"""
FastAPI application entry point for the Electronics Catalog (local only).

Run with (from backend/):
    .venv\\Scripts\\python -m uvicorn app.main:app --host 127.0.0.1 --port 8000
"""
from __future__ import annotations

import logging
import os
import threading
from contextlib import asynccontextmanager
from pathlib import Path

from fastapi import FastAPI, HTTPException, Request
from fastapi.encoders import jsonable_encoder
from fastapi.exceptions import RequestValidationError
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import FileResponse, JSONResponse
from fastapi.staticfiles import StaticFiles

from app.api.routers import auth, elec, elec_admin, health
from app.infrastructure.security import auth_config_summary
from app.infrastructure.settings import API_CORS_ORIGINS, DB_HOST, DB_NAME, DB_PORT, cleaned_env_names
from app.mcp_server import mcp
from fastmcp.utilities.lifespan import combine_lifespans

logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
)
logger = logging.getLogger(__name__)


def _init_schema() -> None:
    """Apply pending migrations and make sure reference data exists. Runs on a
    thread so the API answers /api/health even while Postgres is starting."""
    try:
        from app.electronics.db import repository as repo
        from app.electronics.db.migrate import run_migrations
        from app.electronics.reference import load_reference

        applied = run_migrations()
        if applied:
            logger.info("Applied migrations: %s", ", ".join(applied))
        repo.seed_reference(load_reference())
    except Exception as exc:  # noqa: BLE001 - the health endpoint reports the DB state
        logger.warning("Schema initialisation skipped: %s", exc)


@asynccontextmanager
async def lifespan(_app: FastAPI):
    logger.info("Electronics Catalog using database %s at %s:%s", DB_NAME, DB_HOST, DB_PORT)
    threading.Thread(target=_init_schema, daemon=True).start()
    yield


# MCP endpoint (FastMCP) for AI assistants, served at /mcp/ by this same app.
# Its session manager must start with the app, hence the combined lifespan.
mcp_app = mcp.http_app(path="/")

app = FastAPI(
    title="Electronics Catalog API",
    description=(
        "Local, evidence-backed catalogue of electronics sold in India (Tamil Nadu focus). "
        "Products, prices, availability and images are collected from real retail listings "
        "found through web search; nothing is generated."
    ),
    version="1.0.0",
    lifespan=combine_lifespans(lifespan, mcp_app.lifespan),
)

_allow_credentials = "*" not in API_CORS_ORIGINS
app.add_middleware(
    CORSMiddleware,
    allow_origins=API_CORS_ORIGINS,
    allow_credentials=_allow_credentials,
    allow_methods=["*"],
    allow_headers=["*"],
)


def _json_safe(value):
    if isinstance(value, float) and (value != value or value in (float("inf"), float("-inf"))):
        return str(value)
    if isinstance(value, dict):
        return {k: _json_safe(v) for k, v in value.items()}
    if isinstance(value, (list, tuple)):
        return [_json_safe(v) for v in value]
    return value


@app.exception_handler(RequestValidationError)
async def _validation_error_as_422(request: Request, exc: RequestValidationError) -> JSONResponse:
    return JSONResponse(status_code=422, content={"detail": _json_safe(jsonable_encoder(exc.errors()))})


_auth_cfg = auth_config_summary()
logger.info(
    "Auth config: enabled=%s allow_any_login=%s admin_username=%r hash_valid=%s",
    _auth_cfg["enabled"], _auth_cfg["allow_any_login"], _auth_cfg["admin_username"],
    _auth_cfg["password_hash_valid"],
)
if _auth_cfg["allow_any_login"]:
    logger.warning("AUTH_ALLOW_ANY_LOGIN=true: any password is accepted. Keep the API on 127.0.0.1.")
if cleaned_env_names():
    logger.warning("Settings arrived quoted or padded and were cleaned: %s", ", ".join(cleaned_env_names()))

app.include_router(health.router, prefix="/api")
app.include_router(auth.router, prefix="/api")
app.include_router(elec.router, prefix="/api")
app.include_router(elec_admin.router, prefix="/api")
app.mount("/mcp", mcp_app)

_dist_override = os.getenv("FRONTEND_DIST_DIR", "").strip()
FRONTEND_DIST = Path(_dist_override) if _dist_override else Path(__file__).resolve().parents[2] / "frontend" / "dist"

if (FRONTEND_DIST / "assets").exists():
    logger.info("Serving built frontend from %s", FRONTEND_DIST)
    app.mount("/assets", StaticFiles(directory=str(FRONTEND_DIST / "assets")), name="assets")

    @app.get("/{full_path:path}")
    def serve_frontend(full_path: str):
        if full_path.startswith(("api", "mcp", "docs", "redoc", "openapi.json")):
            raise HTTPException(status_code=404, detail="Not found")
        file_path = FRONTEND_DIST / full_path
        if file_path.exists() and file_path.is_file():
            return FileResponse(file_path)
        return FileResponse(FRONTEND_DIST / "index.html")
else:
    @app.get("/")
    def root() -> dict:
        return {"service": "Electronics Catalog API", "docs": "/docs", "health": "/api/health", "mcp": "/mcp/"}