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

/// MCP 服务器的控制通道。
const MethodChannel mcpChannel = MethodChannel('com.nonvioce.cal/mcp');

/// MCP 服务器的状态。
class McpStatus {
  final bool running;
  final int port;
  final List<String> tools;
  final String? error;

  const McpStatus({
    required this.running,
    required this.port,
    this.tools = const [],
    this.error,
  });

  /// 局域网地址。真正的 IP 由服务端在状态里给出，这里只是兜底显示。
  String get endpoint => 'http://<本机 IP>:$port/mcp';

  static const idle = McpStatus(running: false, port: 0);
}

/// 读写 MCP 服务器状态。
///
/// 按设计（Q18/Q25），MCP 是**只读 + 求值**的服务：AI 客户端能算、能取会话状态、
/// 能读语法文档，但**不能**往里塞代码或文件 —— 插件相关的五个工具已经全部删掉，
/// 也没有 Rhino。
class McpController extends ChangeNotifier {
  McpStatus status = McpStatus.idle;
  bool busy = false;

  Future<void> refresh() async {
    try {
      final m = await mcpChannel.invokeMapMethod<String, dynamic>('status');
      status = _parse(m);
    } on PlatformException catch (e) {
      status = McpStatus(running: false, port: 0, error: e.message);
    }
    notifyListeners();
  }

  Future<void> start() async {
    busy = true;
    notifyListeners();
    try {
      final m = await mcpChannel.invokeMapMethod<String, dynamic>('start');
      status = _parse(m);
    } on PlatformException catch (e) {
      status = McpStatus(running: false, port: 0, error: e.message);
    }
    busy = false;
    notifyListeners();
  }

  Future<void> stop() async {
    busy = true;
    notifyListeners();
    try {
      await mcpChannel.invokeMethod<Object?>('stop');
      status = McpStatus.idle;
    } on PlatformException catch (e) {
      status = McpStatus(running: false, port: 0, error: e.message);
    }
    busy = false;
    notifyListeners();
  }

  static McpStatus _parse(Map<String, dynamic>? m) {
    if (m == null) return McpStatus.idle;
    return McpStatus(
      running: m['running'] == true,
      port: (m['port'] as num?)?.toInt() ?? 0,
      tools: ((m['tools'] as List?) ?? const []).map((e) => '$e').toList(),
      error: m['error'] as String?,
    );
  }
}

/// 弹出 MCP 控制面板。控制台的 `mcp` 命令走这里。
Future<void> showMcpPanel(BuildContext context) async {
  final ctrl = McpController();
  await ctrl.refresh();
  if (!context.mounted) return;

  await showModalBottomSheet<void>(
    context: context,
    showDragHandle: true,
    builder: (_) => ChangeNotifierProvider.value(
      value: ctrl,
      child: const _McpSheet(),
    ),
  );
}

class _McpSheet extends StatelessWidget {
  const _McpSheet();

  @override
  Widget build(BuildContext context) {
    final ctrl = context.watch<McpController>();
    final s = ctrl.status;
    final scheme = Theme.of(context).colorScheme;

    return SafeArea(
      child: Padding(
        padding: const EdgeInsets.fromLTRB(20, 0, 20, 20),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                Icon(
                  s.running ? Icons.cloud_done_outlined : Icons.cloud_off_outlined,
                  color: s.running ? scheme.primary : scheme.outline,
                ),
                const SizedBox(width: 8),
                Text('MCP 服务器',
                    style: Theme.of(context).textTheme.titleMedium),
                const Spacer(),
                if (s.running)
                  Text('端口 ${s.port}',
                      style: const TextStyle(fontFamily: 'monospace')),
              ],
            ),
            const SizedBox(height: 12),
            const Text(
              '把计算引擎开放给 AI 客户端。只读 + 求值：'
              '对方可以计算、读取当前变量和语法文档，但不能创建插件或写入文件。',
              style: TextStyle(fontSize: 13),
            ),
            if (s.error != null) ...[
              const SizedBox(height: 10),
              Text(s.error!,
                  style: TextStyle(color: scheme.error, fontSize: 13)),
            ],
            if (s.running && s.tools.isNotEmpty) ...[
              const SizedBox(height: 12),
              Text('暴露的工具（${s.tools.length}）',
                  style: Theme.of(context).textTheme.labelLarge),
              const SizedBox(height: 6),
              Wrap(
                spacing: 6,
                runSpacing: 6,
                children: [
                  for (final t in s.tools)
                    Chip(
                      label: Text(t, style: const TextStyle(fontSize: 12)),
                      visualDensity: VisualDensity.compact,
                      materialTapTargetSize:
                          MaterialTapTargetSize.shrinkWrap,
                    ),
                ],
              ),
              const SizedBox(height: 12),
              SelectableText(
                s.endpoint,
                style: const TextStyle(fontFamily: 'monospace', fontSize: 13),
              ),
            ],
            const SizedBox(height: 16),
            Row(
              children: [
                FilledButton.icon(
                  onPressed: ctrl.busy
                      ? null
                      : () => s.running ? ctrl.stop() : ctrl.start(),
                  icon: Icon(s.running ? Icons.stop : Icons.play_arrow),
                  label: Text(s.running ? '停止' : '启动'),
                ),
                const SizedBox(width: 12),
                TextButton(
                  onPressed: ctrl.busy ? null : ctrl.refresh,
                  child: const Text('刷新'),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}