using System.Net;
using MeterVault.Infrastructure.Options;
using MeterVault.Infrastructure.Update;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;

namespace MeterVault.Integration.Tests;

/// <summary>
/// Version comparison behind the update banner. Pure — no database, no network.
/// </summary>
/// <remarks>
/// The failure mode worth guarding is a banner that never clears: it trains the operator to ignore
/// it, and the next real update goes unnoticed. Every case here is one that would produce exactly
/// that if the parse or the ordering were naive.
/// </remarks>
public sealed class UpdateCheckTests
{
    [Theory]
    [InlineData("0.1.0", 0, 1, 0)]
    [InlineData("v0.2.0", 0, 2, 0)]
    [InlineData("  1.4.7  ", 1, 4, 7)]
    // The shape the running assembly actually reports — MSBuild appends the commit hash.
    [InlineData("0.1.0+8fe5f4411b467943c6717cc994ca74d8883d2839", 0, 1, 0)]
    // A prerelease compares equal to its release, so an rc tag never nags a released instance.
    [InlineData("0.2.0-rc.1", 0, 2, 0)]
    public void Parses_the_forms_tags_and_assemblies_actually_use(string text, int major, int minor, int patch)
    {
        Assert.True(ReleaseVersion.TryParse(text, out var version));
        Assert.Equal(new ReleaseVersion(major, minor, patch), version);
    }

    [Theory]
    [InlineData(null)]
    [InlineData("")]
    [InlineData("   ")]
    [InlineData("latest")]
    [InlineData("1.0")]        // System.Version would accept this and invent a -1
    [InlineData("1.0.0.0")]    // ...and this, silently changing the comparison
    [InlineData("v1.x.0")]
    public void Rejects_anything_it_cannot_order(string? text)
    {
        Assert.False(ReleaseVersion.TryParse(text, out _));
    }

    [Fact]
    public void Orders_numerically_not_lexically()
    {
        Assert.True(ReleaseVersion.TryParse("0.10.0", out var ten));
        Assert.True(ReleaseVersion.TryParse("0.9.0", out var nine));

        // "0.10.0" < "0.9.0" as strings — the classic way an update banner goes permanently quiet.
        Assert.True(ten > nine);
        Assert.False(nine > ten);
    }

    [Fact]
    public void Picks_the_highest_tag_regardless_of_listing_order()
    {
        // Gitea does not promise semver ordering, so taking the first entry is not safe.
        string?[] tags = ["v0.9.0", "v0.10.0", "v0.2.0"];

        Assert.True(ReleaseVersion.TryPickLatest(tags, out var latest));
        Assert.Equal(new ReleaseVersion(0, 10, 0), latest!.Value);
    }

    [Fact]
    public void Ignores_tags_that_are_not_versions()
    {
        string?[] tags = ["nightly", null, "v0.3.0", "release-candidate", ""];

        Assert.True(ReleaseVersion.TryPickLatest(tags, out var latest));
        Assert.Equal(new ReleaseVersion(0, 3, 0), latest!.Value);
    }

    [Fact]
    public void Reports_nothing_when_no_tag_is_a_version()
    {
        Assert.False(ReleaseVersion.TryPickLatest(["nightly", "main"], out _));
    }

    [Fact]
    public void An_update_is_only_available_when_the_published_version_is_strictly_newer()
    {
        var running = new ReleaseVersion(0, 1, 0);

        Assert.True(new UpdateStatus(running, new ReleaseVersion(0, 2, 0), DateTimeOffset.UtcNow).UpdateAvailable);
        Assert.False(new UpdateStatus(running, running, DateTimeOffset.UtcNow).UpdateAvailable);

        // A dev build ahead of the newest tag must not be told to "update" backwards.
        Assert.False(new UpdateStatus(new ReleaseVersion(0, 3, 0), running, DateTimeOffset.UtcNow).UpdateAvailable);
    }

    [Fact]
    public void An_unknown_version_on_either_side_shows_no_banner()
    {
        // Never guess. A missing version means "cannot tell", which is silence, not a nag.
        Assert.False(new UpdateStatus(null, new ReleaseVersion(9, 9, 9), null).UpdateAvailable);
        Assert.False(new UpdateStatus(new ReleaseVersion(0, 1, 0), null, null).UpdateAvailable);
    }

    [Fact]
    public void The_running_assembly_reports_the_version_from_the_VERSION_file()
    {
        // Guards the MSBuild plumbing: without VERSION stamped into the assembly this is null and
        // the banner can never appear, however well the comparison works. Compared against the file
        // itself, so reading the host process's version by mistake cannot pass this.
        var repoRoot = FindRepoRoot();
        Assert.True(ReleaseVersion.TryParse(File.ReadAllText(Path.Combine(repoRoot, "VERSION")), out var declared));

        Assert.Equal(declared, UpdateCheckService.RunningVersion());
    }

    [Fact]
    public async Task Reads_the_newest_tag_out_of_a_gitea_tag_listing()
    {
        // The payload shape is the real one, captured from
        // /api/v1/repos/FinalFactory/MeterVault/tags — the seam the unit tests above cannot cover.
        const string Payload = """
            [
              {"name":"v0.1.0","message":"Release v0.1.0","id":"4a51306"},
              {"name":"v0.3.0","message":"Release v0.3.0","id":"aa11bb2"},
              {"name":"v0.2.0","message":"Release v0.2.0","id":"cc33dd4"}
            ]
            """;

        var status = await NewService(HttpStatusCode.OK, Payload).GetAsync();

        Assert.Equal(new ReleaseVersion(0, 3, 0), status.Latest);
        Assert.NotNull(status.CheckedAt);
    }

    [Fact]
    public async Task An_unreachable_repository_reports_no_latest_instead_of_throwing()
    {
        // A dashboard on an instance with no outbound access must still render.
        var status = await NewService(HttpStatusCode.ServiceUnavailable, "nope").GetAsync();

        Assert.Null(status.Latest);
        Assert.False(status.UpdateAvailable);
    }

    [Fact]
    public async Task Garbage_in_the_response_is_treated_as_cannot_tell()
    {
        var status = await NewService(HttpStatusCode.OK, "<html>login page</html>").GetAsync();

        Assert.Null(status.Latest);
        Assert.False(status.UpdateAvailable);
    }

    [Fact]
    public async Task Disabling_the_check_makes_no_request_at_all()
    {
        var handler = new StubHandler(HttpStatusCode.OK, "[]");
        var service = new UpdateCheckService(
            new StubHttpClientFactory(handler),
            Microsoft.Extensions.Options.Options.Create(new MeterVaultOptions { UpdateCheckEnabled = false }),
            NullLogger<UpdateCheckService>.Instance);

        await service.GetAsync();

        Assert.Equal(0, handler.Calls);
    }

    private static UpdateCheckService NewService(HttpStatusCode status, string payload) =>
        new(new StubHttpClientFactory(new StubHandler(status, payload)),
            Microsoft.Extensions.Options.Options.Create(new MeterVaultOptions
            {
                UpdateCheckEnabled = true,
                UpdateCheckUrl = "https://example.invalid/tags",
            }),
            NullLogger<UpdateCheckService>.Instance);

    private sealed class StubHttpClientFactory(HttpMessageHandler handler) : IHttpClientFactory
    {
        public HttpClient CreateClient(string name) => new(handler, disposeHandler: false);
    }

    private sealed class StubHandler(HttpStatusCode status, string payload) : HttpMessageHandler
    {
        public int Calls { get; private set; }

        protected override Task<HttpResponseMessage> SendAsync(
            HttpRequestMessage request, CancellationToken cancellationToken)
        {
            Calls++;
            return Task.FromResult(new HttpResponseMessage(status) { Content = new StringContent(payload) });
        }
    }

    private static string FindRepoRoot()
    {
        var directory = new DirectoryInfo(AppContext.BaseDirectory);
        while (directory is not null && !File.Exists(Path.Combine(directory.FullName, "VERSION")))
        {
            directory = directory.Parent;
        }

        Assert.NotNull(directory);
        return directory!.FullName;
    }
}