"""S0 FastAPI app foundation (APP-30, APP-45, APP-55, APP-65, SETTINGS-10/25, OPS-25).
Base /api/v1; health at /api/health (non-200 on storage not writable).
Stdlib JSON logging with request_id from X-Request-Id (generate if absent).
Startup guards refuse on bad WOO_BASE_URL or missing SLAB_AES_KEY.
No secrets in logs. Minimal, no S1+.
"""
from __future__ import annotations

import json
import logging
import os
import sys
import uuid
from contextvars import ContextVar
from pathlib import Path
from typing import Any

from contextlib import asynccontextmanager

from fastapi import FastAPI, HTTPException, Request
from fastapi.middleware.cors import CORSMiddleware
from starlette.middleware.base import BaseHTTPMiddleware

from .db import get_connection, init_db, probe_images_writable, probe_writable

__version__ = "0.5.0-m3-s0"

# --- Structured JSON logging (stdlib only) ---
request_id_var: ContextVar[str] = ContextVar("request_id", default="")


class _JsonFormatter(logging.Formatter):
    """JSON lines; redacts any secret-looking content (APP-65)."""

    def format(self, record: logging.LogRecord) -> str:
        rid = getattr(record, "request_id", None) or request_id_var.get("")
        msg = record.getMessage()
        # Redact secrets: never log creds, keys, aes material
        lower = msg.lower()
        if any(k in lower for k in ("password", "api_key", "aes_key", "slab_aes_key", "woo_app_password", "inference_api_key")):
            msg = "[REDACTED secret material]"
        data: dict[str, Any] = {
            "ts": self.formatTime(record, self.datefmt),
            "level": record.levelname,
            "logger": record.name,
            "request_id": rid,
            "msg": msg,
        }
        if record.exc_info:
            data["exc"] = self.formatException(record.exc_info)
        return json.dumps(data, ensure_ascii=False, separators=(",", ":"))


def _configure_logging() -> None:
    level = os.getenv("LOG_LEVEL", "INFO").upper()
    handler = logging.StreamHandler(sys.stdout)
    handler.setFormatter(_JsonFormatter())
    root = logging.getLogger()
    root.handlers.clear()
    root.addHandler(handler)
    root.setLevel(getattr(logging, level, logging.INFO))
    # uvicorn access logs also json? for S0 keep simple; they inherit
    logging.getLogger("uvicorn.access").setLevel(logging.WARNING)


_configure_logging()
logger = logging.getLogger("slab.backend")


# --- Startup guards (refuse with clear message) ---
def _enforce_startup_guards() -> None:
    woo_url = os.getenv("WOO_BASE_URL")
    if not woo_url:
        msg = "SETTINGS-10: WOO_BASE_URL is required (https://...)"
        logger.error(msg)
        raise RuntimeError(msg)
    if not woo_url.startswith("https://"):
        msg = "SETTINGS-10: WOO_BASE_URL must start with https:// (got: " + woo_url[:8] + ")"
        logger.error(msg)
        raise RuntimeError(msg)
    if not os.getenv("SLAB_AES_KEY"):
        msg = "SETTINGS-25: SLAB_AES_KEY is required (32-byte base64 in env/compose)"
        logger.error(msg)
        raise RuntimeError(msg)
    # db/images envs are required by db.py on use; guards here only per spec


_enforce_startup_guards()


# --- Request ID middleware (threads X-Request-Id or generates) ---
class RequestIdMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request: Request, call_next):
        rid = request.headers.get("X-Request-Id") or str(uuid.uuid4())
        token = request_id_var.set(rid)
        try:
            response = await call_next(request)
            response.headers["X-Request-Id"] = rid
            return response
        finally:
            request_id_var.reset(token)


# --- App ---
@asynccontextmanager
async def lifespan(app: FastAPI):
    logger.info("startup: applying schema (idempotent)")
    try:
        init_db()
        logger.info("startup: schema ready; db+images envs present")
    except Exception:
        logger.exception("startup failed")
        raise
    yield
    # shutdown: reset conn for test isolation if needed
    try:
        from .db import _reset_for_tests
        _reset_for_tests()
    except Exception:
        pass


app = FastAPI(
    title="SlabUploader",
    version=__version__,
    docs_url=None,
    redoc_url=None,
    lifespan=lifespan,
)

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


@app.get("/api/health")
async def health() -> dict[str, Any]:
    """Health per APP-30/45: non-200 when db or image volume not writable (probe file)."""
    db_ok = probe_writable()
    img_ok = probe_images_writable()
    if not (db_ok and img_ok):
        logger.warning("health: storage not writable", extra={"request_id": request_id_var.get("")})
        raise HTTPException(status_code=503, detail="storage not writable")
    return {
        "status": "ok",
        "version": __version__,
        "woo_reachable": False,  # S0 stub; S4 will implement real check
    }


@app.get("/api/v1/meta")
async def meta() -> dict[str, Any]:
    """Per API.md §3."""
    return {"version": __version__}


# expose for tests
__all__ = ["app", "__version__"]