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

namespace DramaLing.Api.Tests.Services;

/// <summary>
/// OptionsVocabularyService 單元測試
/// </summary>
public class OptionsVocabularyServiceTests : TestBase
{
    private readonly OptionsVocabularyService _service;
    private readonly Mock<ILogger<OptionsVocabularyService>> _mockLogger;

    public OptionsVocabularyServiceTests()
    {
        _mockLogger = CreateMockLogger<OptionsVocabularyService>();
        _service = new OptionsVocabularyService(DbContext, MemoryCache, _mockLogger.Object);
    }

    #region GenerateDistractorsAsync Tests

    [Fact]
    public async Task GenerateDistractorsAsync_WithValidParameters_ShouldReturnDistractors()
    {
        // Arrange
        await SeedTestVocabularyData();

        // Act
        var result = await _service.GenerateDistractorsAsync("target", "B1", "noun", 3);

        // Assert
        result.Should().NotBeNull();
        result.Should().HaveCountLessOrEqualTo(3);
        result.Should().NotContain("target"); // 不應包含目標詞彙
    }

    [Fact]
    public async Task GenerateDistractorsAsync_WithNoAvailableVocabulary_ShouldReturnEmptyList()
    {
        // Arrange - 空資料庫

        // Act
        var result = await _service.GenerateDistractorsAsync("target", "B1", "noun", 3);

        // Assert
        result.Should().BeEmpty();
    }

    [Fact]
    public async Task GenerateDistractorsAsync_WithInsufficientVocabulary_ShouldReturnAvailableWords()
    {
        // Arrange
        await SeedLimitedVocabularyData(); // 只有2個詞彙

        // Act
        var result = await _service.GenerateDistractorsAsync("target", "A1", "noun", 5);

        // Assert
        result.Should().HaveCount(2); // 只能返回2個
    }

    [Fact]
    public async Task GenerateDistractorsAsync_ShouldExcludeTargetWord()
    {
        // Arrange
        await SeedTestVocabularyData();

        // Act
        var result = await _service.GenerateDistractorsAsync("cat", "A1", "noun", 3);

        // Assert
        result.Should().NotContain("cat");
    }

    [Theory]
    [InlineData("", "B1", "noun", 3)]
    [InlineData("word", "", "noun", 3)]
    [InlineData("word", "B1", "", 3)]
    [InlineData("word", "B1", "noun", 0)]
    public async Task GenerateDistractorsAsync_WithInvalidParameters_ShouldHandleGracefully(
        string targetWord, string cefrLevel, string partOfSpeech, int count)
    {
        // Act & Assert
        var result = await _service.GenerateDistractorsAsync(targetWord, cefrLevel, partOfSpeech, count);
        result.Should().NotBeNull();
    }

    #endregion

    #region GenerateDistractorsWithDetailsAsync Tests

    [Fact]
    public async Task GenerateDistractorsWithDetailsAsync_ShouldReturnDetailedVocabulary()
    {
        // Arrange
        await SeedTestVocabularyData();

        // Act
        var result = await _service.GenerateDistractorsWithDetailsAsync("target", "B1", "noun", 2);

        // Assert
        result.Should().NotBeNull();
        result.Should().HaveCountLessOrEqualTo(2);
        result.Should().OnlyContain(v => v.CEFRLevel != null && v.PartOfSpeech != null);
    }

    [Fact]
    public async Task GenerateDistractorsWithDetailsAsync_ShouldMatchWordLengthRange()
    {
        // Arrange
        await SeedTestVocabularyData();
        const string targetWord = "hello"; // 5個字元

        // Act
        var result = await _service.GenerateDistractorsWithDetailsAsync(targetWord, "B1", "noun", 5);

        // Assert
        result.Should().OnlyContain(v => v.WordLength >= 3 && v.WordLength <= 7); // targetLength ± 2
    }

    #endregion

    #region HasSufficientVocabularyAsync Tests

    [Fact]
    public async Task HasSufficientVocabularyAsync_WithSufficientVocabulary_ShouldReturnTrue()
    {
        // Arrange
        await SeedTestVocabularyData();

        // Act
        var result = await _service.HasSufficientVocabularyAsync("A1", "noun");

        // Assert
        result.Should().BeTrue();
    }

    [Fact]
    public async Task HasSufficientVocabularyAsync_WithInsufficientVocabulary_ShouldReturnFalse()
    {
        // Arrange
        await SeedLimitedVocabularyData();

        // Act
        var result = await _service.HasSufficientVocabularyAsync("C2", "adverb");

        // Assert
        result.Should().BeFalse();
    }

    [Fact]
    public async Task HasSufficientVocabularyAsync_WithEmptyDatabase_ShouldReturnFalse()
    {
        // Act
        var result = await _service.HasSufficientVocabularyAsync("B1", "noun");

        // Assert
        result.Should().BeFalse();
    }

    #endregion

    #region Caching Tests

    [Fact]
    public async Task GenerateDistractorsWithDetailsAsync_ShouldUseCaching()
    {
        // Arrange
        await SeedTestVocabularyData();

        // Act - 第一次呼叫
        var result1 = await _service.GenerateDistractorsWithDetailsAsync("target", "B1", "noun", 3);

        // Act - 第二次呼叫（應該使用快取）
        var result2 = await _service.GenerateDistractorsWithDetailsAsync("target", "B1", "noun", 3);

        // Assert
        result1.Should().NotBeNull();
        result2.Should().NotBeNull();
        // 注意：由於有隨機性，我們主要測試快取功能不會拋出異常
    }

    [Fact]
    public async Task CacheInvalidation_ShouldWorkCorrectly()
    {
        // Arrange
        await SeedTestVocabularyData();
        await _service.GenerateDistractorsWithDetailsAsync("target", "B1", "noun", 3);

        // Act
        ClearCache();
        var resultAfterClearCache = await _service.GenerateDistractorsWithDetailsAsync("target", "B1", "noun", 3);

        // Assert
        resultAfterClearCache.Should().NotBeNull();
    }

    #endregion

    #region CEFR Level Tests

    [Fact]
    public async Task GenerateDistractorsAsync_ShouldIncludeAdjacentCEFRLevels()
    {
        // Arrange
        await SeedVocabularyWithDifferentLevels();

        // Act
        var result = await _service.GenerateDistractorsWithDetailsAsync("target", "B1", "noun", 10);

        // Assert
        result.Should().Contain(v => v.CEFRLevel == "A2" || v.CEFRLevel == "B1" || v.CEFRLevel == "B2");
    }

    #endregion

    #region Error Handling Tests

    [Fact]
    public async Task GenerateDistractorsAsync_WithDatabaseError_ShouldReturnEmptyListAndLog()
    {
        // Arrange
        await DbContext.Database.EnsureDeletedAsync(); // 破壞資料庫連接

        // Act
        var result = await _service.GenerateDistractorsAsync("target", "B1", "noun", 3);

        // Assert
        result.Should().BeEmpty();

        // 驗證日誌記錄
        _mockLogger.Verify(
            x => x.Log(
                LogLevel.Error,
                It.IsAny<EventId>(),
                It.Is<It.IsAnyType>((v, t) => v.ToString()!.Contains("Error generating distractors")),
                It.IsAny<Exception>(),
                It.IsAny<Func<It.IsAnyType, Exception?, string>>()),
            Times.Once);
    }

    #endregion

    #region Test Data Setup

    private async Task SeedTestVocabularyData()
    {
        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 },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "house", CEFRLevel = "A1", PartOfSpeech = "noun", WordLength = 5, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "beautiful", CEFRLevel = "B1", PartOfSpeech = "adjective", WordLength = 9, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "quickly", CEFRLevel = "B1", PartOfSpeech = "adverb", WordLength = 7, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "table", CEFRLevel = "A2", PartOfSpeech = "noun", WordLength = 5, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "computer", CEFRLevel = "B1", PartOfSpeech = "noun", WordLength = 8, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "wonderful", CEFRLevel = "B1", PartOfSpeech = "adjective", WordLength = 9, IsActive = true }
        };

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

    private async Task SeedLimitedVocabularyData()
    {
        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 SeedVocabularyWithDifferentLevels()
    {
        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 = "A2", PartOfSpeech = "noun", WordLength = 3, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "book", CEFRLevel = "B1", PartOfSpeech = "noun", WordLength = 4, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "table", CEFRLevel = "B2", PartOfSpeech = "noun", WordLength = 5, IsActive = true },
            new OptionsVocabulary { Id = Guid.NewGuid(), Word = "chair", CEFRLevel = "C1", PartOfSpeech = "noun", WordLength = 5, IsActive = true }
        };

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

    #endregion

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