namespace AcDream.App.Tests.Diagnostics;

public sealed class ConnectedR6SoakContractTests
{
    private static readonly string[] ExpectedCheckpointNames =
    [
        "caul-baseline",
        "sawato-baseline",
        "rynthid",
        "aerlinthe",
        "sawato-return",
        "holtburg",
        "caul-return",
        "sawato-plateau",
        "caul-plateau",
    ];

    [Fact]
    public void RouteContainsExactlyNineOrderedCheckpointBarriers()
    {
        string[] checkpoints = File.ReadAllLines(Path.Combine(
                FindRepoRoot(),
                "tools",
                "connected-r6-soak.route.txt"))
            .Select(static line => line.Trim())
            .Where(static line => line.StartsWith(
                "checkpoint ",
                StringComparison.Ordinal))
            .Select(static line => line["checkpoint ".Length..])
            .ToArray();

        Assert.Equal(ExpectedCheckpointNames, checkpoints);
    }

    [Fact]
    public void GateConsumesCanonicalTimelineWithoutWeakeningResidencyFormulas()
    {
        string source = File.ReadAllText(Path.Combine(
            FindRepoRoot(),
            "tools",
            "run-connected-r6-soak.ps1"));

        AssertAppearsInOrder(
            source,
            "$expectedCheckpointNames = @(",
            "'caul-baseline'",
            "'sawato-baseline'",
            "'rynthid'",
            "'aerlinthe'",
            "'sawato-return'",
            "'holtburg'",
            "'caul-return'",
            "'sawato-plateau'",
            "'caul-plateau'");
        AssertAppearsInOrder(
            source,
            "$canonicalCheckpoints = @(Read-CanonicalCheckpoints)",
            "Add-CanonicalCheckpointFailures $process",
            "Add-RelativeGateFailures");
        Assert.Contains("CanonicalCheckpoints = @($canonicalCheckpoints)", source);
        Assert.Contains("CheckpointTimeline = $checkpointTimeline", source);
        Assert.Contains(
            "Join-Path $artifactDir \"checkpoint-$expectedName.json\"",
            source,
            StringComparison.Ordinal);
        Assert.Contains(
            "missing render-world synchronization fields",
            source,
            StringComparison.Ordinal);

        string[] zeroFields =
        [
            "pendingLiveTeardowns",
            "pendingLandblockRetirements",
            "stagedMeshUploads",
            "stagedMeshBytes",
            "compositeWarmupPending",
        ];
        foreach (string field in zeroFields)
            Assert.Contains($"'{field}'", source, StringComparison.Ordinal);

        Assert.Equal(1, CountOccurrences(
            source,
            "$privateLimit = [Math]::Max(192.0, $pair.First.PrivateMiB * 0.20)"));
        Assert.Equal(1, CountOccurrences(
            source,
            "$workingLimit = [Math]::Max(192.0, $pair.First.WorkingSetMiB * 0.20)"));
        Assert.Equal(1, CountOccurrences(
            source,
            "$updateLimit = $pair.First.UpdateP95Ms * 1.5 + 0.5"));
        Assert.Equal(1, CountOccurrences(
            source,
            "$allocLimit = $pair.First.AllocP50Kb * 1.5 + 16.0"));
    }

    private static int CountOccurrences(string source, string value)
    {
        int count = 0;
        int cursor = 0;
        while ((cursor = source.IndexOf(value, cursor, StringComparison.Ordinal)) >= 0)
        {
            count++;
            cursor += value.Length;
        }

        return count;
    }

    private static void AssertAppearsInOrder(string source, params string[] values)
    {
        int cursor = -1;
        foreach (string value in values)
        {
            int next = source.IndexOf(value, cursor + 1, StringComparison.Ordinal);
            Assert.True(next >= 0, $"Missing expected source fragment: {value}");
            Assert.True(next > cursor, $"Out-of-order source fragment: {value}");
            cursor = next;
        }
    }

    private static string FindRepoRoot()
    {
        DirectoryInfo? directory = new(AppContext.BaseDirectory);
        while (directory is not null)
        {
            if (File.Exists(Path.Combine(directory.FullName, "AcDream.slnx")))
                return directory.FullName;
            directory = directory.Parent;
        }

        throw new DirectoryNotFoundException("Could not find AcDream.slnx.");
    }
}