<?php
class TicketModel {
    private $conn;
    
    public function __construct($conn) {
        $this->conn = $conn;
    }
    
    public function getTicketById($id) {
        $sql = "SELECT t.*,
                u_created.username as creator_username,
                u_created.display_name as creator_display_name,
                u_updated.username as updater_username,
                u_updated.display_name as updater_display_name,
                u_assigned.username as assigned_username,
                u_assigned.display_name as assigned_display_name
                FROM tickets t
                LEFT JOIN users u_created ON t.created_by = u_created.user_id
                LEFT JOIN users u_updated ON t.updated_by = u_updated.user_id
                LEFT JOIN users u_assigned ON t.assigned_to = u_assigned.user_id
                WHERE t.ticket_id = ?";
        $stmt = $this->conn->prepare($sql);
        $stmt->bind_param("i", $id);
        $stmt->execute();
        $result = $stmt->get_result();

        if ($result->num_rows === 0) {
            return null;
        }

        return $result->fetch_assoc();
    }
    
    public function getTicketComments($ticketId) {
        $sql = "SELECT * FROM ticket_comments WHERE ticket_id = ? ORDER BY created_at DESC";
        $stmt = $this->conn->prepare($sql);
        $stmt->bind_param("i", $ticketId);
        $stmt->execute();
        $result = $stmt->get_result();
        
        $comments = [];
        while ($row = $result->fetch_assoc()) {
            $comments[] = $row;
        }
        
        return $comments;
    }
    
    public function getAllTickets($page = 1, $limit = 15, $status = 'Open', $sortColumn = 'ticket_id', $sortDirection = 'desc', $category = null, $type = null, $search = null, $filters = []) {
        // Calculate offset
        $offset = ($page - 1) * $limit;

        // Build WHERE clause
        $whereConditions = [];
        $params = [];
        $paramTypes = '';

        // Status filtering
        if ($status) {
            $statuses = explode(',', $status);
            $placeholders = str_repeat('?,', count($statuses) - 1) . '?';
            $whereConditions[] = "status IN ($placeholders)";
            $params = array_merge($params, $statuses);
            $paramTypes .= str_repeat('s', count($statuses));
        }

        // Category filtering
        if ($category) {
            $categories = explode(',', $category);
            $placeholders = str_repeat('?,', count($categories) - 1) . '?';
            $whereConditions[] = "category IN ($placeholders)";
            $params = array_merge($params, $categories);
            $paramTypes .= str_repeat('s', count($categories));
        }

        // Type filtering
        if ($type) {
            $types = explode(',', $type);
            $placeholders = str_repeat('?,', count($types) - 1) . '?';
            $whereConditions[] = "type IN ($placeholders)";
            $params = array_merge($params, $types);
            $paramTypes .= str_repeat('s', count($types));
        }

        // Search Functionality
        if ($search && !empty($search)) {
            $whereConditions[] = "(title LIKE ? OR description LIKE ? OR ticket_id LIKE ? OR category LIKE ? OR type LIKE ?)";
            $searchTerm = "%$search%";
            $params = array_merge($params, [$searchTerm, $searchTerm, $searchTerm, $searchTerm, $searchTerm]);
            $paramTypes .= 'sssss';
        }

        // Advanced search filters
        // Date range - created_at
        if (!empty($filters['created_from'])) {
            $whereConditions[] = "DATE(t.created_at) >= ?";
            $params[] = $filters['created_from'];
            $paramTypes .= 's';
        }
        if (!empty($filters['created_to'])) {
            $whereConditions[] = "DATE(t.created_at) <= ?";
            $params[] = $filters['created_to'];
            $paramTypes .= 's';
        }

        // Date range - updated_at
        if (!empty($filters['updated_from'])) {
            $whereConditions[] = "DATE(t.updated_at) >= ?";
            $params[] = $filters['updated_from'];
            $paramTypes .= 's';
        }
        if (!empty($filters['updated_to'])) {
            $whereConditions[] = "DATE(t.updated_at) <= ?";
            $params[] = $filters['updated_to'];
            $paramTypes .= 's';
        }

        // Priority range
        if (!empty($filters['priority_min'])) {
            $whereConditions[] = "t.priority >= ?";
            $params[] = (int)$filters['priority_min'];
            $paramTypes .= 'i';
        }
        if (!empty($filters['priority_max'])) {
            $whereConditions[] = "t.priority <= ?";
            $params[] = (int)$filters['priority_max'];
            $paramTypes .= 'i';
        }

        // Created by user
        if (!empty($filters['created_by'])) {
            $whereConditions[] = "t.created_by = ?";
            $params[] = (int)$filters['created_by'];
            $paramTypes .= 'i';
        }

        // Assigned to user (including unassigned option)
        if (!empty($filters['assigned_to'])) {
            if ($filters['assigned_to'] === 'unassigned') {
                $whereConditions[] = "t.assigned_to IS NULL";
            } else {
                $whereConditions[] = "t.assigned_to = ?";
                $params[] = (int)$filters['assigned_to'];
                $paramTypes .= 'i';
            }
        }
        
        $whereClause = '';
        if (!empty($whereConditions)) {
            $whereClause = 'WHERE ' . implode(' AND ', $whereConditions);
        }
        
        // Validate sort column to prevent SQL injection
        $allowedColumns = ['ticket_id', 'title', 'status', 'priority', 'category', 'type', 'created_at', 'updated_at', 'created_by', 'assigned_to'];
        if (!in_array($sortColumn, $allowedColumns)) {
            $sortColumn = 'ticket_id';
        }

        // Map column names to actual sort expressions
        // For user columns, sort by display name with NULL handling for unassigned
        $sortExpression = $sortColumn;
        if ($sortColumn === 'created_by') {
            $sortExpression = "COALESCE(u_created.display_name, u_created.username, 'System')";
        } elseif ($sortColumn === 'assigned_to') {
            // Put unassigned (NULL) at the end regardless of sort direction
            $sortExpression = "CASE WHEN t.assigned_to IS NULL THEN 1 ELSE 0 END, COALESCE(u_assigned.display_name, u_assigned.username)";
        } else {
            $sortExpression = "t.$sortColumn";
        }

        // Validate sort direction
        $sortDirection = strtolower($sortDirection) === 'asc' ? 'ASC' : 'DESC';

        // Get total count for pagination
        $countSql = "SELECT COUNT(*) as total FROM tickets t $whereClause";
        $countStmt = $this->conn->prepare($countSql);

        if (!empty($params)) {
            $countStmt->bind_param($paramTypes, ...$params);
        }

        $countStmt->execute();
        $totalResult = $countStmt->get_result();
        $totalTickets = $totalResult->fetch_assoc()['total'];

        // Get tickets with pagination and creator info
        $sql = "SELECT t.*,
                u_created.username as creator_username,
                u_created.display_name as creator_display_name,
                u_assigned.username as assigned_username,
                u_assigned.display_name as assigned_display_name
                FROM tickets t
                LEFT JOIN users u_created ON t.created_by = u_created.user_id
                LEFT JOIN users u_assigned ON t.assigned_to = u_assigned.user_id
                $whereClause
                ORDER BY $sortExpression $sortDirection
                LIMIT ? OFFSET ?";
        $stmt = $this->conn->prepare($sql);
        
        // Add limit and offset parameters
        $params[] = $limit;
        $params[] = $offset;
        $paramTypes .= 'ii';
        
        if (!empty($params)) {
            $stmt->bind_param($paramTypes, ...$params);
        }
        
        $stmt->execute();
        $result = $stmt->get_result();
        
        $tickets = [];
        while ($row = $result->fetch_assoc()) {
            $tickets[] = $row;
        }
        
        return [
            'tickets' => $tickets,
            'total' => $totalTickets,
            'pages' => ceil($totalTickets / $limit),
            'current_page' => $page
        ];
    }
    
    public function updateTicket($ticketData, $updatedBy = null) {
        $sql = "UPDATE tickets SET
                title = ?,
                priority = ?,
                status = ?,
                description = ?,
                category = ?,
                type = ?,
                updated_by = ?,
                updated_at = NOW()
                WHERE ticket_id = ?";

        $stmt = $this->conn->prepare($sql);
        if (!$stmt) {
            return false;
        }

        $stmt->bind_param(
            "sissssii",
            $ticketData['title'],
            $ticketData['priority'],
            $ticketData['status'],
            $ticketData['description'],
            $ticketData['category'],
            $ticketData['type'],
            $updatedBy,
            $ticketData['ticket_id']
        );

        $result = $stmt->execute();
        $stmt->close();

        return $result;
    }
    
    public function createTicket($ticketData, $createdBy = null) {
        // Generate ticket ID (9-digit format with leading zeros)
        $ticket_id = sprintf('%09d', mt_rand(1, 999999999));

        $sql = "INSERT INTO tickets (ticket_id, title, description, status, priority, category, type, created_by, visibility, visibility_groups)
                VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)";

        $stmt = $this->conn->prepare($sql);

        // Set default values if not provided
        $status = $ticketData['status'] ?? 'Open';
        $priority = $ticketData['priority'] ?? '4';
        $category = $ticketData['category'] ?? 'General';
        $type = $ticketData['type'] ?? 'Issue';
        $visibility = $ticketData['visibility'] ?? 'public';
        $visibilityGroups = $ticketData['visibility_groups'] ?? null;

        // Validate visibility
        $allowedVisibilities = ['public', 'internal', 'confidential'];
        if (!in_array($visibility, $allowedVisibilities)) {
            $visibility = 'public';
        }

        // Clear visibility_groups if not internal
        if ($visibility !== 'internal') {
            $visibilityGroups = null;
        }

        $stmt->bind_param(
            "sssssssiss",
            $ticket_id,
            $ticketData['title'],
            $ticketData['description'],
            $status,
            $priority,
            $category,
            $type,
            $createdBy,
            $visibility,
            $visibilityGroups
        );

        if ($stmt->execute()) {
            return [
                'success' => true,
                'ticket_id' => $ticket_id
            ];
        } else {
            return [
                'success' => false,
                'error' => $this->conn->error
            ];
        }
    }
    
    public function addComment($ticketId, $commentData) {
        $sql = "INSERT INTO ticket_comments (ticket_id, user_name, comment_text, markdown_enabled) 
                VALUES (?, ?, ?, ?)";
                
        $stmt = $this->conn->prepare($sql);
        
        // Set default username
        $username = $commentData['user_name'] ?? 'User';
        $markdownEnabled = $commentData['markdown_enabled'] ? 1 : 0;
        
        $stmt->bind_param(
            "sssi",
            $ticketId,
            $username,
            $commentData['comment_text'],
            $markdownEnabled
        );
        
        if ($stmt->execute()) {
            return [
                'success' => true,
                'user_name' => $username,
                'created_at' => date('M d, Y H:i')
            ];
        } else {
            return [
                'success' => false,
                'error' => $this->conn->error
            ];
        }
    }

    /**
     * Assign ticket to a user
     *
     * @param int $ticketId Ticket ID
     * @param int $userId User ID to assign to
     * @param int $assignedBy User ID performing the assignment
     * @return bool Success status
     */
    public function assignTicket($ticketId, $userId, $assignedBy) {
        $sql = "UPDATE tickets SET assigned_to = ?, updated_by = ?, updated_at = NOW() WHERE ticket_id = ?";
        $stmt = $this->conn->prepare($sql);
        $stmt->bind_param("iii", $userId, $assignedBy, $ticketId);
        $result = $stmt->execute();
        $stmt->close();
        return $result;
    }

    /**
     * Unassign ticket (set assigned_to to NULL)
     *
     * @param int $ticketId Ticket ID
     * @param int $updatedBy User ID performing the unassignment
     * @return bool Success status
     */
    public function unassignTicket($ticketId, $updatedBy) {
        $sql = "UPDATE tickets SET assigned_to = NULL, updated_by = ?, updated_at = NOW() WHERE ticket_id = ?";
        $stmt = $this->conn->prepare($sql);
        $stmt->bind_param("ii", $updatedBy, $ticketId);
        $result = $stmt->execute();
        $stmt->close();
        return $result;
    }

    /**
     * Get multiple tickets by IDs in a single query (batch loading)
     * Eliminates N+1 query problem in bulk operations
     *
     * @param array $ticketIds Array of ticket IDs
     * @return array Associative array keyed by ticket_id
     */
    public function getTicketsByIds($ticketIds) {
        if (empty($ticketIds)) {
            return [];
        }

        // Sanitize ticket IDs
        $ticketIds = array_map('intval', $ticketIds);

        // Create placeholders for IN clause
        $placeholders = str_repeat('?,', count($ticketIds) - 1) . '?';

        $sql = "SELECT t.*,
                u_created.username as creator_username,
                u_created.display_name as creator_display_name,
                u_updated.username as updater_username,
                u_updated.display_name as updater_display_name,
                u_assigned.username as assigned_username,
                u_assigned.display_name as assigned_display_name
                FROM tickets t
                LEFT JOIN users u_created ON t.created_by = u_created.user_id
                LEFT JOIN users u_updated ON t.updated_by = u_updated.user_id
                LEFT JOIN users u_assigned ON t.assigned_to = u_assigned.user_id
                WHERE t.ticket_id IN ($placeholders)";

        $stmt = $this->conn->prepare($sql);
        $types = str_repeat('i', count($ticketIds));
        $stmt->bind_param($types, ...$ticketIds);
        $stmt->execute();
        $result = $stmt->get_result();

        $tickets = [];
        while ($row = $result->fetch_assoc()) {
            $tickets[$row['ticket_id']] = $row;
        }

        $stmt->close();
        return $tickets;
    }

    /**
     * Check if a user can access a ticket based on visibility settings
     *
     * @param array $ticket The ticket data
     * @param array $user The user data (must include user_id, is_admin, groups)
     * @return bool True if user can access the ticket
     */
    public function canUserAccessTicket($ticket, $user) {
        // Admins can access all tickets
        if (!empty($user['is_admin'])) {
            return true;
        }

        $visibility = $ticket['visibility'] ?? 'public';

        // Public tickets are accessible to all authenticated users
        if ($visibility === 'public') {
            return true;
        }

        // Confidential tickets: only creator, assignee, and admins
        if ($visibility === 'confidential') {
            $userId = $user['user_id'] ?? null;
            return ($ticket['created_by'] == $userId || $ticket['assigned_to'] == $userId);
        }

        // Internal tickets: check if user is in any of the allowed groups
        if ($visibility === 'internal') {
            $allowedGroups = array_filter(array_map('trim', explode(',', $ticket['visibility_groups'] ?? '')));
            if (empty($allowedGroups)) {
                return false; // No groups specified means no access
            }

            $userGroups = array_filter(array_map('trim', explode(',', $user['groups'] ?? '')));
            // Check if any user group matches any allowed group
            return !empty(array_intersect($userGroups, $allowedGroups));
        }

        return false;
    }

    /**
     * Build visibility filter SQL for queries
     *
     * @param array $user The current user
     * @return array ['sql' => string, 'params' => array, 'types' => string]
     */
    public function getVisibilityFilter($user) {
        // Admins see all tickets
        if (!empty($user['is_admin'])) {
            return ['sql' => '1=1', 'params' => [], 'types' => ''];
        }

        $userId = $user['user_id'] ?? 0;
        $userGroups = array_filter(array_map('trim', explode(',', $user['groups'] ?? '')));

        // Build the visibility filter
        // 1. Public tickets
        // 2. Confidential tickets where user is creator or assignee
        // 3. Internal tickets where user's groups overlap with visibility_groups
        $conditions = [];
        $params = [];
        $types = '';

        // Public visibility
        $conditions[] = "(t.visibility = 'public' OR t.visibility IS NULL)";

        // Confidential - user is creator or assignee
        $conditions[] = "(t.visibility = 'confidential' AND (t.created_by = ? OR t.assigned_to = ?))";
        $params[] = $userId;
        $params[] = $userId;
        $types .= 'ii';

        // Internal - check group membership
        if (!empty($userGroups)) {
            $groupConditions = [];
            foreach ($userGroups as $group) {
                $groupConditions[] = "FIND_IN_SET(?, REPLACE(t.visibility_groups, ' ', ''))";
                $params[] = $group;
                $types .= 's';
            }
            $conditions[] = "(t.visibility = 'internal' AND (" . implode(' OR ', $groupConditions) . "))";
        }

        return [
            'sql' => '(' . implode(' OR ', $conditions) . ')',
            'params' => $params,
            'types' => $types
        ];
    }

    /**
     * Update ticket visibility settings
     *
     * @param int $ticketId
     * @param string $visibility ('public', 'internal', 'confidential')
     * @param string|null $visibilityGroups Comma-separated group names for 'internal' visibility
     * @param int $updatedBy User ID
     * @return bool
     */
    public function updateVisibility($ticketId, $visibility, $visibilityGroups, $updatedBy) {
        $allowedVisibilities = ['public', 'internal', 'confidential'];
        if (!in_array($visibility, $allowedVisibilities)) {
            $visibility = 'public';
        }

        // Clear visibility_groups if not internal
        if ($visibility !== 'internal') {
            $visibilityGroups = null;
        }

        $sql = "UPDATE tickets SET visibility = ?, visibility_groups = ?, updated_by = ?, updated_at = NOW() WHERE ticket_id = ?";
        $stmt = $this->conn->prepare($sql);
        $stmt->bind_param("ssii", $visibility, $visibilityGroups, $updatedBy, $ticketId);
        $result = $stmt->execute();
        $stmt->close();
        return $result;
    }
}