import asyncio
import json
import logging
from typing import AsyncGenerator
from app.config import OPENCODE_SERVE_URL

logger = logging.getLogger("opencode_proxy")


class OpenCodeUnavailableError(Exception):
    pass


async def query_opencode(
    message: str,
    session_id: str,
    user_context: str = "",
) -> AsyncGenerator[str, None]:
    prompt = message
    if user_context:
        prompt = f"[User context: {user_context}]\n\n{message}"

    try:
        proc = await asyncio.create_subprocess_exec(
            "opencode", "run", "--attach", OPENCODE_SERVE_URL,
            "--format", "json",
            prompt,
            stdout=asyncio.subprocess.PIPE,
            stderr=asyncio.subprocess.PIPE,
        )

        while True:
            line = await proc.stdout.readline()
            if not line:
                break
            line = line.decode().strip()
            if line:
                try:
                    data = json.loads(line)
                    content = data.get("content", data.get("text", line))
                    yield content
                except json.JSONDecodeError:
                    yield line

        await proc.wait()
    except FileNotFoundError:
        logger.error("opencode binary not found in PATH")
        raise OpenCodeUnavailableError(
            "opencode binary not found. Install opencode or run `opencode serve`."
        )
    except Exception as e:
        logger.error("opencode proxy error: %s", e)
        raise OpenCodeUnavailableError(f"AI coach unavailable: {e}")