import 'package:flutter_test/flutter_test.dart';
import 'package:kouyu_english/core/generated_content.dart';

void main() {
  const valid = '''{
    "schemaVersion":"review-variant-1",
    "variantId":"ai-a0-p12-001",
    "targetItemId":"A0-P12",
    "prompt":"请用英语说你来自哪里。",
    "expectedAnswer":"I’m from [place]."
  }''';

  test('accepts a bounded variant for its requested frozen target', () {
    final item = decodeGeneratedReviewVariant(
      valid,
      expectedTargetItemId: 'A0-P12',
    );

    expect(item, isNotNull);
    expect(item!.targetItemId, 'A0-P12');
  });

  test('rejects an AI variant that changes the target identity', () {
    expect(
      decodeGeneratedReviewVariant(valid, expectedTargetItemId: 'A0-P01'),
      isNull,
    );
  });

  test('rejects unknown schema fields', () {
    final invalid = valid.replaceFirst('}', ',"unsafe":"ignore"}');
    expect(
      decodeGeneratedReviewVariant(invalid, expectedTargetItemId: 'A0-P12'),
      isNull,
    );
  });

  const writing = '''{
    "schemaVersion":"writing-feedback-1",
    "lessonId":"a0-06",
    "verdict":"rewrite",
    "feedback":"加上 from 就能说清来自哪里。",
    "suggestion":"I'm from Hong Kong.",
    "missing":["来自哪里"]
  }''';

  test('accepts bounded writing feedback for its lesson', () {
    final feedback = decodeWritingAiFeedback(
      writing,
      expectedLessonId: 'a0-06',
    );

    expect(feedback, isNotNull);
    expect(feedback!.verdict, 'rewrite');
  });

  test('rejects writing feedback for a different lesson', () {
    expect(decodeWritingAiFeedback(writing, expectedLessonId: 'a0-07'), isNull);
  });

  const lesson = '''{
    "schemaVersion":"lesson-1",
    "lessonId":"ai-a0-p12-1",
    "revision":1,
    "stageVersion":"A0-1.0",
    "source":"aiGenerated",
    "status":"validated",
    "abilityIds":["A0-C06"],
    "prerequisiteIds":["a0-05"],
    "targetItemIds":["A0-P12"],
    "receptiveChunks":[],
    "newItemIds":[],
    "previewItemIds":[],
    "estimatedMinutes":10,
    "tasks":[
      {"taskId":"l","skill":"listening","type":"listenChoice","prompt":"听后选择。","stimulus":"I am from Hong Kong.","answer":"Hong Kong","targetItemIds":["A0-P12"]},
      {"taskId":"s","skill":"speaking","type":"repeat","prompt":"跟读。","stimulus":"I am from Hong Kong.","answer":"I am from Hong Kong.","targetItemIds":["A0-P12"]},
      {"taskId":"r","skill":"reading","type":"readAnswer","prompt":"读后回答。","stimulus":"I am from Hong Kong.","answer":"Hong Kong","targetItemIds":["A0-P12"]},
      {"taskId":"w","skill":"writing","type":"writeAnswer","prompt":"写一句。","stimulus":"来自香港。","answer":"I am from Hong Kong.","targetItemIds":["A0-P12"]}
    ]
  }''';

  test('accepts a bounded four-skill adaptive lesson', () {
    final decoded = decodeGeneratedLesson(
      lesson,
      expectedTargetItemId: 'A0-P12',
    );

    expect(decoded, isNotNull);
    expect(decoded!.tasks.map((task) => task.skill).toSet(), hasLength(4));
  });

  test('adaptive answer check accepts harmless punctuation variation', () {
    final task = decodeGeneratedLesson(
      lesson,
      expectedTargetItemId: 'A0-P12',
    )!.tasks[3];

    expect(matchesAdaptiveLessonAnswer(task, "i am from hong kong!"), isTrue);
  });

  test('adaptive answer check rejects a missing target token', () {
    final task = decodeGeneratedLesson(
      lesson,
      expectedTargetItemId: 'A0-P12',
    )!.tasks[3];

    expect(matchesAdaptiveLessonAnswer(task, 'I am from Hong.'), isFalse);
  });

  test('adaptive answer spec accepts listed slots and rejects exclusions', () {
    const task = GeneratedLessonTask(
      taskId: 'speaking',
      skill: 'speaking',
      type: 'repeat',
      prompt: '说一句。',
      stimulus: 'I am from Hong Kong.',
      answer: 'I am from Hong Kong.',
      targetItemIds: ['A0-P12'],
      answerSpec: GeneratedAnswerSpec(
        requiredAnyPhrases: [
          ['I am', "I'm"],
          ['from'],
          ['Hong Kong'],
        ],
        acceptedAnswers: ['I am from Hong Kong.', "I'm from Hong Kong."],
        forbiddenPhrases: ['Beijing'],
      ),
    );

    expect(matchesAdaptiveLessonAnswer(task, "I'm from Hong Kong!"), isTrue);
    expect(matchesAdaptiveLessonAnswer(task, 'I am from Beijing.'), isFalse);
    expect(matchesAdaptiveLessonAnswer(task, 'Hong Kong.'), isFalse);
  });

  test('rejects an adaptive lesson with a different frozen target', () {
    expect(
      decodeGeneratedLesson(lesson, expectedTargetItemId: 'A0-P11'),
      isNull,
    );
  });

  test(
    'rejects an adaptive lesson that introduces an unknown English word',
    () {
      final invalid = lesson.replaceFirst('Hong Kong', 'library');

      expect(
        decodeGeneratedLesson(invalid, expectedTargetItemId: 'A0-P12'),
        isNull,
      );
    },
  );
}