CODE_ASSISTANT/5_django_backend/apps/gateway/views.py

"""`/api/ito/*` — OpenCode 가 붙는 OpenAI 호환 중계. 본문은 손 안 대고 FabriX 로 흘림.

    GET  /api/ito/healthcheck        기동 확인(무인증)
    GET  /api/ito/models             설정된 모델 목록(OpenAI 형식)
    POST /api/ito/chat/completions   스트림/비스트림 통과 중계

설정이 비어 있어도 서버는 뜸 — 이 엔드포인트만 503 으로 이유를 말함(다른 기능까지 죽이지 않게).
"""

from __future__ import annotations

import asyncio
import json
import time
import uuid
from datetime import datetime, timezone
import logging
from typing import AsyncIterator

import httpx
from django.conf import settings
from django.http import HttpRequest, HttpResponse, JsonResponse, StreamingHttpResponse
from django.views.decorators.csrf import csrf_exempt

from . import langfuse
from .fabrix import FabrixConfig, Variant, auth_variants

log = logging.getLogger(__name__)

# 테스트가 httpx.MockTransport 를 꽂는 자리. None 이면 진짜 네트워크.
TRANSPORT: httpx.AsyncBaseTransport | None = None
# 마지막에 통과한 인증 형식 — 프로세스당 하나. 다음 요청은 이것부터 시도.
_last_ok: dict[str, Variant | None] = {"variant": None}
RETRY_PAUSE_S = 1.0  # 마지막 재시도 전 쉬는 시간


def _cfg() -> FabrixConfig:
    return FabrixConfig.from_env(settings.FABRIX_ENV)


def _err(status: int, message: str, typ: str) -> JsonResponse:
    """OpenAI 형식 오류 — OpenCode 가 이 모양을 읽음(우리 envelope 아님)."""
    return JsonResponse({"error": {"message": message, "type": typ}}, status=status)


def _key_rejected(request: HttpRequest, cfg: FabrixConfig) -> JsonResponse | None:
    """AAF_GATEWAY_KEY 가 있으면 Authorization: Bearer <키> 대조. 비우면 검사 안 함(로컬 전용)."""
    if not cfg.gateway_key:
        return None
    auth = request.headers.get("Authorization", "")
    if auth.startswith("Bearer ") and auth[7:].strip() == cfg.gateway_key:
        return None
    return _err(401, "게이트웨이 키가 틀려 — opencode.json 의 apiKey 와 AAF_GATEWAY_KEY 확인", "unauthorized")


def _client(cfg: FabrixConfig) -> httpx.AsyncClient:
    timeout = httpx.Timeout(cfg.total_timeout_s, connect=cfg.connect_timeout_s, read=cfg.read_timeout_s)
    return httpx.AsyncClient(timeout=timeout, transport=TRANSPORT)


def _sse_error(status: int, detail: bytes) -> bytes:
    """상류 오류를 SSE 오류 청크로. 연결은 정상 종료해 OpenCode 가 본문을 읽게."""
    payload = {"error": {"message": detail.decode("utf-8", "replace")[:2000], "type": "upstream_error", "status": status}}
    return b"data: " + json.dumps(payload, ensure_ascii=False).encode() + b"\n\ndata: [DONE]\n\n"


class _Collect:
    """상류 응답에서 답변 텍스트·usage 만 긁어 모음(관측용). 스트림은 줄 단위 `data: {json}`."""

    def __init__(self) -> None:
        self.text: list[str] = []
        self.usage: dict | None = None
        self.buf = b""

    def feed(self, chunk: bytes) -> None:
        self.buf += chunk
        while b"\n" in self.buf:
            line, self.buf = self.buf.split(b"\n", 1)
            self._line(line.strip())

    def _line(self, line: bytes) -> None:
        if not line.startswith(b"data:") or line.endswith(b"[DONE]"):
            return
        try:
            d = json.loads(line[5:])
        except ValueError:
            return
        self.json(d)

    def json(self, d: dict) -> None:
        for c in d.get("choices") or []:
            t = (c.get("delta") or c.get("message") or {}).get("content")
            if isinstance(t, str):
                self.text.append(t)
        if d.get("usage"):
            self.usage = d["usage"]


def _observe(model_id: str, body: dict, col: _Collect, started: float, status: int, *, kinds: list[str]) -> None:
    if not langfuse.enabled():
        return
    u = col.usage or {}
    tid = str(uuid.uuid4())
    langfuse.send_later([
        langfuse.trace(tid, "fabrix", tags=["gateway"], metadata={"parts": kinds}),
        langfuse.generation(
            tid, "fabrix.chat", model=model_id,
            startTime=datetime.fromtimestamp(started, timezone.utc).isoformat(), endTime=langfuse.now_iso(),
            input=body.get("messages"), output="".join(col.text),
            usage=langfuse.usage_of(u.get("prompt_tokens"), u.get("completion_tokens")),
            level="ERROR" if status >= 400 else "DEFAULT", statusMessage="" if status < 400 else f"upstream {status}",
            modelParameters={k: v for k, v in body.items() if k in ("temperature", "max_completion_tokens", "max_tokens")},
            metadata={"stream": bool(body.get("stream")), "tools": len(body.get("tools") or [])},
        ),
    ])


async def healthcheck(_request: HttpRequest) -> JsonResponse:
    return JsonResponse({"success": True})


async def models(request: HttpRequest) -> HttpResponse:
    cfg = _cfg()
    if rejected := _key_rejected(request, cfg):
        return rejected
    data = [{"id": mid, "object": "model", "owned_by": "fabrix", "name": name} for mid, name in cfg.model_list().items()]
    return JsonResponse({"object": "list", "data": data})


@csrf_exempt
async def chat_completions(request: HttpRequest) -> HttpResponse:
    if request.method != "POST":
        return _err(405, "POST 만 받아", "method_not_allowed")
    cfg = _cfg()
    if rejected := _key_rejected(request, cfg):
        return rejected
    if missing := cfg.missing():
        return _err(503, f"FabriX 설정 누락: {', '.join(missing)} (.env 확인)", "configuration_error")
    try:
        payload = json.loads(request.body.decode("utf-8"))
        assert isinstance(payload, dict)
    except Exception:
        return _err(400, "본문이 JSON 객체가 아니야", "invalid_request")

    body, headers = cfg.prepare(payload)
    # 어떤 파트가 왔고 어느 모델로 가는지 — 이미지 분기 확인용(본문은 안 찍음)
    kinds = sorted({p.get("type", "?") for m in payload.get("messages") or [] for p in (m.get("content") if isinstance(m.get("content"), list) else [])})
    log.info("ito → model=%s parts=%s stream=%s", headers.get("x-llm-model-id"), kinds or ["text"], bool(body.get("stream")))
    variants = auth_variants(headers, _last_ok["variant"])
    # FabriX 가 맞는 조합에도 가끔 401 을 뱉음(2026-09-21 고객사 실측: curl 10번 중 1~2번).
    # 4개 조합 다 돌고 나서 제일 유력한 조합(맨 앞)을 잠깐 쉬고 한 번 더 — 그래도 401 이면 진짜 인증 문제
    variants = variants + variants[:1]
    model_id = headers.get("x-llm-model-id", "")
    started = time.time()
    col = _Collect()

    if body.get("stream"):

        async def gen() -> AsyncIterator[bytes]:
            async with _client(cfg) as client:
                resp: httpx.Response | None = None
                vkey: Variant | None = None
                for i, (vkey, vh) in enumerate(variants):
                    req = client.build_request("POST", cfg.url, headers=vh, json=body)
                    resp = await client.send(req, stream=True)
                    log.info("ito ← %s (auth %s/%s: %s)", resp.status_code, i + 1, len(variants), vkey)
                    if resp.status_code == 401 and i + 1 < len(variants):
                        await resp.aclose()  # 인증 형식이 안 맞은 것 — 다른 조합으로 한 번 더
                        if i + 2 == len(variants):
                            await asyncio.sleep(RETRY_PAUSE_S)
                        continue
                    break
                assert resp is not None
                try:
                    if resp.status_code >= 400:
                        yield _sse_error(resp.status_code, await resp.aread())
                        return
                    _last_ok["variant"] = vkey
                    async for chunk in resp.aiter_raw():
                        col.feed(chunk)
                        yield chunk
                finally:
                    await resp.aclose()
                    _observe(model_id, body, col, started, resp.status_code, kinds=kinds or ["text"])

        out = StreamingHttpResponse(gen(), content_type="text/event-stream")
        out["Cache-Control"] = "no-cache"
        out["X-Accel-Buffering"] = "no"
        return out

    try:
        async with _client(cfg) as client:
            for i, (vkey, vh) in enumerate(variants):
                resp = await client.post(cfg.url, headers=vh, json=body)
                if resp.status_code == 401 and i + 1 < len(variants):
                    if i + 2 == len(variants):
                        await asyncio.sleep(RETRY_PAUSE_S)
                    continue
                if resp.status_code < 400:
                    _last_ok["variant"] = vkey
                break
    except httpx.HTTPError as e:
        return _err(502, f"FabriX 호출 실패: {type(e).__name__}: {e}", "upstream_error")
    if resp.status_code < 400:
        try:
            col.json(resp.json())
        except ValueError:
            pass
    _observe(model_id, body, col, started, resp.status_code, kinds=kinds or ["text"])
    return HttpResponse(resp.content, status=resp.status_code, content_type="application/json")