import "package:auto_route/auto_route.dart";
import "package:flutter/material.dart";
import "package:flutter_riverpod/flutter_riverpod.dart";

import "package:smol_mail/data/providers/providers.dart";
import "package:smol_mail/presentation/routes/app_router.gr.dart";
import "package:smol_mail/presentation/widgets/image_banner.dart";
import "package:smol_mail/presentation/widgets/message/message_list.dart";
import "package:smol_mail/presentation/widgets/qr_code_sheet.dart";
import "package:smol_mail/shared/utils/snackbar.dart";
import "package:smol_mail/smol/errors.dart";

const _folders = ["inbox", "requests", "sent"];

/// No server push in v1 (SPEC.md §13): new mail arrives when the user taps
/// fetch, which pulls everything and acknowledges what verifies. One FETCH
/// call populates both Inbox and Requests (they're tiers of the same
/// mailbox), so both — but not the purely local Sent folder — offer fetch.
@RoutePage()
class InboxScreen extends ConsumerStatefulWidget {
  const InboxScreen({super.key});

  @override
  ConsumerState<InboxScreen> createState() => _InboxScreenState();
}

class _InboxScreenState extends ConsumerState<InboxScreen>
    with SingleTickerProviderStateMixin {
  late final TabController _tabController;

  @override
  void initState() {
    super.initState();
    _tabController = TabController(length: _folders.length, vsync: this)
      ..addListener(() {
        // Fires once settled, whether the change came from a tap or a swipe;
        // only the AppBar's fetch button depends on which tab is active.
        if (!_tabController.indexIsChanging) setState(() {});
      });
  }

  @override
  void dispose() {
    _tabController.dispose();
    super.dispose();
  }

  Future<void> _fetch(BuildContext context, WidgetRef ref) async {
    final client = ref.read(clientProvider);
    try {
      final summary = await client.fetch();
      ref.read(revisionProvider.notifier).bump();
      if (context.mounted) {
        final tail = summary.rejected.isEmpty
            ? ""
            : "\n${summary.rejected.length} left on the server";
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text("${summary.stored} new$tail")),
        );
      }
    } on SmolError catch (err) {
      if (context.mounted) {
        showErrorSnackBar(context, err.message);
      }
    }
  }

  Widget _folderView(BuildContext context, WidgetRef ref, String folder) {
    final messages = ref.watch(messagesForFolderProvider(folder));
    final canFetch = folder != "sent";
    final onRefresh = canFetch ? () => _fetch(context, ref) : () => Future.value();

    if (messages.isEmpty) {
      return RefreshIndicator(
        onRefresh: onRefresh,
        child: ListView(
          children: const [
            ImageBanner(
              imgSrc: "assets/images/empty.png",
              text: "Nothing here yet!",
            ),
          ],
        ),
      );
    }
    return MessageList(folder: folder, onRefresh: onRefresh);
  }

  @override
  Widget build(BuildContext context) {
    final unread = ref.watch(unreadProvider);
    final requestsUnread = ref.watch(requestsUnreadProvider);
    final canFetch = _folders[_tabController.index] != "sent";
    // The same self-certifying URI the settings share row shows, one tap
    // closer: what a second device scans to import this identity.
    final me = ref.watch(identityProvider);
    final account = ref.watch(accountProvider);
    final share = (me == null || account == null)
        ? null
        : account.uri(me.publicKey);

    return Scaffold(
      appBar: AppBar(
        title: const Text("kirakira"),
        actions: [
          if (share != null)
            IconButton(
              tooltip: "Show QR code",
              onPressed: () => showQrCodeSheet(context, share),
              icon: const Icon(Icons.qr_code),
            ),
          if (canFetch)
            IconButton(
              tooltip: "Fetch",
              onPressed: () => _fetch(context, ref),
              icon: const Icon(Icons.cloud_download),
            ),
        ],
        bottom: TabBar(
          controller: _tabController,
          tabs: [
            Tab(text: unread > 0 ? "Inbox ($unread)" : "Inbox"),
            Tab(text: requestsUnread > 0 ? "Requests ($requestsUnread)" : "Requests"),
            const Tab(text: "Sent"),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () => AutoRouter.of(context).push(ComposeRoute()),
        child: const Icon(Icons.edit),
      ),
      body: TabBarView(
        controller: _tabController,
        children: [
          for (final folder in _folders) _folderView(context, ref, folder),
        ],
      ),
    );
  }
}