"""AI Gateway — 모델 라우팅, 폴백, 비용 제어, 요청 로깅"""

import os
from datetime import date

from fastapi import FastAPI, HTTPException, Request
from fastapi.responses import JSONResponse
import httpx

app = FastAPI(title="AI Gateway", version="1.0.0")

PRIMARY = os.getenv("PRIMARY_ENDPOINT", "http://localhost:8800/v1/chat/completions")
FALLBACK = os.getenv("FALLBACK_ENDPOINT", "http://localhost:11434/v1/chat/completions")
CLAUDE_API_KEY = os.getenv("CLAUDE_API_KEY", "")
DAILY_BUDGET = float(os.getenv("DAILY_BUDGET_USD", "5.00"))

# 일일 비용 추적 (메모리, 재시작 시 리셋)
_daily_cost: dict[str, float] = {}
_http = httpx.AsyncClient(timeout=120)


@app.get("/health")
async def health():
    return {"status": "ok", "service": "ai-gateway"}


@app.post("/v1/chat/completions")
async def chat_completions(request: Request):
    """OpenAI 호환 채팅 엔드포인트 — 자동 폴백"""
    body = await request.json()
    tier = request.headers.get("x-model-tier", "primary")

    if tier == "premium":
        return await _call_premium(body)

    # Primary → Fallback 폴백
    try:
        resp = await _http.post(PRIMARY, json=body, timeout=60)
        resp.raise_for_status()
        return JSONResponse(content=resp.json())
    except (httpx.TimeoutException, httpx.ConnectError, httpx.HTTPStatusError):
        # 폴백
        resp = await _http.post(FALLBACK, json=body, timeout=120)
        resp.raise_for_status()
        return JSONResponse(content=resp.json())


async def _call_premium(body: dict):
    """Claude API 호출 — 비용 제어"""
    today = date.today().isoformat()
    if _daily_cost.get(today, 0) >= DAILY_BUDGET:
        raise HTTPException(429, f"일일 예산 초과: ${DAILY_BUDGET}")

    if not CLAUDE_API_KEY:
        raise HTTPException(503, "CLAUDE_API_KEY 미설정")

    # TODO: Anthropic API 호출 + 비용 계산 (Phase 3에서 구현)
    raise HTTPException(501, "Premium 모델 호출은 Phase 3에서 구현")