import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import 'session_store.dart';

/// 全局设置。目前两项：MCP 端口、E-Ink 模式。
///
/// 存成单独一个 `settings.json`（见 [SessionStore]），不跟会话存档混在一起 ——
/// 会话存档每次求值都会重写，设置却是偶尔改一次的东西。
class AppSettings extends ChangeNotifier {
  AppSettings({SessionStore? store})
    : _store = store ?? SessionStore(fileName: 'settings.json');

  final SessionStore _store;

  static const int defaultMcpPort = 8734;
  static const int minPort = 1024;
  static const int maxPort = 65535;

  /// 近似值保留几位**小数**（工具页和计算器的"近似"都听这个）。
  static const int defaultApproxDigits = 10;
  static const int minDigits = 0;
  static const int maxDigits = 15;

  int _mcpPort = defaultMcpPort;
  int _approxDigits = defaultApproxDigits;
  bool _eInk = false;
  bool _loaded = false;

  /// MCP 服务器监听的端口。
  int get mcpPort => _mcpPort;

  /// 近似值位数。计算器顶栏的"近似"用它，工具页的"（近似）"那行也用它。
  int get approxDigits => _approxDigits;

  /// 是否已从存档读过一次（界面据此决定要不要提示"设置已恢复"）。
  bool get loaded => _loaded;

  /// E-Ink 模式：所有颜色换成灰阶，动画关掉。
  ///
  /// 给墨水屏/阳光下看屏幕用 —— 彩色在这种屏上会被抖成难看的网点，
  /// 动画则会留下拖影。
  bool get eInk => _eInk;

  Future<void> load() async {
    final data = await _store.load();
    if (data != null) {
      final p = (data['mcpPort'] as num?)?.toInt();
      if (p != null && p >= minPort && p <= maxPort) _mcpPort = p;
      final d = (data['approxDigits'] as num?)?.toInt();
      if (d != null && d >= minDigits && d <= maxDigits) _approxDigits = d;
      _eInk = data['eInk'] == true;
    }
    _loaded = true;
    notifyListeners();
  }

  Future<void> setMcpPort(int port) async {
    if (port < minPort || port > maxPort || port == _mcpPort) return;
    _mcpPort = port;
    notifyListeners();
    await _save();
  }

  Future<void> setApproxDigits(int digits) async {
    if (digits < minDigits || digits > maxDigits || digits == _approxDigits) {
      return;
    }
    _approxDigits = digits;
    notifyListeners();
    await _save();
  }

  Future<void> setEInk(bool on) async {
    if (on == _eInk) return;
    _eInk = on;
    notifyListeners();
    await _save();
  }

  Future<void> _save() => _store.save(<String, dynamic>{
    'mcpPort': _mcpPort,
    'approxDigits': _approxDigits,
    'eInk': _eInk,
  });
}

/// 弹出设置面板。控制台顶栏的齿轮按钮走这里。
Future<void> showSettingsPanel(BuildContext context) async {
  await showModalBottomSheet<void>(
    context: context,
    showDragHandle: true,
    isScrollControlled: true,
    builder: (_) => const _SettingsSheet(),
  );
}

class _SettingsSheet extends StatefulWidget {
  const _SettingsSheet();

  @override
  State<_SettingsSheet> createState() => _SettingsSheetState();
}

class _SettingsSheetState extends State<_SettingsSheet> {
  late final AppSettings _settings = context.read<AppSettings>();
  late final TextEditingController _port = TextEditingController(
    text: '${_settings.mcpPort}',
  );
  String? _portError;

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

  void _applyPort() {
    final v = int.tryParse(_port.text.trim());
    if (v == null || v < AppSettings.minPort || v > AppSettings.maxPort) {
      setState(
        () => _portError =
            '端口要在 ${AppSettings.minPort}~${AppSettings.maxPort} 之间',
      );
      return;
    }
    setState(() => _portError = null);
    _settings.setMcpPort(v);
  }

  @override
  Widget build(BuildContext context) {
    final settings = context.watch<AppSettings>();
    final eInk = settings.eInk;
    final digits = settings.approxDigits;

    return SafeArea(
      child: Padding(
        padding: EdgeInsets.fromLTRB(
          20,
          0,
          20,
          20 + MediaQuery.viewInsetsOf(context).bottom,
        ),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text('设置', style: Theme.of(context).textTheme.titleMedium),
            const SizedBox(height: 16),
            TextField(
              controller: _port,
              keyboardType: TextInputType.number,
              onSubmitted: (_) => _applyPort(),
              onTapOutside: (_) {
                FocusScope.of(context).unfocus();
                _applyPort();
              },
              decoration: InputDecoration(
                labelText: 'MCP 服务器端口',
                helperText: '默认 ${AppSettings.defaultMcpPort}。服务器正在运行时改端口会重启它。',
                errorText: _portError,
                border: const OutlineInputBorder(),
                isDense: true,
              ),
            ),
            const SizedBox(height: 8),
            Row(
              children: [
                const Text('近似值小数位数'),
                const Spacer(),
                Text(
                  '$digits',
                  style: const TextStyle(fontFamily: 'monospace'),
                ),
              ],
            ),
            Slider(
              value: digits.toDouble(),
              min: AppSettings.minDigits.toDouble(),
              max: AppSettings.maxDigits.toDouble(),
              divisions: AppSettings.maxDigits - AppSettings.minDigits,
              label: '$digits',
              onChanged: (v) => _settings.setApproxDigits(v.round()),
            ),
            const Text(
              '工具页的「（近似）」和计算器的「近似」都用这个位数。',
              style: TextStyle(fontSize: 12),
            ),
            const SizedBox(height: 8),
            SwitchListTile(
              contentPadding: EdgeInsets.zero,
              value: eInk,
              title: const Text('E-Ink 模式'),
              subtitle: const Text('所有颜色换成灰阶，动画关闭'),
              onChanged: (v) => _settings.setEInk(v),
            ),
          ],
        ),
      ),
    );
  }
}