using System.Net;
using System.Text;
using CursorLang.Core.Models;
using CursorLang.Core.Services;
using CursorLang.Tests.Shared;

namespace CursorLang.Core.Tests.Services;

/// <summary>
/// What the app does with a release once it has found one: whether it is newer
/// at all, and what ends up on disk.
/// </summary>
public sealed class UpdateServiceTests
{
    [Theory]
    [InlineData("1.0.0.0", "1.0.1.0", true)]
    [InlineData("1.0.0.0", "2.0.0.0", true)]
    [InlineData("1.0.0.0", "1.0.0.0", false)]
    [InlineData("1.0.1.0", "1.0.0.0", false)]
    public async Task Only_a_higher_version_counts_as_an_update(string current, string found, bool offered)
    {
        var feed = new FakeReleaseFeed { Release = Release(found) };
        using TempFolder folder = new();
        using UpdateService service = Create(feed, folder, current);

        ReleaseInfo? update = await service.CheckAsync(TestContext.Current.CancellationToken);

        Assert.Equal(offered, update is not null);
    }

    [Fact]
    public async Task An_empty_repository_leaves_the_app_with_nothing()
    {
        var feed = new FakeReleaseFeed { Release = null };
        using TempFolder folder = new();
        using UpdateService service = Create(feed, folder);

        Assert.Null(await service.CheckAsync(TestContext.Current.CancellationToken));
    }

    [Fact]
    public async Task The_package_ends_up_on_disk_whole()
    {
        byte[] content = Encoding.UTF8.GetBytes(new string('p', 300_000));
        using TempFolder folder = new();
        using UpdateService service = Create(new FakeReleaseFeed(), folder, client: FakeHttpHandler.Bytes(content));

        string path = await service.DownloadAsync(Release("2.0.0.0"), null, TestContext.Current.CancellationToken);

        Assert.Equal(content, await File.ReadAllBytesAsync(path, TestContext.Current.CancellationToken));
    }

    // The name comes from the version, not from the answer: the app creates a
    // file with it, and the answer comes from the other side
    [Fact]
    public async Task The_name_of_the_file_is_built_by_the_app_itself()
    {
        using TempFolder folder = new();
        using UpdateService service = Create(new FakeReleaseFeed(), folder, client: FakeHttpHandler.Bytes([1, 2, 3]));

        var release = new ReleaseInfo(
            new Version(2, 0, 0, 0),
            "v2.0.0",
            null,
            new ReleaseAsset(@"..\..\evil.msixbundle", new Uri("https://host/a"), 3));

        string path = await service.DownloadAsync(release, null, TestContext.Current.CancellationToken);

        Assert.Equal("CursorLang-2.0.0.0.msixbundle", Path.GetFileName(path));
        Assert.Equal(folder.Path, Path.GetDirectoryName(path));
    }

    [Fact]
    public async Task The_download_reports_how_far_it_has_come()
    {
        byte[] content = new byte[500_000];
        using TempFolder folder = new();
        using UpdateService service = Create(new FakeReleaseFeed(), folder, client: FakeHttpHandler.Bytes(content));

        var reported = new CollectingProgress();
        await service.DownloadAsync(Release("2.0.0.0"), reported, TestContext.Current.CancellationToken);

        Assert.NotEmpty(reported.Values);
        Assert.All(reported.Values, value => Assert.InRange(value, 0, 1));
        Assert.Equal(reported.Values, [.. reported.Values.Order()]);
        Assert.Equal(1, reported.Values[^1]);
    }

    [Fact]
    public async Task A_closed_repository_gets_the_token_with_the_download_too()
    {
        var feed = new FakeReleaseFeed();
        using TempFolder folder = new();
        using UpdateService service = Create(feed, folder, client: FakeHttpHandler.Bytes([1]));

        await service.DownloadAsync(Release("2.0.0.0"), null, TestContext.Current.CancellationToken);

        Assert.Single(feed.Authorized);
    }

    [Fact]
    public async Task A_refusal_of_the_hosting_service_leaves_no_package_behind()
    {
        using TempFolder folder = new();
        using UpdateService service = Create(
            new FakeReleaseFeed(), folder, client: FakeHttpHandler.Status(HttpStatusCode.NotFound));

        await Assert.ThrowsAsync<HttpRequestException>(
            () => service.DownloadAsync(Release("2.0.0.0"), null, TestContext.Current.CancellationToken));

        Assert.Empty(Directory.GetFiles(folder.Path));
    }

    // A package left from an earlier download takes up room and is of no use
    // once it has been installed
    [Fact]
    public async Task An_older_download_is_cleared_away()
    {
        using TempFolder folder = new();
        string leftover = folder.File("CursorLang-1.5.0.0.msixbundle");
        await File.WriteAllTextAsync(leftover, "old", TestContext.Current.CancellationToken);

        using UpdateService service = Create(new FakeReleaseFeed(), folder, client: FakeHttpHandler.Bytes([1]));
        string path = await service.DownloadAsync(Release("2.0.0.0"), null, TestContext.Current.CancellationToken);

        Assert.False(File.Exists(leftover));
        Assert.True(File.Exists(path));
    }

    /// <summary>
    /// The reports as the download makes them. <c>Progress&lt;T&gt;</c> would
    /// hand them over to another thread, and a test has nowhere to wait for that.
    /// </summary>
    private sealed class CollectingProgress : IProgress<double>
    {
        internal List<double> Values { get; } = [];

        public void Report(double value) => Values.Add(value);
    }

    private static ReleaseInfo Release(string version) => new(
        Version.Parse(version),
        $"v{version}",
        new Uri("https://host/releases/tag"),
        new ReleaseAsset($"CursorLang-{version}.msixbundle", new Uri("https://host/package"), 0));

    private static UpdateService Create(
        IReleaseFeed feed,
        TempFolder folder,
        string current = "1.0.0.0",
        FakeHttpHandler? client = null) =>
        new(feed,
            (client ?? FakeHttpHandler.Bytes([])).CreateClient(),
            Version.Parse(current),
            folder.Path);
}