<?php
if ( ! defined( 'ABSPATH' ) ) exit;

/**
 * Booking emails are sent AFTER the buyer already has their answer.
 *
 * Checkout used to wait for every email (≈3–4 s each over Gmail SMTP).
 * Now booking hooks only queue the email; at the end of the request the
 * response is flushed to the browser first (PHP-FPM / LiteSpeed), then
 * the queued emails go out over ONE SMTP connection. Where the server
 * can't finish a response early, the batch runs from WP-Cron right away
 * instead. A failed send is retried once from WP-Cron.
 *
 * Every email is still sent — only the waiting moved.
 */
class SEATT_Mail_Queue {

	/** @var array[] pending jobs: array( type, booking_id ) */
	private static $jobs = array();

	/** True while a batch is being sent (SEATT_SMTP keeps the connection open). */
	public static $running = false;

	private static $hooked = false;

	public static function init() {
		add_action( 'seatt_mail_batch', array( __CLASS__, 'run_batch' ), 10, 1 );
	}

	/** Queues one email of a booking (deduplicated within the request). */
	public static function add( $type, $booking_id ) {
		$key = $type . ':' . (int) $booking_id;
		self::$jobs[ $key ] = array( (string) $type, (int) $booking_id );
		if ( ! self::$hooked ) {
			self::$hooked = true;
			add_action( 'shutdown', array( __CLASS__, 'flush' ), 1 );
		}
	}

	/** Pending jobs (tests / debugging). */
	public static function pending() {
		return array_values( self::$jobs );
	}

	/** End of request: answer the browser first, then send. */
	public static function flush() {
		if ( ! self::$jobs ) {
			return;
		}
		$jobs       = array_values( self::$jobs );
		self::$jobs = array();
		$early      = false;
		if ( function_exists( 'fastcgi_finish_request' ) ) {
			$early = fastcgi_finish_request();
		} elseif ( function_exists( 'litespeed_finish_request' ) ) {
			$early = litespeed_finish_request();
		}
		if ( $early || ( defined( 'DOING_CRON' ) && DOING_CRON ) || ( defined( 'WP_CLI' ) && WP_CLI ) ) {
			ignore_user_abort( true );
			self::run_batch( $jobs );
			return;
		}
		// No way to finish the response early (mod_php): hand the batch to
		// WP-Cron and trigger it now, so the buyer doesn't wait for it.
		wp_schedule_single_event( time(), 'seatt_mail_batch', array( $jobs ) );
		if ( function_exists( 'spawn_cron' ) ) {
			spawn_cron();
		}
	}

	/**
	 * Sends a batch over one SMTP connection. Each email is sent once
	 * (a short-lived marker prevents doubles if cron and a retry overlap).
	 */
	public static function run_batch( $jobs ) {
		$jobs = is_array( $jobs ) ? $jobs : array();
		if ( ! $jobs || ! class_exists( 'SEATT_Notifications' ) ) {
			return;
		}
		$n             = SEATT_Notifications::instance();
		self::$running = true;
		$failed        = array();
		foreach ( $jobs as $job ) {
			list( $type, $booking_id, $attempt ) = array_pad( (array) $job, 3, 0 );
			$marker = 'seatt_mailed_' . $type . '_' . (int) $booking_id;
			if ( ! $n || get_transient( $marker ) ) {
				continue;
			}
			set_transient( $marker, 1, DAY_IN_SECONDS );
			$ok = $n->dispatch( $type, (int) $booking_id );
			if ( false === $ok ) {
				delete_transient( $marker );
				if ( (int) $attempt < 1 ) {
					$failed[] = array( $type, (int) $booking_id, 1 );
				}
			}
		}
		self::$running = false;
		global $phpmailer;
		if ( is_object( $phpmailer ) && method_exists( $phpmailer, 'smtpClose' ) ) {
			$phpmailer->smtpClose();
		}
		// One retry a couple of minutes later for anything that failed.
		if ( $failed ) {
			wp_schedule_single_event( time() + 2 * MINUTE_IN_SECONDS, 'seatt_mail_batch', array( $failed ) );
		}
	}
}