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

import 'curve_plot.dart';
import 'mcp.dart';
import 'session_store.dart';
import 'settings.dart';
import 'symja.dart';

class ConsolePage extends StatefulWidget {
  const ConsolePage({super.key});

  @override
  State<ConsolePage> createState() => _ConsolePageState();
}

class _ConsolePageState extends State<ConsolePage> {
  // 一行一条，不用分栏 —— 中英文混排在等宽字体里对不齐，分栏只会更乱
  static const _helpText = '''
输入任意 Symja 表达式，例如
  Integrate[x^2, x]
  Solve[x^2-1==0, x]
  a = 42

% 表示上一次求值的结果。
变量、函数定义和历史都会自动保存，重启后恢复。

命令（小写；大写的是 Symja 函数）
  help 或 ?        显示这份帮助
  clear 或 cls     清空历史
  clear 变量名      删除某个变量
  reset            清空全部变量和历史
  history          列出输入过的表达式
  vars             列出当前变量
  plot 表达式       画图（x 从 -6.3 到 6.3）
  N 表达式 [位数]   取近似值，默认 15 位
  mcp              MCP 服务器开关
  settings         设置（MCP 端口、E-Ink 模式）''';

  final _ctrl = TextEditingController();
  final _focus = FocusNode();
  final _scroll = ScrollController();
  final _store = SessionStore();

  /// 提交过的原始输入（含命令），供上下翻。
  final List<String> _typed = [];
  int _recall = -1;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) => _bootstrap());
  }

  @override
  void dispose() {
    _ctrl.dispose();
    _focus.dispose();
    _scroll.dispose();
    super.dispose();
  }

  // ------------------------------------------------------------------ 启动恢复

  Future<void> _bootstrap() async {
    if (!mounted) return;
    final session = context.read<SymjaSession>();
    final data = await _store.load();
    if (data != null) {
      final defs =
          ((data['defs'] as List?) ?? const []).map((e) => '$e').toList();
      final r = await session.importSession(defs);

      final hist = (data['history'] as List?) ?? const [];
      session.restoreHistory(hist.map((h) {
        final m = h as Map;
        return (
          input: '${m['input']}',
          text: '${m['text']}',
          ms: (m['ms'] as num?)?.toInt() ?? 0,
        );
      }));

      if (defs.isNotEmpty && mounted) {
        session.addLocal(
          '（会话恢复）',
          text: '恢复了 ${r.applied} 个定义'
              '${r.failed.isEmpty ? '' : '，${r.failed.length} 个失败'}',
        );
      }
    }
    await session.refreshVariables();
    if (mounted) _scrollToEnd();
  }

  // ------------------------------------------------------------------ 持久化

  /// 注意：session 由调用方传进来，不在这里 context.read ——
  /// 本方法会在 await 之后被调用，那时页面可能已经销毁。
  Future<void> _persist(SymjaSession session) async {
    final defs = await session.exportSession();
    await _store.save(<String, dynamic>{
      'defs': defs,
      'history': session.history
          .where((e) => e.result != null)
          .map((e) => <String, dynamic>{
                'input': e.input,
                'text': e.result!.text,
                'ms': e.result!.elapsedMs,
              })
          .toList(),
    });
  }

  // ------------------------------------------------------------------ 输入

  void _recallPrev() {
    if (_typed.isEmpty) return;
    setState(() {
      _recall = _recall < 0 ? _typed.length - 1 : (_recall - 1).clamp(0, _typed.length - 1);
      _ctrl.text = _typed[_recall];
      _ctrl.selection = TextSelection.collapsed(offset: _ctrl.text.length);
    });
  }

  void _recallNext() {
    if (_recall < 0) return;
    setState(() {
      _recall++;
      if (_recall >= _typed.length) {
        _recall = -1;
        _ctrl.text = '';
      } else {
        _ctrl.text = _typed[_recall];
        _ctrl.selection = TextSelection.collapsed(offset: _ctrl.text.length);
      }
    });
  }

  Future<void> _submit(String raw) async {
    final input = raw.trim();
    if (input.isEmpty) return;
    final session = context.read<SymjaSession>();

    _typed.add(input);
    _recall = -1;
    _ctrl.clear();

    final handled = await _runCommand(input, session);
    if (!handled) {
      try {
        await session.evaluate(input);
      } on SymjaException {
        // 失败已记进 session.history，不需要额外处理
      }
      await session.refreshVariables();
    }
    await _persist(session);
    _scrollToEnd();
  }

  /// 返回 true 表示是控制台命令、已经处理掉了。
  Future<bool> _runCommand(String input, SymjaSession s) async {
    final parts = input.split(RegExp(r'\s+'));
    switch (parts.first) {
      case 'help':
      case '?':
        s.addLocal(input, text: _helpText);
        return true;

      case 'cls':
        s.clearHistory();
        return true;

      case 'clear':
        if (parts.length == 1) {
          s.clearHistory();
        } else {
          await s.clearVariable(parts[1]);
          s.addLocal(input, text: '已清除 ${parts[1]}');
        }
        return true;

      case 'reset':
        await s.clearAll();
        _typed.clear();
        await _persist(s);
        s.addLocal(input, text: '已清空全部变量与历史');
        return true;

      case 'history':
        s.addLocal(
          input,
          text: _typed.isEmpty
              ? '(无)'
              : [
                  for (var i = 0; i < _typed.length; i++) '[${i + 1}] ${_typed[i]}',
                ].join('\n'),
        );
        return true;

      case 'vars':
        await s.refreshVariables();
        s.addLocal(
          input,
          text: s.variables.isEmpty
              ? '(无变量)'
              : s.variables.map((v) => '${v.name} = ${v.value}').join('\n'),
        );
        return true;

      case 'mcp':
        if (mounted) await showMcpPanel(context);
        return true;

      case 'settings':
        if (mounted) await showSettingsPanel(context);
        return true;

      case 'plot':
        final expr = input.substring('plot'.length).trim();
        if (expr.isEmpty) {
          s.addLocal(input, error: '用法：plot <表达式>');
          return true;
        }
        final ok = await _plot(s, expr);
        if (ok) {
          s.addLocal(input, text: '$expr  （x ∈ [-6.3, 6.3]，240 个采样点）');
        }
        return true;

      case 'N':
        if (parts.length < 2) {
          s.addLocal(input, error: '用法：N <表达式> [位数]');
          return true;
        }
        final digits = parts.length >= 3 ? parts.last : '30';
        final expr = parts.length >= 3
            ? parts.sublist(1, parts.length - 1).join(' ')
            : parts.sublist(1).join(' ');
        try {
          await s.evaluate('N[$expr, $digits]');
        } on SymjaException {
          // 同上
        }
        await s.refreshVariables();
        return true;
    }
    return false;
  }

  Future<bool> _plot(SymjaSession session, String expr) async {
    try {
      final s = await session.sample(expr, from: -6.3, to: 6.3, count: 240);
      if (!mounted) return false;
      final plot = CurveSeries(
        label: expr,
        color: const Color(0xFF3F51B5),
        points: [
          for (var i = 0; i < s.ys.length; i++) Offset(s.xAt(i), s.ys[i]),
        ],
      );
      await showDialog<void>(
        context: context,
        builder: (_) => AlertDialog(
          title: Text('$expr   （${s.ys.length} 点，${s.elapsedMs} ms）'),
          content: SizedBox(
            width: 360,
            height: 420,
            child: CurvePlot(series: [plot]),
          ),
          actions: [
            TextButton(
              onPressed: () => Navigator.pop(context),
              child: const Text('关闭'),
            ),
          ],
        ),
      );
      return true;
    } on SymjaException catch (e) {
      session.addLocal('plot $expr', error: '$e');
      return false;
    }
  }

  void _scrollToEnd() {
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!_scroll.hasClients) return;
      _scroll.jumpTo(_scroll.position.maxScrollExtent);
    });
  }

  // ------------------------------------------------------------------ UI

  @override
  Widget build(BuildContext context) {
    final session = context.watch<SymjaSession>();
    final entries = session.history;

    return Scaffold(
      appBar: AppBar(
        // 不显示标题 —— 三个 tab 里只有这页还挂着应用名，切页面时顶栏
        // 忽长忽短。应用名在启动器和最近任务里都看得到，这里没必要占一行。
        actions: [
          IconButton(
            tooltip: 'MCP 服务器',
            icon: const Icon(Icons.cloud_outlined),
            onPressed: () => showMcpPanel(context),
          ),
          IconButton(
            tooltip: '变量',
            icon: Badge(
              isLabelVisible: session.variables.isNotEmpty,
              label: Text('${session.variables.length}'),
              child: const Icon(Icons.functions),
            ),
            onPressed: () => _submit('vars'),
          ),
          IconButton(
            tooltip: '帮助',
            icon: const Icon(Icons.help_outline),
            onPressed: () => _submit('help'),
          ),
          IconButton(
            tooltip: '清空历史',
            icon: const Icon(Icons.cleaning_services_outlined),
            onPressed: () => _submit('cls'),
          ),
          IconButton(
            tooltip: '设置',
            icon: const Icon(Icons.settings_outlined),
            onPressed: () => showSettingsPanel(context),
          ),
        ],
      ),
      body: Column(
        children: [
          Expanded(
            child: entries.isEmpty
                ? const Center(child: Text('输入表达式开始，或输入 help'))
                : ListView.builder(
                    controller: _scroll,
                    padding: const EdgeInsets.fromLTRB(12, 12, 12, 4),
                    itemCount: entries.length,
                    itemBuilder: (_, i) =>
                        _EntryTile(index: i + 1, entry: entries[i]),
                  ),
          ),
          SafeArea(top: false, child: _inputBar(session)),
        ],
      ),
    );
  }

  Widget _inputBar(SymjaSession session) {
    return Container(
      decoration: BoxDecoration(
        border: Border(
          top: BorderSide(color: Theme.of(context).dividerColor),
        ),
      ),
      padding: const EdgeInsets.fromLTRB(8, 6, 8, 6),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.center,
        children: [
          Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              _tinyBtn(Icons.keyboard_arrow_up, '上一条', _recallPrev),
              _tinyBtn(Icons.keyboard_arrow_down, '下一条', _recallNext),
            ],
          ),
          const SizedBox(width: 4),
          Text(
            '[${session.history.length + 1}]:',
            style: const TextStyle(fontFamily: 'monospace', fontSize: 13),
          ),
          const SizedBox(width: 6),
          Expanded(
            // 用 Focus 捕获方向键做历史回翻。输入框是单行的，
            // 上下键不会被光标移动占用，所以能冒泡到这里。
            child: Focus(
              onKeyEvent: (_, e) {
                if (e is! KeyDownEvent) return KeyEventResult.ignored;
                if (e.logicalKey == LogicalKeyboardKey.arrowUp) {
                  _recallPrev();
                  return KeyEventResult.handled;
                }
                if (e.logicalKey == LogicalKeyboardKey.arrowDown) {
                  _recallNext();
                  return KeyEventResult.handled;
                }
                return KeyEventResult.ignored;
              },
              child: TextField(
                controller: _ctrl,
                focusNode: _focus,
                style: const TextStyle(fontFamily: 'monospace', fontSize: 15),
                decoration: const InputDecoration(
                  isDense: true,
                  border: InputBorder.none,
                  hintText: '输入表达式或 help',
                ),
                onSubmitted: _submit,
              ),
            ),
          ),
          if (session.busy)
            IconButton(
              tooltip: '取消',
              icon: const Icon(Icons.stop_circle_outlined),
              onPressed: session.cancel,
            )
          else
            IconButton(
              tooltip: '求值',
              icon: const Icon(Icons.send),
              onPressed: () => _submit(_ctrl.text),
            ),
        ],
      ),
    );
  }

  Widget _tinyBtn(IconData icon, String tip, VoidCallback onTap) => InkWell(
        onTap: onTap,
        child: Tooltip(
          message: tip,
          child: Icon(icon, size: 18),
        ),
      );
}

/// 历史里的一条：`[n]: 输入` + 结果（LaTeX 渲染 + 纯文本）或错误。
class _EntryTile extends StatelessWidget {
  const _EntryTile({required this.index, required this.entry});

  final int index;
  final SymjaEntry entry;

  @override
  Widget build(BuildContext context) {
    final scheme = Theme.of(context).colorScheme;
    return Padding(
      padding: const EdgeInsets.only(bottom: 14),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          SelectableText(
            '[$index]: ${entry.input}',
            style: TextStyle(
              fontFamily: 'monospace',
              fontSize: 14,
              color: scheme.primary,
            ),
          ),
          const SizedBox(height: 6),
          if (entry.ok) _ok(context, scheme) else _err(scheme),
        ],
      ),
    );
  }

  Widget _ok(BuildContext context, ColorScheme scheme) {
    final r = entry.result!;
    final plain = SelectableText(
      r.text,
      style: const TextStyle(fontFamily: 'monospace', fontSize: 16),
    );
    if (r.tex == null) return plain;
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        // 同样缩到放得下：控制台的结果可能很长（大矩阵、长小数）
        FittedBox(
          fit: BoxFit.scaleDown,
          alignment: Alignment.centerLeft,
          child: Math.tex(
            r.tex!,
            mathStyle: MathStyle.display,
            textStyle: TextStyle(fontSize: 22, color: scheme.onSurface),
            // ComplexInfinity 之类的输出不是合法 LaTeX，直接退回纯文本
            onErrorFallback: (_) => plain,
          ),
        ),
        const SizedBox(height: 4),
        SelectableText(
          r.text,
          style: TextStyle(
            fontFamily: 'monospace',
            fontSize: 12,
            color: scheme.onSurfaceVariant,
          ),
        ),
      ],
    );
  }

  Widget _err(ColorScheme scheme) => Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Icon(Icons.error_outline, size: 18, color: scheme.error),
          const SizedBox(width: 6),
          Expanded(
            child: SelectableText(
              entry.error ?? '未知错误',
              style: TextStyle(
                fontFamily: 'monospace',
                fontSize: 13,
                color: scheme.error,
              ),
            ),
          ),
        ],
      );
}