from flask import Blueprint, request, jsonify
from flask_jwt_extended import jwt_required, get_jwt_identity, get_jwt
from datetime import datetime, date, timedelta
from sqlalchemy import or_, and_
from sqlalchemy.orm import selectinload, joinedload
from models import (
    db, TodoItem, TodoItemResponsible, TodoItemFollower,
    TodoAuditLog, TodoUserPref
)
from utils.logger import get_logger
from utils.ldap_utils import validate_ad_accounts
import uuid

todos_bp = Blueprint('todos', __name__)
logger = get_logger(__name__)

@todos_bp.route('', methods=['GET'])
@jwt_required()
def get_todos():
    """Get todos with filtering and pagination"""
    try:
        identity = get_jwt_identity()
        page = request.args.get('page', 1, type=int)
        per_page = request.args.get('per_page', 20, type=int)
        
        # Filters
        status = request.args.get('status')
        priority = request.args.get('priority')
        starred = request.args.get('starred', type=bool)
        due_from = request.args.get('due_from')
        due_to = request.args.get('due_to')
        search = request.args.get('search')
        view_type = request.args.get('view', 'all')  # all, created, responsible, following
        
        # Base query with eager loading to prevent N+1 queries
        query = TodoItem.query.options(
            joinedload(TodoItem.responsible_users),
            joinedload(TodoItem.followers)
        )
        
        # Apply view type filter
        if view_type == 'created':
            query = query.filter(TodoItem.creator_ad == identity)
        elif view_type == 'responsible':
            query = query.join(TodoItemResponsible).filter(
                TodoItemResponsible.ad_account == identity
            )
        elif view_type == 'following':
            query = query.join(TodoItemFollower).filter(
                TodoItemFollower.ad_account == identity
            )
        else:  # all
            query = query.filter(
                or_(
                    TodoItem.creator_ad == identity,
                    TodoItem.responsible_users.any(TodoItemResponsible.ad_account == identity),
                    TodoItem.followers.any(TodoItemFollower.ad_account == identity)
                )
            )
        
        # Apply filters
        if status:
            query = query.filter(TodoItem.status == status)
        if priority:
            query = query.filter(TodoItem.priority == priority)
        if starred is not None:
            query = query.filter(TodoItem.starred == starred)
        if due_from:
            query = query.filter(TodoItem.due_date >= datetime.strptime(due_from, '%Y-%m-%d').date())
        if due_to:
            query = query.filter(TodoItem.due_date <= datetime.strptime(due_to, '%Y-%m-%d').date())
        if search:
            query = query.filter(
                or_(
                    TodoItem.title.contains(search),
                    TodoItem.description.contains(search)
                )
            )
        
        # Order by due date and priority (MySQL compatible)
        query = query.order_by(
            TodoItem.due_date.asc(),
            TodoItem.priority.desc(),
            TodoItem.created_at.desc()
        )
        
        # Paginate
        pagination = query.paginate(page=page, per_page=per_page, error_out=False)
        
        todos = [todo.to_dict() for todo in pagination.items]
        
        return jsonify({
            'todos': todos,
            'total': pagination.total,
            'page': page,
            'per_page': per_page,
            'pages': pagination.pages
        }), 200
        
    except Exception as e:
        logger.error(f"Error fetching todos: {str(e)}")
        return jsonify({'error': 'Failed to fetch todos'}), 500

@todos_bp.route('/<todo_id>', methods=['GET'])
@jwt_required()
def get_todo(todo_id):
    """Get single todo details"""
    try:
        identity = get_jwt_identity()
        
        todo = TodoItem.query.options(
            joinedload(TodoItem.responsible_users),
            joinedload(TodoItem.followers)
        ).filter_by(id=todo_id).first()
        if not todo:
            return jsonify({'error': 'Todo not found'}), 404
        
        # Check permission
        if not todo.can_view(identity):
            return jsonify({'error': 'Access denied'}), 403
        
        return jsonify(todo.to_dict()), 200
        
    except Exception as e:
        logger.error(f"Error fetching todo {todo_id}: {str(e)}")
        return jsonify({'error': 'Failed to fetch todo'}), 500

@todos_bp.route('', methods=['POST'])
@jwt_required()
def create_todo():
    """Create new todo"""
    try:
        identity = get_jwt_identity()
        claims = get_jwt()
        data = request.get_json()
        
        # Validate required fields
        if not data.get('title'):
            return jsonify({'error': 'Title is required'}), 400
        
        # Parse due date if provided
        due_date = None
        if data.get('due_date'):
            try:
                due_date = datetime.strptime(data['due_date'], '%Y-%m-%d').date()
            except ValueError:
                return jsonify({'error': 'Invalid due date format. Use YYYY-MM-DD'}), 400
        
        # Create todo
        todo = TodoItem(
            id=str(uuid.uuid4()),
            title=data['title'],
            description=data.get('description', ''),
            status=data.get('status', 'NEW'),
            priority=data.get('priority', 'MEDIUM'),
            due_date=due_date,
            creator_ad=identity,
            creator_display_name=claims.get('display_name', identity),
            creator_email=claims.get('email', ''),
            starred=data.get('starred', False)
        )
        db.session.add(todo)
        
        # Add responsible users
        responsible_accounts = data.get('responsible_users', [])
        if responsible_accounts:
            valid_accounts = validate_ad_accounts(responsible_accounts)
            for account in responsible_accounts:
                if account in valid_accounts:
                    responsible = TodoItemResponsible(
                        todo_id=todo.id,
                        ad_account=account,
                        added_by=identity
                    )
                    db.session.add(responsible)
        
        # Add followers
        follower_accounts = data.get('followers', [])
        if follower_accounts:
            valid_accounts = validate_ad_accounts(follower_accounts)
            for account in follower_accounts:
                if account in valid_accounts:
                    follower = TodoItemFollower(
                        todo_id=todo.id,
                        ad_account=account,
                        added_by=identity
                    )
                    db.session.add(follower)
        
        # Add audit log
        audit = TodoAuditLog(
            actor_ad=identity,
            todo_id=todo.id,
            action='CREATE',
            detail={'title': todo.title, 'due_date': str(due_date) if due_date else None}
        )
        db.session.add(audit)
        
        db.session.commit()
        
        logger.info(f"Todo created: {todo.id} by {identity}")
        return jsonify(todo.to_dict()), 201
        
    except Exception as e:
        db.session.rollback()
        logger.error(f"Error creating todo: {str(e)}")
        return jsonify({'error': 'Failed to create todo'}), 500

@todos_bp.route('/<todo_id>', methods=['PATCH'])
@jwt_required()
def update_todo(todo_id):
    """Update todo"""
    try:
        identity = get_jwt_identity()
        data = request.get_json()
        
        todo = TodoItem.query.filter_by(id=todo_id).first()
        if not todo:
            return jsonify({'error': 'Todo not found'}), 404
        
        # Check permission
        if not todo.can_edit(identity):
            return jsonify({'error': 'Access denied'}), 403
        
        # Track changes for audit
        changes = {}
        
        # Update fields
        if 'title' in data:
            changes['title'] = {'old': todo.title, 'new': data['title']}
            todo.title = data['title']
        
        if 'description' in data:
            changes['description'] = {'old': todo.description, 'new': data['description']}
            todo.description = data['description']
        
        if 'status' in data:
            changes['status'] = {'old': todo.status, 'new': data['status']}
            todo.status = data['status']
            
            # Set completed_at if status is DONE
            if data['status'] == 'DONE' and not todo.completed_at:
                todo.completed_at = datetime.utcnow()
            elif data['status'] != 'DONE':
                todo.completed_at = None
        
        if 'priority' in data:
            changes['priority'] = {'old': todo.priority, 'new': data['priority']}
            todo.priority = data['priority']
        
        if 'due_date' in data:
            old_due = str(todo.due_date) if todo.due_date else None
            if data['due_date']:
                todo.due_date = datetime.strptime(data['due_date'], '%Y-%m-%d').date()
                new_due = data['due_date']
            else:
                todo.due_date = None
                new_due = None
            changes['due_date'] = {'old': old_due, 'new': new_due}
        
        if 'starred' in data:
            changes['starred'] = {'old': todo.starred, 'new': data['starred']}
            todo.starred = data['starred']
        
        # Update responsible users
        if 'responsible_users' in data:
            # Remove existing
            TodoItemResponsible.query.filter_by(todo_id=todo_id).delete()
            
            # Add new
            responsible_accounts = data['responsible_users']
            if responsible_accounts:
                valid_accounts = validate_ad_accounts(responsible_accounts)
                for account in responsible_accounts:
                    if account in valid_accounts:
                        responsible = TodoItemResponsible(
                            todo_id=todo.id,
                            ad_account=account,
                            added_by=identity
                        )
                        db.session.add(responsible)
            
            changes['responsible_users'] = data['responsible_users']
        
        # Update followers
        if 'followers' in data:
            # Remove existing
            TodoItemFollower.query.filter_by(todo_id=todo_id).delete()
            
            # Add new
            follower_accounts = data['followers']
            if follower_accounts:
                valid_accounts = validate_ad_accounts(follower_accounts)
                for account in follower_accounts:
                    if account in valid_accounts:
                        follower = TodoItemFollower(
                            todo_id=todo.id,
                            ad_account=account,
                            added_by=identity
                        )
                        db.session.add(follower)
            
            changes['followers'] = data['followers']
        
        # Add audit log
        if changes:
            audit = TodoAuditLog(
                actor_ad=identity,
                todo_id=todo.id,
                action='UPDATE',
                detail=changes
            )
            db.session.add(audit)
        
        db.session.commit()
        
        logger.info(f"Todo updated: {todo_id} by {identity}")
        return jsonify(todo.to_dict()), 200
        
    except Exception as e:
        db.session.rollback()
        logger.error(f"Error updating todo {todo_id}: {str(e)}")
        return jsonify({'error': 'Failed to update todo'}), 500

@todos_bp.route('/<todo_id>', methods=['DELETE'])
@jwt_required()
def delete_todo(todo_id):
    """Delete todo"""
    try:
        identity = get_jwt_identity()
        
        todo = TodoItem.query.filter_by(id=todo_id).first()
        if not todo:
            return jsonify({'error': 'Todo not found'}), 404
        
        # Only creator can delete
        if todo.creator_ad != identity:
            return jsonify({'error': 'Only creator can delete todo'}), 403
        
        # Add audit log before deletion
        audit = TodoAuditLog(
            actor_ad=identity,
            todo_id=None,  # Will be null after deletion
            action='DELETE',
            detail={'title': todo.title, 'deleted_todo_id': todo_id}
        )
        db.session.add(audit)
        
        # Delete todo (cascades will handle related records)
        db.session.delete(todo)
        db.session.commit()
        
        logger.info(f"Todo deleted: {todo_id} by {identity}")
        return jsonify({'message': 'Todo deleted successfully'}), 200
        
    except Exception as e:
        db.session.rollback()
        logger.error(f"Error deleting todo {todo_id}: {str(e)}")
        return jsonify({'error': 'Failed to delete todo'}), 500

@todos_bp.route('/batch', methods=['PATCH'])
@jwt_required()
def batch_update_todos():
    """Batch update multiple todos"""
    try:
        identity = get_jwt_identity()
        data = request.get_json()
        
        todo_ids = data.get('todo_ids', [])
        updates = data.get('updates', {})
        
        if not todo_ids or not updates:
            return jsonify({'error': 'Todo IDs and updates required'}), 400
        
        updated_count = 0
        errors = []
        
        for todo_id in todo_ids:
            try:
                todo = TodoItem.query.filter_by(id=todo_id).first()
                if not todo:
                    errors.append({'todo_id': todo_id, 'error': 'Not found'})
                    continue
                
                if not todo.can_edit(identity):
                    errors.append({'todo_id': todo_id, 'error': 'Access denied'})
                    continue
                
                # Apply updates
                if 'status' in updates:
                    todo.status = updates['status']
                    if updates['status'] == 'DONE':
                        todo.completed_at = datetime.utcnow()
                    else:
                        todo.completed_at = None
                
                if 'priority' in updates:
                    todo.priority = updates['priority']
                
                if 'due_date' in updates:
                    if updates['due_date']:
                        todo.due_date = datetime.strptime(updates['due_date'], '%Y-%m-%d').date()
                    else:
                        todo.due_date = None
                
                # Add audit log
                audit = TodoAuditLog(
                    actor_ad=identity,
                    todo_id=todo.id,
                    action='UPDATE',
                    detail={'batch_update': updates}
                )
                db.session.add(audit)
                
                updated_count += 1
                
            except Exception as e:
                errors.append({'todo_id': todo_id, 'error': str(e)})
        
        db.session.commit()
        
        logger.info(f"Batch update: {updated_count} todos updated by {identity}")
        
        return jsonify({
            'updated': updated_count,
            'errors': errors
        }), 200
        
    except Exception as e:
        db.session.rollback()
        logger.error(f"Error in batch update: {str(e)}")
        return jsonify({'error': 'Batch update failed'}), 500

@todos_bp.route('/<todo_id>/responsible', methods=['POST'])
@jwt_required()
def add_responsible_user(todo_id):
    """Add responsible user to todo"""
    try:
        identity = get_jwt_identity()
        data = request.get_json()
        
        if not data or 'ad_account' not in data:
            return jsonify({'error': 'AD account is required'}), 400
        
        ad_account = data['ad_account']
        
        # Get todo
        todo = TodoItem.query.filter_by(id=todo_id).first()
        if not todo:
            return jsonify({'error': 'Todo not found'}), 404
        
        # Check permission
        if not todo.can_edit(identity):
            return jsonify({'error': 'No permission to edit this todo'}), 403
        
        # Validate AD account
        valid_accounts = validate_ad_accounts([ad_account])
        if ad_account not in valid_accounts:
            return jsonify({'error': 'Invalid AD account'}), 400
        
        # Check if already responsible
        existing = TodoItemResponsible.query.filter_by(
            todo_id=todo_id, ad_account=ad_account
        ).first()
        
        if existing:
            return jsonify({'error': 'User is already responsible for this todo'}), 400
        
        # Add responsible user
        responsible = TodoItemResponsible(
            todo_id=todo_id,
            ad_account=ad_account,
            added_by=identity
        )
        db.session.add(responsible)
        
        # Log audit
        audit = TodoAuditLog(
            actor_ad=identity,
            todo_id=todo_id,
            action='UPDATE',
            detail={
                'field': 'responsible_users',
                'action': 'add',
                'ad_account': ad_account
            }
        )
        db.session.add(audit)
        db.session.commit()
        
        logger.info(f"Added responsible user {ad_account} to todo {todo_id} by {identity}")
        return jsonify({'message': 'Responsible user added successfully'}), 201
        
    except Exception as e:
        db.session.rollback()
        logger.error(f"Add responsible user error: {str(e)}")
        return jsonify({'error': 'Failed to add responsible user'}), 500

@todos_bp.route('/<todo_id>/responsible/<ad_account>', methods=['DELETE'])
@jwt_required()
def remove_responsible_user(todo_id, ad_account):
    """Remove responsible user from todo"""
    try:
        identity = get_jwt_identity()
        
        # Get todo
        todo = TodoItem.query.filter_by(id=todo_id).first()
        if not todo:
            return jsonify({'error': 'Todo not found'}), 404
        
        # Check permission
        if not todo.can_edit(identity):
            return jsonify({'error': 'No permission to edit this todo'}), 403
        
        # Find responsible relationship
        responsible = TodoItemResponsible.query.filter_by(
            todo_id=todo_id, ad_account=ad_account
        ).first()
        
        if not responsible:
            return jsonify({'error': 'User is not responsible for this todo'}), 404
        
        # Remove responsible user
        db.session.delete(responsible)
        
        # Log audit
        audit = TodoAuditLog(
            actor_ad=identity,
            todo_id=todo_id,
            action='UPDATE',
            detail={
                'field': 'responsible_users',
                'action': 'remove',
                'ad_account': ad_account
            }
        )
        db.session.add(audit)
        db.session.commit()
        
        logger.info(f"Removed responsible user {ad_account} from todo {todo_id} by {identity}")
        return jsonify({'message': 'Responsible user removed successfully'}), 200
        
    except Exception as e:
        db.session.rollback()
        logger.error(f"Remove responsible user error: {str(e)}")
        return jsonify({'error': 'Failed to remove responsible user'}), 500

@todos_bp.route('/<todo_id>/followers', methods=['POST'])
@jwt_required()
def add_follower(todo_id):
    """Add follower to todo"""
    try:
        identity = get_jwt_identity()
        data = request.get_json()
        
        if not data or 'ad_account' not in data:
            return jsonify({'error': 'AD account is required'}), 400
        
        ad_account = data['ad_account']
        
        # Get todo
        todo = TodoItem.query.filter_by(id=todo_id).first()
        if not todo:
            return jsonify({'error': 'Todo not found'}), 404
        
        # Check permission (anyone who can view the todo can add followers)
        if not todo.can_view(identity):
            return jsonify({'error': 'No permission to view this todo'}), 403
        
        # Validate AD account
        valid_accounts = validate_ad_accounts([ad_account])
        if ad_account not in valid_accounts:
            return jsonify({'error': 'Invalid AD account'}), 400
        
        # Check if already following
        existing = TodoItemFollower.query.filter_by(
            todo_id=todo_id, ad_account=ad_account
        ).first()
        
        if existing:
            return jsonify({'error': 'User is already following this todo'}), 400
        
        # Add follower
        follower = TodoItemFollower(
            todo_id=todo_id,
            ad_account=ad_account,
            added_by=identity
        )
        db.session.add(follower)
        
        # Log audit
        audit = TodoAuditLog(
            actor_ad=identity,
            todo_id=todo_id,
            action='UPDATE',
            detail={
                'field': 'followers',
                'action': 'add',
                'ad_account': ad_account
            }
        )
        db.session.add(audit)
        db.session.commit()
        
        logger.info(f"Added follower {ad_account} to todo {todo_id} by {identity}")
        return jsonify({'message': 'Follower added successfully'}), 201
        
    except Exception as e:
        db.session.rollback()
        logger.error(f"Add follower error: {str(e)}")
        return jsonify({'error': 'Failed to add follower'}), 500

@todos_bp.route('/<todo_id>/followers/<ad_account>', methods=['DELETE'])
@jwt_required()
def remove_follower(todo_id, ad_account):
    """Remove follower from todo"""
    try:
        identity = get_jwt_identity()
        
        # Get todo
        todo = TodoItem.query.filter_by(id=todo_id).first()
        if not todo:
            return jsonify({'error': 'Todo not found'}), 404
        
        # Check permission (user can remove themselves or todo editors can remove anyone)
        if ad_account != identity and not todo.can_edit(identity):
            return jsonify({'error': 'No permission to remove this follower'}), 403
        
        # Find follower relationship
        follower = TodoItemFollower.query.filter_by(
            todo_id=todo_id, ad_account=ad_account
        ).first()
        
        if not follower:
            return jsonify({'error': 'User is not following this todo'}), 404
        
        # Remove follower
        db.session.delete(follower)
        
        # Log audit
        audit = TodoAuditLog(
            actor_ad=identity,
            todo_id=todo_id,
            action='UPDATE',
            detail={
                'field': 'followers',
                'action': 'remove',
                'ad_account': ad_account
            }
        )
        db.session.add(audit)
        db.session.commit()
        
        logger.info(f"Removed follower {ad_account} from todo {todo_id} by {identity}")
        return jsonify({'message': 'Follower removed successfully'}), 200
        
    except Exception as e:
        db.session.rollback()
        logger.error(f"Remove follower error: {str(e)}")
        return jsonify({'error': 'Failed to remove follower'}), 500

@todos_bp.route('/<todo_id>/star', methods=['POST'])
@jwt_required()
def star_todo(todo_id):
    """Star/unstar a todo item"""
    try:
        identity = get_jwt_identity()
        
        # Get todo
        todo = TodoItem.query.filter_by(id=todo_id).first()
        if not todo:
            return jsonify({'error': 'Todo not found'}), 404
        
        # Check permission
        if not todo.can_view(identity):
            return jsonify({'error': 'No permission to view this todo'}), 403
        
        # Only creator can star/unstar
        if todo.creator_ad != identity:
            return jsonify({'error': 'Only creator can star/unstar todos'}), 403
        
        # Toggle star status
        todo.starred = not todo.starred
        
        # Log audit
        audit = TodoAuditLog(
            actor_ad=identity,
            todo_id=todo_id,
            action='UPDATE',
            detail={
                'field': 'starred',
                'value': todo.starred
            }
        )
        db.session.add(audit)
        db.session.commit()
        
        action = 'starred' if todo.starred else 'unstarred'
        logger.info(f"Todo {todo_id} {action} by {identity}")
        
        return jsonify({
            'message': f'Todo {action} successfully',
            'starred': todo.starred
        }), 200
        
    except Exception as e:
        db.session.rollback()
        logger.error(f"Star todo error: {str(e)}")
        return jsonify({'error': 'Failed to star todo'}), 500