<?php
/**
 * Action Scheduler Helper Class
 *
 * Manages async background jobs for email batch processing.
 *
 * @package DDHH_Job_Manager
 * @since 1.0.0
 */

// Exit if accessed directly.
defined( 'ABSPATH' ) || exit;

/**
 * Class DDHH_JM_Scheduler
 *
 * Provides API for scheduling async email batch processing via Action Scheduler.
 */
class DDHH_JM_Scheduler {

	/**
	 * Initialize hooks.
	 */
	public static function setup_hooks() {
		// Register async action callback for mentor notification batches
		add_action( 'ddhh_jm_send_mentor_notification_batch', array( __CLASS__, 'process_mentor_notification_batch' ), 10, 2 );
	}

	/**
	 * Schedule mentor notification batch processing.
	 *
	 * Chunks user IDs into batches of 50 and schedules async actions for each batch.
	 * This prevents email provider limits and timeouts when sending to many mentors.
	 *
	 * @param array $user_ids Array of user IDs to notify.
	 * @param int   $job_id   Job post ID for the notification.
	 * @return int Number of batches scheduled.
	 */
	public static function schedule_mentor_notification_batch( $user_ids, $job_id ) {
		if ( empty( $user_ids ) || empty( $job_id ) ) {
			error_log( 'DDHH_JM_Scheduler: Cannot schedule batch - missing user IDs or job ID' );
			return 0;
		}

		// Chunk user IDs into batches of 50.
		$batches = array_chunk( $user_ids, 50 );
		$batch_count = 0;

		foreach ( $batches as $batch ) {
			// Enqueue async action for this batch.
			// Hook: ddhh_jm_send_mentor_notification_batch
			// Args: batch of user IDs and job ID
			// Group: email-notifications (for organization)
			// Unique: true (prevents duplicate scheduling)
			// Priority: 10 (standard priority)
			as_enqueue_async_action(
				'ddhh_jm_send_mentor_notification_batch',
				array(
					'user_ids' => $batch,
					'job_id'   => $job_id,
				),
				'email-notifications',
				true,
				10
			);

			$batch_count++;
			error_log( sprintf(
				'DDHH_JM_Scheduler: Scheduled batch %d with %d users for job ID %d',
				$batch_count,
				count( $batch ),
				$job_id
			) );
		}

		error_log( sprintf(
			'DDHH_JM_Scheduler: Scheduled %d total batches for %d users for job ID %d',
			$batch_count,
			count( $user_ids ),
			$job_id
		) );

		return $batch_count;
	}

	/**
	 * Process mentor notification batch (async callback).
	 *
	 * Sends emails to batch of users about a newly published job.
	 * Includes rate limiting delay between sends to avoid provider limits.
	 *
	 * @param array $user_ids Array of user IDs in this batch.
	 * @param int   $job_id   Job post ID.
	 */
	public static function process_mentor_notification_batch( $user_ids, $job_id ) {
		// Validate inputs
		if ( empty( $user_ids ) || empty( $job_id ) ) {
			error_log( 'DDHH_JM_Scheduler: Cannot process batch - missing user IDs or job ID' );
			return;
		}

		// Get job post
		$post = get_post( $job_id );
		if ( ! $post || 'job_offer' !== $post->post_type ) {
			error_log( sprintf( 'DDHH_JM_Scheduler: Invalid job_id %d in batch processing', $job_id ) );
			return;
		}

		// Get job details
		$job_title    = $post->post_title;
		$job_location = get_field( 'job_location', $job_id );
		$job_type     = get_field( 'job_type', $job_id );
		$job_link     = get_permalink( $job_id );

		// Track successful sends
		$sent_count = 0;

		// Process each user in batch
		foreach ( $user_ids as $user_id ) {
			// Get user data
			$user = get_userdata( $user_id );
			if ( ! $user ) {
				error_log( sprintf( 'DDHH_JM_Scheduler: User ID %d not found, skipping', $user_id ) );
				continue;
			}

			// Get user email
			$user_email = $user->user_email;
			if ( empty( $user_email ) ) {
				error_log( sprintf( 'DDHH_JM_Scheduler: User ID %d has no email, skipping', $user_id ) );
				continue;
			}

			// Prepare German email subject
			$subject = sprintf( 'Neues Stellenangebot: %s', $job_title );

			// Prepare German email body
			$body = sprintf(
				"Hallo,\n\n" .
				"ein neues Stellenangebot wurde veröffentlicht:\n\n" .
				"Stelle: %s\n" .
				"Standort: %s\n" .
				"Art: %s\n\n" .
				"Sie können das Angebot hier ansehen:\n%s\n\n" .
				"Um keine weiteren Benachrichtigungen zu erhalten, können Sie diese in Ihrem Profil deaktivieren.\n\n" .
				"---\n" .
				"Diese E-Mail wurde automatisch gesendet.",
				$job_title,
				$job_location ? $job_location : 'Nicht angegeben',
				$job_type ? $job_type : 'Nicht angegeben',
				$job_link
			);

			// Set email headers
			$headers = array( 'Content-Type: text/html; charset=UTF-8' );

			// Convert plain text to HTML with line breaks
			$html_body = nl2br( esc_html( $body ) );

			// Send email
			$sent = wp_mail( $user_email, $subject, $html_body, $headers );

			// Log failures
			if ( ! $sent ) {
				error_log(
					sprintf(
						'DDHH_JM_Scheduler: Failed to send mentor notification to user %d for job %d',
						$user_id,
						$job_id
					)
				);
			} else {
				$sent_count++;
			}

			// Rate limit delay: 0.1 seconds between emails
			usleep( 100000 );
		}

		// Log batch completion
		error_log(
			sprintf(
				'DDHH_JM_Scheduler: Processed notification batch: %d emails sent for job %d "%s"',
				$sent_count,
				$job_id,
				$job_title
			)
		);
	}
}