from fastapi import APIRouter, HTTPException, Depends, Body, Path
from typing import List, Dict, Any, Optional
from fastapi import status
from datetime import datetime
from dataclasses import dataclass

# Import auth module
from modules.auth import get_current_active_user, get_user_context

# Import interfaces
from modules.gateway_interface import get_gateway_interface
from modules.gateway_model import User

# Determine all attributes of the model (except internal/special attributes)
def get_model_attributes(model_class):
    return [attr for attr in dir(model_class) 
            if not callable(getattr(model_class, attr)) 
            and not attr.startswith('_')
            and attr != 'metadata'
            and attr != 'query'
            and attr != 'query_class'
            and attr != 'label'
            and attr != 'field_labels']

# Model attributes for User
user_attributes = get_model_attributes(User)

@dataclass
class AppContext:
    """Context object for all required connections and user information"""
    mandate_id: int
    user_id: int
    interface_data: Any  # Gateway Interface

async def get_context(current_user: Dict[str, Any]) -> AppContext:
    """
    Creates a central context object with all required interfaces
    
    Args:
        current_user: Current user from authentication
        
    Returns:
        AppContext object with all required connections
    """
    mandate_id, user_id = await get_user_context(current_user)
    interface_data = get_gateway_interface(mandate_id, user_id)
    
    return AppContext(
        mandate_id=mandate_id,
        user_id=user_id,
        interface_data=interface_data
    )

# Create router for user endpoints
router = APIRouter(
    prefix="/api/users",
    tags=["Users"],
    responses={404: {"description": "Not found"}}
)

@router.get("", response_model=List[Dict[str, Any]])
async def get_users(current_user: Dict[str, Any] = Depends(get_current_active_user)):
    """Get all available users (only for Admin/SysAdmin users)"""
    context = await get_context(current_user)
    
    # Permission check
    if current_user.get("privilege") not in ["admin", "sysadmin"]:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="No permission to access the user list"
        )
    
    # Admin sees only users of own mandate, SysAdmin sees all
    if current_user.get("privilege") == "admin":
        return context.interface_data.get_users_by_mandate(context.mandate_id)
    else:  # sysadmin
        return context.interface_data.get_all_users()

@router.post("/register", response_model=Dict[str, Any])
async def register_user(user_data: dict = Body(...)):
    """Register a new user"""
    # Don't use user context for registration
    gateway = get_gateway_interface()
    
    if "username" not in user_data or "password" not in user_data:
        raise HTTPException(status_code=400, detail="Username and password required")
    
    try:
        # Dynamically filter attributes
        mandate_data = {
            "name": f"Mandate of {user_data['username']}",
            "language": user_data.get("language", "de")
        }
        
        new_mandate = gateway.create_mandate(**mandate_data)
        
        # Filter user attributes from the request
        user_create_data = {}
        for attr in user_attributes:
            if attr in user_data and attr not in ["id"]:  # ID is auto-assigned
                user_create_data[attr] = user_data[attr]
        
        # Required fields
        user_create_data["username"] = user_data["username"]
        user_create_data["password"] = user_data["password"]
        user_create_data["mandate_id"] = new_mandate["id"]
        
        # Default values for optional fields
        if "disabled" not in user_create_data:
            user_create_data["disabled"] = False
        if "privilege" not in user_create_data:
            user_create_data["privilege"] = "user"
        if "language" not in user_create_data:
            user_create_data["language"] = "de"
        
        new_user = gateway.create_user(**user_create_data)
        return new_user
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e))

@router.get("/{user_id}", response_model=Dict[str, Any])
async def get_user(
    user_id: int,
    current_user: Dict[str, Any] = Depends(get_current_active_user)
):
    """Get a specific user"""
    context = await get_context(current_user)
    
    # Initialize gateway interface with user context
    user_to_get = context.interface_data.get_user(user_id)
    if not user_to_get:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=f"User with ID {user_id} not found"
        )
    
    # Permission check
    # User can only view themselves, Admin only users of their own mandate, SysAdmin all
    if user_id == context.user_id:
        # User can view themselves
        pass
    elif current_user.get("privilege") == "admin" and user_to_get.get("mandate_id") == context.mandate_id:
        # Admin can view users of their own mandate
        pass
    elif current_user.get("privilege") == "sysadmin":
        # SysAdmin can view all users
        pass
    else:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="No permission to view this user"
        )
    
    return user_to_get

@router.put("/{user_id}", response_model=Dict[str, Any])
async def update_user(
    user_id: int = Path(..., description="ID of the user to update"),
    user_data: Dict[str, Any] = Body(..., description="Updated user data"),
    current_user: Dict[str, Any] = Depends(get_current_active_user)
):
    """Update an existing user"""
    context = await get_context(current_user)
    
    # User exists?
    user_to_update = context.interface_data.get_user(user_id)
    if not user_to_update:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=f"User with ID {user_id} not found"
        )
    
    # Permission check
    is_self_update = user_id == context.user_id
    is_admin = current_user.get("privilege") == "admin"
    is_sysadmin = current_user.get("privilege") == "sysadmin"
    same_mandate = user_to_update.get("mandate_id") == context.mandate_id
    
    # Filter allowed fields based on permission level
    allowed_fields = {"username", "email", "full_name", "language"}
    sensitive_fields = {"mandate_id", "disabled", "privilege"}
    
    # Check if sensitive fields should be changed
    sensitive_update = any(field in user_data for field in sensitive_fields)
    
    if is_self_update and sensitive_update:
        # Normal users cannot change their sensitive data
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="No permission to change sensitive user data"
        )
    elif is_admin and sensitive_update and not same_mandate:
        # Admins can only change sensitive data for users of their own mandate
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="No permission to change sensitive data for users of other mandates"
        )
    elif not (is_self_update or (is_admin and same_mandate) or is_sysadmin):
        # No permission for other cases
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="No permission to update this user"
        )
    
    # Dynamically filter attributes from the request
    update_data = {}
    for attr in user_attributes:
        if attr in user_data and attr not in ["id"]:  # ID cannot be changed
            update_data[attr] = user_data[attr]
    
    # Remove disallowed fields for normal users
    if not (is_admin or is_sysadmin):
        update_data = {k: v for k, v in update_data.items() if k in allowed_fields}
    
    # Update user data
    updated_user = context.interface_data.update_user(user_id, update_data)
    return updated_user

@router.delete("/{user_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_user(
    user_id: int = Path(..., description="ID of the user to delete"),
    current_user: Dict[str, Any] = Depends(get_current_active_user)
):
    """Delete a user"""
    context = await get_context(current_user)
    
    # User exists?
    user_to_delete = context.interface_data.get_user(user_id)
    if not user_to_delete:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=f"User with ID {user_id} not found"
        )
    
    # Permission check
    is_self_delete = user_id == context.user_id
    is_admin = current_user.get("privilege") == "admin"
    is_sysadmin = current_user.get("privilege") == "sysadmin"
    same_mandate = user_to_delete.get("mandate_id") == context.mandate_id
    
    if is_self_delete:
        # User can delete themselves
        pass
    elif is_admin and same_mandate:
        # Admin can delete users of their own mandate
        pass
    elif is_sysadmin:
        # SysAdmin can delete all users
        pass
    else:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="No permission to delete this user"
        )
    
    # Delete user and all referenced objects
    success = context.interface_data.delete_user(user_id)
    if not success:
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Error deleting user with ID {user_id}"
        )
    
    # Return no content on successful deletion
    return None