<?php
/**
 * Manage cron events for pulling Parallax AI batch requests.
 *
 * @package AIContentByParallax
 */

namespace AIContentByParallax\Cron;

defined( 'ABSPATH' ) || exit;

use AIContentByParallax\Core\Logger;
use AIContentByParallax\Models\BatchRequest;

/**
 * Handles scheduling and running the batch request pull cron job.
 */
class PullBatchRequest {

	public const INTERVAL_KEY = 'ai_content_by_parallax_fifteen_minute';
	public const EVENT_HOOK   = 'ai_content_by_parallax_pull_all_batch_requests';
	public const INTERVAL_MIN = 15;

	/**
	 * IMPORTANT: Keep this as a literal integer so automated scanners
	 * can detect the interval value reliably.
	 *
	 * 15 minutes = 900 seconds.
	 */
	public const INTERVAL_SECONDS = 900;

	/**
	 * Offset by 60s so activation+first run don’t collide with other loads.
	 */
	public const SCHEDULE_OFFSET_SECONDS = 60;

	/**
	 * Register hooks for cron scheduling.
	 */
	public static function register(): void {
		add_filter( 'cron_schedules', array( self::class, 'add_interval' ) );
		add_action( self::EVENT_HOOK, array( self::class, 'run' ) );

		// Ensure scheduled (lightweight check) — safe across deploys.
		add_action( 'init', array( self::class, 'maybe_schedule' ) );
	}

	/**
	 * Add a custom cron schedule.
	 *
	 * @param array $schedules Existing cron schedules.
	 * @return array
	 */
	public static function add_interval( array $schedules ): array {
		if ( ! isset( $schedules[ self::INTERVAL_KEY ] ) ) {
			$schedules[ self::INTERVAL_KEY ] = array(
				'interval' => 900, // 15 minutes in seconds (literal for phpcs/scanners).
				'display'  => sprintf(
					/* translators: %d: number of minutes. */
					__( 'Every %d Minutes (AI Content by Parallax)', 'ai-content-by-parallax' ),
					self::INTERVAL_MIN
				),
			);
		}

		return $schedules;
	}

	/**
	 * Schedule the event if missing.
	 */
	public static function maybe_schedule(): void {
		if ( ! wp_next_scheduled( self::EVENT_HOOK ) ) {
			wp_schedule_event(
				time() + self::SCHEDULE_OFFSET_SECONDS,
				self::INTERVAL_KEY,
				self::EVENT_HOOK
			);
		}
	}

	/**
	 * Activation hook to ensure cron is scheduled.
	 */
	public static function activate(): void {
		self::maybe_schedule();
	}

	/**
	 * Deactivation hook to clear scheduled events and locks.
	 */
	public static function deactivate(): void {
		// Clear all future instances of this hook.
		$timestamp = wp_next_scheduled( self::EVENT_HOOK );
		while ( $timestamp ) {
			wp_unschedule_event( $timestamp, self::EVENT_HOOK );
			$timestamp = wp_next_scheduled( self::EVENT_HOOK );
		}

		// Drop lock if set.
		delete_transient( self::lock_key() );
	}

	/**
	 * Cron callback that pulls pending batch requests while avoiding overlaps.
	 */
	public static function run(): void {
		$lock_key = self::lock_key();

		// Prevent overlapping runs.
		if ( get_transient( $lock_key ) ) {
			Logger::write_log( 'info', '[CRON] pull_all skipped: lock present.' );
			return;
		}

		/*
		 * Lock TTL slightly under interval.
		 * Clamp to a safe range to avoid overly long locks.
		 */
		$ttl_seconds = (int) max( 60, min( self::INTERVAL_SECONDS - 30, 3600 ) );

		// Acquire lock ASAP to avoid race conditions.
		set_transient( $lock_key, 1, $ttl_seconds );

		try {
			if ( ! BatchRequest::has_incomplete_batch_requests() ) {
				Logger::write_log( 'info', '[CRON] No incomplete batch requests. Skipping pull_all.' );
				return;
			}

			Logger::write_log( 'info', '[CRON] Incomplete batch requests found. Running pull_all().' );
			BatchRequest::pull_all();
		} catch ( \Throwable $e ) {
			Logger::write_log( 'info', '[CRON] pull_all error: ' . $e->getMessage() );
		} finally {
			delete_transient( $lock_key );
		}
	}

	/**
	 * Get the lock transient key.
	 *
	 * @return string
	 */
	protected static function lock_key(): string {
		return 'ai_content_by_parallax_pull_all_lock';
	}
}