using DramaLing.Api.Models.Entities;
using DramaLing.Api.Services;
using Microsoft.Extensions.Logging;
using Moq;

namespace DramaLing.Api.Tests.Services;

/// <summary>
/// QuestionGeneratorService 整合測試
/// </summary>
public class QuestionGeneratorServiceTests : TestBase
{
    private readonly QuestionGeneratorService _questionService;
    private readonly OptionsVocabularyService _optionsService;
    private readonly Mock<ILogger<QuestionGeneratorService>> _mockQuestionLogger;
    private readonly Mock<ILogger<OptionsVocabularyService>> _mockOptionsLogger;

    public QuestionGeneratorServiceTests()
    {
        _mockQuestionLogger = CreateMockLogger<QuestionGeneratorService>();
        _mockOptionsLogger = CreateMockLogger<OptionsVocabularyService>();

        _optionsService = new OptionsVocabularyService(DbContext, MemoryCache, _mockOptionsLogger.Object);
        _questionService = new QuestionGeneratorService(DbContext, _optionsService, _mockQuestionLogger.Object);
    }

    #region Vocab Choice Tests

    [Fact]
    public async Task GenerateQuestionAsync_VocabChoice_WithSufficientVocabulary_ShouldUseSmartOptions()
    {
        // Arrange
        await SeedTestData();
        var flashcard = CreateTestFlashcard("beautiful", "B1", "adjective");

        // Act
        var result = await _questionService.GenerateQuestionAsync(flashcard.Id, "vocab-choice");

        // Assert
        result.Should().NotBeNull();
        result.QuestionType.Should().Be("vocab-choice");
        result.Options.Should().HaveCount(4); // 正確答案 + 3個干擾選項
        result.Options.Should().Contain("beautiful");
        result.CorrectAnswer.Should().Be("beautiful");

        // 驗證干擾選項來自智能詞彙庫
        var distractors = result.Options!.Where(o => o != "beautiful").ToList();
        distractors.Should().HaveCount(3);
    }

    [Fact]
    public async Task GenerateQuestionAsync_VocabChoice_WithInsufficientVocabulary_ShouldUseFallback()
    {
        // Arrange
        await SeedLimitedData();
        var flashcard = CreateTestFlashcard("target", "C2", "idiom"); // 使用較少見的組合

        // Act
        var result = await _questionService.GenerateQuestionAsync(flashcard.Id, "vocab-choice");

        // Assert
        result.Should().NotBeNull();
        result.QuestionType.Should().Be("vocab-choice");
        result.Options.Should().HaveCount(4); // 仍應該有4個選項（使用回退機制）
        result.CorrectAnswer.Should().Be("target");
    }

    [Fact]
    public async Task GenerateQuestionAsync_VocabChoice_ShouldUseFlashcardProperties()
    {
        // Arrange
        await SeedTestData();
        var flashcard = CreateTestFlashcard("computer", "B2", "noun");

        // Act
        var result = await _questionService.GenerateQuestionAsync(flashcard.Id, "vocab-choice");

        // Assert
        result.Should().NotBeNull();
        result.CorrectAnswer.Should().Be("computer");

        // 驗證使用了 Flashcard 的 DifficultyLevel 和 PartOfSpeech
        // 這可以通過檢查生成的干擾選項是否符合相應的 CEFR 等級和詞性來間接驗證
    }

    [Fact]
    public async Task GenerateQuestionAsync_VocabChoice_WithNullFlashcardProperties_ShouldUseDefaults()
    {
        // Arrange
        await SeedTestData();
        var flashcard = CreateTestFlashcard("test", null, null); // 空的屬性

        // Act
        var result = await _questionService.GenerateQuestionAsync(flashcard.Id, "vocab-choice");

        // Assert
        result.Should().NotBeNull();
        result.QuestionType.Should().Be("vocab-choice");
        result.CorrectAnswer.Should().Be("test");
        // 應該使用預設值 B1 和 noun
    }

    #endregion

    #region Fill Blank Tests

    [Fact]
    public async Task GenerateQuestionAsync_FillBlank_WithValidExample_ShouldCreateBlankedSentence()
    {
        // Arrange
        var flashcard = CreateTestFlashcard("beautiful", "B1", "adjective", "This is a beautiful flower.");

        // Act
        var result = await _questionService.GenerateQuestionAsync(flashcard.Id, "sentence-fill");

        // Assert
        result.Should().NotBeNull();
        result.QuestionType.Should().Be("sentence-fill");
        result.BlankedSentence.Should().Contain("______");
        result.BlankedSentence.Should().NotContain("beautiful");
        result.CorrectAnswer.Should().Be("beautiful");
        result.Sentence.Should().Be("This is a beautiful flower.");
    }

    [Fact]
    public async Task GenerateQuestionAsync_FillBlank_WithoutExample_ShouldThrowException()
    {
        // Arrange
        var flashcard = CreateTestFlashcard("test", "B1", "noun", null);

        // Act & Assert
        await Assert.ThrowsAsync<ArgumentException>(
            () => _questionService.GenerateQuestionAsync(flashcard.Id, "sentence-fill"));
    }

    #endregion

    #region Sentence Reorder Tests

    [Fact]
    public async Task GenerateQuestionAsync_SentenceReorder_ShouldScrambleWords()
    {
        // Arrange
        var flashcard = CreateTestFlashcard("test", "B1", "noun", "This is a simple test sentence.");

        // Act
        var result = await _questionService.GenerateQuestionAsync(flashcard.Id, "sentence-reorder");

        // Assert
        result.Should().NotBeNull();
        result.QuestionType.Should().Be("sentence-reorder");
        result.ScrambledWords.Should().NotBeNull();
        result.ScrambledWords!.Length.Should().BeGreaterThan(0);
        result.CorrectAnswer.Should().Be("This is a simple test sentence.");

        // 驗證包含所有單字（忽略順序）
        var originalWords = "This is a simple test sentence."
            .Split(' ', StringSplitOptions.RemoveEmptyEntries)
            .Select(w => w.Trim('.', ',', '!', '?', ';', ':'));

        foreach (var word in originalWords)
        {
            result.ScrambledWords.Should().Contain(word);
        }
    }

    #endregion

    #region Sentence Listening Tests

    [Fact]
    public async Task GenerateQuestionAsync_SentenceListening_ShouldProvideOptions()
    {
        // Arrange
        await SeedFlashcardsWithExamples();
        var flashcard = CreateTestFlashcard("test", "B1", "noun", "This is a test sentence.");

        // Act
        var result = await _questionService.GenerateQuestionAsync(flashcard.Id, "sentence-listening");

        // Assert
        result.Should().NotBeNull();
        result.QuestionType.Should().Be("sentence-listening");
        result.Options.Should().HaveCount(4);
        result.Options.Should().Contain("This is a test sentence.");
        result.CorrectAnswer.Should().Be("This is a test sentence.");
        result.AudioUrl.Should().Contain(flashcard.Id.ToString());
    }

    #endregion

    #region Error Handling Tests

    [Fact]
    public async Task GenerateQuestionAsync_WithNonExistentFlashcard_ShouldThrowException()
    {
        // Act & Assert
        await Assert.ThrowsAsync<ArgumentException>(
            () => _questionService.GenerateQuestionAsync(Guid.NewGuid(), "vocab-choice"));
    }

    [Fact]
    public async Task GenerateQuestionAsync_WithUnsupportedQuestionType_ShouldReturnBasicQuestion()
    {
        // Arrange
        var flashcard = CreateTestFlashcard("test", "B1", "noun");

        // Act
        var result = await _questionService.GenerateQuestionAsync(flashcard.Id, "unsupported-type");

        // Assert
        result.Should().NotBeNull();
        result.QuestionType.Should().Be("unsupported-type");
        result.CorrectAnswer.Should().Be("test");
    }

    #endregion

    #region Performance Tests

    [Fact]
    public async Task GenerateQuestionAsync_ShouldCompleteWithinReasonableTime()
    {
        // Arrange
        await SeedTestData();
        var flashcard = CreateTestFlashcard("performance", "B1", "noun");
        var stopwatch = System.Diagnostics.Stopwatch.StartNew();

        // Act
        var result = await _questionService.GenerateQuestionAsync(flashcard.Id, "vocab-choice");

        // Assert
        stopwatch.Stop();
        result.Should().NotBeNull();
        stopwatch.ElapsedMilliseconds.Should().BeLessThan(500); // 應在500ms內完成
    }

    #endregion

    #region Helper Methods

    private async Task SeedTestData()
    {
        var vocabularies = new[]
        {
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "wonderful", CEFRLevel = "B1", PartOfSpeech = "adjective", WordLength = 9, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "amazing", CEFRLevel = "B1", PartOfSpeech = "adjective", WordLength = 7, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "fantastic", CEFRLevel = "B2", PartOfSpeech = "adjective", WordLength = 9, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "excellent", CEFRLevel = "A2", PartOfSpeech = "adjective", WordLength = 9, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "computer", CEFRLevel = "B1", PartOfSpeech = "noun", WordLength = 8, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "keyboard", CEFRLevel = "B1", PartOfSpeech = "noun", WordLength = 8, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "monitor", CEFRLevel = "B2", PartOfSpeech = "noun", WordLength = 7, IsActive = true },
        };

        DbContext.OptionsVocabularies.AddRange(vocabularies);
        await DbContext.SaveChangesAsync();
    }

    private async Task SeedLimitedData()
    {
        var vocabularies = new[]
        {
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "cat", CEFRLevel = "A1", PartOfSpeech = "noun", WordLength = 3, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "dog", CEFRLevel = "A1", PartOfSpeech = "noun", WordLength = 3, IsActive = true }
        };

        DbContext.OptionsVocabularies.AddRange(vocabularies);
        await DbContext.SaveChangesAsync();
    }

    private async Task SeedFlashcardsWithExamples()
    {
        var user = new User { Id = Guid.NewGuid(), Email = "test@example.com", Username = "testuser" };
        DbContext.Users.Add(user);

        var flashcards = new[]
        {
            new Flashcard
            {
                Id = Guid.NewGuid(),
                UserId = user.Id,
                Word = "example1",
                Translation = "範例1",
                Definition = "第一個範例",
                Example = "This is the first example sentence.",
                DifficultyLevel = "B1",
                PartOfSpeech = "noun"
            },
            new Flashcard
            {
                Id = Guid.NewGuid(),
                UserId = user.Id,
                Word = "example2",
                Translation = "範例2",
                Definition = "第二個範例",
                Example = "This is the second example sentence.",
                DifficultyLevel = "B1",
                PartOfSpeech = "noun"
            }
        };

        DbContext.Flashcards.AddRange(flashcards);
        await DbContext.SaveChangesAsync();
    }

    private Flashcard CreateTestFlashcard(string word, string? difficultyLevel, string? partOfSpeech, string? example = null)
    {
        var user = new User { Id = Guid.NewGuid(), Email = "test@example.com", Username = "testuser" };
        DbContext.Users.Add(user);

        var flashcard = new Flashcard
        {
            Id = Guid.NewGuid(),
            UserId = user.Id,
            Word = word,
            Translation = $"{word} 的翻譯",
            Definition = $"{word} 的定義",
            Example = example,
            DifficultyLevel = difficultyLevel,
            PartOfSpeech = partOfSpeech
        };

        DbContext.Flashcards.Add(flashcard);
        DbContext.SaveChanges();

        return flashcard;
    }

    #endregion

    protected override void Dispose()
    {
        ClearDatabase();
        base.Dispose();
    }
}