from datetime import datetime, timedelta
from typing import Union, Any, List
from jose import jwt, JWTError
from fastapi import Depends, HTTPException, status, Request, Query
from fastapi.security import OAuth2PasswordBearer
from sqlalchemy.orm import Session

from app.core.config import settings
from app.core.database import get_db
from app.models import models
from app.crud import crud

oauth2_scheme = OAuth2PasswordBearer(
    tokenUrl=f"{settings.API_V1_STR}/auth/login"
)

def create_access_token(subject: Union[str, Any], role: str, expires_delta: timedelta = None) -> str:
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
    
    to_encode = {
        "exp": expire,
        "sub": str(subject),
        "role": role,
        "type": "access"
    }
    encoded_jwt = jwt.encode(to_encode, settings.JWT_SECRET_KEY, algorithm=settings.JWT_ALGORITHM)
    return encoded_jwt

def create_refresh_token(subject: Union[str, Any], role: str, expires_delta: timedelta = None) -> str:
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(days=settings.REFRESH_TOKEN_EXPIRE_DAYS)
        
    to_encode = {
        "exp": expire,
        "sub": str(subject),
        "role": role,
        "type": "refresh"
    }
    encoded_jwt = jwt.encode(to_encode, settings.JWT_SECRET_KEY, algorithm=settings.JWT_ALGORITHM)
    return encoded_jwt

def get_current_user(
    db: Session = Depends(get_db),
    token: str = Depends(oauth2_scheme)
) -> models.User:
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(
            token, settings.JWT_SECRET_KEY, algorithms=[settings.JWT_ALGORITHM]
        )
        email: str = payload.get("sub")
        token_type: str = payload.get("type")
        
        if email is None or token_type != "access":
            raise credentials_exception
    except JWTError:
        raise credentials_exception
        
    user = crud.get_user_by_email(db, email=email)
    if user is None:
        raise credentials_exception
    if not user.is_active:
        raise HTTPException(status_code=400, detail="Inactive user")
        
    return user

class RoleChecker:
    def __init__(self, allowed_roles: List[str]):
        self.allowed_roles = allowed_roles

    def __call__(
        self,
        current_user: models.User = Depends(get_current_user)
    ) -> models.User:
        if current_user.role.name not in self.allowed_roles:
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail=f"User role '{current_user.role.name}' does not have permission to access this resource. Allowed: {self.allowed_roles}"
            )
        return current_user


def get_current_user_from_token(token: str, db: Session) -> models.User:
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(
            token, settings.JWT_SECRET_KEY, algorithms=[settings.JWT_ALGORITHM]
        )
        email: str = payload.get("sub")
        token_type: str = payload.get("type")
        
        if email is None or token_type != "access":
            raise credentials_exception
    except JWTError:
        raise credentials_exception
        
    user = crud.get_user_by_email(db, email=email)
    if user is None:
        raise credentials_exception
    if not user.is_active:
        raise HTTPException(status_code=400, detail="Inactive user")
        
    return user


def get_current_user_sse(
    request: Request,
    token: str = Query(None),
    db: Session = Depends(get_db)
) -> models.User:
    # 1. Try to get token from query parameter
    if token:
        return get_current_user_from_token(token, db)
        
    # 2. Try to get token from Authorization header
    auth_header = request.headers.get("Authorization")
    if auth_header and auth_header.startswith("Bearer "):
        actual_token = auth_header.split(" ")[1]
        return get_current_user_from_token(actual_token, db)
        
    raise HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Not authenticated",
    )


class RoleCheckerSSE:
    def __init__(self, allowed_roles: List[str]):
        self.allowed_roles = allowed_roles

    def __call__(
        self,
        current_user: models.User = Depends(get_current_user_sse)
    ) -> models.User:
        if current_user.role.name not in self.allowed_roles:
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail=f"User role '{current_user.role.name}' does not have permission to access this resource. Allowed: {self.allowed_roles}"
            )
        return current_user