"""
User Schemas

Pydantic schemas for user-related requests and responses.
Provides input validation and output serialization.
"""

from pydantic import BaseModel, EmailStr, Field, field_validator
from typing import Optional, List
from datetime import datetime


# ==========================================
# Base Schemas
# ==========================================

class UserBase(BaseModel):
    """Base user schema with common fields."""
    username: str = Field(..., min_length=3, max_length=80, description="Username (3-80 characters)")
    email: EmailStr = Field(..., description="Email address")
    name: str = Field(..., min_length=1, max_length=120, description="Full name")
    preferred_username: Optional[str] = Field(None, max_length=80, description="Preferred display name")


# ==========================================
# Request Schemas (Input)
# ==========================================

class UserCreate(UserBase):
    """Schema for creating a new user."""
    password: str = Field(..., min_length=8, description="Password (minimum 8 characters)")
    password_confirm: str = Field(..., description="Password confirmation")
    role: Optional[str] = Field("user", description="User role")
    is_admin: Optional[bool] = Field(False, description="Admin flag")
    is_active: Optional[bool] = Field(True, description="Active status")
    permissions: Optional[List[str]] = Field(default_factory=list, description="List of permissions")

    @field_validator('password')
    @classmethod
    def validate_password(cls, v: str) -> str:
        """Validate password strength."""
        if len(v) < 8:
            raise ValueError('Password must be at least 8 characters long')
        return v

    @field_validator('password_confirm')
    @classmethod
    def passwords_match(cls, v: str, info) -> str:
        """Validate that passwords match."""
        if 'password' in info.data and v != info.data['password']:
            raise ValueError('Passwords do not match')
        return v


class UserUpdate(BaseModel):
    """Schema for updating a user."""
    username: Optional[str] = Field(None, min_length=3, max_length=80)
    email: Optional[EmailStr] = None
    name: Optional[str] = Field(None, min_length=1, max_length=120)
    preferred_username: Optional[str] = Field(None, max_length=80)
    role: Optional[str] = None
    is_admin: Optional[bool] = None
    is_active: Optional[bool] = None
    permissions: Optional[List[str]] = None
    new_password: Optional[str] = Field(None, min_length=8, description="New password (optional)")

    @field_validator('new_password')
    @classmethod
    def validate_password(cls, v: Optional[str]) -> Optional[str]:
        """Validate password strength if provided."""
        if v is not None and len(v) < 8:
            raise ValueError('Password must be at least 8 characters long')
        return v


class UserLogin(BaseModel):
    """Schema for user login."""
    username: str = Field(..., description="Username")
    password: str = Field(..., description="Password")


class PasswordChange(BaseModel):
    """Schema for changing user password."""
    current_password: str = Field(..., description="Current password")
    new_password: str = Field(..., min_length=8, description="New password")
    new_password_confirm: str = Field(..., description="New password confirmation")

    @field_validator('new_password')
    @classmethod
    def validate_password(cls, v: str) -> str:
        """Validate password strength."""
        if len(v) < 8:
            raise ValueError('Password must be at least 8 characters long')
        return v

    @field_validator('new_password_confirm')
    @classmethod
    def passwords_match(cls, v: str, info) -> str:
        """Validate that passwords match."""
        if 'new_password' in info.data and v != info.data['new_password']:
            raise ValueError('Passwords do not match')
        return v


# ==========================================
# Response Schemas (Output)
# ==========================================

class UserResponse(UserBase):
    """Schema for user responses."""
    id: int
    role: str
    is_admin: bool
    is_active: bool
    permissions: List[str]
    created_at: datetime
    updated_at: datetime

    model_config = {"from_attributes": True}


class UserListResponse(BaseModel):
    """Schema for paginated user list."""
    users: List[UserResponse]
    total: int
    page: int
    per_page: int
    total_pages: int


class UserStatistics(BaseModel):
    """Schema for user statistics."""
    total_users: int
    active_users: int
    inactive_users: int
    admin_users: int