from typing import Optional

from pydantic import BaseModel, EmailStr, Field, validator


class UserBase(BaseModel):
    """
    Base schema for user data
    """
    email: Optional[EmailStr] = None
    username: Optional[str] = Field(None, min_length=3, max_length=20, pattern=r'^[a-zA-Z0-9_]+$')
    is_active: Optional[bool] = True
    is_superuser: bool = False

    @validator('username')
    def username_not_empty(cls, v):
        if v == "":
            raise ValueError('Username cannot be empty string')
        return v

    @validator('email', 'username')
    def check_one_field_present(cls, v, values):
        # If this is the second field (email or username) and both are None, raise error
        if 'email' in values and v is None and values['email'] is None:
            raise ValueError('Either email or username must be provided')
        if 'username' in values and v is None and values['username'] is None:
            raise ValueError('Either email or username must be provided')
        return v


class UserCreate(UserBase):
    """
    Schema for creating a new user
    """
    password: str = Field(..., min_length=8)


class UserUpdate(UserBase):
    """
    Schema for updating a user
    """
    password: Optional[str] = Field(None, min_length=8)


class UserInDBBase(UserBase):
    """
    Schema for user in DB
    """
    id: int

    class Config:
        orm_mode = True


class User(UserInDBBase):
    """
    Schema for returning user information
    """
    pass


class UserInDB(UserInDBBase):
    """
    Schema with password hash (for internal use)
    """
    hashed_password: str


class Token(BaseModel):
    """
    Token schema
    """
    access_token: str
    token_type: str


class TokenPayload(BaseModel):
    """
    Token payload schema
    """
    sub: Optional[int] = None