import 'package:flutter_test/flutter_test.dart';
import 'package:kouyu_english/core/courses/course_repository.dart';
import 'package:kouyu_english/core/courses/courses.dart';
import 'package:kouyu_english/core/models.dart';

/// Every level goes through the same pack structure and the same rules, so
/// the model answers every pack ships have to pass the rules it ships.
void main() {
  setUpAll(() => CourseRepository.instance.load());
  tearDownAll(() => CourseRepository.instance.resetForTest());

  test('each core item and its dictation sentence pass its own rule', () {
    final failures = <String>[];
    for (final pack in CourseRepository.instance.units) {
      for (final item in pack.coreItems) {
        if (item.match.isEmpty) continue;
        // A slot like [place] is filled by the learner, so only a fixed
        // phrase can be checked as written.
        if (!item.en.contains('[') && !matchesRule(item.en, item.match)) {
          failures.add('${item.id} en "${item.en}"');
        }
        if (item.dictationSentence.isNotEmpty &&
            !matchesRule(item.dictationSentence, item.match)) {
          failures.add('${item.id} dictation "${item.dictationSentence}"');
        }
      }
    }
    expect(failures, isEmpty);
  });

  test('each writing example passes its writing rule', () {
    final failures = [
      for (final MapEntry(key: id, value: activity)
          in segmentActivities.entries)
        if (activity.writingExample.isNotEmpty &&
            activity.writingRequiredTerms.isNotEmpty &&
            !matchesRule(
              activity.writingExample,
              activity.writingRequiredTerms,
            ))
          '$id "${activity.writingExample}"',
    ];
    expect(failures, isEmpty);
  });

  test('each dialogue model answer passes its turn', () {
    final failures = <String>[];
    final dialogues = {
      ...segmentDialogues,
      for (final scene in allScenes) 'scene ${scene.id}': scene.script,
    };
    for (final MapEntry(key: id, value: script) in dialogues.entries) {
      for (var stage = 0; stage < script.hints.length; stage++) {
        if (!matchesDialogueStage(script, stage, script.hints[stage])) {
          failures.add('$id #${stage + 1} "${script.hints[stage]}"');
        }
      }
    }
    expect(failures, isEmpty);
  });

  test('every A0 pattern says when it is used', () {
    final missing = [
      for (final pack in CourseRepository.instance.units)
        if (pack.level == 'A0')
          for (final item in pack.coreItems)
            if (item.type != 'word' && (coreUsage(item.id)?.when ?? '').isEmpty)
              '${item.id} "${item.en}"',
    ];
    expect(
      missing,
      isEmpty,
      reason: '句型要写清什么时候用，否则学会了也不知道该用哪一句',
    );
  });

  test('every confusable points at a real taught item with a note', () {
    final broken = <String>[];
    for (final pack in CourseRepository.instance.units) {
      for (final item in pack.coreItems) {
        for (final other in item.usage.confuse) {
          if (!isCoreItem(other.id)) broken.add('${item.id} → ${other.id} 不存在');
          if (other.note.isEmpty) broken.add('${item.id} → ${other.id} 没写区别');
          if (other.id == item.id) broken.add('${item.id} 指向自己');
        }
      }
    }
    expect(broken, isEmpty);
  });

  test('every A0 pattern has something to be told apart from', () {
    final alone = [
      for (final pack in CourseRepository.instance.units)
        if (pack.level == 'A0')
          for (final item in pack.coreItems)
            if (item.type != 'word' && item.usage.confuse.isEmpty)
              '${item.id} "${item.en}"',
    ];
    expect(alone, isEmpty, reason: '每个句型都要有一句容易混的，才出得了辨析题');
  });

  test('a pattern can be told apart from something already taught', () {
    final order = {
      for (var i = 0; i < CourseRepository.instance.units.length; i++)
        CourseRepository.instance.units[i].id: i,
    };
    final late = <String>[];
    for (final pack in CourseRepository.instance.units) {
      if (pack.level != 'A0') continue;
      for (final item in pack.coreItems) {
        if (item.type == 'word' || item.usage.confuse.isEmpty) continue;
        // The first review of an item comes a day after its own unit, so a
        // pairing that only names later units has nothing to ask about then.
        final reachable = item.usage.confuse.any((other) {
          final unit = coreItemRegistry[other.id]?.unit;
          return unit != null && (order[unit] ?? 999) <= order[pack.id]!;
        });
        if (!reachable) late.add('${item.id} 的易混句都在后面的单元');
      }
    }
    expect(late, isEmpty);
  });

  test('a contrast question offers the item and something else to pick', () {
    final broken = <String>[];
    for (final id in allCoreItemIds) {
      if ((coreUsage(id)?.confuse ?? const []).isEmpty) continue;
      final question = coreContrastQuestion(id);
      if (question == null) {
        broken.add('$id has confusables but no question');
        continue;
      }
      // Two options is a real choice; more than three turns recall into a
      // reading exercise.
      if (question.options.length < 2 || question.options.length > 3) {
        broken.add('$id has ${question.options.length} options');
      }
      // A situation that quotes one of the sentences gives the choice away.
      for (final option in question.options) {
        if (question.situation.contains(option)) {
          broken.add('$id 的情境里写出了选项「$option」');
        }
      }
      if (!question.options.contains(question.answer)) {
        broken.add('$id answer is not among the options');
      }
      // Two sentences a learner has to tell apart cannot be the same string.
      if (question.options.toSet().length != question.options.length) {
        broken.add('$id repeats an option');
      }
    }
    expect(broken, isEmpty);
  });

  test('assessment tasks are answerable and replacements point home', () {
    final ids = {for (final pack in assessmentPacks) pack.id};
    final failures = <String>[];
    for (final pack in assessmentPacks) {
      if (pack.replaces != null && !ids.contains(pack.replaces)) {
        failures.add('${pack.id} replaces missing ${pack.replaces}');
      }
      for (final task in pack.tasks) {
        final open =
            task.skill == AssessmentSkill.writing ||
            task.skill == AssessmentSkill.speaking;
        if (open) {
          if (task.accept.isEmpty) failures.add('${task.id} has no accept');
          if (task.guide.isEmpty) failures.add('${task.id} has no guide');
        } else {
          final index = task.answerIndex;
          if (index == null || index < 0 || index >= task.choices.length) {
            failures.add('${task.id} answerIndex out of range');
          }
        }
      }
    }
    expect(a0AssessmentPacks, isNotEmpty);
    expect(failures, isEmpty);
  });
}