"""
Vignette 엔진 게이트웨이 — 로컬 claude -p(Opus 4.8) 상주 멀티턴 풀.

컨테이너 밖(호스트)에서 실행한다. api 컨테이너가 ENGINE_URL(예: http://host.docker.internal:9099)로 HTTP 호출.
회기당 1 EngineSession = claude -p 1 프로세스 상주. 페르소나 시스템프롬프트를 고정하고 발화마다 stdin 주입.
턴 간 컨텍스트 유지 + prompt caching 재사용(2026-06-25 실증, reference_claude_p_resident_engine).

실행:
  cd apps/api && uvicorn engine_gateway.gateway:app --host 0.0.0.0 --port 9099
"""
import asyncio
import json
import os
import uuid

from fastapi import FastAPI, HTTPException
from pydantic import BaseModel

CLAUDE_BIN = os.environ.get("CLAUDE_BIN", "claude")
DEFAULT_MODEL = os.environ.get("ENGINE_MODEL", "")  # 비우면 CLI 기본(Opus 4.8)
FALLBACK_MODEL = os.environ.get("ENGINE_FALLBACK_MODEL", "")
DEFAULT_BUDGET = float(os.environ.get("SESSION_BUDGET_USD", "5.0"))

BASE_ARGS = [
    "-p",
    "--input-format", "stream-json",
    "--output-format", "stream-json",
    "--verbose",
    "--dangerously-skip-permissions",
]


class EngineSession:
    """claude -p 상주 프로세스 1개 = 상담 회기 1개."""

    def __init__(self, system_prompt: str | None = None, budget: float = DEFAULT_BUDGET):
        self.id = uuid.uuid4().hex
        self.system_prompt = system_prompt
        self.budget = budget
        self.proc: asyncio.subprocess.Process | None = None
        self.lock = asyncio.Lock()  # 한 회기 안의 턴은 직렬(상담 왕복)
        self.cost_usd = 0.0
        self.turns = 0

    async def start(self) -> None:
        args = [CLAUDE_BIN, *BASE_ARGS, "--max-budget-usd", str(self.budget)]
        if DEFAULT_MODEL:
            args += ["--model", DEFAULT_MODEL]
        if FALLBACK_MODEL:
            args += ["--fallback-model", FALLBACK_MODEL]
        if self.system_prompt:
            args += ["--append-system-prompt", self.system_prompt]
        self.proc = await asyncio.create_subprocess_exec(
            *args,
            stdin=asyncio.subprocess.PIPE,
            stdout=asyncio.subprocess.PIPE,
            stderr=asyncio.subprocess.PIPE,
        )

    async def turn(self, content: str, timeout: float = 120.0) -> dict:
        if self.proc is None or self.proc.returncode is not None:
            raise RuntimeError("engine session not running")
        async with self.lock:
            msg = json.dumps(
                {"type": "user", "message": {"role": "user", "content": content}},
                ensure_ascii=False,
            )
            self.proc.stdin.write((msg + "\n").encode("utf-8"))
            await self.proc.stdin.drain()

            text_parts: list[str] = []

            async def _read_until_result() -> dict:
                # 한 턴: system(init/hook) 라인 무시 → assistant 텍스트 누적 → result 에서 종료
                while True:
                    line = await self.proc.stdout.readline()
                    if not line:
                        return {}
                    try:
                        obj = json.loads(line)
                    except json.JSONDecodeError:
                        continue
                    t = obj.get("type")
                    if t == "assistant":
                        for c in obj.get("message", {}).get("content", []):
                            if c.get("type") == "text":
                                text_parts.append(c["text"])
                    elif t == "result":
                        return obj

            result = await asyncio.wait_for(_read_until_result(), timeout=timeout)
            self.cost_usd = result.get("total_cost_usd", self.cost_usd)
            self.turns += 1
            return {
                "text": "".join(text_parts),
                "cost_usd": self.cost_usd,
                "turns": self.turns,
                "is_error": result.get("is_error", False),
                "error": (result.get("errors") or [None])[0],
            }

    async def close(self) -> None:
        if self.proc and self.proc.returncode is None:
            try:
                self.proc.stdin.close()
            except Exception:
                pass
            try:
                await asyncio.wait_for(self.proc.wait(), timeout=5)
            except Exception:
                self.proc.kill()


SESSIONS: dict[str, EngineSession] = {}
app = FastAPI(title="Vignette Engine Gateway")


class CreateReq(BaseModel):
    system_prompt: str | None = None
    budget_usd: float | None = None


class TurnReq(BaseModel):
    content: str


@app.get("/health")
async def health():
    return {"ok": True, "engine": "claude_p", "model": DEFAULT_MODEL or "default(opus-4-8)", "sessions": len(SESSIONS)}


@app.post("/session")
async def create_session(req: CreateReq):
    s = EngineSession(system_prompt=req.system_prompt, budget=req.budget_usd or DEFAULT_BUDGET)
    await s.start()
    SESSIONS[s.id] = s
    return {"session_id": s.id}


@app.post("/session/{sid}/turn")
async def turn(sid: str, req: TurnReq):
    s = SESSIONS.get(sid)
    if not s:
        raise HTTPException(404, "session not found")
    return await s.turn(req.content)


@app.delete("/session/{sid}")
async def close_session(sid: str):
    s = SESSIONS.pop(sid, None)
    if s:
        await s.close()
    return {"closed": bool(s)}