using BudgetApp.Data;
using BudgetApp.Services;
using BudgetApp.Tests.Helpers;
using Microsoft.EntityFrameworkCore;
using Xunit;

namespace BudgetApp.Tests.Services;

public class CategoryServiceTests
{
    [Fact]
    public async Task GetCategoriesAsync_ReturnsOnlyUserCategories()
    {
        using var factory = new TestDbContextFactory();
        using (var ctx = factory.CreateContext())
        {
            ctx.Categories.AddRange(
                new Category { Name = "Mine", UserId = TestDbContextFactory.TestUserId },
                new Category { Name = "Theirs", UserId = TestDbContextFactory.OtherUserId });
            await ctx.SaveChangesAsync();
        }

        using var context = factory.CreateContext();
        var service = new CategoryService(context);

        var result = await service.GetCategoriesAsync(TestDbContextFactory.TestUserId);

        Assert.Single(result);
        Assert.Equal("Mine", result[0].Name);
    }

    [Fact]
    public async Task GetCategoriesAsync_OrderedByName()
    {
        using var factory = new TestDbContextFactory();
        using (var ctx = factory.CreateContext())
        {
            ctx.Categories.AddRange(
                new Category { Name = "Zebra", UserId = TestDbContextFactory.TestUserId },
                new Category { Name = "Alpha", UserId = TestDbContextFactory.TestUserId });
            await ctx.SaveChangesAsync();
        }

        using var context = factory.CreateContext();
        var service = new CategoryService(context);

        var result = await service.GetCategoriesAsync(TestDbContextFactory.TestUserId);

        Assert.Equal("Alpha", result[0].Name);
        Assert.Equal("Zebra", result[1].Name);
    }

    [Fact]
    public async Task EnsureDefaultCategoriesAsync_CreatesDefaults_WhenEmpty()
    {
        using var factory = new TestDbContextFactory();
        using var context = factory.CreateContext();
        var service = new CategoryService(context);

        await service.EnsureDefaultCategoriesAsync(TestDbContextFactory.TestUserId);

        using var verifyCtx = factory.CreateContext();
        var categories = await verifyCtx.Categories
            .Where(c => c.UserId == TestDbContextFactory.TestUserId)
            .ToListAsync();

        Assert.Equal(18, categories.Count);
        Assert.Contains(categories, c => c.Name == "Groceries" && c.Icon == "🛒");
        Assert.Contains(categories, c => c.Name == "Transport" && c.Icon == "🚗");
        Assert.Contains(categories, c => c.Name == "Salary" && c.Icon == "💰");
    }

    [Fact]
    public async Task EnsureDefaultCategoriesAsync_DoesNotDuplicate_WhenCalledAgain()
    {
        using var factory = new TestDbContextFactory();

        using (var ctx = factory.CreateContext())
        {
            var service = new CategoryService(ctx);
            await service.EnsureDefaultCategoriesAsync(TestDbContextFactory.TestUserId);
        }

        using (var ctx = factory.CreateContext())
        {
            var service = new CategoryService(ctx);
            await service.EnsureDefaultCategoriesAsync(TestDbContextFactory.TestUserId);
        }

        using var verifyCtx = factory.CreateContext();
        var count = await verifyCtx.Categories
            .Where(c => c.UserId == TestDbContextFactory.TestUserId)
            .CountAsync();

        Assert.Equal(18, count);
    }

    [Fact]
    public async Task EnsureDefaultCategoriesAsync_BackfillsIcons_WhenMissing()
    {
        using var factory = new TestDbContextFactory();
        using (var ctx = factory.CreateContext())
        {
            ctx.Categories.Add(new Category
            {
                Name = "Groceries",
                Icon = "",
                UserId = TestDbContextFactory.TestUserId
            });
            await ctx.SaveChangesAsync();
        }

        using var context = factory.CreateContext();
        var service = new CategoryService(context);
        await service.EnsureDefaultCategoriesAsync(TestDbContextFactory.TestUserId);

        using var verifyCtx = factory.CreateContext();
        var category = await verifyCtx.Categories
            .SingleAsync(c => c.Name == "Groceries" && c.UserId == TestDbContextFactory.TestUserId);

        Assert.Equal("🛒", category.Icon);
    }

    [Fact]
    public async Task EnsureDefaultCategoriesAsync_DoesNotOverwrite_ExistingIcons()
    {
        using var factory = new TestDbContextFactory();
        using (var ctx = factory.CreateContext())
        {
            ctx.Categories.Add(new Category
            {
                Name = "Groceries",
                Icon = "🥕",
                UserId = TestDbContextFactory.TestUserId
            });
            await ctx.SaveChangesAsync();
        }

        using var context = factory.CreateContext();
        var service = new CategoryService(context);
        await service.EnsureDefaultCategoriesAsync(TestDbContextFactory.TestUserId);

        using var verifyCtx = factory.CreateContext();
        var category = await verifyCtx.Categories
            .SingleAsync(c => c.Name == "Groceries" && c.UserId == TestDbContextFactory.TestUserId);

        Assert.Equal("🥕", category.Icon);
    }

    [Fact]
    public async Task EnsureDefaultCategoriesAsync_IsolatedPerUser()
    {
        using var factory = new TestDbContextFactory();

        using (var ctx = factory.CreateContext())
        {
            var service = new CategoryService(ctx);
            await service.EnsureDefaultCategoriesAsync(TestDbContextFactory.TestUserId);
        }

        using (var ctx = factory.CreateContext())
        {
            var service = new CategoryService(ctx);
            await service.EnsureDefaultCategoriesAsync(TestDbContextFactory.OtherUserId);
        }

        using var verifyCtx = factory.CreateContext();
        var totalCount = await verifyCtx.Categories.CountAsync();
        Assert.Equal(36, totalCount);
    }

    [Fact]
    public async Task CreateCategoryAsync_AddsToDatabase()
    {
        using var factory = new TestDbContextFactory();
        using var context = factory.CreateContext();
        var service = new CategoryService(context);

        await service.CreateCategoryAsync(new Category
        {
            Name = "Custom",
            Icon = "🎯",
            UserId = TestDbContextFactory.TestUserId
        });

        using var verifyCtx = factory.CreateContext();
        Assert.Single(verifyCtx.Categories);
    }

    [Fact]
    public async Task UpdateCategoryAsync_UpdatesNameAndIcon()
    {
        using var factory = new TestDbContextFactory();
        int categoryId;
        using (var ctx = factory.CreateContext())
        {
            var category = new Category { Name = "Old", Icon = "📁", UserId = TestDbContextFactory.TestUserId };
            ctx.Categories.Add(category);
            await ctx.SaveChangesAsync();
            categoryId = category.Id;
        }

        using var context = factory.CreateContext();
        var service = new CategoryService(context);
        await service.UpdateCategoryAsync(categoryId, TestDbContextFactory.TestUserId, "New", "🎯");

        using var verifyCtx = factory.CreateContext();
        var updated = verifyCtx.Categories.Single();
        Assert.Equal("New", updated.Name);
        Assert.Equal("🎯", updated.Icon);
    }

    [Fact]
    public async Task UpdateCategoryAsync_WrongUser_DoesNothing()
    {
        using var factory = new TestDbContextFactory();
        int categoryId;
        using (var ctx = factory.CreateContext())
        {
            var category = new Category { Name = "Original", Icon = "📁", UserId = TestDbContextFactory.TestUserId };
            ctx.Categories.Add(category);
            await ctx.SaveChangesAsync();
            categoryId = category.Id;
        }

        using var context = factory.CreateContext();
        var service = new CategoryService(context);
        await service.UpdateCategoryAsync(categoryId, TestDbContextFactory.OtherUserId, "Hacked", "💀");

        using var verifyCtx = factory.CreateContext();
        Assert.Equal("Original", verifyCtx.Categories.Single().Name);
    }

    [Fact]
    public async Task DeleteCategoryAsync_RemovesCategory()
    {
        using var factory = new TestDbContextFactory();
        int categoryId;
        using (var ctx = factory.CreateContext())
        {
            var category = new Category { Name = "ToDelete", UserId = TestDbContextFactory.TestUserId };
            ctx.Categories.Add(category);
            await ctx.SaveChangesAsync();
            categoryId = category.Id;
        }

        using var context = factory.CreateContext();
        var service = new CategoryService(context);
        await service.DeleteCategoryAsync(categoryId, TestDbContextFactory.TestUserId);

        using var verifyCtx = factory.CreateContext();
        Assert.Empty(verifyCtx.Categories);
    }

    [Fact]
    public async Task DeleteCategoryAsync_WrongUser_DoesNothing()
    {
        using var factory = new TestDbContextFactory();
        int categoryId;
        using (var ctx = factory.CreateContext())
        {
            var category = new Category { Name = "Protected", UserId = TestDbContextFactory.TestUserId };
            ctx.Categories.Add(category);
            await ctx.SaveChangesAsync();
            categoryId = category.Id;
        }

        using var context = factory.CreateContext();
        var service = new CategoryService(context);
        await service.DeleteCategoryAsync(categoryId, TestDbContextFactory.OtherUserId);

        using var verifyCtx = factory.CreateContext();
        Assert.Single(verifyCtx.Categories);
    }
}