<?php
/**
 * MLS Media Handler
 *
 * Handles downloading and managing media files from MLS listings
 * Uses a queue-based system with rate limiting to comply with API limits
 *
 * Rate limits: 2 requests/second (500ms minimum between requests)
 * We use 700ms between requests (25% buffer)
 */

if (!defined('ABSPATH')) {
    exit;
}

class MLS_Media_Handler {

    /**
     * Upload subdirectory for MLS media
     */
    const UPLOAD_SUBDIR = 'mls-listings';

    /**
     * Minimum delay between media downloads in milliseconds (700ms = 25% buffer over 500ms limit)
     */
    const DOWNLOAD_DELAY_MS = 700;

    /**
     * Retry backoff time in hours for failed downloads
     */
    const RETRY_BACKOFF_HOURS = 3;

    /**
     * Maximum download attempts before permanent failure
     */
    const MAX_ATTEMPTS = 5;

    /**
     * Database instance
     */
    private $db;

    /**
     * Logger instance
     */
    private $logger;

    /**
     * Constructor
     */
    public function __construct(MLS_DB $db, MLS_Logger $logger) {
        $this->db = $db;
        $this->logger = $logger;
    }

    /**
     * Get base upload directory for MLS media
     *
     * @return string Absolute path
     */
    public function get_upload_dir() {
        $upload_dir = wp_upload_dir();
        return $upload_dir['basedir'] . '/' . self::UPLOAD_SUBDIR;
    }

    /**
     * Get base upload URL for MLS media
     *
     * @return string URL
     */
    public function get_upload_url() {
        $upload_dir = wp_upload_dir();
        return $upload_dir['baseurl'] . '/' . self::UPLOAD_SUBDIR;
    }

    /**
     * Get storage directory for a specific listing
     *
     * @param string $listing_key Listing key
     * @return string Absolute path
     */
    public function get_listing_dir($listing_key) {
        // Use first 2 characters as subdirectory to prevent too many files in one folder
        $prefix = substr($listing_key, 0, 2);
        return $this->get_upload_dir() . '/' . $prefix . '/' . $listing_key;
    }

    /**
     * Queue media for a property (does NOT download immediately)
     *
     * @param string $listing_key Listing key
     * @param array $media_array Media array from API
     * @param callable|null $progress_callback Callback for progress updates
     */
    public function queue_property_media($listing_key, $media_array, $progress_callback = null) {
        global $wpdb;

        if (empty($media_array)) {
            return;
        }

        $received_keys = array();
        $queued_count = 0;
        $skipped_count = 0;

        foreach ($media_array as $media) {
            $media_key = $media['MediaKey'] ?? null;
            if (!$media_key) {
                continue;
            }

            $received_keys[] = $media_key;

            // Check if media record exists
            $existing = $wpdb->get_row($wpdb->prepare(
                "SELECT * FROM {$this->db->media_table()}
                 WHERE listing_key = %s AND media_key = %s",
                $listing_key,
                $media_key
            ));

            $data = array(
                'listing_key' => $listing_key,
                'media_key' => $media_key,
                'media_type' => $media['MediaType'] ?? 'Photo',
                'media_order' => $media['Order'] ?? 0,
                'media_url' => $media['MediaURL'] ?? null,
                'image_width' => $media['ImageWidth'] ?? null,
                'image_height' => $media['ImageHeight'] ?? null,
                'media_modification_timestamp' => isset($media['MediaModificationTimestamp'])
                    ? date('Y-m-d H:i:s', strtotime($media['MediaModificationTimestamp']))
                    : null,
                'updated_at' => current_time('mysql'),
            );

            if ($existing) {
                // Update existing record
                $wpdb->update(
                    $this->db->media_table(),
                    $data,
                    array('id' => $existing->id)
                );

                // Check if we need to re-download (queue it)
                if ($this->needs_download($existing, $media)) {
                    $this->mark_for_download($existing->id);
                    $queued_count++;
                    if ($progress_callback) {
                        call_user_func($progress_callback, 'media_queued', array('media_key' => $media_key));
                    }
                } else {
                    $skipped_count++;
                    if ($progress_callback) {
                        call_user_func($progress_callback, 'media_skipped', array('media_key' => $media_key));
                    }
                }
            } else {
                // Insert new record - queued for download
                $data['created_at'] = current_time('mysql');
                $data['queued_at'] = current_time('mysql');
                $data['download_status'] = 'pending';
                $wpdb->insert($this->db->media_table(), $data);
                $queued_count++;
                if ($progress_callback) {
                    call_user_func($progress_callback, 'media_queued', array('media_key' => $media_key));
                }
            }
        }

        // Delete media that no longer exists
        if (!empty($received_keys)) {
            $placeholders = implode(',', array_fill(0, count($received_keys), '%s'));
            $values = array_merge(array($listing_key), $received_keys);

            $orphaned = $wpdb->get_results($wpdb->prepare(
                "SELECT id, local_path FROM {$this->db->media_table()}
                 WHERE listing_key = %s AND media_key NOT IN ({$placeholders})",
                $values
            ));

            foreach ($orphaned as $record) {
                // Delete file if exists
                if ($record->local_path) {
                    $file_path = $this->get_upload_dir() . '/' . $record->local_path;
                    if (file_exists($file_path)) {
                        unlink($file_path);
                    }
                }

                // Delete record
                $wpdb->delete($this->db->media_table(), array('id' => $record->id));
            }
        }

        return array(
            'queued' => $queued_count,
            'skipped' => $skipped_count,
        );
    }

    /**
     * Mark a media record for download
     *
     * @param int $media_id Media ID
     */
    private function mark_for_download($media_id) {
        global $wpdb;

        $wpdb->update(
            $this->db->media_table(),
            array(
                'download_status' => 'pending',
                'queued_at' => current_time('mysql'),
                'local_path' => null,
                'local_url' => null,
                'downloaded_at' => null,
                'download_error' => null,
            ),
            array('id' => $media_id)
        );
    }

    /**
     * Check if media needs to be downloaded
     *
     * @param object $existing Existing media record
     * @param array $new_data New media data from API
     * @return bool
     */
    private function needs_download($existing, $new_data) {
        // No local file
        if (empty($existing->local_path)) {
            return true;
        }

        // File doesn't exist
        $file_path = $this->get_upload_dir() . '/' . $existing->local_path;
        if (!file_exists($file_path)) {
            return true;
        }

        // Media URL changed
        if ($existing->media_url !== ($new_data['MediaURL'] ?? null)) {
            return true;
        }

        return false;
    }

    /**
     * Get the next media item to download from the queue
     *
     * @return object|null Media record or null if queue is empty
     */
    public function get_next_queued() {
        global $wpdb;

        $now = current_time('mysql');

        // Get next pending item that's not in retry backoff
        return $wpdb->get_row($wpdb->prepare(
            "SELECT * FROM {$this->db->media_table()}
             WHERE download_status = 'pending'
             AND media_url IS NOT NULL
             AND download_attempts < %d
             AND (retry_after IS NULL OR retry_after <= %s)
             ORDER BY queued_at ASC
             LIMIT 1",
            self::MAX_ATTEMPTS,
            $now
        ));
    }

    /**
     * Get queue statistics
     *
     * @return array Queue stats
     */
    public function get_queue_stats() {
        global $wpdb;

        $now = current_time('mysql');

        return array(
            'pending' => (int) $wpdb->get_var(
                "SELECT COUNT(*) FROM {$this->db->media_table()}
                 WHERE download_status = 'pending'"
            ),
            'ready' => (int) $wpdb->get_var($wpdb->prepare(
                "SELECT COUNT(*) FROM {$this->db->media_table()}
                 WHERE download_status = 'pending'
                 AND media_url IS NOT NULL
                 AND download_attempts < %d
                 AND (retry_after IS NULL OR retry_after <= %s)",
                self::MAX_ATTEMPTS,
                $now
            )),
            'in_backoff' => (int) $wpdb->get_var($wpdb->prepare(
                "SELECT COUNT(*) FROM {$this->db->media_table()}
                 WHERE download_status = 'pending'
                 AND retry_after > %s",
                $now
            )),
            'failed' => (int) $wpdb->get_var($wpdb->prepare(
                "SELECT COUNT(*) FROM {$this->db->media_table()}
                 WHERE download_status = 'failed'
                 OR download_attempts >= %d",
                self::MAX_ATTEMPTS
            )),
            'completed' => (int) $wpdb->get_var(
                "SELECT COUNT(*) FROM {$this->db->media_table()}
                 WHERE download_status = 'completed'"
            ),
        );
    }

    /**
     * Process media queue with rate limiting
     *
     * @param int $limit Max items to process
     * @param callable|null $progress_callback Callback for progress updates
     * @return array Processing stats
     */
    public function process_queue($limit = 100, $progress_callback = null) {
        $stats = array(
            'processed' => 0,
            'success' => 0,
            'failed' => 0,
            'skipped' => 0,
        );

        $last_download_time = 0;

        for ($i = 0; $i < $limit; $i++) {
            $media = $this->get_next_queued();

            if (!$media) {
                // Queue empty
                break;
            }

            // Rate limiting: ensure minimum delay between downloads
            $now_ms = microtime(true) * 1000;
            $elapsed = $now_ms - $last_download_time;

            if ($elapsed < self::DOWNLOAD_DELAY_MS && $last_download_time > 0) {
                $wait_ms = (int) (self::DOWNLOAD_DELAY_MS - $elapsed);
                usleep($wait_ms * 1000);
            }

            // Download the media
            $result = $this->download_media($media->id);
            $last_download_time = microtime(true) * 1000;

            $stats['processed']++;

            if ($result === true) {
                $stats['success']++;
                if ($progress_callback) {
                    call_user_func($progress_callback, 'media_downloaded', array(
                        'media_key' => $media->media_key,
                        'listing_key' => $media->listing_key,
                    ));
                }
            } elseif ($result === 'backoff') {
                $stats['skipped']++;
                if ($progress_callback) {
                    call_user_func($progress_callback, 'media_backoff', array(
                        'media_key' => $media->media_key,
                        'listing_key' => $media->listing_key,
                    ));
                }
            } else {
                $stats['failed']++;
                if ($progress_callback) {
                    call_user_func($progress_callback, 'media_error', array(
                        'media_key' => $media->media_key,
                        'listing_key' => $media->listing_key,
                        'error' => $result,
                    ));
                }
            }
        }

        return $stats;
    }

    /**
     * Download a media file
     *
     * @param int $media_id Media record ID
     * @return bool|string True on success, 'backoff' if set for retry, error message on failure
     */
    public function download_media($media_id) {
        global $wpdb;

        $media = $wpdb->get_row($wpdb->prepare(
            "SELECT * FROM {$this->db->media_table()} WHERE id = %d",
            $media_id
        ));

        if (!$media || empty($media->media_url)) {
            return 'No media URL';
        }

        // Increment attempt counter
        $wpdb->update(
            $this->db->media_table(),
            array('download_attempts' => $media->download_attempts + 1),
            array('id' => $media_id)
        );

        // Make the request
        $start_time = microtime(true);

        $response = wp_remote_get($media->media_url, array(
            'timeout' => 60,
            'stream' => false,
        ));

        $response_time_ms = (int) ((microtime(true) - $start_time) * 1000);
        $status_code = 0;
        $error_msg = null;

        if (is_wp_error($response)) {
            $error_msg = $response->get_error_message();
            $this->log_download($media, 'error', null, $response_time_ms, $error_msg);
            $this->handle_download_failure($media_id, $error_msg, false);
            return $error_msg;
        }

        $status_code = wp_remote_retrieve_response_code($response);
        $this->log_download($media, 'attempt', $status_code, $response_time_ms, null);

        // Success
        if ($status_code === 200) {
            $body = wp_remote_retrieve_body($response);
            if (empty($body)) {
                $error_msg = 'Empty response body';
                $this->log_download($media, 'error', $status_code, $response_time_ms, $error_msg);
                $this->handle_download_failure($media_id, $error_msg, false);
                return $error_msg;
            }

            // Save the file
            $save_result = $this->save_media_file($media, $body, $response);
            if ($save_result !== true) {
                $this->log_download($media, 'error', $status_code, $response_time_ms, $save_result);
                $this->handle_download_failure($media_id, $save_result, false);
                return $save_result;
            }

            $this->log_download($media, 'success', $status_code, $response_time_ms, null);
            return true;
        }

        // Rate limited (429) or server error (5xx) - set backoff
        $retryable = in_array($status_code, array(429, 500, 502, 503, 504));
        $error_msg = "HTTP {$status_code}";

        if ($retryable) {
            $this->log_download($media, 'rate_limited', $status_code, $response_time_ms, $error_msg);
            $this->handle_download_failure($media_id, $error_msg, true);
            return 'backoff';
        }

        // Permanent failure (404, 403, etc.)
        $this->log_download($media, 'permanent_error', $status_code, $response_time_ms, $error_msg);
        $this->handle_download_failure($media_id, $error_msg, false);
        return $error_msg;
    }

    /**
     * Handle download failure
     *
     * @param int $media_id Media ID
     * @param string $error Error message
     * @param bool $set_backoff Whether to set retry backoff
     */
    private function handle_download_failure($media_id, $error, $set_backoff) {
        global $wpdb;

        $media = $wpdb->get_row($wpdb->prepare(
            "SELECT * FROM {$this->db->media_table()} WHERE id = %d",
            $media_id
        ));

        $update_data = array(
            'download_error' => $error,
        );

        if ($set_backoff) {
            // Set retry_after to 3 hours from now
            $retry_after = date('Y-m-d H:i:s', strtotime('+' . self::RETRY_BACKOFF_HOURS . ' hours'));
            $update_data['retry_after'] = $retry_after;
        }

        // Check if max attempts reached
        if ($media && $media->download_attempts >= self::MAX_ATTEMPTS) {
            $update_data['download_status'] = 'failed';
            $this->log_missing_media($media, $error);
        }

        $wpdb->update(
            $this->db->media_table(),
            $update_data,
            array('id' => $media_id)
        );
    }

    /**
     * Save downloaded media file to disk
     *
     * @param object $media Media record
     * @param string $body File contents
     * @param array $response HTTP response
     * @return bool|string True on success, error message on failure
     */
    private function save_media_file($media, $body, $response) {
        global $wpdb;

        // Determine file extension from content type or URL
        $content_type = wp_remote_retrieve_header($response, 'content-type');
        $extension = $this->get_extension_from_content_type($content_type, $media->media_url);

        // Create directory
        $listing_dir = $this->get_listing_dir($media->listing_key);
        if (!file_exists($listing_dir)) {
            wp_mkdir_p($listing_dir);
        }

        // Save file
        $filename = $media->media_order . '.' . $extension;
        $file_path = $listing_dir . '/' . $filename;

        if (file_put_contents($file_path, $body) === false) {
            return 'Failed to write file';
        }

        // Calculate relative path
        $prefix = substr($media->listing_key, 0, 2);
        $relative_path = $prefix . '/' . $media->listing_key . '/' . $filename;
        $local_url = $this->get_upload_url() . '/' . $relative_path;

        // Update record
        $wpdb->update(
            $this->db->media_table(),
            array(
                'local_path' => $relative_path,
                'local_url' => $local_url,
                'file_size' => strlen($body),
                'mime_type' => $content_type,
                'downloaded_at' => current_time('mysql'),
                'download_error' => null,
                'download_status' => 'completed',
                'retry_after' => null,
            ),
            array('id' => $media->id)
        );

        return true;
    }

    /**
     * Log a download attempt to the media log table
     *
     * @param object $media Media record
     * @param string $action Action type (attempt, success, error, rate_limited, permanent_error)
     * @param int|null $status_code HTTP status code
     * @param int $response_time_ms Response time in milliseconds
     * @param string|null $error Error message
     */
    private function log_download($media, $action, $status_code, $response_time_ms, $error) {
        global $wpdb;

        $wpdb->insert(
            $this->db->media_log_table(),
            array(
                'media_id' => $media->id,
                'listing_key' => $media->listing_key,
                'media_key' => $media->media_key,
                'action' => $action,
                'status_code' => $status_code,
                'response_time_ms' => $response_time_ms,
                'error_message' => $error,
                'url' => $media->media_url,
                'created_at' => current_time('mysql'),
            )
        );
    }

    /**
     * Get file extension from content type
     *
     * @param string $content_type Content type header
     * @param string $url Original URL as fallback
     * @return string File extension
     */
    private function get_extension_from_content_type($content_type, $url) {
        // Extract main type from content-type header
        $content_type = strtolower(explode(';', $content_type)[0]);

        $map = array(
            'image/jpeg' => 'jpg',
            'image/jpg' => 'jpg',
            'image/png' => 'png',
            'image/gif' => 'gif',
            'image/webp' => 'webp',
        );

        if (isset($map[$content_type])) {
            return $map[$content_type];
        }

        // Fallback to URL extension
        $path = parse_url($url, PHP_URL_PATH);
        $ext = pathinfo($path, PATHINFO_EXTENSION);

        return $ext ?: 'jpg';
    }

    /**
     * Get the path to the missing media log file
     *
     * @return string File path
     */
    public function get_missing_log_path() {
        $upload_dir = wp_upload_dir();
        return $upload_dir['basedir'] . '/mls-missing-media.log';
    }

    /**
     * Log a failed media download to the missing media log file
     *
     * @param object $media Media record
     * @param string $error Error message
     */
    private function log_missing_media($media, $error) {
        $log_file = $this->get_missing_log_path();
        $timestamp = date('Y-m-d H:i:s');
        $line = sprintf(
            "[%s] %s | %s | %s | %s\n",
            $timestamp,
            $media->listing_key,
            $media->media_key,
            $error,
            $media->media_url
        );
        file_put_contents($log_file, $line, FILE_APPEND | LOCK_EX);
    }

    /**
     * Clear the missing media log file
     */
    public function clear_missing_log() {
        $log_file = $this->get_missing_log_path();
        if (file_exists($log_file)) {
            unlink($log_file);
        }
    }

    /**
     * Get missing media count from log file
     *
     * @return int Number of missing media entries
     */
    public function get_missing_count() {
        $log_file = $this->get_missing_log_path();
        if (!file_exists($log_file)) {
            return 0;
        }
        $content = file_get_contents($log_file);
        return substr_count($content, "\n");
    }

    /**
     * Delete all media for a property
     *
     * @param string $listing_key Listing key
     */
    public function delete_property_media($listing_key) {
        global $wpdb;

        // Delete files
        $listing_dir = $this->get_listing_dir($listing_key);
        if (file_exists($listing_dir)) {
            $this->recursive_delete($listing_dir);
        }

        // Delete records
        $wpdb->delete(
            $this->db->media_table(),
            array('listing_key' => $listing_key)
        );
    }

    /**
     * Recursively delete a directory
     *
     * @param string $dir Directory path
     */
    private function recursive_delete($dir) {
        if (!is_dir($dir)) {
            return;
        }

        $files = array_diff(scandir($dir), array('.', '..'));

        foreach ($files as $file) {
            $path = $dir . '/' . $file;
            if (is_dir($path)) {
                $this->recursive_delete($path);
            } else {
                unlink($path);
            }
        }

        rmdir($dir);
    }

    /**
     * Get media for a listing
     *
     * @param string $listing_key Listing key
     * @return array Media records
     */
    public function get_listing_media($listing_key) {
        global $wpdb;

        return $wpdb->get_results($wpdb->prepare(
            "SELECT * FROM {$this->db->media_table()}
             WHERE listing_key = %s
             ORDER BY media_order ASC",
            $listing_key
        ));
    }

    /**
     * Get primary image URL for a listing
     *
     * @param string $listing_key Listing key
     * @return string|null Image URL
     */
    public function get_primary_image($listing_key) {
        global $wpdb;

        $media = $wpdb->get_row($wpdb->prepare(
            "SELECT local_url, media_url FROM {$this->db->media_table()}
             WHERE listing_key = %s AND local_path IS NOT NULL
             ORDER BY media_order ASC
             LIMIT 1",
            $listing_key
        ));

        if ($media && $media->local_url) {
            return $media->local_url;
        }

        return null;
    }

    /**
     * Reset failed downloads for retry
     *
     * @param string|null $listing_key Optional listing key to filter
     * @return int Number of records reset
     */
    public function reset_failed_downloads($listing_key = null) {
        global $wpdb;

        $where = "download_status = 'failed' OR download_attempts >= " . self::MAX_ATTEMPTS;
        $values = array();

        if ($listing_key) {
            $where .= " AND listing_key = %s";
            $values[] = $listing_key;
        }

        if (!empty($values)) {
            $sql = $wpdb->prepare(
                "UPDATE {$this->db->media_table()}
                 SET download_status = 'pending',
                     download_attempts = 0,
                     download_error = NULL,
                     retry_after = NULL,
                     queued_at = %s
                 WHERE {$where}",
                array_merge(array(current_time('mysql')), $values)
            );
        } else {
            $sql = $wpdb->prepare(
                "UPDATE {$this->db->media_table()}
                 SET download_status = 'pending',
                     download_attempts = 0,
                     download_error = NULL,
                     retry_after = NULL,
                     queued_at = %s
                 WHERE {$where}",
                current_time('mysql')
            );
        }

        $wpdb->query($sql);
        return $wpdb->rows_affected;
    }

    /**
     * Clean up orphaned media (files without database records)
     *
     * @return int Number of files deleted
     */
    public function cleanup_orphaned_files() {
        $deleted = 0;
        $base_dir = $this->get_upload_dir();

        if (!is_dir($base_dir)) {
            return 0;
        }

        // Iterate through prefix directories
        foreach (scandir($base_dir) as $prefix) {
            if ($prefix === '.' || $prefix === '..' || !is_dir($base_dir . '/' . $prefix)) {
                continue;
            }

            $prefix_dir = $base_dir . '/' . $prefix;

            // Iterate through listing directories
            foreach (scandir($prefix_dir) as $listing_key) {
                if ($listing_key === '.' || $listing_key === '..') {
                    continue;
                }

                $listing_dir = $prefix_dir . '/' . $listing_key;
                if (!is_dir($listing_dir)) {
                    continue;
                }

                // Check if listing exists in database
                global $wpdb;
                $exists = $wpdb->get_var($wpdb->prepare(
                    "SELECT COUNT(*) FROM {$this->db->properties_table()} WHERE listing_key = %s",
                    $listing_key
                ));

                if (!$exists) {
                    $this->recursive_delete($listing_dir);
                    $deleted++;
                }
            }
        }

        return $deleted;
    }

    /**
     * Get recent download logs
     *
     * @param int $limit Number of entries to return
     * @param string|null $action Optional action filter
     * @return array Log entries
     */
    public function get_download_logs($limit = 100, $action = null) {
        global $wpdb;

        $where = '';
        $values = array();

        if ($action) {
            $where = "WHERE action = %s";
            $values[] = $action;
        }

        $values[] = $limit;

        return $wpdb->get_results($wpdb->prepare(
            "SELECT * FROM {$this->db->media_log_table()}
             {$where}
             ORDER BY created_at DESC
             LIMIT %d",
            $values
        ));
    }

    /**
     * Clear old download logs
     *
     * @param int $days_old Delete logs older than this many days
     * @return int Number of entries deleted
     */
    public function clear_old_logs($days_old = 7) {
        global $wpdb;

        $cutoff = date('Y-m-d H:i:s', strtotime("-{$days_old} days"));

        $wpdb->query($wpdb->prepare(
            "DELETE FROM {$this->db->media_log_table()} WHERE created_at < %s",
            $cutoff
        ));

        return $wpdb->rows_affected;
    }

    /**
     * Legacy sync method - now queues media instead of downloading immediately
     * Kept for backward compatibility
     *
     * @param string $listing_key Listing key
     * @param array $media_array Media array from API
     * @param bool $force Force re-download all media
     * @param callable|null $progress_callback Callback for progress updates
     */
    public function sync_property_media($listing_key, $media_array, $force = false, $progress_callback = null) {
        // Now just queues media - actual download happens via process_queue()
        return $this->queue_property_media($listing_key, $media_array, $progress_callback);
    }

    /**
     * Legacy download_pending method - now uses process_queue
     * Kept for backward compatibility
     *
     * @param int $limit Max media to download
     * @param callable|null $progress_callback Callback for progress updates
     * @return array Stats
     */
    public function download_pending($limit = 100, $progress_callback = null) {
        return $this->process_queue($limit, $progress_callback);
    }
}