using Grpc.Core;
using Mishima.Nexus.Wire.V1;

namespace Robotico.Nexus.Client.Tests.TestSupport;

/// <summary>
/// Sentinel logical-database names (sent via the <c>x-nexus-database</c> metadata header) that let
/// tests deterministically drive the failure branches of <c>Ping</c>-fronted RPCs without a real
/// unreachable engine.
/// </summary>
public static class FakeNexusTriggers
{
    /// <summary>Ping succeeds at the transport level but the engine reports a non-OK status.</summary>
    public const string PingReportsFailure = "trigger-ping-status-failure";

    /// <summary>Ping fails at the transport level (simulated <see cref="RpcException"/>).</summary>
    public const string PingThrows = "trigger-ping-rpc-exception";

    /// <summary>Returns a failure <see cref="NexusStatus"/> when the request's database header is <see cref="PingReportsFailure"/>, or throws when it is <see cref="PingThrows"/>.</summary>
    public static NexusStatus? TryStatusFailure(ServerCallContext context)
    {
        string? database = context.RequestHeaders.GetValue(NexusCallMetadata.DatabaseKey);
        if (string.Equals(database, PingThrows, StringComparison.Ordinal))
        {
            throw new RpcException(new Status(StatusCode.Unavailable, "Simulated transport failure."));
        }

        return string.Equals(database, PingReportsFailure, StringComparison.Ordinal)
            ? NexusStatuses.Failure("NXS_UNAVAILABLE", "Simulated engine-reported failure.")
            : null;
    }
}