from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import selectinload
from sqlalchemy import select, func
from typing import List, Optional
from pydantic import BaseModel, EmailStr

from app.database import get_db
from app.models.db import User
from app.services.auth import hash_password, verify_password
from app.services.auth_deps import get_current_user, require_admin
from app.services.system_settings_service import system_settings_service

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

# Pydantic models
class UserListItem(BaseModel):
    id: int
    username: str
    email: str | None
    full_name: str | None
    is_active: bool
    roles: list[str]
    last_login_at: str | None
    created_at: str

    class Config:
        from_attributes = True

class UserStatusUpdate(BaseModel):
    is_active: bool

class ProfileUpdateRequest(BaseModel):
    full_name: Optional[str] = None
    email: Optional[EmailStr] = None

class PasswordChangeRequest(BaseModel):
    old_password: str
    new_password: str

@router.get("/list")
async def get_user_list(
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user) # Protect this route
):
    """Get a list of all users"""
    # Ensure only admins can see all users
    if "admin" not in [role.name for role in current_user.roles]:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Not authorized")

    result = await db.execute(
        select(User).options(selectinload(User.roles)).order_by(User.id)
    )
    users = result.scalars().all()

    users_list = []
    for user in users:
        users_list.append({
            "id": user.id,
            "username": user.username,
            "email": user.email,
            "full_name": user.full_name,
            "is_active": user.is_active,
            "roles": [role.name for role in user.roles],
            "last_login_at": user.last_login_at.isoformat() if user.last_login_at else None,
            "created_at": user.created_at.isoformat()
        })
        
    return {"users": users_list}


@router.put("/{user_id}/status")
async def update_user_status(
    user_id: int,
    status_update: UserStatusUpdate,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """Update a user's active status"""
    if "admin" not in [role.name for role in current_user.roles]:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Not authorized")

    result = await db.execute(select(User).where(User.id == user_id))
    user = result.scalar_one_or_none()
    if not user:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="User not found")

    user.is_active = status_update.is_active
    await db.commit()
    
    return {"message": "User status updated successfully"}


@router.post("/{user_id}/reset-password")
async def reset_user_password(
    user_id: int,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """Reset a user's password to the system default"""
    if "admin" not in [role.name for role in current_user.roles]:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Not authorized")

    result = await db.execute(select(User).where(User.id == user_id))
    user = result.scalar_one_or_none()
    if not user:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="User not found")

    # Get default password from system settings
    default_password = await system_settings_service.get_setting_value(
        "default_password",
        db,
        default="cosmo"  # Fallback if setting doesn't exist
    )

    user.password_hash = hash_password(default_password)

    await db.commit()

    return {
        "message": f"Password for user {user.username} has been reset to system default.",
        "default_password": default_password
    }

@router.get("/count", response_model=dict)
async def get_user_count(
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user)  # All authenticated users can access
):
    """
    Get the total count of registered users.
    Available to all authenticated users.
    """
    result = await db.execute(select(func.count(User.id)))
    total_users = result.scalar_one()
    return {"total_users": total_users}


@router.get("/me")
async def get_current_user_profile(
    current_user: User = Depends(get_current_user)
):
    """
    Get current user's profile information
    """
    return {
        "id": current_user.id,
        "username": current_user.username,
        "email": current_user.email,
        "full_name": current_user.full_name,
        "is_active": current_user.is_active,
        "roles": [role.name for role in current_user.roles],
        "created_at": current_user.created_at.isoformat(),
        "last_login_at": current_user.last_login_at.isoformat() if current_user.last_login_at else None
    }


@router.put("/me/profile")
async def update_current_user_profile(
    profile_update: ProfileUpdateRequest,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Update current user's profile information (nickname/full_name and email)
    """
    # Check if email is being changed and if it's already taken
    if profile_update.email and profile_update.email != current_user.email:
        # Check if email is already in use by another user
        result = await db.execute(
            select(User).where(User.email == profile_update.email, User.id != current_user.id)
        )
        existing_user = result.scalar_one_or_none()
        if existing_user:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="Email already in use by another user"
            )
        current_user.email = profile_update.email

    # Update full_name (nickname)
    if profile_update.full_name is not None:
        current_user.full_name = profile_update.full_name

    await db.commit()
    await db.refresh(current_user)

    return {
        "message": "Profile updated successfully",
        "user": {
            "id": current_user.id,
            "username": current_user.username,
            "email": current_user.email,
            "full_name": current_user.full_name
        }
    }


@router.put("/me/password")
async def change_current_user_password(
    password_change: PasswordChangeRequest,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Change current user's password
    """
    # Verify old password
    if not verify_password(password_change.old_password, current_user.password_hash):
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Current password is incorrect"
        )

    # Validate new password
    if len(password_change.new_password) < 6:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="New password must be at least 6 characters long"
        )

    if password_change.old_password == password_change.new_password:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="New password must be different from the old password"
        )

    # Update password
    current_user.password_hash = hash_password(password_change.new_password)
    await db.commit()

    return {"message": "Password changed successfully"}