from fastapi import APIRouter, Depends, HTTPException, status, Response
from fastapi.security import OAuth2PasswordRequestForm
from sqlalchemy.orm import Session
from typing import Optional, List

from database import get_db
from auth import (
    verify_password,
    get_password_hash,
    create_access_token,
    create_refresh_token,
    verify_token,
    get_current_user,
    require_admin,
    create_default_admin,
    log_action,
)
from models import User
from schemas import UserCreate, UserOut, LoginPayload, Token, TokenRefresh, UserUpdate, UserListOut

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


@router.post("/register", response_model=UserOut, status_code=status.HTTP_201_CREATED)
def register(payload: UserCreate, db: Session = Depends(get_db)):
    existing = db.query(User).filter(User.username == payload.username).first()
    if existing:
        raise HTTPException(status_code=400, detail="Username already exists")
    user = User(
        username=payload.username,
        password_hash=get_password_hash(payload.password),
        role="viewer",
    )
    db.add(user)
    db.commit()
    db.refresh(user)
    return user


@router.post("/login", response_model=Token)
def login(
    response: Response,
    form_data: OAuth2PasswordRequestForm = Depends(),
    db: Session = Depends(get_db),
):
    create_default_admin(db)
    user = db.query(User).filter(User.username == form_data.username).first()
    if not user or not verify_password(form_data.password, user.password_hash):
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid credentials")
    access = create_access_token({"sub": user.username, "role": user.role})
    refresh = create_refresh_token({"sub": user.username, "role": user.role})
    response.set_cookie(
        key="access_token",
        value=access,
        httponly=True,
        max_age=1800,
        samesite="lax",
    )
    return {"access_token": access, "refresh_token": refresh}


@router.post("/refresh", response_model=Token)
def refresh(payload: TokenRefresh, response: Response, db: Session = Depends(get_db)):
    data = verify_token(payload.refresh_token, "refresh")
    if not data or "sub" not in data:
        raise HTTPException(status_code=401, detail="Invalid refresh token")
    user = db.query(User).filter(User.username == data["sub"]).first()
    if not user:
        raise HTTPException(status_code=401, detail="User not found")
    access = create_access_token({"sub": user.username, "role": user.role})
    refresh = create_refresh_token({"sub": user.username, "role": user.role})
    response.set_cookie(
        key="access_token",
        value=access,
        httponly=True,
        max_age=1800,
        samesite="lax",
    )
    return {"access_token": access, "refresh_token": refresh}


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


@router.post("/logout")
def logout(response: Response):
    response.delete_cookie("access_token")
    return {"ok": True}


# Admin user management

@router.get("/users", response_model=List[UserListOut])
def list_users(
    db: Session = Depends(get_db),
    admin: User = Depends(require_admin),
):
    return db.query(User).order_by(User.username).all()


@router.post("/users", response_model=UserOut, status_code=status.HTTP_201_CREATED)
def create_user(
    payload: UserCreate,
    db: Session = Depends(get_db),
    admin: User = Depends(require_admin),
):
    existing = db.query(User).filter(User.username == payload.username).first()
    if existing:
        raise HTTPException(status_code=400, detail="Username already exists")
    user = User(
        username=payload.username,
        password_hash=get_password_hash(payload.password),
        role="viewer",
    )
    db.add(user)
    db.commit()
    db.refresh(user)
    log_action(db, admin, "user_created", f"Created user {user.username} (id={user.id})")
    return user


@router.patch("/users/{user_id}", response_model=UserOut)
def update_user(
    user_id: int,
    payload: UserUpdate,
    db: Session = Depends(get_db),
    admin: User = Depends(require_admin),
):
    user = db.query(User).filter(User.id == user_id).first()
    if not user:
        raise HTTPException(status_code=404, detail="User not found")

    if user.id == admin.id and payload.role and payload.role != "admin":
        raise HTTPException(status_code=400, detail="Cannot downgrade yourself")

    if payload.role:
        if payload.role not in ("admin", "viewer"):
            raise HTTPException(status_code=400, detail="Invalid role")
        user.role = payload.role

    if payload.password:
        user.password_hash = get_password_hash(payload.password)

    db.commit()
    db.refresh(user)
    log_action(db, admin, "user_updated", f"Updated user {user.username} (id={user.id}), role={user.role}, password_changed={bool(payload.password)}")
    return user


@router.delete("/users/{user_id}")
def delete_user(
    user_id: int,
    db: Session = Depends(get_db),
    admin: User = Depends(require_admin),
):
    user = db.query(User).filter(User.id == user_id).first()
    if not user:
        raise HTTPException(status_code=404, detail="User not found")
    if user.id == admin.id:
        raise HTTPException(status_code=400, detail="Cannot delete yourself")

    # prevent deleting last admin
    if user.role == "admin":
        admin_count = db.query(User).filter(User.role == "admin").count()
        if admin_count <= 1:
            raise HTTPException(status_code=400, detail="Cannot delete the last admin")

    username = user.username
    db.delete(user)
    db.commit()
    log_action(db, admin, "user_deleted", f"Deleted user {username} (id={user_id})")
    return {"ok": True}