import math
from datetime import datetime, timezone, timedelta
from zoneinfo import ZoneInfo, ZoneInfoNotFoundError

from fastapi import APIRouter, BackgroundTasks, Depends, HTTPException, Request, Response, status
from sqlalchemy import select
from sqlalchemy.orm import Session

from database import get_db
from models import User
from ntfy import notify
from schemas import LoginRequest, UserOut, UserCreate, ChangePasswordRequest, TimezoneUpdate, AuthResponse
from auth import (
    verify_password, hash_password, create_access_token, get_current_user,
    set_auth_cookie, clear_auth_cookie, token_to_user_payload,
)

router = APIRouter(prefix="/api/auth", tags=["auth"])

_LOGIN_MAX_ATTEMPTS = 5
_LOGIN_LOCKOUT_MINUTES = 15


def _issue(response: Response, user: User, admin_id=None) -> AuthResponse:
    token = create_access_token(user.id, user.username, user.is_admin, user.timezone, admin_id=admin_id)
    set_auth_cookie(response, token)
    return AuthResponse(user=token_to_user_payload(token))


@router.post("/login", response_model=AuthResponse)
def login(body: LoginRequest, response: Response, request: Request, background_tasks: BackgroundTasks, db: Session = Depends(get_db)):
    ip = request.headers.get("X-Forwarded-For", request.client.host if request.client else "unknown")
    ua = request.headers.get("User-Agent", "unknown")

    user = db.scalars(select(User).where(User.username == body.username)).first()

    # Check lockout before verifying password (don't reveal whether account exists)
    if user and user.locked_until:
        now = datetime.now(timezone.utc).replace(tzinfo=None)
        if user.locked_until > now:
            remaining = math.ceil((user.locked_until - now).total_seconds() / 60)
            background_tasks.add_task(
                notify,
                title="Yolkbook Login Attempt on Locked Account",
                message=f"User: {user.username}\nLocked for {remaining} more minute(s)\nIP: {ip}\nUA: {ua}",
                priority="high",
                tags=["lock"],
            )
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail=f"Account is temporarily locked. Try again in {remaining} minute(s).",
            )
        else:
            # Lockout expired — reset counters
            user.failed_login_attempts = 0
            user.locked_until = None
            db.commit()

    if not user or not verify_password(body.password, user.hashed_password):
        if user:
            user.failed_login_attempts += 1
            if user.failed_login_attempts >= _LOGIN_MAX_ATTEMPTS:
                user.locked_until = datetime.now(timezone.utc).replace(tzinfo=None) + timedelta(minutes=_LOGIN_LOCKOUT_MINUTES)
                db.commit()
                background_tasks.add_task(
                    notify,
                    title="Yolkbook Account Locked",
                    message=f"User: {user.username}\nLocked after {user.failed_login_attempts} failed attempts\nIP: {ip}\nUA: {ua}",
                    priority="urgent",
                    tags=["warning"],
                )
                raise HTTPException(
                    status_code=status.HTTP_403_FORBIDDEN,
                    detail=f"Account locked after too many failed attempts. Try again in {_LOGIN_LOCKOUT_MINUTES} minutes.",
                )
            db.commit()
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid username or password",
        )

    if user.is_disabled:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Account is disabled. Contact your administrator.",
        )

    # Successful login — reset failure counters
    user.failed_login_attempts = 0
    user.locked_until = None
    db.commit()

    if user.is_admin:
        background_tasks.add_task(
            notify,
            title="Yolkbook Admin Login",
            message=f"User: {user.username}\nIP: {ip}\nUA: {ua}",
            priority="high",
            tags=["key"],
        )
    return _issue(response, user)


@router.post("/register", response_model=AuthResponse, status_code=201)
def register(body: UserCreate, response: Response, request: Request, background_tasks: BackgroundTasks, db: Session = Depends(get_db)):
    existing = db.scalars(select(User).where(User.username == body.username)).first()
    if existing:
        raise HTTPException(status_code=409, detail="Username already taken")
    user = User(
        username=body.username,
        hashed_password=hash_password(body.password),
        is_admin=False,
        timezone="UTC",
    )
    db.add(user)
    db.commit()
    db.refresh(user)
    ip = request.headers.get("X-Forwarded-For", request.client.host if request.client else "unknown")
    ua = request.headers.get("User-Agent", "unknown")
    background_tasks.add_task(
        notify,
        title="Yolkbook New User Registered",
        message=f"Username: {user.username}\nIP: {ip}\nUA: {ua}",
        priority="default",
        tags=["bust_in_silhouette"],
    )
    return _issue(response, user)


@router.post("/logout")
def logout(response: Response):
    clear_auth_cookie(response)
    return {"detail": "Logged out"}


@router.get("/me", response_model=UserOut)
def me(current_user: User = Depends(get_current_user)):
    return current_user


@router.post("/change-password")
def change_password(
    body: ChangePasswordRequest,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db),
):
    if not verify_password(body.current_password, current_user.hashed_password):
        raise HTTPException(status_code=400, detail="Current password is incorrect")
    current_user.hashed_password = hash_password(body.new_password)
    db.commit()
    return {"detail": "Password updated"}


@router.put("/timezone", response_model=AuthResponse)
def update_timezone(
    body: TimezoneUpdate,
    response: Response,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db),
):
    try:
        ZoneInfo(body.timezone)
    except ZoneInfoNotFoundError:
        raise HTTPException(status_code=400, detail=f"Unknown timezone: {body.timezone}")
    current_user.timezone = body.timezone
    db.commit()
    db.refresh(current_user)
    return _issue(response, current_user)