"""FastAPI app: /api/duties and static webapp."""
import logging
import re
from pathlib import Path

import config
from fastapi import FastAPI, Header, HTTPException, Query, Request
from fastapi.middleware.cors import CORSMiddleware
from fastapi.staticfiles import StaticFiles

from db.session import session_scope
from db.repository import get_duties
from db.schemas import DutyWithUser
from api.telegram_auth import validate_init_data

log = logging.getLogger(__name__)

# ISO date YYYY-MM-DD
_DATE_RE = re.compile(r"^\d{4}-\d{2}-\d{2}$")


def _validate_duty_dates(from_date: str, to_date: str) -> None:
    """Raise HTTPException 400 if dates are invalid or from_date > to_date."""
    if not _DATE_RE.match(from_date) or not _DATE_RE.match(to_date):
        raise HTTPException(
            status_code=400,
            detail="Параметры from и to должны быть в формате YYYY-MM-DD",
        )
    if from_date > to_date:
        raise HTTPException(
            status_code=400,
            detail="Дата from не должна быть позже to",
        )


def _fetch_duties_response(from_date: str, to_date: str) -> list[DutyWithUser]:
    """Fetch duties in range and return list of DutyWithUser. Uses config.DATABASE_URL."""
    with session_scope(config.DATABASE_URL) as session:
        rows = get_duties(session, from_date=from_date, to_date=to_date)
        return [
            DutyWithUser(
                id=duty.id,
                user_id=duty.user_id,
                start_at=duty.start_at,
                end_at=duty.end_at,
                full_name=full_name,
            )
            for duty, full_name in rows
        ]


def _is_private_client(client_host: str | None) -> bool:
    """True if client is localhost or private LAN (dev / same-machine access)."""
    if not client_host:
        return False
    if client_host in ("127.0.0.1", "::1"):
        return True
    parts = client_host.split(".")
    if len(parts) == 4:  # IPv4
        try:
            a, b, c, d = (int(x) for x in parts)
            if (a == 10) or (a == 172 and 16 <= b <= 31) or (a == 192 and b == 168):
                return True
        except (ValueError, IndexError):
            pass
    return False


app = FastAPI(title="Duty Teller API")
app.add_middleware(
    CORSMiddleware,
    allow_origins=config.CORS_ORIGINS,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


@app.get("/api/duties", response_model=list[DutyWithUser])
def list_duties(
    request: Request,
    from_date: str = Query(..., description="ISO date YYYY-MM-DD", alias="from"),
    to_date: str = Query(..., description="ISO date YYYY-MM-DD", alias="to"),
    x_telegram_init_data: str | None = Header(None, alias="X-Telegram-Init-Data"),
) -> list[DutyWithUser]:
    _validate_duty_dates(from_date, to_date)
    log.info("GET /api/duties from %s, has initData: %s", request.client.host if request.client else "?", bool((x_telegram_init_data or "").strip()))
    init_data = (x_telegram_init_data or "").strip()
    if not init_data:
        client_host = request.client.host if request.client else None
        if _is_private_client(client_host) or config.MINI_APP_SKIP_AUTH:
            if config.MINI_APP_SKIP_AUTH:
                log.warning("duties: allowing without initData (MINI_APP_SKIP_AUTH is set)")
            return _fetch_duties_response(from_date, to_date)
        log.warning("duties: no X-Telegram-Init-Data header (client=%s)", client_host)
        raise HTTPException(status_code=403, detail="Откройте календарь из Telegram")
    username = validate_init_data(init_data, config.BOT_TOKEN)
    if username is None:
        log.warning("duties: initData validation failed (invalid signature or no username)")
        raise HTTPException(status_code=403, detail="Неверные данные авторизации")
    if not config.can_access_miniapp(username):
        log.warning("duties: username not in allowlist")
        raise HTTPException(status_code=403, detail="Доступ запрещён")
    return _fetch_duties_response(from_date, to_date)


webapp_path = Path(__file__).resolve().parent.parent / "webapp"
if webapp_path.is_dir():
    app.mount("/app", StaticFiles(directory=str(webapp_path), html=True), name="webapp")