import 'dart:async';

import 'package:desktop_drop/desktop_drop.dart';
import 'package:flutter/material.dart';
import 'package:stacked/stacked.dart';

import '../../about/internal/application/NotificationType.dart';
import '../../about/internal/application/ServerProfile.dart';
import '../../about/internal/application/TextType.dart';
import '../../comms/Comms.dart' show RemoteEntry, TransferProgress;
import '../../designs/text/Text.dart';
import '../../utils/Colors.dart';
import '../../utils/CommonUtils.dart';
import 'ConnectFiles.dart';
import 'Files.dart';
import 'ViewFiles.dart';

class FilesState extends State<Files> implements ConnectFiles {
  ViewFiles? _model;

  StreamSubscription<TransferProgress?>? _progressSub;

  String _path = '.';
  List<RemoteEntry> _entries = [];
  bool _loading = true;
  bool _busy = false;
  bool _dragging = false;
  String? _error;
  double? _progress;

  ServerProfile get _server => widget.server;

  @override
  void dispose() {
    _progressSub?.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return ViewModelBuilder<ViewFiles>.reactive(
      viewModelBuilder: () => ViewFiles(context, this),
      onViewModelReady: _onReady,
      builder: (context, viewModel, child) => Scaffold(
        appBar: AppBar(
          title: text(
            '${_server.name} · files',
            20,
            TextType.Bold,
            color: context.jp.text,
          ),
          actions: [
            IconButton(
              tooltip: 'Refresh',
              onPressed: _busy ? null : _onRefresh,
              icon: const Icon(Icons.refresh),
            ),
            const SizedBox(width: 4),
          ],
        ),
        floatingActionButton: FloatingActionButton.extended(
          onPressed: _busy ? null : _onUploadPicked,
          icon: const Icon(Icons.upload),
          label: text('Upload', 14, TextType.Bold, color: colorWhite),
        ),
        body: DropTarget(
          onDragEntered: _onDragEntered,
          onDragExited: _onDragExited,
          onDragDone: _onDragDone,
          child: Column(
            children: [
              _pathBar(),
              if (_progress != null)
                LinearProgressIndicator(
                  value: _progress == 0 ? null : _progress,
                  minHeight: 3,
                ),
              Expanded(child: _body()),
            ],
          ),
        ),
      ),
    );
  }

  void _onReady(ViewFiles model) {
    _model = model;
    // onViewModelReady fires mid-build; a synchronous setState from the
    // first load would dirty this State while it is still being built.
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (mounted) _initiate();
    });
  }

  Future<void> _initiate() async {
    _progressSub = _model?.transferProgress.listen(_onProgress);
    _model?.resolveHome(_server);
  }

  void _onProgress(TransferProgress? p) {
    if (!mounted) return;
    setState(() => _progress = p?.fraction);
  }

  // ── named handlers ─────────────────────────────────────────────────────────

  void _onRefresh() {
    setState(() {
      _loading = true;
      _error = null;
    });
    _model?.listDirectory(_server, _path);
  }

  void _onEnter(RemoteEntry e) {
    if (!e.isDir) return;
    setState(() => _path = joinRemote(_path, e.name));
    _onRefresh();
  }

  void _onUp() {
    setState(() => _path = parentRemote(_path));
    _onRefresh();
  }

  void _onUploadPicked() {
    setState(() {
      _busy = true;
      _progress = 0;
    });
    _model?.uploadPicked(_server, _path, joinRemote);
  }

  void _onDragEntered(DropEventDetails _) => setState(() => _dragging = true);

  void _onDragExited(DropEventDetails _) => setState(() => _dragging = false);

  Future<void> _onDragDone(DropDoneDetails details) async {
    setState(() {
      _dragging = false;
      _busy = true;
      _progress = 0;
    });
    for (final file in details.files) {
      final bytes = await file.readAsBytes();
      _model?.uploadBytes(
        _server,
        joinRemote(_path, file.name),
        bytes,
        file.name,
      );
    }
  }

  void _onDownload(RemoteEntry e) {
    setState(() {
      _busy = true;
      _progress = 0;
    });
    _model?.downloadFile(_server, joinRemote(_path, e.name), e.name);
  }

  void _onDelete(RemoteEntry e) {
    _model?.showApplicationNotification(
      NotificationType.warning,
      'Delete "${e.name}"?',
      e.isDir
          ? 'Removes the directory (it must be empty).'
          : 'Permanently deletes this file on the server.',
      true,
      true,
      null,
      action: 'Delete',
      positiveAction: () => _onConfirmDelete(e),
    );
  }

  void _onConfirmDelete(RemoteEntry e) {
    Navigator.pop(context);
    _model?.deleteEntry(_server, joinRemote(_path, e.name), e.isDir);
  }

  void _onRowMenu(String value, RemoteEntry e) {
    if (value == 'download') _onDownload(e);
    if (value == 'delete') _onDelete(e);
  }

  void _notify(String message) {
    if (!mounted) return;
    ScaffoldMessenger.of(
      context,
    ).showSnackBar(SnackBar(content: Text(message)));
  }

  // ── ConnectFiles ───────────────────────────────────────────────────────────

  @override
  void onHomeResolved(String path) {
    if (!mounted) return;
    setState(() => _path = path);
    _model?.listDirectory(_server, path);
  }

  @override
  void onDirectoryLoaded(List<RemoteEntry> entries) {
    if (!mounted) return;
    setState(() {
      _entries = entries;
      _loading = false;
      _error = null;
    });
  }

  @override
  void onDirectoryFailed(String message) {
    if (!mounted) return;
    setState(() {
      _loading = false;
      _error = message;
    });
  }

  @override
  void onTransferFinished(String message) {
    if (!mounted) return;
    setState(() {
      _busy = false;
      _progress = null;
    });
    _notify(message);
    _onRefresh();
  }

  @override
  void onEntryDeleted() {
    _onRefresh();
  }

  // ── screen-only widgets ────────────────────────────────────────────────────

  Widget _pathBar() {
    final jp = context.jp;
    return Container(
      color: _dragging ? PeachTheme.seed.withValues(alpha: 0.12) : jp.surface,
      padding: const EdgeInsets.fromLTRB(8, 8, 12, 8),
      child: Row(
        children: [
          IconButton(
            tooltip: 'Up',
            onPressed: _busy || _path == '/' ? null : _onUp,
            icon: const Icon(Icons.arrow_upward),
          ),
          Expanded(
            child: text(
              _dragging ? 'Drop files to upload here' : _path,
              13,
              _dragging ? TextType.Bold : TextType.Regular,
              color: _dragging ? PeachTheme.seed : jp.textDim,
              maxLines: 1,
              overflow: TextOverflow.ellipsis,
            ),
          ),
        ],
      ),
    );
  }

  Widget _body() {
    if (_loading) return const Center(child: CircularProgressIndicator());
    if (_error != null) return _errorView();
    if (_entries.isEmpty) {
      return Center(
        child: text(
          'Empty directory',
          14,
          TextType.Regular,
          color: context.jp.textFaint,
        ),
      );
    }
    return ListView.separated(
      itemCount: _entries.length,
      separatorBuilder: (_, i) => Divider(height: 1, color: context.jp.border),
      itemBuilder: (_, i) => _row(_entries[i]),
    );
  }

  Widget _errorView() => Center(
    child: Padding(
      padding: const EdgeInsets.all(24),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          Icon(Icons.error_outline, color: colorNegative, size: 40),
          const SizedBox(height: 12),
          text(
            _error!,
            14,
            TextType.Regular,
            color: colorNegative,
            align: TextAlign.center,
          ),
          const SizedBox(height: 16),
          FilledButton.icon(
            onPressed: _onRefresh,
            icon: const Icon(Icons.refresh),
            label: text('Retry', 14, TextType.Bold, color: colorWhite),
          ),
        ],
      ),
    ),
  );

  Widget _row(RemoteEntry e) {
    final jp = context.jp;
    return ListTile(
      leading: Icon(
        e.isDir ? Icons.folder : Icons.insert_drive_file_outlined,
        color: e.isDir ? PeachTheme.accent : jp.textDim,
      ),
      title: text(
        e.name,
        14,
        TextType.Regular,
        color: jp.text,
        maxLines: 1,
        overflow: TextOverflow.ellipsis,
      ),
      subtitle: e.isDir
          ? null
          : text(formatBytes(e.size), 12, TextType.Light, color: jp.textFaint),
      onTap: e.isDir ? () => _onEnter(e) : null,
      trailing: PopupMenuButton<String>(
        onSelected: (v) => _onRowMenu(v, e),
        itemBuilder: (_) => [
          if (!e.isDir)
            const PopupMenuItem(
              value: 'download',
              child: ListTile(
                leading: Icon(Icons.download),
                title: Text('Download'),
                contentPadding: EdgeInsets.zero,
              ),
            ),
          const PopupMenuItem(
            value: 'delete',
            child: ListTile(
              leading: Icon(Icons.delete_outline),
              title: Text('Delete'),
              contentPadding: EdgeInsets.zero,
            ),
          ),
        ],
      ),
    );
  }
}