"""Forge sidecar: the agent's only door to the forge.

The agent calls the sidecar over a line-delimited JSON-RPC AF_UNIX
socket; the sidecar dispatches to an injected `forge` (already
scope-wrapped by bootstrap) and holds the token, so the agent never sees
a credential or a forge endpoint. Every call is appended to a semantic
operation log (the provenance raw material). `signal_done` additionally
drops an event file in the queue dir the orchestrator drains.

`dispatch` is pure and testable; `serve` wraps it in a socket server.
"""

from __future__ import annotations

import dataclasses
import json
import socketserver
import uuid
from collections.abc import Callable
from datetime import datetime
from pathlib import Path
from typing import Any

_READ_METHODS = {"read_issue", "read_pr", "read_comments"}
_WRITE_METHODS = {"post_comment", "update_description"}


def _iso_now() -> str:
    return datetime.now().astimezone().isoformat(timespec="seconds")


def _jsonable(value: Any) -> Any:
    if dataclasses.is_dataclass(value) and not isinstance(value, type):
        return dataclasses.asdict(value)
    if isinstance(value, list):
        return [_jsonable(v) for v in value]
    return value


class OpLog:
    """Append-only JSONL log of semantic forge operations."""

    def __init__(self, path: Path, *, now: Callable[[], str] = _iso_now) -> None:
        self._path = path
        self._now = now
        path.parent.mkdir(parents=True, exist_ok=True)

    def record(self, op: str, target: int | None, detail: str) -> None:
        entry = {"at": self._now(), "op": op, "target": target, "detail": detail}
        with self._path.open("a", encoding="utf-8") as fh:
            fh.write(json.dumps(entry) + "\n")

    def read(self) -> list[dict[str, Any]]:
        if not self._path.exists():
            return []
        return [
            json.loads(line)
            for line in self._path.read_text(encoding="utf-8").splitlines()
            if line.strip()
        ]


def write_done_event(queue_dir: Path, event: dict[str, Any]) -> Path:
    """Atomically drop a done-signal event file in the queue dir."""
    queue_dir.mkdir(parents=True, exist_ok=True)
    path = queue_dir / f"done-{uuid.uuid4().hex}.json"
    tmp = path.with_suffix(".json.tmp")
    tmp.write_text(json.dumps(event), encoding="utf-8")
    tmp.replace(path)
    return path


def drain_done_events(queue_dir: Path) -> list[dict[str, Any]]:
    """Read and remove every queued done-signal event."""
    if not queue_dir.is_dir():
        return []
    events: list[dict[str, Any]] = []
    for path in sorted(queue_dir.glob("done-*.json")):
        try:
            events.append(json.loads(path.read_text(encoding="utf-8")))
        except (OSError, ValueError):
            continue
        finally:
            path.unlink(missing_ok=True)
    return events


class ForgeSidecar:
    """Dispatches sidecar protocol calls to the forge, logging each and
    relaying `signal_done` to the queue dir. `run_key` is the
    (owner, repo, issue_number) the run is bound to."""

    def __init__(
        self,
        *,
        forge: object,
        op_log: OpLog,
        queue_dir: Path,
        run_key: tuple[str, str, int],
    ) -> None:
        self._forge = forge
        self._log = op_log
        self._queue_dir = queue_dir
        self._owner, self._repo, self._issue = run_key

    def dispatch(self, method: str, params: dict[str, Any]) -> dict[str, Any]:
        try:
            result = self._invoke(method, params)
        except Exception as exc:  # noqa: BLE001 — surface as JSON-RPC error
            self._log.record(method, params.get("number"), f"error: {exc}")
            return {"ok": False, "error": str(exc)}
        return {"ok": True, "result": result}

    def _invoke(self, method: str, params: dict[str, Any]) -> Any:
        if method in _READ_METHODS:
            number = int(params["number"])
            result = getattr(self._forge, method)(number)
            self._log.record(method, number, "ok")
            return _jsonable(result)
        if method in _WRITE_METHODS:
            number = int(params["number"])
            getattr(self._forge, method)(number, params["body"])
            self._log.record(method, number, "ok")
            return None
        if method == "signal_done":
            status = str(params.get("status", ""))
            summary = str(params.get("summary", ""))
            self._log.record("signal_done", None, f"{status}: {summary}")
            write_done_event(
                self._queue_dir,
                {
                    "owner": self._owner,
                    "repo": self._repo,
                    "issue_number": self._issue,
                    "status": status,
                    "summary": summary,
                },
            )
            return None
        raise ValueError(f"unknown method: {method}")


class _Handler(socketserver.StreamRequestHandler):
    def handle(self) -> None:
        line = self.rfile.readline()
        if not line:
            return
        try:
            req = json.loads(line)
        except ValueError:
            self.wfile.write(b'{"ok": false, "error": "invalid json"}\n')
            return
        resp = self.server.sidecar.dispatch(  # type: ignore[attr-defined]
            str(req.get("method", "")), dict(req.get("params", {}))
        )
        self.wfile.write((json.dumps(resp) + "\n").encode())


class _Server(socketserver.ThreadingUnixStreamServer):
    def __init__(self, socket_path: str, sidecar: ForgeSidecar) -> None:
        super().__init__(socket_path, _Handler)
        self.sidecar = sidecar


def serve(sidecar: ForgeSidecar, socket_path: Path) -> _Server:
    """Bind a threaded AF_UNIX server for `sidecar`. Caller runs
    `serve_forever()` (or `handle_request()` in tests) and closes it."""
    if socket_path.exists():
        socket_path.unlink()
    socket_path.parent.mkdir(parents=True, exist_ok=True)
    return _Server(str(socket_path), sidecar)