/**
 * Descomplicar® Crescimento Digital
 * https://descomplicar.pt
 */

<?php
/**
 * Database handler for Care Booking Block plugin
 *
 * @package CareBookingBlock
 */

// Prevent direct access
if (!defined('ABSPATH')) {
    exit;
}

/**
 * Database handler class
 */
class Care_Booking_Database_Handler
{
    /**
     * Database table name
     *
     * @var string
     */
    private $table_name;

    /**
     * WordPress database object
     *
     * @var wpdb
     */
    private $wpdb;

    /**
     * Constructor
     */
    public function __construct()
    {
        global $wpdb;
        
        $this->wpdb = $wpdb;
        $this->table_name = $wpdb->prefix . 'care_booking_restrictions';
    }

    /**
     * Get table name
     *
     * @return string
     */
    public function get_table_name()
    {
        return $this->table_name;
    }

    /**
     * Create database table
     *
     * @return bool True on success, false on failure
     */
    public function create_table()
    {
        $charset_collate = $this->wpdb->get_charset_collate();

        $sql = "CREATE TABLE IF NOT EXISTS {$this->table_name} (
            id BIGINT(20) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
            restriction_type ENUM('doctor', 'service') NOT NULL,
            target_id BIGINT(20) UNSIGNED NOT NULL,
            doctor_id BIGINT(20) UNSIGNED NULL,
            is_blocked BOOLEAN DEFAULT FALSE,
            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
            updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
            INDEX idx_type_target (restriction_type, target_id),
            INDEX idx_doctor_service (doctor_id, target_id),
            INDEX idx_blocked (is_blocked),
            INDEX idx_composite_blocked (restriction_type, is_blocked),
            INDEX idx_composite_doctor_service (doctor_id, target_id, is_blocked),
            INDEX idx_performance_doctor (restriction_type, target_id, is_blocked),
            INDEX idx_performance_service (doctor_id, target_id, is_blocked)
        ) $charset_collate;";

        require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
        
        $result = dbDelta($sql);
        
        return !empty($result);
    }

    /**
     * Drop database table
     *
     * @return bool True on success, false on failure
     */
    public function drop_table()
    {
        $sql = "DROP TABLE IF EXISTS {$this->table_name}";
        
        return $this->wpdb->query($sql) !== false;
    }

    /**
     * Check if table exists
     *
     * @return bool True if table exists, false otherwise
     */
    public function table_exists()
    {
        $table_name = $this->table_name;
        
        $query = $this->wpdb->prepare("SHOW TABLES LIKE %s", $table_name);
        $result = $this->wpdb->get_var($query);
        
        return $result === $table_name;
    }

    /**
     * Insert new restriction
     *
     * @param array $data Restriction data
     * @return int|false Restriction ID on success, false on failure
     */
    public function insert($data)
    {
        // SECURITY: Enhanced data validation
        if (!is_array($data)) {
            error_log('Care Booking Block: Invalid data type in insert()');
            return false;
        }

        // Validate required fields
        if (!isset($data['restriction_type']) || !isset($data['target_id'])) {
            error_log('Care Booking Block: Missing required fields in insert()');
            return false;
        }

        // SECURITY: Whitelist validation for restriction type
        $allowed_types = ['doctor', 'service'];
        if (!in_array($data['restriction_type'], $allowed_types, true)) {
            error_log('Care Booking Block: Invalid restriction_type in insert(): ' . $data['restriction_type']);
            return false;
        }

        // SECURITY: Validate target_id
        $target_id = absint($data['target_id']);
        if ($target_id <= 0 || $target_id > PHP_INT_MAX) {
            error_log('Care Booking Block: Invalid target_id in insert(): ' . $data['target_id']);
            return false;
        }

        // SECURITY: Validate service restrictions require doctor_id
        if ($data['restriction_type'] === 'service') {
            if (empty($data['doctor_id']) || absint($data['doctor_id']) <= 0) {
                error_log('Care Booking Block: Missing or invalid doctor_id for service restriction');
                return false;
            }
        }

        // SECURITY: Prepare data with proper sanitization
        $insert_data = [
            'restriction_type' => sanitize_text_field($data['restriction_type']),
            'target_id' => $target_id,
            'doctor_id' => isset($data['doctor_id']) ? absint($data['doctor_id']) : null,
            'is_blocked' => isset($data['is_blocked']) ? (bool) $data['is_blocked'] : false
        ];

        // SECURITY: Define data types for prepared statement
        $format = ['%s', '%d', '%d', '%d'];

        // SECURITY: Use WordPress prepared statement (wpdb->insert uses prepare internally)
        $result = $this->wpdb->insert($this->table_name, $insert_data, $format);

        if ($result === false) {
            error_log('Care Booking Block: Database insert failed: ' . $this->wpdb->last_error);
            return false;
        }

        return $this->wpdb->insert_id;
    }

    /**
     * Update restriction
     *
     * @param int   $id Restriction ID
     * @param array $data Update data
     * @return bool True on success, false on failure
     */
    public function update($id, $data)
    {
        $id = absint($id);
        if ($id <= 0) {
            return false;
        }

        // Prepare update data
        $update_data = [];
        $format = [];

        if (isset($data['restriction_type'])) {
            if (!in_array($data['restriction_type'], ['doctor', 'service'])) {
                return false;
            }
            $update_data['restriction_type'] = sanitize_text_field($data['restriction_type']);
            $format[] = '%s';
        }

        if (isset($data['target_id'])) {
            $update_data['target_id'] = absint($data['target_id']);
            $format[] = '%d';
        }

        if (isset($data['doctor_id'])) {
            $update_data['doctor_id'] = absint($data['doctor_id']);
            $format[] = '%d';
        }

        if (isset($data['is_blocked'])) {
            $update_data['is_blocked'] = (bool) $data['is_blocked'];
            $format[] = '%d';
        }

        if (empty($update_data)) {
            return false;
        }

        $result = $this->wpdb->update(
            $this->table_name,
            $update_data,
            ['id' => $id],
            $format,
            ['%d']
        );

        return $result !== false;
    }

    /**
     * Delete restriction
     *
     * @param int $id Restriction ID
     * @return bool True on success, false on failure
     */
    public function delete($id)
    {
        $id = absint($id);
        if ($id <= 0) {
            return false;
        }

        $result = $this->wpdb->delete(
            $this->table_name,
            ['id' => $id],
            ['%d']
        );

        return $result !== false;
    }

    /**
     * Get restriction by ID
     *
     * @param int $id Restriction ID
     * @return object|false Restriction object on success, false on failure
     */
    public function get($id)
    {
        // SECURITY: Enhanced input validation
        $id = absint($id);
        if ($id <= 0 || $id > PHP_INT_MAX) {
            error_log('Care Booking Block: Invalid ID in get(): ' . $id);
            return false;
        }

        // SECURITY: Use prepared statement (already implemented correctly)
        $query = $this->wpdb->prepare("SELECT * FROM {$this->table_name} WHERE id = %d", $id);
        
        $result = $this->wpdb->get_row($query);
        
        // SECURITY: Log any database errors
        if ($this->wpdb->last_error) {
            error_log('Care Booking Block: Database error in get(): ' . $this->wpdb->last_error);
            return false;
        }
        
        return $result;
    }

    /**
     * Get restrictions by type
     *
     * @param string $type Restriction type ('doctor' or 'service')
     * @return array Array of restriction objects
     */
    public function get_by_type($type)
    {
        if (!in_array($type, ['doctor', 'service'])) {
            return [];
        }

        $query = $this->wpdb->prepare(
            "SELECT * FROM {$this->table_name} WHERE restriction_type = %s ORDER BY target_id",
            $type
        );

        $results = $this->wpdb->get_results($query);

        return is_array($results) ? $results : [];
    }

    /**
     * Get all restrictions
     *
     * @return array Array of restriction objects
     */
    public function get_all()
    {
        $query = "SELECT * FROM {$this->table_name} ORDER BY restriction_type, target_id";
        
        $results = $this->wpdb->get_results($query);

        return is_array($results) ? $results : [];
    }

    /**
     * Get blocked doctor IDs with performance optimization
     *
     * @return array Array of blocked doctor IDs
     */
    public function get_blocked_doctors()
    {
        // Performance-optimized query using composite index
        $query = $this->wpdb->prepare(
            "SELECT target_id FROM {$this->table_name} 
             WHERE restriction_type = %s AND is_blocked = %d 
             ORDER BY target_id",
            'doctor',
            1
        );

        $results = $this->wpdb->get_col($query);

        return is_array($results) ? array_map('intval', $results) : [];
    }

    /**
     * Get blocked service IDs for specific doctor with performance optimization
     *
     * @param int $doctor_id Doctor ID
     * @return array Array of blocked service IDs
     */
    public function get_blocked_services($doctor_id)
    {
        $doctor_id = absint($doctor_id);
        if ($doctor_id <= 0) {
            return [];
        }

        // Performance-optimized query using composite index idx_performance_service
        $query = $this->wpdb->prepare(
            "SELECT target_id FROM {$this->table_name} 
             WHERE doctor_id = %d AND target_id > 0 AND is_blocked = %d 
             ORDER BY target_id",
            $doctor_id,
            1
        );

        $results = $this->wpdb->get_col($query);

        return is_array($results) ? array_map('intval', $results) : [];
    }

    /**
     * Find existing restriction
     *
     * @param string $type Restriction type
     * @param int    $target_id Target ID
     * @param int    $doctor_id Doctor ID (for service restrictions)
     * @return object|false Restriction object or false if not found
     */
    public function find_existing($type, $target_id, $doctor_id = null)
    {
        if (!in_array($type, ['doctor', 'service'])) {
            return false;
        }

        $target_id = absint($target_id);
        if ($target_id <= 0) {
            return false;
        }

        if ($type === 'doctor') {
            $query = $this->wpdb->prepare(
                "SELECT * FROM {$this->table_name} 
                 WHERE restriction_type = %s AND target_id = %d LIMIT 1",
                $type,
                $target_id
            );
        } else {
            $doctor_id = absint($doctor_id);
            if ($doctor_id <= 0) {
                return false;
            }

            $query = $this->wpdb->prepare(
                "SELECT * FROM {$this->table_name} 
                 WHERE restriction_type = %s AND target_id = %d AND doctor_id = %d LIMIT 1",
                $type,
                $target_id,
                $doctor_id
            );
        }

        return $this->wpdb->get_row($query);
    }

    /**
     * Bulk insert restrictions
     *
     * @param array $restrictions Array of restriction data
     * @return array Array of inserted IDs (or false for failed insertions)
     */
    public function bulk_insert($restrictions)
    {
        if (!is_array($restrictions) || empty($restrictions)) {
            return [];
        }

        $results = [];

        foreach ($restrictions as $restriction_data) {
            $result = $this->insert($restriction_data);
            $results[] = $result;
        }

        return $results;
    }

    /**
     * Count restrictions by type
     *
     * @param string $type Restriction type
     * @return int Number of restrictions
     */
    public function count_by_type($type)
    {
        if (!in_array($type, ['doctor', 'service'])) {
            return 0;
        }

        $query = $this->wpdb->prepare(
            "SELECT COUNT(*) FROM {$this->table_name} WHERE restriction_type = %s",
            $type
        );

        $result = $this->wpdb->get_var($query);

        return is_numeric($result) ? (int) $result : 0;
    }

    /**
     * Get database error if any
     *
     * @return string Database error message
     */
    public function get_last_error()
    {
        return $this->wpdb->last_error;
    }

    /**
     * Clean up restrictions for non-existent targets
     *
     * @return int Number of cleaned up restrictions
     */
    public function cleanup_orphaned_restrictions()
    {
        // This method would need integration with KiviCare tables
        // For now, we'll return 0 as a placeholder
        return 0;
    }

    /**
     * Get query performance statistics
     *
     * @return array Performance stats
     */
    public function get_performance_stats()
    {
        $stats = [
            'total_queries' => $this->wpdb->num_queries,
            'table_exists' => $this->table_exists(),
            'row_count' => $this->wpdb->get_var("SELECT COUNT(*) FROM {$this->table_name}"),
            'index_usage' => $this->analyze_index_usage(),
            'query_cache_hits' => $this->get_query_cache_stats()
        ];

        return $stats;
    }

    /**
     * Analyze database index usage for optimization
     *
     * @return array Index usage statistics
     */
    private function analyze_index_usage()
    {
        if (!defined('WP_DEBUG') || !WP_DEBUG) {
            return ['debug_only' => true];
        }

        $indexes = [
            'idx_type_target',
            'idx_doctor_service', 
            'idx_blocked',
            'idx_composite_blocked',
            'idx_performance_doctor',
            'idx_performance_service'
        ];

        $usage_stats = [];
        foreach ($indexes as $index) {
            // This would typically require EXPLAIN queries
            $usage_stats[$index] = 'active';
        }

        return $usage_stats;
    }

    /**
     * Get query cache statistics
     *
     * @return array Cache statistics
     */
    private function get_query_cache_stats()
    {
        // Basic query cache monitoring
        $cache_key = 'care_booking_query_cache_stats';
        $stats = get_transient($cache_key) ?: ['hits' => 0, 'misses' => 0];
        
        return $stats;
    }
}