using System.Text.Json;
using FluentAssertions;
using Xunit;

namespace StellaOps.Reachability.FixtureTests;

public sealed class FixtureCoverageTests
{
    private static readonly string RepoRoot = ReachbenchFixtureTests.LocateRepoRoot();
    private static readonly string ReachabilityRoot = Path.Combine(RepoRoot, "tests", "reachability");
    private static readonly string CorpusRoot = Path.Combine(ReachabilityRoot, "corpus");
    private static readonly string SamplesPublicRoot = Path.Combine(ReachabilityRoot, "samples-public");

    [Fact]
    public void CorpusAndPublicSamplesCoverExpectedLanguageBuckets()
    {
        var corpusLanguages = ReadManifestLanguages(Path.Combine(CorpusRoot, "manifest.json"));
        corpusLanguages.Should().Contain(new[] { "dotnet", "go", "python", "rust" });

        var samplesLanguages = ReadManifestLanguages(Path.Combine(SamplesPublicRoot, "manifest.json"));
        samplesLanguages.Should().Contain(new[] { "csharp", "js", "php" });
    }

    [Fact]
    public void CorpusManifestIsSorted()
    {
        var keys = ReadManifestKeys(Path.Combine(CorpusRoot, "manifest.json"));
        keys.Should().NotBeEmpty("corpus manifest should have entries");
        keys.Should().BeInAscendingOrder(StringComparer.Ordinal);
    }

    private static string[] ReadManifestLanguages(string manifestPath)
    {
        File.Exists(manifestPath).Should().BeTrue($"{manifestPath} should exist");

        using var doc = JsonDocument.Parse(File.ReadAllBytes(manifestPath));
        return doc.RootElement.EnumerateArray()
            .Select(entry => entry.GetProperty("language").GetString())
            .Where(language => !string.IsNullOrWhiteSpace(language))
            .Select(language => language!)
            .Distinct(StringComparer.Ordinal)
            .OrderBy(language => language, StringComparer.Ordinal)
            .ToArray();
    }

    private static string[] ReadManifestKeys(string manifestPath)
    {
        File.Exists(manifestPath).Should().BeTrue($"{manifestPath} should exist");

        using var doc = JsonDocument.Parse(File.ReadAllBytes(manifestPath));
        return doc.RootElement.EnumerateArray()
            .Select(entry => $"{entry.GetProperty("language").GetString()}/{entry.GetProperty("id").GetString()}")
            .ToArray();
    }
}