using System.IO.Pipes;
using ZB.MOM.WW.OtOpcUa.Core.Scripting.Protocol;

namespace ZB.MOM.WW.OtOpcUa.ScriptWorker;

/// <summary>Entry point: connect to the host's pipe named in the environment and serve until told to stop.</summary>
internal static class Program
{
    private static async Task<int> Main()
    {
        var pipeName = Environment.GetEnvironmentVariable(ScriptWorkerEnvironment.PipeName);
        var nonce = Environment.GetEnvironmentVariable(ScriptWorkerEnvironment.Nonce);
        if (string.IsNullOrEmpty(pipeName) || string.IsNullOrEmpty(nonce))
        {
            await Console.Error.WriteLineAsync("ScriptWorker: launched without a pipe name or nonce; exiting.");
            return ScriptWorkerEnvironment.ExitProtocolFault;
        }
        _ = int.TryParse(Environment.GetEnvironmentVariable(ScriptWorkerEnvironment.ParentPid), out var parentPid);

        // CurrentUserOnly: the client verifies the server end is owned by this account as well.
        var pipe = new NamedPipeClientStream(".", pipeName, PipeDirection.InOut,
            PipeOptions.Asynchronous | PipeOptions.CurrentUserOnly);
        try
        {
            // Synchronous, so the socket under a Unix pipe stays blocking (ScriptWorkerFrameCodec.BlockingStream).
            pipe.Connect(TimeSpan.FromSeconds(10));
        }
        catch (Exception ex)
        {
            await Console.Error.WriteLineAsync($"ScriptWorker: could not connect to the host pipe: {ex.Message}");
            return ScriptWorkerEnvironment.ExitProtocolFault;
        }

        var host = new WorkerHost(ScriptWorkerFrameCodec.BlockingStream(pipe), nonce, parentPid);
        return await host.RunAsync();
    }
}