"""FastAPI app: /api/duties, /api/calendar-events, personal ICS, and static webapp at /app."""

import logging
import re
from datetime import date, timedelta
from typing import Literal

import duty_teller.config as config
from fastapi import Depends, FastAPI, Request
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import Response
from fastapi.staticfiles import StaticFiles
from sqlalchemy.orm import Session

from duty_teller.api.calendar_ics import get_calendar_events
from duty_teller.api.dependencies import (
    fetch_duties_response,
    get_db_session,
    get_validated_dates,
    require_miniapp_username,
)
from duty_teller.api.personal_calendar_ics import build_personal_ics
from duty_teller.db.repository import get_duties_for_user, get_user_by_calendar_token
from duty_teller.db.schemas import CalendarEvent, DutyWithUser

log = logging.getLogger(__name__)

# Calendar tokens are secrets.token_urlsafe(32) → base64url, length 43
_CALENDAR_TOKEN_RE = re.compile(r"^[A-Za-z0-9_-]{40,50}$")


def _is_valid_calendar_token(token: str) -> bool:
    """Return True if token matches expected format (length and alphabet). Rejects invalid before DB."""
    return bool(token and _CALENDAR_TOKEN_RE.match(token))


app = FastAPI(title="Duty Teller API")


@app.get("/health", summary="Health check")
def health() -> dict:
    """Return 200 when the app is up. Used by Docker HEALTHCHECK."""
    return {"status": "ok"}


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


@app.get(
    "/api/duties",
    response_model=list[DutyWithUser],
    summary="List duties",
    description=(
        "Returns duties for the given date range. Requires Telegram Mini App initData "
        "(or MINI_APP_SKIP_AUTH / private IP in dev)."
    ),
)
def list_duties(
    request: Request,
    dates: tuple[str, str] = Depends(get_validated_dates),
    _username: str = Depends(require_miniapp_username),
    session: Session = Depends(get_db_session),
):
    from_date_val, to_date_val = dates
    log.info(
        "GET /api/duties from %s",
        request.client.host if request.client else "?",
    )
    return fetch_duties_response(session, from_date_val, to_date_val)


@app.get(
    "/api/calendar-events",
    response_model=list[CalendarEvent],
    summary="List calendar events",
    description=(
        "Returns calendar events for the date range, including external ICS when "
        "EXTERNAL_CALENDAR_ICS_URL is set. Auth same as /api/duties."
    ),
)
def list_calendar_events(
    dates: tuple[str, str] = Depends(get_validated_dates),
    _username: str = Depends(require_miniapp_username),
):
    from_date_val, to_date_val = dates
    url = config.EXTERNAL_CALENDAR_ICS_URL
    if not url:
        return []
    events = get_calendar_events(url, from_date=from_date_val, to_date=to_date_val)
    return [CalendarEvent(date=e["date"], summary=e["summary"]) for e in events]


@app.get(
    "/api/calendar/ical/{token}.ics",
    summary="Personal calendar ICS",
    description=(
        "Returns an ICS calendar with the subscribing user's events. "
        "By default only duty shifts are included; use query parameter events=all "
        "for all event types (duty, unavailable, vacation). "
        "No Telegram auth; access is by secret token in the URL."
    ),
)
def get_personal_calendar_ical(
    token: str,
    events: Literal["duty", "all"] = "duty",
    session: Session = Depends(get_db_session),
) -> Response:
    """
    Return ICS calendar with the subscribing user's events.
    Default: only duty shifts. Use ?events=all for duty, unavailable, vacation.
    No Telegram auth; access is by secret token in the URL.
    """
    if not _is_valid_calendar_token(token):
        return Response(status_code=404, content="Not found")
    user = get_user_by_calendar_token(session, token)
    if user is None:
        return Response(status_code=404, content="Not found")
    today = date.today()
    from_date = (today - timedelta(days=365)).strftime("%Y-%m-%d")
    to_date = (today + timedelta(days=365 * 2)).strftime("%Y-%m-%d")
    event_types = ["duty"] if events == "duty" else None
    duties_with_name = get_duties_for_user(
        session, user.id, from_date=from_date, to_date=to_date, event_types=event_types
    )
    ics_bytes = build_personal_ics(duties_with_name)
    return Response(
        content=ics_bytes,
        media_type="text/calendar; charset=utf-8",
    )


webapp_path = config.PROJECT_ROOT / "webapp"
if webapp_path.is_dir():
    app.mount("/app", StaticFiles(directory=str(webapp_path), html=True), name="webapp")