using System.Reflection;
using FinalFactory.Rendezvous.Contracts;

namespace FinalFactory.Rendezvous.Server.Operations;

internal static class ReleaseCompatibility
{
    private static readonly Assembly ServerAssembly = typeof(ReleaseCompatibility).Assembly;

    internal static string MinimumClientVersion => Metadata("RendezvousMinimumClientVersion");
    internal static int MaximumClientMajorVersion => MetadataInteger("RendezvousMaximumClientMajorVersion");
    internal static int UdpContractVersion => MetadataInteger("RendezvousUdpContractVersion");
    internal static int ConnectionTicketFormatVersion => MetadataInteger("RendezvousConnectionTicketFormatVersion");
    internal static int LiteNetLibMajorVersion => MetadataInteger("RendezvousLiteNetLibMajorVersion");

    internal static OperatorCompatibilityResponse CreateResponse() => new()
    {
        ServerVersion = ServerAssembly
            .GetCustomAttribute<AssemblyInformationalVersionAttribute>()?
            .InformationalVersion.Split('+', 2)[0]
            ?? ServerAssembly.GetName().Version?.ToString(3)
            ?? "unknown",
        MinimumClientVersion = MinimumClientVersion,
        MaximumClientMajorVersion = MaximumClientMajorVersion,
        HttpContractVersions = [ContractLimits.ContractVersion],
        UdpContractVersions = [UdpContractVersion],
        ConnectionTicketFormatVersions = [ConnectionTicketFormatVersion],
        LiteNetLibMajorVersion = LiteNetLibMajorVersion,
        GameplayProtocolCompatibility = "exact-per-tenant",
    };

    private static string Metadata(string key) => ServerAssembly
        .GetCustomAttributes<AssemblyMetadataAttribute>()
        .Single(attribute => string.Equals(attribute.Key, key, StringComparison.Ordinal))
        .Value
        ?? throw new InvalidOperationException($"Assembly metadata {key} has no value.");

    private static int MetadataInteger(string key) => int.Parse(
        Metadata(key),
        System.Globalization.CultureInfo.InvariantCulture);
}