using FluentAssertions;
using Microsoft.EntityFrameworkCore.Storage;
using Microsoft.Extensions.Logging;
using NSubstitute;
using SlpModularCms.Modules.Offerings.Data.Entities;
using SlpModularCms.Modules.Offerings.Models;
using SlpModularCms.Modules.Offerings.Repositories;
using SlpModularCms.Modules.Offerings.Services;

namespace SlpModularCms.Modules.Offerings.Tests.Services;

public class OfferingsServiceTests
{
    private readonly IOfferingRepository _repo = Substitute.For<IOfferingRepository>();
    private readonly ILogger<OfferingsService> _logger = Substitute.For<ILogger<OfferingsService>>();

    public OfferingsServiceTests()
    {
        _repo.BeginTransactionAsync().Returns(Substitute.For<IDbContextTransaction>());
    }

    private OfferingsService CreateSut() => new(_repo, _logger);

    private static CreateOfferingRequest CreateRequest(bool featured = false) => new(
        "Title", "Description", "€ 100", "per month", ["Feature 1"], "Contact", featured);

    private static Offering ExistingOffering(bool featured = false, int displayOrder = 0) => new()
    {
        Id = Guid.NewGuid(),
        Slug = "existing",
        Title = "Existing",
        Description = "Description",
        Price = "€ 100",
        PriceNote = "per month",
        Features = ["Feature 1"],
        CtaLabel = "Contact",
        Featured = featured,
        DisplayOrder = displayOrder,
        CreatedAt = DateTimeOffset.UtcNow,
        UpdatedAt = DateTimeOffset.UtcNow,
        LastModifiedByUserId = Guid.NewGuid(),
    };

    // --- CreateAsync / BR-OFF-01 featured exclusivity ---

    [Fact]
    public async Task CreateAsync_AppendsToEndOfDisplayOrder()
    {
        _repo.GetMaxDisplayOrderAsync().Returns(4);
        var callerId = Guid.NewGuid();

        var result = await CreateSut().CreateAsync(CreateRequest(), callerId);

        result.DisplayOrder.Should().Be(5);
    }

    [Fact]
    public async Task CreateAsync_SetsLastModifiedByUserId()
    {
        _repo.GetMaxDisplayOrderAsync().Returns(-1);
        var callerId = Guid.NewGuid();

        var dto = await CreateSut().CreateAsync(CreateRequest(), callerId);

        // The DTO doesn't expose LastModifiedByUserId (never shown to any caller) —
        // verify via the entity actually persisted through the repository instead.
        await _repo.Received(1).AddAsync(Arg.Is<Offering>(o => o.LastModifiedByUserId == callerId));
        dto.Should().NotBeNull();
    }

    [Fact]
    public async Task CreateAsync_UnfeaturesCurrentlyFeaturedOffering_WhenNewOneIsFeatured()
    {
        var current = ExistingOffering(featured: true);
        _repo.GetFeaturedAsync().Returns(current);
        _repo.GetMaxDisplayOrderAsync().Returns(-1);

        await CreateSut().CreateAsync(CreateRequest(featured: true), Guid.NewGuid());

        current.Featured.Should().BeFalse();
        await _repo.Received(1).BeginTransactionAsync();
    }

    [Fact]
    public async Task CreateAsync_DoesNotTouchFeatured_WhenNewOfferingNotFeatured()
    {
        _repo.GetMaxDisplayOrderAsync().Returns(-1);

        await CreateSut().CreateAsync(CreateRequest(featured: false), Guid.NewGuid());

        await _repo.DidNotReceive().GetFeaturedAsync();
        await _repo.DidNotReceive().BeginTransactionAsync();
    }

    // --- Slug generation ---

    [Fact]
    public async Task CreateAsync_GeneratesSlugFromTitle()
    {
        _repo.GetMaxDisplayOrderAsync().Returns(-1);

        var dto = await CreateSut().CreateAsync(CreateRequest(), Guid.NewGuid());

        dto.Slug.Should().Be("title");
    }

    [Fact]
    public async Task CreateAsync_AppendsSuffix_WhenSlugAlreadyTaken()
    {
        _repo.GetMaxDisplayOrderAsync().Returns(-1);
        _repo.ExistsBySlugAsync("title", null).Returns(true);
        _repo.ExistsBySlugAsync("title-2", null).Returns(true);
        _repo.ExistsBySlugAsync("title-3", null).Returns(false);

        var dto = await CreateSut().CreateAsync(CreateRequest(), Guid.NewGuid());

        dto.Slug.Should().Be("title-3");
    }

    [Fact]
    public async Task UpdateAsync_RegeneratesSlug_WhenTitleChanges()
    {
        var target = ExistingOffering();
        _repo.GetByIdAsync(target.Id).Returns(target);
        _repo.ExistsBySlugAsync("new-title", target.Id).Returns(false);

        var request = new UpdateOfferingRequest("New Title", "Description", "€ 100", "per month", ["Feature 1"], "Contact");
        var dto = await CreateSut().UpdateAsync(target.Id, request, Guid.NewGuid());

        dto!.Slug.Should().Be("new-title");
    }

    [Fact]
    public async Task UpdateAsync_KeepsExistingSlug_WhenTitleUnchanged()
    {
        var target = ExistingOffering();
        _repo.GetByIdAsync(target.Id).Returns(target);

        var request = new UpdateOfferingRequest(target.Title, "Description", "€ 100", "per month", ["Feature 1"], "Contact");
        var dto = await CreateSut().UpdateAsync(target.Id, request, Guid.NewGuid());

        dto!.Slug.Should().Be("existing");
        await _repo.DidNotReceive().ExistsBySlugAsync(Arg.Any<string>(), Arg.Any<Guid?>());
    }

    // --- Explicit slug override (admin-supplied via CMS) ---

    [Fact]
    public async Task CreateAsync_NormalizesExplicitSlug()
    {
        _repo.GetMaxDisplayOrderAsync().Returns(-1);
        _repo.ExistsBySlugAsync("my-custom-slug", null).Returns(false);

        var request = new CreateOfferingRequest(
            "Title", "Description", "€ 100", "per month", ["Feature 1"], "Contact", Slug: "  My Custom Slug!! ");
        var dto = await CreateSut().CreateAsync(request, Guid.NewGuid());

        dto.Slug.Should().Be("my-custom-slug");
    }

    [Fact]
    public async Task CreateAsync_Throws_WhenExplicitSlugAlreadyTaken()
    {
        _repo.GetMaxDisplayOrderAsync().Returns(-1);
        _repo.ExistsBySlugAsync("taken", null).Returns(true);

        var request = new CreateOfferingRequest(
            "Title", "Description", "€ 100", "per month", ["Feature 1"], "Contact", Slug: "taken");

        var act = () => CreateSut().CreateAsync(request, Guid.NewGuid());

        await act.Should().ThrowAsync<OfferingSlugConflictException>();
    }

    [Fact]
    public async Task UpdateAsync_UsesExplicitSlug_EvenWhenTitleUnchanged()
    {
        var target = ExistingOffering();
        _repo.GetByIdAsync(target.Id).Returns(target);
        _repo.ExistsBySlugAsync("manually-set", target.Id).Returns(false);

        var request = new UpdateOfferingRequest(
            target.Title, "Description", "€ 100", "per month", ["Feature 1"], "Contact", Slug: "manually-set");
        var dto = await CreateSut().UpdateAsync(target.Id, request, Guid.NewGuid());

        dto!.Slug.Should().Be("manually-set");
    }

    [Fact]
    public async Task UpdateAsync_Throws_WhenExplicitSlugTakenByAnotherOffering()
    {
        var target = ExistingOffering();
        _repo.GetByIdAsync(target.Id).Returns(target);
        _repo.ExistsBySlugAsync("taken", target.Id).Returns(true);

        var request = new UpdateOfferingRequest(
            target.Title, "Description", "€ 100", "per month", ["Feature 1"], "Contact", Slug: "taken");

        var act = () => CreateSut().UpdateAsync(target.Id, request, Guid.NewGuid());

        await act.Should().ThrowAsync<OfferingSlugConflictException>();
    }

    // --- UpdateAsync ---

    [Fact]
    public async Task UpdateAsync_ReturnsNull_WhenOfferingNotFound()
    {
        _repo.GetByIdAsync(Arg.Any<Guid>()).Returns((Offering?)null);

        var request = new UpdateOfferingRequest("Title", "Description", "€ 100", "per month", ["Feature 1"], "Contact");
        var result = await CreateSut().UpdateAsync(Guid.NewGuid(), request, Guid.NewGuid());

        result.Should().BeNull();
    }

    [Fact]
    public async Task UpdateAsync_UnfeaturesOtherOffering_ExceptItself()
    {
        var target = ExistingOffering(featured: false);
        var other = ExistingOffering(featured: true);
        _repo.GetByIdAsync(target.Id).Returns(target);
        _repo.GetFeaturedAsync().Returns(other);

        var request = new UpdateOfferingRequest("Title", "Description", "€ 100", "per month", ["Feature 1"], "Contact", true);
        await CreateSut().UpdateAsync(target.Id, request, Guid.NewGuid());

        target.Featured.Should().BeTrue();
        other.Featured.Should().BeFalse();
    }

    [Fact]
    public async Task UpdateAsync_DoesNotUnfeatureItself_WhenAlreadyFeatured()
    {
        var target = ExistingOffering(featured: true);
        _repo.GetByIdAsync(target.Id).Returns(target);
        _repo.GetFeaturedAsync().Returns(target);

        var request = new UpdateOfferingRequest("Title", "Description", "€ 100", "per month", ["Feature 1"], "Contact", true);
        await CreateSut().UpdateAsync(target.Id, request, Guid.NewGuid());

        target.Featured.Should().BeTrue();
    }

    // --- DeleteAsync / BR-OFF-02 ---

    [Fact]
    public async Task DeleteAsync_ReturnsFalse_WhenNotFound()
    {
        _repo.GetByIdAsync(Arg.Any<Guid>()).Returns((Offering?)null);

        var result = await CreateSut().DeleteAsync(Guid.NewGuid(), Guid.NewGuid());

        result.Should().BeFalse();
    }

    [Fact]
    public async Task DeleteAsync_SoftDeletes_EvenForLastRemainingOffering()
    {
        var offering = ExistingOffering();
        _repo.GetByIdAsync(offering.Id).Returns(offering);

        var result = await CreateSut().DeleteAsync(offering.Id, Guid.NewGuid());

        result.Should().BeTrue();
        offering.IsDeleted.Should().BeTrue();
        offering.DeletedAt.Should().NotBeNull();
    }

    // --- ReorderAsync / BR-OFF-03 ---

    [Fact]
    public async Task ReorderAsync_ReassignsDisplayOrderSequentially()
    {
        var first = ExistingOffering(displayOrder: 5);
        var second = ExistingOffering(displayOrder: 2);
        _repo.GetByIdAsync(first.Id).Returns(first);
        _repo.GetByIdAsync(second.Id).Returns(second);

        await CreateSut().ReorderAsync([first.Id, second.Id], Guid.NewGuid());

        first.DisplayOrder.Should().Be(0);
        second.DisplayOrder.Should().Be(1);
    }

    // --- MoveUpAsync / MoveDownAsync / BR-OFF-03 boundaries ---

    [Fact]
    public async Task MoveUpAsync_IsNoOp_WhenAlreadyFirst()
    {
        var offering = ExistingOffering(displayOrder: 0);
        _repo.GetByIdAsync(offering.Id).Returns(offering);
        _repo.GetPreviousAsync(0).Returns((Offering?)null);

        await CreateSut().MoveUpAsync(offering.Id, Guid.NewGuid());

        await _repo.DidNotReceive().BeginTransactionAsync();
    }

    [Fact]
    public async Task MoveUpAsync_SwapsDisplayOrder_WithPrevious()
    {
        var offering = ExistingOffering(displayOrder: 1);
        var previous = ExistingOffering(displayOrder: 0);
        _repo.GetByIdAsync(offering.Id).Returns(offering);
        _repo.GetPreviousAsync(1).Returns(previous);

        await CreateSut().MoveUpAsync(offering.Id, Guid.NewGuid());

        offering.DisplayOrder.Should().Be(0);
        previous.DisplayOrder.Should().Be(1);
    }

    [Fact]
    public async Task MoveDownAsync_IsNoOp_WhenAlreadyLast()
    {
        var offering = ExistingOffering(displayOrder: 0);
        _repo.GetByIdAsync(offering.Id).Returns(offering);
        _repo.GetNextAsync(0).Returns((Offering?)null);

        await CreateSut().MoveDownAsync(offering.Id, Guid.NewGuid());

        await _repo.DidNotReceive().BeginTransactionAsync();
    }

    [Fact]
    public async Task MoveDownAsync_SwapsDisplayOrder_WithNext()
    {
        var offering = ExistingOffering(displayOrder: 0);
        var next = ExistingOffering(displayOrder: 1);
        _repo.GetByIdAsync(offering.Id).Returns(offering);
        _repo.GetNextAsync(0).Returns(next);

        await CreateSut().MoveDownAsync(offering.Id, Guid.NewGuid());

        offering.DisplayOrder.Should().Be(1);
        next.DisplayOrder.Should().Be(0);
    }

    // --- GetPublicOfferingsAsync / GetAllForAdminAsync ---

    [Fact]
    public async Task GetPublicOfferingsAsync_MapsToPublicDto()
    {
        _repo.GetAllAsync().Returns([ExistingOffering()]);

        var result = await CreateSut().GetPublicOfferingsAsync();

        result.Should().ContainSingle();
    }

    [Fact]
    public async Task GetAllForAdminAsync_IncludesDisplayOrder()
    {
        var offering = ExistingOffering(displayOrder: 3);
        _repo.GetAllAsync().Returns([offering]);

        var result = await CreateSut().GetAllForAdminAsync();

        result[0].DisplayOrder.Should().Be(3);
    }
}