"""Utilities for permission checking and decorators"""
from functools import wraps
from flask import flash, redirect, url_for, abort
from flask_login import current_user
from flask_babel import gettext as _


def permission_required(*permissions, require_all=False):
    """
    Decorator to require one or more permissions.
    
    Args:
        *permissions: Permission name(s) required
        require_all: If True, user must have ALL permissions. If False, user needs ANY permission.
    
    Example:
        @permission_required('edit_projects')
        def edit_project():
            ...
        
        @permission_required('view_reports', 'export_reports', require_all=True)
        def export_report():
            ...
    """
    def decorator(f):
        @wraps(f)
        def decorated_function(*args, **kwargs):
            if not current_user.is_authenticated:
                flash(_('Please log in to access this page'), 'error')
                return redirect(url_for('auth.login'))
            
            # Check if user has required permissions
            if require_all:
                has_access = current_user.has_all_permissions(*permissions)
            else:
                has_access = current_user.has_any_permission(*permissions)
            
            if not has_access:
                flash(_('You do not have permission to access this page'), 'error')
                abort(403)
            
            return f(*args, **kwargs)
        return decorated_function
    return decorator


def admin_or_permission_required(*permissions):
    """
    Decorator that allows access if user is an admin OR has any of the specified permissions.
    This is useful for gradual migration from admin-only to permission-based access.
    
    Example:
        @admin_or_permission_required('delete_projects')
        def delete_project():
            ...
    """
    def decorator(f):
        @wraps(f)
        def decorated_function(*args, **kwargs):
            if not current_user.is_authenticated:
                flash(_('Please log in to access this page'), 'error')
                return redirect(url_for('auth.login'))
            
            # Allow access if user is admin or has any of the required permissions
            if current_user.is_admin or current_user.has_any_permission(*permissions):
                return f(*args, **kwargs)
            
            flash(_('You do not have permission to access this page'), 'error')
            abort(403)
        
        return decorated_function
    return decorator


def check_permission(user, permission_name):
    """
    Check if a user has a specific permission.
    
    Args:
        user: User object
        permission_name: Name of the permission to check
    
    Returns:
        bool: True if user has the permission, False otherwise
    """
    if not user or not user.is_authenticated:
        return False
    
    return user.has_permission(permission_name)


def check_any_permission(user, *permission_names):
    """
    Check if a user has any of the specified permissions.
    
    Args:
        user: User object
        *permission_names: Names of permissions to check
    
    Returns:
        bool: True if user has any of the permissions, False otherwise
    """
    if not user or not user.is_authenticated:
        return False
    
    return user.has_any_permission(*permission_names)


def check_all_permissions(user, *permission_names):
    """
    Check if a user has all of the specified permissions.
    
    Args:
        user: User object
        *permission_names: Names of permissions to check
    
    Returns:
        bool: True if user has all of the permissions, False otherwise
    """
    if not user or not user.is_authenticated:
        return False
    
    return user.has_all_permissions(*permission_names)


def get_user_permissions(user):
    """
    Get all permissions for a user.
    
    Args:
        user: User object
    
    Returns:
        list: List of Permission objects
    """
    if not user:
        return []
    
    return user.get_all_permissions()


def get_user_permission_names(user):
    """
    Get all permission names for a user.
    
    Args:
        user: User object
    
    Returns:
        list: List of permission name strings
    """
    if not user:
        return []
    
    permissions = user.get_all_permissions()
    return [p.name for p in permissions]


# Template helper functions (register these in app context)
def init_permission_helpers(app):
    """
    Initialize permission helper functions for use in templates.
    
    Usage in templates:
        {% if has_permission('edit_projects') %}
            <button>Edit Project</button>
        {% endif %}
    """
    @app.context_processor
    def inject_permission_helpers():
        return {
            'has_permission': lambda perm: check_permission(current_user, perm),
            'has_any_permission': lambda *perms: check_any_permission(current_user, *perms),
            'has_all_permissions': lambda *perms: check_all_permissions(current_user, *perms),
            'get_user_permissions': lambda: get_user_permission_names(current_user) if current_user.is_authenticated else [],
        }