using System.Xml.Linq;

namespace FinalFactory.Rendezvous.Tests.Contracts;

internal static class ContractTestFiles
{
    public static string Read(string fileName) => File
        .ReadAllText(Path.Combine(DirectoryFor(fileName), fileName))
        .TrimEnd('\r', '\n');

    public static string Directory
    {
        get
        {
            return VersionedDirectory(Property("RendezvousMajorVersion"));
        }
    }

    public static string OpenApiDocument
    {
        get
        {
            string httpVersion = Property("HttpContractVersion");
            return Path.Combine(RepositoryRoot, $"docs/api/rendezvous-v{httpVersion}.json");
        }
    }

    private static string DirectoryFor(string fileName)
    {
        string property = fileName switch
        {
            "client-public-api.txt" or "contracts-public-api.txt" => "RendezvousMajorVersion",
            "connection-ticket.json" => "ConnectionTicketFormatVersion",
            _ when fileName.EndsWith(".hex", StringComparison.Ordinal) => "UdpContractVersion",
            _ when fileName.EndsWith(".json", StringComparison.Ordinal) => "HttpContractVersion",
            _ => throw new InvalidOperationException($"No contract version dimension maps {fileName}."),
        };
        return VersionedDirectory(Property(property));
    }

    private static string VersionedDirectory(string version) => Path.Combine(
        RepositoryRoot,
        $"tests/FinalFactory.Rendezvous.Tests/TestData/Contracts/v{version}");

    private static string Property(string name)
    {
        XDocument versions = XDocument.Load(Path.Combine(RepositoryRoot, "eng/Versions.props"));
        return versions.Descendants(name).Single().Value;
    }

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

                directory = directory.Parent;
            }

            throw new DirectoryNotFoundException("Could not locate repository root.");
        }
    }
}