using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using GermanApp.Application.DTOs;
using GermanApp.Application.Services;
using GermanApp.Presentation.Controllers;
using Microsoft.AspNetCore.Mvc;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Moq;

namespace GermanApp.Tests.Integration.Controllers;

/// <summary>
/// Integration tests for LessonsController.
/// Tests controller behavior with mocked services.
/// </summary>
[TestClass]
public class LessonsControllerTests
{
    private Mock<LessonService>? _mockLessonService;
    private Mock<ProgressService>? _mockProgressService;
    private LessonsController? _controller;

    [TestInitialize]
    public void TestInitialize()
    {
        _mockLessonService = new Mock<LessonService>(null!, null!);
        _mockProgressService = new Mock<ProgressService>(null!, null!, null!);
        _controller = new LessonsController(_mockLessonService.Object, _mockProgressService.Object);
    }

    [TestCleanup]
    public void TestCleanup()
    {
        _controller = null;
        _mockLessonService = null;
        _mockProgressService = null;
    }

    private static DateTime TestDate => new DateTime(2024, 1, 1, 0, 0, 0, DateTimeKind.Utc);

    // ==================== GET ALL LESSONS TESTS ====================

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("GetAllLessons")]
    public async Task GetAllLessons_WithData_ReturnsOkWithLessons()
    {
        // Arrange
        var expectedLessons = new List<LessonDto>
        {
            new LessonDto(1, "Greetings", "Learn basic greetings", 1, "A1", "Beginner A1", 1, "Vocabulary", TestDate, null),
            new LessonDto(2, "Introductions", "Learn to introduce yourself", 1, "A1", "Beginner A1", 2, "Vocabulary", TestDate, null)
        };
        
        _mockLessonService!.Setup(s => s.GetAllLessonsAsync(It.IsAny<CancellationToken>()))
            .ReturnsAsync(expectedLessons);

        // Act
        var result = await _controller!.GetAllLessonsAsync();

        // Assert
        Assert.IsInstanceOfType(result, typeof(OkObjectResult));
        var okResult = result as OkObjectResult;
        Assert.IsNotNull(okResult);
        var returnedLessons = okResult.Value as IReadOnlyList<LessonDto>;
        Assert.IsNotNull(returnedLessons);
        Assert.AreEqual(2, returnedLessons.Count);
    }

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("GetAllLessons")]
    public async Task GetAllLessons_WithNoData_ReturnsEmptyList()
    {
        // Arrange
        var expectedLessons = new List<LessonDto>();
        
        _mockLessonService!.Setup(s => s.GetAllLessonsAsync(It.IsAny<CancellationToken>()))
            .ReturnsAsync(expectedLessons);

        // Act
        var result = await _controller!.GetAllLessonsAsync();

        // Assert
        Assert.IsInstanceOfType(result, typeof(OkObjectResult));
        var okResult = result as OkObjectResult;
        Assert.IsNotNull(okResult);
        var returnedLessons = okResult.Value as IReadOnlyList<LessonDto>;
        Assert.IsNotNull(returnedLessons);
        Assert.AreEqual(0, returnedLessons.Count);
    }

    // ==================== GET LESSON BY ID TESTS ====================

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("GetLessonById")]
    public async Task GetLessonById_WithExistingId_ReturnsOkWithLesson()
    {
        // Arrange
        var expectedLesson = new LessonDto(1, "Greetings", "Learn basic greetings", 1, "A1", "Beginner A1", 1, "Vocabulary", TestDate, null);
        
        _mockLessonService!.Setup(s => s.GetLessonByIdAsync(1, It.IsAny<CancellationToken>()))
            .ReturnsAsync(expectedLesson);

        // Act
        var result = await _controller!.GetLessonByIdAsync(1);

        // Assert
        Assert.IsInstanceOfType(result, typeof(OkObjectResult));
        var okResult = result as OkObjectResult;
        Assert.IsNotNull(okResult);
        var returnedLesson = okResult.Value as LessonDto;
        Assert.IsNotNull(returnedLesson);
        Assert.AreEqual(1, returnedLesson.Id);
        Assert.AreEqual("Greetings", returnedLesson.Title);
    }

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("GetLessonById")]
    public async Task GetLessonById_WithNonExistingId_ReturnsNotFound()
    {
        // Arrange
        _mockLessonService!.Setup(s => s.GetLessonByIdAsync(999, It.IsAny<CancellationToken>()))
            .ReturnsAsync((LessonDto?)null);

        // Act
        var result = await _controller!.GetLessonByIdAsync(999);

        // Assert
        Assert.IsInstanceOfType(result, typeof(NotFoundResult));
    }

    // ==================== GET LESSONS BY LEVEL TESTS ====================

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("GetLessonsByLevel")]
    public async Task GetLessonsByLevel_WithExistingLevel_ReturnsOkWithLessons()
    {
        // Arrange
        var expectedLessons = new List<LessonDto>
        {
            new LessonDto(1, "Greetings", "Learn basic greetings", 1, "A1", "Beginner A1", 1, "Vocabulary", TestDate, null)
        };
        
        _mockLessonService!.Setup(s => s.GetLessonsByLevelAsync(1, It.IsAny<CancellationToken>()))
            .ReturnsAsync(expectedLessons);

        // Act
        var result = await _controller!.GetLessonsByLevelAsync(1);

        // Assert
        Assert.IsInstanceOfType(result, typeof(OkObjectResult));
        var okResult = result as OkObjectResult;
        Assert.IsNotNull(okResult);
        var returnedLessons = okResult.Value as IReadOnlyList<LessonDto>;
        Assert.IsNotNull(returnedLessons);
        Assert.AreEqual(1, returnedLessons.Count);
    }

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("GetLessonsByLevel")]
    public async Task GetLessonsByLevel_WithNonExistingLevel_ReturnsEmptyList()
    {
        // Arrange
        var expectedLessons = new List<LessonDto>();
        
        _mockLessonService!.Setup(s => s.GetLessonsByLevelAsync(999, It.IsAny<CancellationToken>()))
            .ReturnsAsync(expectedLessons);

        // Act
        var result = await _controller!.GetLessonsByLevelAsync(999);

        // Assert
        Assert.IsInstanceOfType(result, typeof(OkObjectResult));
        var okResult = result as OkObjectResult;
        Assert.IsNotNull(okResult);
        var returnedLessons = okResult.Value as IReadOnlyList<LessonDto>;
        Assert.IsNotNull(returnedLessons);
        Assert.AreEqual(0, returnedLessons.Count);
    }

    // ==================== CREATE LESSON TESTS ====================

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("CreateLesson")]
    public async Task CreateLesson_WithValidData_ReturnsCreatedAtAction()
    {
        // Arrange
        var createDto = new CreateLessonDto("Greetings", "Learn basic greetings", 1, 1, "Vocabulary");
        var expectedLesson = new LessonDto(1, "Greetings", "Learn basic greetings", 1, "A1", "Beginner A1", 1, "Vocabulary", TestDate, null);
        
        _mockLessonService!.Setup(s => s.CreateLessonAsync(createDto, It.IsAny<CancellationToken>()))
            .ReturnsAsync(expectedLesson);

        // Act
        var result = await _controller!.CreateLessonAsync(createDto);

        // Assert
        Assert.IsInstanceOfType(result, typeof(CreatedAtActionResult));
        var createdResult = result as CreatedAtActionResult;
        Assert.IsNotNull(createdResult);
        var returnedLesson = createdResult.Value as LessonDto;
        Assert.IsNotNull(returnedLesson);
        Assert.AreEqual(1, returnedLesson.Id);
    }

    // ==================== UPDATE LESSON TESTS ====================

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("UpdateLesson")]
    public async Task UpdateLesson_WithExistingId_ReturnsOkWithUpdatedLesson()
    {
        // Arrange
        var updateDto = new UpdateLessonDto("Updated Greetings", "Updated description", 1, 1, "Updated Topic");
        var expectedLesson = new LessonDto(1, "Updated Greetings", "Updated description", 1, "A1", "Beginner A1", 1, "Updated Topic", TestDate, TestDate);
        
        _mockLessonService!.Setup(s => s.UpdateLessonAsync(1, updateDto, It.IsAny<CancellationToken>()))
            .ReturnsAsync(expectedLesson);

        // Act
        var result = await _controller!.UpdateLessonAsync(1, updateDto);

        // Assert
        Assert.IsInstanceOfType(result, typeof(OkObjectResult));
        var okResult = result as OkObjectResult;
        Assert.IsNotNull(okResult);
        var returnedLesson = okResult.Value as LessonDto;
        Assert.IsNotNull(returnedLesson);
        Assert.AreEqual("Updated Greetings", returnedLesson.Title);
    }

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("UpdateLesson")]
    public async Task UpdateLesson_WithNonExistingId_ReturnsNotFound()
    {
        // Arrange
        var updateDto = new UpdateLessonDto("Updated Greetings", "Updated description", 1, 1, "Updated Topic");
        
        _mockLessonService!.Setup(s => s.UpdateLessonAsync(999, updateDto, It.IsAny<CancellationToken>()))
            .ReturnsAsync((LessonDto?)null);

        // Act
        var result = await _controller!.UpdateLessonAsync(999, updateDto);

        // Assert
        Assert.IsInstanceOfType(result, typeof(NotFoundResult));
    }

    // ==================== DELETE LESSON TESTS ====================

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("DeleteLesson")]
    public async Task DeleteLesson_WithExistingId_ReturnsNoContent()
    {
        // Arrange
        _mockLessonService!.Setup(s => s.DeleteLessonAsync(1, It.IsAny<CancellationToken>()))
            .ReturnsAsync(true);

        // Act
        var result = await _controller!.DeleteLessonAsync(1);

        // Assert
        Assert.IsInstanceOfType(result, typeof(NoContentResult));
    }

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("DeleteLesson")]
    public async Task DeleteLesson_WithNonExistingId_ReturnsNotFound()
    {
        // Arrange
        _mockLessonService!.Setup(s => s.DeleteLessonAsync(999, It.IsAny<CancellationToken>()))
            .ReturnsAsync(false);

        // Act
        var result = await _controller!.DeleteLessonAsync(999);

        // Assert
        Assert.IsInstanceOfType(result, typeof(NotFoundResult));
    }

    // ==================== GET FIRST LESSON IN LEVEL TESTS ====================

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("GetFirstLessonInLevel")]
    public async Task GetFirstLessonInLevel_WithExistingLevel_ReturnsOkWithLesson()
    {
        // Arrange
        var expectedLesson = new LessonDto(1, "Greetings", "Learn basic greetings", 1, "A1", "Beginner A1", 1, "Vocabulary", TestDate, null);
        
        _mockLessonService!.Setup(s => s.GetFirstLessonInLevelAsync(1, It.IsAny<CancellationToken>()))
            .ReturnsAsync(expectedLesson);

        // Act
        var result = await _controller!.GetFirstLessonInLevelAsync(1);

        // Assert
        Assert.IsInstanceOfType(result, typeof(OkObjectResult));
        var okResult = result as OkObjectResult;
        Assert.IsNotNull(okResult);
        var returnedLesson = okResult.Value as LessonDto;
        Assert.IsNotNull(returnedLesson);
        Assert.AreEqual(1, returnedLesson.Order);
    }

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("GetFirstLessonInLevel")]
    public async Task GetFirstLessonInLevel_WithNonExistingLevel_ReturnsNotFound()
    {
        // Arrange
        _mockLessonService!.Setup(s => s.GetFirstLessonInLevelAsync(999, It.IsAny<CancellationToken>()))
            .ReturnsAsync((LessonDto?)null);

        // Act
        var result = await _controller!.GetFirstLessonInLevelAsync(999);

        // Assert
        Assert.IsInstanceOfType(result, typeof(NotFoundResult));
    }

    // ==================== IS NEXT LESSON UNLOCKED TESTS ====================

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("IsNextLessonUnlocked")]
    public async Task IsNextLessonUnlocked_WithCompletedPrevious_ReturnsTrue()
    {
        // Arrange
        _mockProgressService!.Setup(s => s.IsNextLessonUnlockedAsync(1, 1, It.IsAny<CancellationToken>()))
            .ReturnsAsync(true);

        // Act
        var result = await _controller!.IsNextLessonUnlockedAsync(1, 1);

        // Assert
        Assert.IsInstanceOfType(result, typeof(OkObjectResult));
        var okResult = result as OkObjectResult;
        Assert.IsNotNull(okResult);
        Assert.AreEqual(true, okResult.Value);
    }

    [TestMethod]
    [TestCategory("LessonsController")]
    [TestCategory("IsNextLessonUnlocked")]
    public async Task IsNextLessonUnlocked_WithIncompletePrevious_ReturnsFalse()
    {
        // Arrange
        _mockProgressService!.Setup(s => s.IsNextLessonUnlockedAsync(1, 1, It.IsAny<CancellationToken>()))
            .ReturnsAsync(false);

        // Act
        var result = await _controller!.IsNextLessonUnlockedAsync(1, 1);

        // Assert
        Assert.IsInstanceOfType(result, typeof(OkObjectResult));
        var okResult = result as OkObjectResult;
        Assert.IsNotNull(okResult);
        Assert.AreEqual(false, okResult.Value);
    }
}