some(snap) = &app.snapshot else {
        return column![top_bar(app)].into();
    };
    let who = &snap.who;
    let identity = column![
        header_line("address", &who.address),
        header_line("key", &who.key),
        header_line("fingerprint", &who.fingerprint),
        header_line("rotations", who.rotations),
        row![
            action("rotate", Message::RotatePressed),
            quiet_action("learn key", Message::SettingsLearnKey),
        ]
        .spacing(8),
    ]
    .spacing(1);

    let mut pins = column![].spacing(1);
    for (label, key) in &snap.pins {
        pins = pins.push(
            row![
                cell(mono(label), ADDR_W),
                cell(mono(short(&b32(key), 32)), KEY_W),
                danger_action("unpin", Message::UnpinPressed(label.clone())),
            ]
            .spacing(10)
            .align_y(Alignment::Center),
        );
    }
    if snap.pins.is_empty() {
        pins = pins.push(muted("no server keys pinned"));
    }

    // Pinned to the app borrow: the column mixes owned rows with the
    // `text_editor` that borrows `app.import_body`.
    let mut export: iced::widget::Column<'_, Message> = column![].spacing(4);
    export = export.push(
        row![
            action("export", Message::ExportPressed),
            quiet_action("copy", Message::CopyExport),
        ]
        .spacing(8),
    );
    if let Some(text) = &app.backup_text {
        export = export.push(scrollable(mono(short(text, 4000))).height(Length::Fixed(80.0)));
    }
    export = export.push(muted("import a backup (gsmol): paste it below"));
    export = export.push(
        text_editor(&app.import_body)
            .on_action(Message::ImportBody)
            .font(Font::MONOSPACE)
            .size(12)
            .height(Length::Fixed(100.0)),
    );
    export = export.push(action("import", Message::ImportPressed));

    let sections = column![
        section("identity", identity.into()),
        section("server keys", pins.into()),
        section("backup", export.into()),
        section(
            "network",
            row![
                muted("timeout"),
                text_input("30", &app.timeout_text)
                    .on_input(Message::TimeoutEdited)
                    .size(12)
                    .width(80),
                muted("seconds"),
            ]
            .spacing(8)
            .align_y(Alignment::Center)
            .into(),
        ),
    ]
    .spacing(10);

    column![
        top_bar(app),
        pin_offer_banner(app),
        scrollable(container(sections).padding(10)).height(Length::Fill),
    ]
    .spacing(0)
    .height(Length::Fill)
    .into()
}

fn section<'a>(title: &str, body: Element<'a, Message>) -> Element<'a, Message> {
    container(
        column![container(accent(title)).padding([2, 0]), body]
            .spacing(6)
            .max_width(720),
    )
    .style(theme::card)
    .padding(10)
    .width(Length::Fill)
    .into()
}

// --- onboarding and signup ---------------------------------------------------

fn centered<'a>(body: Element<'a, Message>) -> Element<'a, Message> {
    container(body)
        .center(Length::Fill)
        .max_width(520)
        .padding(20)
        .into()
}

fn onboard<'a>(app: &'a Carrier) -> Element<'a, Message> {
    let body = match app.onboard.mode {
        OnboardMode::Start => column![
            text("carrier").font(Font::MONOSPACE).size(24).color(ACCENT),
            muted("smolmail: one seed, sealed mail, five operations"),
            row![
                action("create an identity", Message::OnboardCreate),
                quiet_action("restore from a seed", Message::OnboardRestore),
            ]
            .spacing(8)
            .padding([12, 0]),
        ]
        .spacing(10)
        .align_x(Alignment::Start),
        OnboardMode::Created => column![
            muted("this seed is the only secret — write it down now; it is shown once"),
            container(
                text_input("", &app.onboard.seed_shown)
                    .font(Font::MONOSPACE)
                    .size(12)
                    .width(Length::Fill)
            )
            .style(theme::card)
            .padding(6),
            row![
                action("i saved it", Message::OnboardSeedSaved),
                quiet_action("back", Message::OnboardBack),
            ]
            .spacing(8),
        ]
        .spacing(10),
        OnboardMode::Restore => column![
            muted("paste the 32-byte seed, base32 or hex"),
            text_input("seed", &app.onboard.seed)
                .on_input(Message::OnboardSeedEdited)
                .on_submit(Message::OnboardRestoreFromSeed)
                .size(12)
                .width(Length::Fill),
            row![
                action("restore", Message::OnboardRestoreFromSeed),
                quiet_action("back", Message::OnboardBack),
            ]
            .spacing(8),
        ]
        .spacing(10),
    };
    centered(body.into())
}

fn signup<'a>(app: &'a Carrier) -> Element<'a, Message> {
    let mut body = column![
        accent("set up the address"),
        row![
            muted("user"),
            text_input("alice", &app.signup.user)
                .on_input(Message::SignupUserEdited)
                .size(12)
                .width(Length::Fill),
        ]
        .spacing(8),
        row![
            muted("host"),
            text_input("example.org", &app.signup.host)
                .on_input(Message::SignupHostEdited)
                .size(12)
                .width(Length::Fill),
        ]
        .spacing(8),
        row![
            muted("invite"),
            text_input("optional token", &app.signup.invite)
                .on_input(Message::SignupInviteEdited)
                .size(12)
                .width(Length::Fill),
        ]
        .spacing(8),
        row![
            muted("key"),
            text_input("server key, if the operator published one", &app.signup.key)
                .on_input(Message::SignupKeyEdited)
                .size(12)
                .width(Length::Fill),
        ]
        .spacing(8),
    ]
    .spacing(8);
    if app.signup.key.is_empty() {
        body = body.push(
            row![
                muted("or"),
                quiet_action("learn the server key", Message::SignupLearnKey),
                muted("and pin what it presents"),
            ]
            .spacing(8)
            .align_y(Alignment::Center),
        );
    }
    body = body.push(pin_offer_banner(app));
    body = body.push(
        row![
            action("register", Message::SignupRegister),
            quiet_action("i already have this address", Message::SignupRecall),
        ]
        .spacing(8)
        .padding([8, 0]),
    );
    if app.signup.fresh {
        body = body.push(quiet_action("back", Message::SignupBack));
    }
    centered(body.into())
}

// --- small helpers -----------------------------------------------------------

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 short(text: &str, max: usize) -> String {
    if text.len() <= max {
        text.to_string()
    } else {
        format!("{}…{}", &text[..max / 2], &text[text.len() - 3..])
    }
}