from contextlib import asynccontextmanager

from fastapi import FastAPI, Request
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import JSONResponse
from slowapi import Limiter, _rate_limit_exceeded_handler
from slowapi.errors import RateLimitExceeded
from slowapi.util import get_remote_address

from app.config import settings
from app.routers.extract import router as extract_router
from app.routers.sanitize import router as sanitize_router
from app.services.sanitizer import preload_pipeline


def _get_real_ip(request: Request) -> str:
    """Extract the real client IP — honours X-Forwarded-For set by HF Spaces / reverse proxy."""
    forwarded_for = request.headers.get("X-Forwarded-For")
    if forwarded_for:
        # X-Forwarded-For: client, proxy1, proxy2 — take the leftmost (real client)
        return forwarded_for.split(",")[0].strip()
    return get_remote_address(request)


limiter = Limiter(key_func=_get_real_ip, default_limits=["100/minute"])


@asynccontextmanager
async def lifespan(app: FastAPI):
    # Pre-load default model at startup; other models are lazy-loaded on first use
    preload_pipeline(settings.default_model_name)
    yield


app = FastAPI(
    title="Privacy Text Sanitizer API",
    version="1.0.0",
    lifespan=lifespan,
)

app.state.limiter = limiter
app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)

app.add_middleware(
    CORSMiddleware,
    allow_origins=settings.allowed_origins,
    allow_methods=["GET", "POST", "OPTIONS"],
    allow_headers=["Content-Type"],
)

app.include_router(sanitize_router, prefix="/api")
app.include_router(extract_router, prefix="/api")


@app.get("/health")
async def health() -> dict[str, str]:
    return {"status": "ok"}