using Elternbeirat.Contracts;
using Elternbeirat.Web.Features.Posts;

namespace Elternbeirat.Web.Tests;

/// <summary>
/// Unit tests for the older/newer post next to a post. The list comes newest
/// first, as from PocketBase; "previous" is the older post. Pure logic, no
/// PocketBase needed.
/// </summary>
public class PostNeighborsTests
{
    // Newest first, like PocketBaseClient.GetPostsAsync.
    private static readonly Post[] Posts = [Post("march"), Post("february"), Post("january")];

    private static Post Post(string slug) =>
        new() { Id = slug, Title = slug, Slug = slug };

    [Fact]
    public void Middle_post_has_the_older_as_previous_and_the_newer_as_next()
    {
        var neighbors = PostNeighbors.Of(Posts, "february");

        neighbors.Previous?.Slug.ShouldBe("january");
        neighbors.Next?.Slug.ShouldBe("march");
    }

    [Fact]
    public void Newest_post_has_no_next()
    {
        var neighbors = PostNeighbors.Of(Posts, "march");

        neighbors.Previous?.Slug.ShouldBe("february");
        neighbors.Next.ShouldBeNull();
    }

    [Fact]
    public void Oldest_post_has_no_previous()
    {
        var neighbors = PostNeighbors.Of(Posts, "january");

        neighbors.Previous.ShouldBeNull();
        neighbors.Next?.Slug.ShouldBe("february");
    }

    [Fact]
    public void Only_post_has_no_neighbors() =>
        PostNeighbors.Of([Post("only")], "only").ShouldBe(new PostNeighbors(null, null));

    [Fact]
    public void Unknown_slug_has_no_neighbors() =>
        PostNeighbors.Of(Posts, "december").ShouldBe(new PostNeighbors(null, null));

    [Fact]
    public void Slug_is_compared_case_insensitively() =>
        PostNeighbors.Of(Posts, "February").Next?.Slug.ShouldBe("march");
}