// Dart 侧验证：把 Symja 通道 mock 掉，检查外壳、计算器按键、控制台命令、工具页。
// 真机端到端验证另做（本构建机没有 KVM，跑不了模拟器）。
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_test/flutter_test.dart';

import 'package:cal/calculator_page.dart';
import 'package:cal/console_page.dart';
import 'package:cal/expr_editor.dart';
import 'package:cal/main.dart';
import 'package:cal/tools_page.dart';

void main() {
  const symja = MethodChannel('com.nonvioce.cal/symja');
  const mcp = MethodChannel('com.nonvioce.cal/mcp');
  final calls = <MethodCall>[];

  setUp(() {
    calls.clear();
    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
        .setMockMethodCallHandler(symja, (call) async {
      calls.add(call);
      switch (call.method) {
        case 'evaluate':
          final expr = call.arguments['expr'] as String;
          if (expr == 'boom') {
            return <String, dynamic>{'ok': false, 'error': '模拟的失败'};
          }
          return <String, dynamic>{
            'ok': true,
            'text': 'x^3/3',
            'tex': r'\frac{{x}^{3}}{3}',
            'ms': 12,
          };
        case 'variables':
          return <String, dynamic>{
            'ok': true,
            'vars': [
              {'name': 'a', 'value': '42'},
            ],
          };
        case 'exportSession':
          return <String, dynamic>{'ok': true, 'defs': ['a=42']};
        case 'importSession':
          return <String, dynamic>{'ok': true, 'applied': 1, 'failed': []};
        case 'clearVariable':
        case 'clearAll':
          return <String, dynamic>{'ok': true};
        case 'sample':
          return <String, dynamic>{
            'ok': true,
            'ys': [0.0, 1.0, 0.0],
            'ms': 5,
          };
        case 'cancel':
          return null;
        default:
          return null;
      }
    });
    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
        .setMockMethodCallHandler(mcp, (call) async {
      calls.add(call);
      switch (call.method) {
        case 'status':
          return <String, dynamic>{
            'running': false,
            'port': 8734,
            'tools': ['evaluate', 'solve'],
          };
        default:
          return null;
      }
    });
  });

  tearDown(() {
    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
        .setMockMethodCallHandler(symja, null);
    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
        .setMockMethodCallHandler(mcp, null);
  });

  Future<void> pumpApp(WidgetTester tester) async {
    await tester.pumpWidget(const CalApp());
    await tester.pumpAndSettle();
  }

  Future<void> goTo(WidgetTester tester, String tab) async {
    await tester.tap(find.text(tab));
    await tester.pumpAndSettle();
  }

  /// IndexedStack 会让三个页面同时存在，所以查找必须限定在某一页里。
  Finder inPage(Type page, Finder matching) =>
      find.descendant(of: find.byType(page), matching: matching);

  Future<void> submit(WidgetTester tester, String text) async {
    await tester.enterText(inPage(ConsolePage, find.byType(TextField)), text);
    await tester.testTextInput.receiveAction(TextInputAction.done);
    await tester.pumpAndSettle();
  }

  /// 按计算器上的某个键。按键带 ValueKey，避免和编辑器里的字面量撞车。
  Future<void> press(WidgetTester tester, String label) async {
    await tester.tap(find.byKey(ValueKey('key-$label')));
    await tester.pumpAndSettle();
  }

  group('外壳', () {
    testWidgets('三个界面：计算器 / 工具 / 控制台', (tester) async {
      await pumpApp(tester);
      expect(find.text('计算器'), findsWidgets);
      expect(find.text('工具'), findsWidgets);
      expect(find.text('控制台'), findsWidgets);
      // 默认进计算器
      expect(find.byType(CalculatorPage), findsOneWidget);
    });
  });

  group('计算器（结构化输入）', () {
    testWidgets('按 ∫ 插出 Integrate 模板，并在显示区露出序列化结果', (tester) async {
      await pumpApp(tester);
      await press(tester, '∫');

      // 空槽序列化成 Null，用户一眼能看出还没填
      expect(find.text('Integrate[Null, x]'), findsOneWidget);
    });

    testWidgets('模板槽里能接着打字（光标落在第一个参数）', (tester) async {
      await pumpApp(tester);
      await press(tester, '∫');
      await press(tester, 'x');

      expect(find.text('Integrate[x, x]'), findsOneWidget);
    });

    testWidgets('^ 把左边的节点收成底，光标落到指数', (tester) async {
      await pumpApp(tester);
      await press(tester, 'x');
      await press(tester, '^');
      await press(tester, '2');

      expect(find.text('x^2'), findsOneWidget);
    });

    testWidgets('数字键并入同一个字面量', (tester) async {
      await pumpApp(tester);
      await press(tester, '4');
      await press(tester, '2');

      // 编辑器里的字面量 42 和下面那行序列化结果都是 '42'，所以是 findsWidgets
      expect(find.text('42'), findsWidgets);
    });

    testWidgets('实时预览走 preview 标志，不污染 %', (tester) async {
      await pumpApp(tester);
      await press(tester, 'sin');
      await press(tester, 'x');
      // 等防抖
      await tester.pump(const Duration(milliseconds: 700));
      await tester.pumpAndSettle();

      // 按 sin 的那次也会触发预览（expr = Sin[Null]），所以取最后一次
      final c = calls.lastWhere((c) => c.method == 'evaluate');
      expect(c.arguments['preview'], true);
      expect(c.arguments['expr'], 'Sin[x]');
    });

    testWidgets('按 = 提交时把 preview 置 false（正式求值要更新 %）', (tester) async {
      await pumpApp(tester);
      await press(tester, 'sin');
      await press(tester, 'x');
      await press(tester, '=');

      final evals = calls.where((c) => c.method == 'evaluate').toList();
      final committed = evals.where((c) => c.arguments['preview'] == false);
      expect(committed, isNotEmpty);
      expect(committed.last.arguments['expr'], 'Sin[x]');
    });

    testWidgets('打完字光标仍在（回归：光标槽判定不能比槽内位置）', (tester) async {
      await pumpApp(tester);
      expect(find.byKey(const ValueKey('expr-caret')), findsOneWidget);

      await press(tester, 'x');
      // 以前这里会消失：offset 从 0 变成 1，而它错误地参与了对"槽"的相等判断
      expect(find.byKey(const ValueKey('expr-caret')), findsOneWidget);

      await press(tester, '2');
      expect(find.byKey(const ValueKey('expr-caret')), findsOneWidget);
    });

    testWidgets('点节点左半边能把光标放回最前面', (tester) async {
      await pumpApp(tester);
      await press(tester, 'x');
      await press(tester, '+');
      await press(tester, '1');
      expect(find.text('x+1'), findsOneWidget);

      // 点 x 的左半边 → 光标应当落到 x 前面
      final xRect = tester.getRect(
        find.descendant(of: find.byType(ExprEditor), matching: find.text('x')),
      );
      await tester.tapAt(Offset(xRect.left + 1, xRect.center.dy));
      await tester.pumpAndSettle();

      // 再打一个 2：插到最前面才是 2x+1；若光标落在 x 之后就成 x2+1
      await press(tester, '2');
      expect(find.text('2x+1'), findsOneWidget);
    });

    testWidgets('点节点右半边把光标放到它后面', (tester) async {
      await pumpApp(tester);
      await press(tester, 'x');
      await press(tester, '+');

      final xRect = tester.getRect(
        find.descendant(of: find.byType(ExprEditor), matching: find.text('x')),
      );
      await tester.tapAt(Offset(xRect.right - 1, xRect.center.dy));
      await tester.pumpAndSettle();

      await press(tester, '2');
      expect(find.text('x2+'), findsOneWidget);
    });

    testWidgets('默认精确：求值原样送出去', (tester) async {
      await pumpApp(tester);
      await press(tester, 'sin');
      await press(tester, 'x');
      await press(tester, '=');

      final committed = calls.where(
          (c) => c.method == 'evaluate' && c.arguments['preview'] == false);
      expect(committed.last.arguments['expr'], 'Sin[x]');
    });

    testWidgets('切到近似后，求值套上 N[...]', (tester) async {
      await pumpApp(tester);
      await press(tester, 'sin');
      await press(tester, 'x');

      await tester.tap(find.text('精确'));
      await tester.pumpAndSettle();
      expect(find.text('≈ 近似'), findsOneWidget);

      await press(tester, '=');
      final committed = calls.where(
          (c) => c.method == 'evaluate' && c.arguments['preview'] == false);
      expect(committed.last.arguments['expr'], 'N[Sin[x], 15]');
    });

    testWidgets('近似模式不碰赋值表达式（否则赋值会被变成求值）', (tester) async {
      await pumpApp(tester);
      // 先在计算器里打开近似
      await tester.tap(find.text('精确'));
      await tester.pumpAndSettle();

      // 到控制台提交一个赋值
      await goTo(tester, '控制台');
      await submit(tester, 'a = 1/3');

      final committed = calls.where(
          (c) => c.method == 'evaluate' && c.arguments['preview'] == false);
      expect(committed.last.arguments['expr'], 'a = 1/3');
    });

    testWidgets('CLR 清空', (tester) async {
      await pumpApp(tester);
      await press(tester, 'sin');
      expect(find.text('Sin[Null]'), findsOneWidget);

      await press(tester, 'CLR');
      expect(find.text('Null'), findsOneWidget);
    });
  });

  group('复制粘贴', () {
    /// 把系统通道的剪贴板换成内存版，并记录写入。
    ({List<String> copied, void Function(String?) feed}) mockClipboard(
        WidgetTester tester) {
      final copied = <String>[];
      String? available;
      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
          .setMockMethodCallHandler(SystemChannels.platform, (call) async {
        switch (call.method) {
          case 'Clipboard.setData':
            final t = (call.arguments as Map)['text'] as String;
            copied.add(t);
            available = t; // 有写有读，跟真剪贴板一样
            return null;
          case 'Clipboard.getData':
            return available == null ? null : <String, dynamic>{'text': available};
          default:
            return null;
        }
      });
      addTearDown(() => TestDefaultBinaryMessengerBinding
          .instance.defaultBinaryMessenger
          .setMockMethodCallHandler(SystemChannels.platform, null));
      return (copied: copied, feed: (v) => available = v);
    }

    Future<void> pickMenu(WidgetTester tester, String item) async {
      await tester.tap(find.byIcon(Icons.more_vert));
      await tester.pumpAndSettle();
      await tester.tap(find.text(item));
      await tester.pumpAndSettle();
    }

    Finder inEditor(String text) => find.descendant(
        of: find.byType(ExprEditor), matching: find.text(text));

    testWidgets('长按选中一段 → 操作栏自动出现 → 剪切', (tester) async {
      final clip = mockClipboard(tester);
      await pumpApp(tester);
      for (final k in ['2', 'x', '+', '1']) {
        await press(tester, k);
      }

      await tester.longPress(inEditor('2'));
      await tester.pumpAndSettle();
      // 选中后操作栏自动出现
      expect(find.textContaining('已选中'), findsOneWidget);

      // 再点另一个节点 → 扩展选区
      await tester.tap(inEditor('1'));
      await tester.pumpAndSettle();
      expect(find.textContaining('已选中  2x+1'), findsOneWidget);

      await tester.tap(find.text('剪切'));
      await tester.pumpAndSettle();
      expect(clip.copied, ['2x+1']);
      expect(find.text('Null'), findsOneWidget); // 全剪掉了
    });

    testWidgets('剪切后粘到 Log 的括号里', (tester) async {
      final clip = mockClipboard(tester);
      await pumpApp(tester);
      for (final k in ['2', 'x', '+', '1']) {
        await press(tester, k);
      }
      await tester.longPress(inEditor('2'));
      await tester.pumpAndSettle();
      await tester.tap(inEditor('1'));
      await tester.pumpAndSettle();
      await tester.tap(find.text('剪切'));
      await tester.pumpAndSettle();

      // 建一个空的 Log，光标在参数槽里
      await press(tester, 'ln');
      expect(find.text('Log[Null]'), findsOneWidget);

      await pickMenu(tester, '从剪贴板粘贴');
      expect(find.text('Log[2x+1]'), findsWidgets);
    });

    testWidgets('点光标所在位置会弹出粘贴入口', (tester) async {
      final clip = mockClipboard(tester);
      clip.feed('7');
      await pumpApp(tester);
      await press(tester, 'x'); // 光标停在 x 之后

      // 点 x 的右半边 = 光标已经在的地方
      final r = tester.getRect(inEditor('x'));
      await tester.tapAt(Offset(r.right - 1, r.center.dy));
      await tester.pumpAndSettle();
      expect(find.text('粘贴到光标处'), findsOneWidget);

      await tester.tap(find.text('粘贴'));
      await tester.pumpAndSettle();
      expect(find.textContaining('已粘贴到光标处'), findsOneWidget);
    });

    testWidgets('复制表达式进剪贴板', (tester) async {
      final clip = mockClipboard(tester);
      await pumpApp(tester);
      await press(tester, 'x');
      await press(tester, '^');
      await press(tester, '2');

      await pickMenu(tester, '复制表达式');
      expect(clip.copied, ['x^2']);
    });

    testWidgets('粘贴一段 Symja 表达式，转成结构化输入', (tester) async {
      final clip = mockClipboard(tester);
      clip.feed('Integrate[x^2, x]');
      await pumpApp(tester);

      await pickMenu(tester, '从剪贴板粘贴');
      // 编辑器显示区和序列化行都会出现它
      expect(find.text('Integrate[x^2, x]'), findsWidgets);
    });

    testWidgets('粘贴解析不了的东西会明确报错，不会乱猜', (tester) async {
      final clip = mockClipboard(tester);
      clip.feed('x@y');
      await pumpApp(tester);

      await pickMenu(tester, '从剪贴板粘贴');
      expect(find.textContaining('没法转成按钮式输入'), findsOneWidget);
    });

    testWidgets('复制粘贴走一圈，结果一致', (tester) async {
      final clip = mockClipboard(tester);
      await pumpApp(tester);
      for (final k in ['2', 'x', '+', '1']) {
        await press(tester, k);
      }
      await pickMenu(tester, '复制表达式');
      expect(clip.copied.single, '2x+1');

      clip.feed(clip.copied.single);
      await pickMenu(tester, '清空');
      await pickMenu(tester, '从剪贴板粘贴');
      expect(find.text('2x+1'), findsWidgets);
    });
  });

  group('控制台', () {
    testWidgets('提交表达式会送到通道并渲染结果', (tester) async {
      await pumpApp(tester);
      await goTo(tester, '控制台');
      await submit(tester, 'Integrate[x^2, x]');

      final eval = calls.lastWhere((c) => c.method == 'evaluate');
      expect(eval.arguments['expr'], 'Integrate[x^2, x]');
      expect(eval.arguments['preview'], false);
      expect(find.text('x^3/3'), findsWidgets);
    });

    testWidgets('help 是本地命令，不求值', (tester) async {
      await pumpApp(tester);
      await goTo(tester, '控制台');
      await submit(tester, 'help');

      expect(calls.where((c) => c.method == 'evaluate' && c.arguments['preview'] == false),
          isEmpty);
      expect(find.textContaining('命令（小写'), findsOneWidget);
    });

    testWidgets('vars 命令列出变量', (tester) async {
      await pumpApp(tester);
      await goTo(tester, '控制台');
      await submit(tester, 'vars');
      expect(find.text('a = 42'), findsOneWidget);
    });

    testWidgets('失败时显示错误', (tester) async {
      await pumpApp(tester);
      await goTo(tester, '控制台');
      await submit(tester, 'boom');
      expect(find.text('模拟的失败'), findsOneWidget);
    });
  });

  group('工具页', () {
    testWidgets('列出插件，并能按名字过滤', (tester) async {
      await pumpApp(tester);
      await goTo(tester, '工具');

      // 网格是懒加载的，靠后的卡片在测试视口外，所以只断言前几个
      expect(find.text('错位相减法'), findsOneWidget);
      expect(find.text('二项分布'), findsOneWidget);

      await tester.enterText(inPage(ToolsPage, find.byType(TextField)), '回归');
      await tester.pumpAndSettle();

      expect(find.text('线性回归'), findsOneWidget);
      expect(find.text('二项分布'), findsNothing);
    });

    testWidgets('拼音首字母也能搜到', (tester) async {
      await pumpApp(tester);
      await goTo(tester, '工具');

      await tester.enterText(inPage(ToolsPage, find.byType(TextField)), 'xxhg');
      await tester.pumpAndSettle();
      expect(find.text('线性回归'), findsOneWidget);
    });
  });
}