/// Flutter-side mirror of the daemon's active-editor state.
///
/// Listens to `editor.*` events over IPC and tracks: the active
/// buffer's id/path/content/selection, and whether the buffer is
/// dirty. The widget layer consumes this via [ListenableBuilder].
///
/// User edits flow the other way — the widget calls into the
/// controller, which calls `editor.set-content` / `editor.save` on
/// the daemon. The daemon is the source of truth; the widget is a
/// reconciled view.
library;

import 'dart:async';

import 'package:clide/clide.dart';
import 'package:clide/kernel/kernel.dart';
import 'package:clide/src/editor/editor_settings.dart';
import 'package:flutter/foundation.dart';

/// Lightweight view of one open buffer for the tab strip — the
/// daemon's authoritative content lives behind [EditorController];
/// this is just what the tabs need to render.
typedef OpenBuffer = ({String id, String path, bool dirty});

class EditorController extends ChangeNotifier {
  EditorController({required this.ipc, required DaemonBus events}) {
    _eventSub = events.on<DaemonEvent>().listen(_onEvent);
  }

  final DaemonClient ipc;

  StreamSubscription<DaemonEvent>? _eventSub;

  String? _activeId;
  String? _activePath;
  String _content = '';
  Selection _selection = const Selection.collapsed(0);
  bool _dirty = false;
  String? _error;
  EditorSettings _settings = EditorSettings.empty;

  /// All open buffers, in daemon order, for the tab strip.
  List<OpenBuffer> _buffers = const [];

  bool _suppressNextRemoteEdit = false;
  int _pendingLocalEdits = 0;

  String? get activeId => _activeId;
  String? get activePath => _activePath;
  String get content => _content;
  Selection get selection => _selection;
  bool get dirty => _dirty;
  String? get error => _error;
  List<OpenBuffer> get buffers => _buffers;

  /// Effective editor settings for the active buffer (T-29).
  EditorSettings get settings => _settings;

  /// On first mount we don't know what's already open. Ask the daemon
  /// for the buffer list and the active buffer.
  Future<void> hydrate() async {
    await _refreshList();
    final r = await ipc.request('editor.active');
    if (!r.ok) {
      _error = r.error?.message;
      notifyListeners();
      return;
    }
    final active = r.data['active'];
    if (active is! Map) {
      _activeId = null;
      _activePath = null;
      _content = '';
      notifyListeners();
      return;
    }
    final id = active['id']! as String;
    await _loadBuffer(id);
  }

  /// Make [id] the active buffer. The daemon echoes an
  /// `editor.active-changed` event which loads its content.
  Future<void> activate(String id) async {
    if (id == _activeId) return;
    await ipc.request('editor.activate', args: {'id': id});
  }

  /// Close the buffer [id]. The daemon emits `editor.closed` (and an
  /// `editor.active-changed` if it was the active one).
  Future<void> closeBuffer(String id) async {
    await ipc.request('editor.close', args: {'id': id});
  }

  /// Re-fetch the open-buffer list from the daemon (authoritative).
  Future<void> _refreshList() async {
    final r = await ipc.request('editor.list');
    if (!r.ok) return;
    final raw = r.data['buffers'];
    if (raw is! List) return;
    _buffers = [
      for (final b in raw)
        if (b is Map) (id: b['id']! as String, path: b['path']! as String, dirty: (b['dirty'] as bool?) ?? false),
    ];
    notifyListeners();
  }

  void _markDirty(String id, bool dirty) {
    var changed = false;
    _buffers = [
      for (final b in _buffers)
        if (b.id == id && b.dirty != dirty)
          (() {
            changed = true;
            return (id: b.id, path: b.path, dirty: dirty);
          })()
        else
          b,
    ];
    if (changed) notifyListeners();
  }

  Future<void> _loadBuffer(String id) async {
    final r = await ipc.request('editor.read', args: {'id': id});
    if (!r.ok) {
      _error = r.error?.message;
      notifyListeners();
      return;
    }
    _activeId = r.data['id']! as String;
    _activePath = r.data['path']! as String;
    _settings = EditorSettings.fromJson(r.data['editorSettings']);
    _content = (r.data['content'] as String?) ?? '';
    final sel = r.data['selection'];
    _selection = sel is Map ? Selection.fromJson(sel.cast<String, Object?>()) : const Selection.collapsed(0);
    _dirty = (r.data['dirty'] as bool?) ?? false;
    _error = null;
    notifyListeners();
  }

  /// Called by the widget on every local text edit.
  void pushLocalEdit({required String newContent, required Selection newSelection}) {
    final id = _activeId;
    if (id == null) return;

    _content = newContent;
    _selection = newSelection;
    _dirty = true;
    _markDirty(id, true);
    notifyListeners();

    // Mirror to daemon. Use editor.set-content for the first cut —
    // it's coarse but simple and avoids diff computation. Future
    // tuning: diff + editor.insert / editor.replace-selection for
    // large buffers, so event broadcasts stay small.
    _pendingLocalEdits++;
    _suppressNextRemoteEdit = true;
    ipc.request('editor.set-content', args: {'id': id, 'text': newContent, 'selection': newSelection.toJson()}).whenComplete(() => _pendingLocalEdits--);
  }

  Future<void> save() async {
    final id = _activeId;
    if (id == null) return;
    await ipc.request('editor.save', args: {'id': id});
  }

  void _onEvent(DaemonEvent e) {
    if (e.subsystem != 'editor') return;
    switch (e.kind) {
      case 'editor.opened':
        // A new buffer joined the set — refresh the tab list, then
        // load whatever the daemon now considers active.
        unawaited(_refreshList());
        final id = e.data['id'] as String?;
        if (id == null) {
          _clearActive();
        } else if (id != _activeId) {
          _loadBuffer(id);
        }
      case 'editor.active-changed':
        final id = e.data['id'] as String?;
        if (id == null) {
          _clearActive();
        } else if (id != _activeId) {
          _loadBuffer(id);
        }
      case 'editor.edited':
        // Our own set-content echoes back as editor.edited. Skip one
        // bounce so we don't clobber the caret the user just moved.
        if (_suppressNextRemoteEdit) {
          _suppressNextRemoteEdit = false;
          return;
        }
        // Remote edit (another client, or the CLI inserting bytes).
        // Reload the authoritative buffer.
        final id = e.data['id'] as String?;
        if (id != null) _markDirty(id, true);
        if (id != null && id == _activeId && _pendingLocalEdits == 0) {
          _loadBuffer(id);
        }
      case 'editor.saved':
        final id = e.data['id'] as String?;
        if (id != null) _markDirty(id, false);
        if (id == _activeId) {
          _dirty = false;
          notifyListeners();
        }
      case 'editor.selection-changed':
        // An external setSelection moved the caret server-side (find-in-files
        // line jump, ex-line `:N` goto — T-407). Mirror it onto the active
        // buffer so the view's caret follows. Skipped while our own local edits
        // are in flight — their echo already carries the authoritative caret.
        final id = e.data['id'] as String?;
        if (id != null && id == _activeId && _pendingLocalEdits == 0) {
          final sel = e.data['selection'];
          if (sel is Map) {
            _selection = Selection.fromJson(sel.cast<String, Object?>());
            notifyListeners();
          }
        }
      case 'editor.settings-changed':
        // A source (e.g. a saved .editorconfig) re-resolved the buffer's
        // settings. Refresh the active buffer's copy so indent/ruler update.
        if (e.data['id'] == _activeId) {
          _settings = EditorSettings.fromJson(e.data['editorSettings']);
          notifyListeners();
        }
      case 'editor.closed':
        // A buffer left the set — refresh the tab list. If it was the
        // active one the daemon promotes another and emits
        // active-changed; reflect the cleared state in the meantime.
        unawaited(_refreshList());
        if (e.data['id'] == _activeId) {
          _clearActive();
        }
    }
  }

  void _clearActive() {
    _activeId = null;
    _activePath = null;
    _content = '';
    _selection = const Selection.collapsed(0);
    _dirty = false;
    _settings = EditorSettings.empty;
    notifyListeners();
  }

  @override
  void dispose() {
    _eventSub?.cancel();
    _eventSub = null;
    super.dispose();
  }
}