import uuid, bcrypt, random, string
from sqlalchemy.orm import Session
from datetime import datetime, timedelta
from redis.asyncio import Redis
from app.utils.redis_utils import redis_qpush
from app.core.auth import get_current_user
from app.core.biz_exception import NotFoundError, PermissionDeniedError, BizLogicError
from app.models.user import VasUser
from app.models.session import VasSession
from app.models.email_verification import VasEmailVerification
from app.schemas.auth import AutoRegisterRequest, SendBindCodeRequest, SendResetCodeRequest, BindEmailRequest, ResetPasswordRequest, LoginRequest
from app.services.notification_service import NotificationService


def _random_password(length=16):
    return ''.join(random.choices(string.ascii_letters + string.digits + "!@#$%", k=length))

class AuthService:
    # -----------------------
    # 自动注册
    # -----------------------
    @staticmethod
    def auto_register(db: Session, req:AutoRegisterRequest):
        uid = f'usr-{uuid.uuid4().hex[:8]}'

        user = VasUser(
            id=uid,
            role="user",
            nickname="anonymous visitor",
            preferred_language="en",
            timezone="Asia/Shanghai",
            register_ip=req.register_ip,
        )
        db.add(user)
        db.commit()

        # 创建 session
        token = f"tok_{uuid.uuid4().hex}"

        session = VasSession(
            id=token,
            user_id=uid,
            user_agent=req.user_agent or "",
            ip=req.register_ip,
            expire_at=datetime.utcnow() + timedelta(days=7)
        )
        db.add(session)
        db.commit()
        return {
            "user": user,
            "token": token
        }
        
    def send_bind_code(db: Session, payload: SendBindCodeRequest, auth_user: VasUser, redis_client:Redis):
        token = uuid.uuid4().hex[0:6]
        record = VasEmailVerification(
            user_id=auth_user.id,
            email=payload.email,
            token=token,
            expire_at=datetime.utcnow() + timedelta(minutes=30)
        )
        db.add(record)
        db.commit()
        
        print(f"📧 send verification email token={token}")
        NotificationService.create(
            redis_client=redis_client,
            ntype="email verification email",
            user_id=auth_user.id,
            channels=["email"],
            template_id="email_verification_for_bind",
            payload={
                "token": token
            }
        )
        
    def send_reset_code(db: Session, payload: SendResetCodeRequest, redis_client:Redis):
        user = db.query(VasUser).filter(
            VasUser.email == payload.email,
            VasUser.email_verified == 1
        ).first()
        if not user:
            raise BizLogicError("User not exist")
        
        token = uuid.uuid4().hex[0:6]
        record = VasEmailVerification(
            user_id=user.id,
            email=payload.email,
            token=token,
            expire_at=datetime.utcnow() + timedelta(minutes=30)
        )
        db.add(record)
        db.commit()
        
        print(f"📧 send verification email token={token}")
        NotificationService.create(
            redis_client=redis_client,
            ntype="email verification email",
            user_id=user.id,
            channels=["email"],
            template_id="email_verification_for_reset",
            payload={
                "token": token
            }
        )
    # -----------------------
    # 绑定邮箱
    # -----------------------
    @staticmethod
    def bind_email(db: Session, payload: BindEmailRequest, auth_user: VasUser, redis_client:Redis):
        user = db.query(VasUser).filter(
            VasUser.email == payload.email,
            VasUser.email_verified == 1
        ).first()
        if user:
            raise BizLogicError("Email has been bound")
        
        record = (
            db.query(VasEmailVerification)
            .filter_by(token=payload.code, used=0)
            .first()
        )
        if not record:
            raise BizLogicError("Token invalid")

        if record.expire_at < datetime.utcnow():
            raise BizLogicError("Token expired")
 
        # 更新 user.email
        user = db.query(VasUser).filter_by(id=record.user_id).first()
        user.email = payload.email

        # 随机密码
        plain = _random_password()
        hashed = bcrypt.hashpw(plain.encode(), bcrypt.gensalt()).decode()
        user.password_hash = hashed
        user.email_verified = 1
        record.used = 1
        
        # 创建 session
        session_id = "tok_" + uuid.uuid4().hex

        session = VasSession(
            id=session_id,
            user_id=user.id,
            user_agent="",
            ip="",
            expire_at=datetime.utcnow() + timedelta(days=30)
        )
        db.add(session)
        db.commit()
        db.refresh(user)
        
        print(f"📧 send login email and password")
        NotificationService.create(
            redis_client=redis_client,
            ntype="login credentials",
            user_id=user.id,
            channels=["email"],
            template_id="login_credentials",
            payload={
                "username": payload.email,
                "password": plain
            }
        )
        
        return {
            "user": user,
            "token": session_id
        }
    
    def reset_password(db: Session, payload: ResetPasswordRequest):
        user = db.query(VasUser).filter(
            VasUser.email == payload.email,
            VasUser.email_verified == 1
        ).first()
        if not user:
            raise BizLogicError("User not exist")
        
        record = (
            db.query(VasEmailVerification)
            .filter_by(token=payload.code, used=0)
            .first()
        )
        if not record:
            raise BizLogicError("Token invalid")

        if record.expire_at < datetime.utcnow():
            raise BizLogicError("Token expired")
        
        hashed = bcrypt.hashpw(payload.new_password.encode(), bcrypt.gensalt()).decode()
        user.password_hash = hashed
        record.used = 1
        db.commit()
        return True
    # -----------------------
    # 用户登录
    # -----------------------
    @staticmethod
    def login(db: Session, req:LoginRequest):
        user = db.query(VasUser).filter_by(email=req.email).first()
        if not user:
            raise NotFoundError("User not found")

        # 对比密码
        if not bcrypt.checkpw(req.password.encode(), user.password_hash.encode()):
            raise PermissionDeniedError("Password incorrect")

        # 创建 session
        token = "tok_" + uuid.uuid4().hex

        session = VasSession(
            id=token,
            user_id=user.id,
            user_agent="",
            ip="",
            expire_at=datetime.utcnow() + timedelta(days=7)
        )
        db.add(session)
        db.commit()

        return {
            "user": user,
            "token": token
        }