from utils .auth import auth_required, requires_role
from flask import Blueprint, jsonify, g
from db.model import User, Course, Enrollment, Chat, db
from sqlalchemy import select, func, desc, and_
from datetime import datetime, timedelta
from constants import UserRole

admin = Blueprint('admin', __name__)

@admin.route('/stats/users', methods=['GET'])
@auth_required()
@requires_role([UserRole.ADMIN])
def get_user_stats():
    """
    Get total users and authors count.
    Only accessible by admin users.
    """
    try:
        # Get total users
        total_users = db.session.execute(
            select(func.count()).select_from(User)
        ).scalar()

        # Get authors (users who have created courses)
        distinct_authors_count = db.session.execute(
            select(func.count(func.distinct(Course.authorID)))
        ).scalar()

        return jsonify({
            'stats': {
                'totalUsers': total_users,
                'totalAuthors': distinct_authors_count
            }
        }), 200

    except Exception as e:
        return jsonify({'message': f'An error occurred: {str(e)}'}), 500

@admin.route('/stats/enrollments', methods=['GET'])
@auth_required()
@requires_role([UserRole.ADMIN])
def get_enrollment_stats():
    """
    Get course enrollment and discussion statistics.
    Only accessible by admin users.
    """
    try:
        # Get enrollment and user counts
        enrollment_stats = db.session.execute(
            select(
                func.count(Enrollment.id).label('total_enrollments'),
                func.count(func.distinct(Enrollment.userID)).label('enrolled_users')
            )
            .select_from(Enrollment)
        ).first()

        # Get course-wise enrollment counts
        course_stats = db.session.execute(
            select(
                Course.name,
                func.count(Enrollment.id).label('enrollment_count')
            )
            .join(Course, Course.id == Enrollment.courseID)
            .group_by(Course.id)
            .order_by(desc('enrollment_count'))
        ).all()

        return jsonify({
            'stats': {
                'totalEnrollments': enrollment_stats.total_enrollments,
                'totalEnrolledUsers': enrollment_stats.enrolled_users,
                'courseEnrollments': [{
                    'courseName': stat.name,
                    'enrollmentCount': stat.enrollment_count
                } for stat in course_stats]
            }
        }), 200

    except Exception as e:
        return jsonify({'message': f'An error occurred: {str(e)}'}), 500

@admin.route('/stats/discussions', methods=['GET'])
@auth_required()
@requires_role([UserRole.ADMIN])
def get_discussion_stats():
    """
    Get chat room activity statistics.
    Only accessible by admin users.
    """
    try:
        # Get activity for last 24 hours
        twenty_four_hours_ago = datetime.now() - timedelta(hours=24)

        # Get active rooms and their stats
        active_rooms = db.session.execute(
            select(
                Course.name,
                func.count(Chat.id).label('message_count'),
                func.count(func.distinct(Chat.userID)).label('active_users')
            )
            .join(Course, Course.id == Chat.courseID)
            .where(Chat.chatDate >= twenty_four_hours_ago)
            .group_by(Course.id)
            .order_by(desc('message_count'))
        ).all()

        # Get total active rooms
        total_active_rooms = len(active_rooms)

        # Get most active room
        most_active_room = None
        if active_rooms:
            most_active = active_rooms[0]
            most_active_room = {
                'name': most_active.name,
                'messageCount': most_active.message_count,
                'activeUsers': most_active.active_users
            }

        # Get total active users across all rooms
        total_active_users = db.session.execute(
            select(func.count(func.distinct(Chat.userID)))
            .where(Chat.chatDate >= twenty_four_hours_ago)
        ).scalar()

        return jsonify({
            'stats': {
                'totalActiveRooms': total_active_rooms,
                'totalActiveUsers': total_active_users,
                'mostActiveRoom': most_active_room,
                'activeRooms': [{
                    'roomName': room.name,
                    'messageCount': room.message_count,
                    'activeUsers': room.active_users
                } for room in active_rooms]
            }
        }), 200

    except Exception as e:
        return jsonify({'message': f'An error occurred: {str(e)}'}), 500