using System.Text.Json;
using System.Threading.Tasks;

namespace Extend.Callbacks;

/// <summary>
/// RPC server methods
/// </summary>
public static class RpcServer
{
	/// <summary>
	/// Sends an RPC message to the client.
	/// This method is tagged with the <see cref="Rpc.Host"/> attribute, which means it will be executed on the server and callable by clients.
	/// </summary>
	/// <param name="request">The RPC message to send.</param>
	/// <param name="args">The arguments to pass to the RPC method.</param>
	[Rpc.Host]
	public static async void SendRpc( RpcMessage request, params object[] args )
	{
		try
		{
			if ( !RpcCallbackSystem.Current.Handlers.TryGetValue( request.MethodIdent, out var handler ) )
			{
				var error = RpcError.CallbackNotFound( request.MethodIdent );

				using ( Rpc.FilterInclude( Rpc.Caller ) )
					RpcClient.OnRpcError( request.Id, error, request.MethodIdent );

				return;
			}

			var taskResult = handler.Method.InvokeWithReturn<Task>( handler.Instance, args );
			await taskResult;
			
			var json = Json.Serialize( taskResult );
			var dict = Json.Deserialize<Dictionary<string, JsonElement>>( json ).GetValueOrDefault( "Result" );
			
			var returnType = TypeLibrary.GetTypeByIdent( request.MethodReturnTypeIdent );
			var returnTargetType = returnType.TargetType;

			object? finalResult;

			if ( returnType.IsGenericType )
			{
				var genericTypes = request.GenericArguments.Select( x => TypeLibrary.GetType( x ).TargetType ).ToArray();
				var baseGenericType = returnType.MakeGenericType( genericTypes );
				
				finalResult = dict.Deserialize( baseGenericType );
			}
			else
			{
				finalResult = dict.Deserialize( returnTargetType );
			}
			
			using ( Rpc.FilterInclude( Rpc.Caller ) )
				RpcClient.OnRpcResponse( request, finalResult, request.MethodIdent );
		}
		catch ( Exception e )
		{
			var error = RpcError.Unknown( request.MethodIdent, e );
			Log.Error( $"RPC execution error for {request.MethodIdent}: {e}" );

			using ( Rpc.FilterInclude( Rpc.Caller ) )
				RpcClient.OnRpcError( request.Id, error, request.MethodIdent );
		}
	}
}