"""
gRPC Client - Used by FastAPI to communicate with workers.
"""

import json
import logging
import os
from typing import Callable, Iterator, Optional

import grpc

# Generated stubs - run `python schema/generate.py --proto` if missing
try:
    from . import worker_pb2, worker_pb2_grpc
except ImportError:
    import worker_pb2
    import worker_pb2_grpc

logger = logging.getLogger(__name__)

# Configuration from environment
GRPC_HOST = os.environ.get("GRPC_HOST", "grpc")
GRPC_PORT = int(os.environ.get("GRPC_PORT", "50051"))


class WorkerClient:
    """gRPC client for worker communication."""

    def __init__(self, host: str = None, port: int = None):
        """
        Initialize the client.

        Args:
            host: gRPC server host (defaults to GRPC_HOST env var)
            port: gRPC server port (defaults to GRPC_PORT env var)
        """
        self.host = host or GRPC_HOST
        self.port = port or GRPC_PORT
        self.address = f"{self.host}:{self.port}"
        self._channel: Optional[grpc.Channel] = None
        self._stub: Optional[worker_pb2_grpc.WorkerServiceStub] = None

    def _ensure_connected(self) -> worker_pb2_grpc.WorkerServiceStub:
        """Ensure channel is connected and return stub."""
        if self._channel is None:
            self._channel = grpc.insecure_channel(self.address)
            self._stub = worker_pb2_grpc.WorkerServiceStub(self._channel)
        return self._stub

    def close(self) -> None:
        """Close the channel."""
        if self._channel:
            self._channel.close()
            self._channel = None
            self._stub = None

    def __enter__(self):
        self._ensure_connected()
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.close()

    def submit_job(
        self,
        job_id: str,
        source_path: str,
        output_path: str,
        preset: Optional[dict] = None,
        trim_start: Optional[float] = None,
        trim_end: Optional[float] = None,
    ) -> tuple[bool, str]:
        """
        Submit a job to the worker.

        Args:
            job_id: Unique job identifier
            source_path: Path to source file
            output_path: Path for output file
            preset: Transcode preset dict (optional)
            trim_start: Trim start time in seconds (optional)
            trim_end: Trim end time in seconds (optional)

        Returns:
            Tuple of (accepted: bool, message: str)
        """
        stub = self._ensure_connected()

        request = worker_pb2.JobRequest(
            job_id=job_id,
            source_path=source_path,
            output_path=output_path,
            preset_json=json.dumps(preset) if preset else "",
        )

        if trim_start is not None:
            request.trim_start = trim_start
        if trim_end is not None:
            request.trim_end = trim_end

        try:
            response = stub.SubmitJob(request)
            return response.accepted, response.message
        except grpc.RpcError as e:
            logger.error(f"SubmitJob RPC failed: {e}")
            return False, str(e)

    def stream_progress(
        self,
        job_id: str,
        callback: Optional[Callable[[dict], None]] = None,
    ) -> Iterator[dict]:
        """
        Stream progress updates for a job.

        Args:
            job_id: Job identifier
            callback: Optional callback for each update

        Yields:
            Progress update dicts
        """
        stub = self._ensure_connected()

        request = worker_pb2.ProgressRequest(job_id=job_id)

        try:
            for update in stub.StreamProgress(request):
                progress = {
                    "job_id": update.job_id,
                    "progress": update.progress,
                    "current_frame": update.current_frame,
                    "current_time": update.current_time,
                    "speed": update.speed,
                    "status": update.status,
                    "error": update.error if update.HasField("error") else None,
                }

                if callback:
                    callback(progress)

                yield progress

                if update.status in ("completed", "failed", "cancelled"):
                    break

        except grpc.RpcError as e:
            logger.error(f"StreamProgress RPC failed: {e}")
            yield {
                "job_id": job_id,
                "progress": 0,
                "status": "error",
                "error": str(e),
            }

    def cancel_job(self, job_id: str) -> tuple[bool, str]:
        """
        Cancel a running job.

        Args:
            job_id: Job identifier

        Returns:
            Tuple of (cancelled: bool, message: str)
        """
        stub = self._ensure_connected()

        request = worker_pb2.CancelRequest(job_id=job_id)

        try:
            response = stub.CancelJob(request)
            return response.cancelled, response.message
        except grpc.RpcError as e:
            logger.error(f"CancelJob RPC failed: {e}")
            return False, str(e)

    def get_worker_status(self) -> Optional[dict]:
        """
        Get worker status and capabilities.

        Returns:
            Status dict or None on error
        """
        stub = self._ensure_connected()

        try:
            response = stub.GetWorkerStatus(worker_pb2.Empty())
            return {
                "available": response.available,
                "active_jobs": response.active_jobs,
                "supported_codecs": list(response.supported_codecs),
                "gpu_available": response.gpu_available,
            }
        except grpc.RpcError as e:
            logger.error(f"GetWorkerStatus RPC failed: {e}")
            return None


# Singleton client instance
_client: Optional[WorkerClient] = None


def get_client() -> WorkerClient:
    """Get or create the singleton client (uses env vars for config)."""
    global _client
    if _client is None:
        _client = WorkerClient()
    return _client