using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using GermanApp.Application.DTOs;
using GermanApp.Application.Services;
using GermanApp.Domain.Entities;
using GermanApp.Domain.Interfaces;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Moq;

namespace GermanApp.Tests.Unit.Application.Services;

[TestClass]
public class LevelServiceTests
{
    private Mock<ILevelRepository> _mockRepo;
    private LevelService _service;

    [TestInitialize]
    public void Setup()
    {
        _mockRepo = new Mock<ILevelRepository>();
        _service = new LevelService(_mockRepo.Object);
    }

    [TestMethod]
    public async Task GetAllLevelsAsync_ReturnsMappedDtoList()
    {
        var levels = new List<Level> { Level.Create("A1", "A1", 1) };
        _mockRepo.Setup(r => r.GetAllOrderedAsync(It.IsAny<CancellationToken>()))
            .ReturnsAsync(levels);

        var result = await _service.GetAllLevelsAsync();

        Assert.AreEqual(1, result.Count);
        Assert.AreEqual("A1", result[0].Name);
    }

    [TestMethod]
    public async Task GetLevelByIdAsync_WithExistingId_ReturnsLevel()
    {
        var level = Level.Create("A1", "A1", 1);
        _mockRepo.Setup(r => r.GetByIdAsync(1, It.IsAny<CancellationToken>()))
            .ReturnsAsync(level);

        var result = await _service.GetLevelByIdAsync(1);

        Assert.IsNotNull(result);
        Assert.AreEqual("A1", result.Name);
    }

    [TestMethod]
    public async Task GetLevelByIdAsync_WithNonExistingId_ReturnsNull()
    {
        _mockRepo.Setup(r => r.GetByIdAsync(999, It.IsAny<CancellationToken>()))
            .ReturnsAsync((Level?)null);

        var result = await _service.GetLevelByIdAsync(999);

        Assert.IsNull(result);
    }

    [TestMethod]
    public async Task GetLevelByCodeAsync_WithExistingCode_ReturnsLevel()
    {
        var level = Level.Create("A1", "A1", 1);
        _mockRepo.Setup(r => r.GetByCodeAsync("A1", It.IsAny<CancellationToken>()))
            .ReturnsAsync(level);

        var result = await _service.GetLevelByCodeAsync("A1");

        Assert.IsNotNull(result);
        Assert.AreEqual("A1", result.Code);
    }

    [TestMethod]
    public async Task CreateLevelAsync_WithValidDto_CallsAddAsync()
    {
        var dto = new CreateLevelDto("Test", "T1", 1);
        var level = Level.Create("Test", "T1", 1);
        _mockRepo.Setup(r => r.AddAsync(It.IsAny<Level>(), It.IsAny<CancellationToken>()))
            .ReturnsAsync(level);

        var result = await _service.CreateLevelAsync(dto);

        Assert.IsNotNull(result);
        _mockRepo.Verify(r => r.AddAsync(It.IsAny<Level>(), It.IsAny<CancellationToken>()), Times.Once);
    }

    [TestMethod]
    public async Task UpdateLevelAsync_WithExistingLevel_CallsUpdateAsync()
    {
        var existing = Level.Create("A1", "A1", 1);
        var dto = new UpdateLevelDto("New", "N1", 2);
        _mockRepo.Setup(r => r.GetByIdAsync(1, It.IsAny<CancellationToken>()))
            .ReturnsAsync(existing);
        _mockRepo.Setup(r => r.UpdateAsync(existing, It.IsAny<CancellationToken>()))
            .Returns(Task.CompletedTask);

        var result = await _service.UpdateLevelAsync(1, dto);

        Assert.IsNotNull(result);
        _mockRepo.Verify(r => r.UpdateAsync(existing, It.IsAny<CancellationToken>()), Times.Once);
    }

    [TestMethod]
    public async Task UpdateLevelAsync_WithNonExistingLevel_ReturnsNull()
    {
        var dto = new UpdateLevelDto("New", "N1", 2);
        _mockRepo.Setup(r => r.GetByIdAsync(999, It.IsAny<CancellationToken>()))
            .ReturnsAsync((Level?)null);

        var result = await _service.UpdateLevelAsync(999, dto);

        Assert.IsNull(result);
    }

    [TestMethod]
    public async Task DeleteLevelAsync_WithExistingLevel_ReturnsTrue()
    {
        var level = Level.Create("A1", "A1", 1);
        _mockRepo.Setup(r => r.GetByIdAsync(1, It.IsAny<CancellationToken>()))
            .ReturnsAsync(level);
        _mockRepo.Setup(r => r.DeleteAsync(level, It.IsAny<CancellationToken>()))
            .Returns(Task.CompletedTask);

        var result = await _service.DeleteLevelAsync(1);

        Assert.IsTrue(result);
    }

    [TestMethod]
    public async Task DeleteLevelAsync_WithNonExistingLevel_ReturnsFalse()
    {
        _mockRepo.Setup(r => r.GetByIdAsync(999, It.IsAny<CancellationToken>()))
            .ReturnsAsync((Level?)null);

        var result = await _service.DeleteLevelAsync(999);

        Assert.IsFalse(result);
    }
}