"""FastAPI application entry point.

Run with:
    uvicorn api.main:app --reload --host 0.0.0.0 --port 8000

Environment variables (see .env.example):
    MODEL_PATH            — path to ONNX weights file
    VIDEO_SOURCE          — default video source (file path, webcam index, RTSP URL)
    CONFIDENCE_THRESHOLD  — detection confidence threshold (default 0.35)
    IOU_THRESHOLD         — NMS IoU threshold (default 0.45)
    CORS_ORIGINS          — comma-separated allowed CORS origins (default *)
    SERVE_FRONTEND        — set to "1" to serve the built React app from dashboard/dist
                            (used in HF Spaces single-container deployment)
"""
from __future__ import annotations

import os
from contextlib import asynccontextmanager
from pathlib import Path

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from fastapi.staticfiles import StaticFiles

from api.database import init_db
from api.routes import analytics, health, stream


# ── Lifespan ──────────────────────────────────────────────────────────────────

@asynccontextmanager
async def lifespan(app: FastAPI):
    # Startup
    await init_db()
    print("[API] Database initialised.")

    # Auto-start pipeline if VIDEO_SOURCE env var is set
    source = os.environ.get("VIDEO_SOURCE", "").strip()
    if source:
        from api.pipeline_manager import manager
        from core.pipeline import PipelineConfig

        try:
            src: str | int = int(source)
        except ValueError:
            src = source

        config = PipelineConfig(
            source=src,
            model_path=os.environ.get("MODEL_PATH") or None,
            confidence_threshold=float(os.environ.get("CONFIDENCE_THRESHOLD", "0.35")),
            iou_threshold=float(os.environ.get("IOU_THRESHOLD", "0.45")),
        )
        await manager.start(config)
        print(f"[API] Pipeline auto-started with source={src!r}")

    yield

    # Shutdown
    from api.pipeline_manager import manager
    await manager.stop()
    print("[API] Pipeline stopped.")


# ── App ───────────────────────────────────────────────────────────────────────

app = FastAPI(
    title="TrafficVision API",
    description="Real-time vehicle detection, tracking, and traffic analytics.",
    version="1.0.0",
    lifespan=lifespan,
)

# CORS — allow React dev server by default; tighten in production
_origins_env = os.environ.get("CORS_ORIGINS", "*")
_origins = [o.strip() for o in _origins_env.split(",")]

app.add_middleware(
    CORSMiddleware,
    allow_origins=_origins,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# ── Routes ────────────────────────────────────────────────────────────────────

app.include_router(health.router, prefix="/api")
app.include_router(stream.router, prefix="/api")
app.include_router(analytics.router, prefix="/api")


# ── Frontend static files (HF Spaces single-container mode) ──────────────────
# Set SERVE_FRONTEND=1 to have FastAPI serve the built React app.
# In local dev the Vite dev server handles this instead.

_dist = Path(__file__).parent.parent / "dashboard" / "dist"

if os.environ.get("SERVE_FRONTEND", "").strip() == "1" and _dist.is_dir():
    # Mount the entire dist folder last — StaticFiles with html=True serves
    # index.html as the fallback for any path not matched by the API routes above.
    # Because this is mounted after include_router calls, API routes always win.
    app.mount("/", StaticFiles(directory=_dist, html=True), name="spa")

else:
    @app.get("/", include_in_schema=False)
    async def root():
        return {"message": "TrafficVision API", "docs": "/docs"}