"""Async HTTP client for the local OpenCode server."""

import atexit
import json
from typing import Any, Optional

from tornado.httpclient import AsyncHTTPClient, HTTPRequest
from tornado.httputil import HTTPHeaders

from .config import OpenCodeConfig


class OpenCodeError(Exception):
    """Raised when an OpenCode API request fails."""


# Ensure the tornado AsyncHTTPClient singleton is closed at interpreter
# shutdown so the IOLoop can finish and the process can exit cleanly
# (otherwise Ctrl+C on `jupyter lab` hangs after "received signal 2,
# stopping" because the singleton keeps persistent connections alive).
def _close_opencode_http() -> None:
    try:
        AsyncHTTPClient().close()
    except Exception:
        # Never block interpreter shutdown on close errors.
        pass


atexit.register(_close_opencode_http)


class OpenCodeClient:
    def __init__(
        self,
        config: OpenCodeConfig,
        http_client: Optional[AsyncHTTPClient] = None,
    ) -> None:
        self._config = config
        # Use a dedicated client (not the singleton) so close() can
        # deterministically release its connections without affecting
        # other components. The module-level atexit still closes the
        # singleton as a safety net.
        self._http_client = http_client or AsyncHTTPClient(force_instance=True)
        self._owns_http_client = http_client is None

    def close(self) -> None:
        """Release the underlying HTTP client's connections. Idempotent."""
        if getattr(self, "_http_client", None) is None:
            return
        try:
            if self._owns_http_client:
                self._http_client.close()
        except Exception:
            pass
        self._http_client = None  # type: ignore[assignment]
        self._owns_http_client = False

    async def health(self) -> dict[str, Any]:
        return await self._request("GET", "/global/health")

    async def list_providers(self) -> list[dict[str, Any]]:
        return await self._request("GET", "/config/providers")

    async def create_session(self, title: str) -> dict[str, Any]:
        return await self._request("POST", "/session", {"title": title})

    async def send_message_sync(
        self,
        session_id: str,
        parts: list[dict[str, Any]],
        provider_id: Optional[str] = None,
        model_id: Optional[str] = None,
        system: Optional[str] = None,
    ) -> dict[str, Any]:
        body: dict[str, Any] = {"parts": parts}
        if provider_id is not None and model_id is not None:
            body["model"] = {"providerID": provider_id, "modelID": model_id}
        if system is not None:
            body["system"] = system
        return await self._request(
            "POST",
            "/session/%s/message" % session_id,
            body,
        )

    async def abort(self, session_id: str) -> bool:
        result = await self._request("POST", "/session/%s/abort" % session_id)
        return result is not None

    async def delete_session(self, session_id: str) -> bool:
        result = await self._request("DELETE", "/session/%s" % session_id)
        return result is not None

    @property
    def endpoint(self) -> str:
        return self._config.url

    async def _request(
        self,
        method: str,
        path: str,
        body: Optional[dict[str, Any]] = None,
    ) -> Optional[Any]:
        url = self._config.url + path
        headers = HTTPHeaders(
            {
                "Content-Type": "application/json",
                "Accept": "application/json",
            }
        )
        request_kwargs: dict[str, Any] = {
            "method": method,
            "headers": headers,
            "request_timeout": self._config.request_timeout_seconds,
        }
        if body is not None:
            request_kwargs["body"] = json.dumps(body).encode("utf-8")
        # HTTP Basic Auth must be set on the HTTPRequest itself; passing
        # auth_* as **kwargs to fetch() when the first arg is already an
        # HTTPRequest is rejected by tornado ("kwargs can't be used if
        # request is an HTTPRequest object").
        if self._config.auth is not None:
            request_kwargs["auth_username"] = self._config.auth[0]
            request_kwargs["auth_password"] = self._config.auth[1]

        request = HTTPRequest(url, **request_kwargs)

        response = await self._http_client.fetch(request)

        if 200 <= response.code < 300:
            if not response.body:
                return True
            return json.loads(response.body.decode("utf-8"))
        if response.code == 404:
            return None

        response_body = response.body.decode("utf-8") if response.body else ""
        raise OpenCodeError(
            "OpenCode request %s %s failed with status %s: %s"
            % (method, url, response.code, response_body)
        )