<?php

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

class AIEO_Send_Time {

	const MIN_EVENTS = 3;   
	const MAX_SCAN   = 500; 

	
	public static function best_hour( $user_id, $email = '' ) {
		global $wpdb;
		$user_id = (int) $user_id;
		$email   = strtolower( trim( (string) $email ) );
		$disp    = $wpdb->prefix . 'aieo_push_dispatch';
		if ( (string) $wpdb->get_var( $wpdb->prepare( 'SHOW TABLES LIKE %s', $disp ) ) !== $disp ) {
			return null;
		}
		if ( $user_id > 0 ) {
			$where = 'user_id = %d';
			$val   = $user_id;
		} elseif ( '' !== $email ) {
			$where = 'recipient_email = %s';
			$val   = $email;
		} else {
			return null;
		}
		
		$limit = (int) self::MAX_SCAN;
		
		$sql = "(SELECT clicked_at AS ts FROM `{$disp}` WHERE {$where} AND clicked_at IS NOT NULL ORDER BY clicked_at DESC LIMIT {$limit})
		        UNION ALL
		        (SELECT opened_at AS ts FROM `{$disp}` WHERE {$where} AND opened_at IS NOT NULL ORDER BY opened_at DESC LIMIT {$limit})";
		$rows = $wpdb->get_col( $wpdb->prepare( $sql, $val, $val ) );
		if ( count( $rows ) < self::MIN_EVENTS ) {
			return null;
		}
		$hist = array_fill( 0, 24, 0 );
		foreach ( $rows as $ts ) {
			if ( empty( $ts ) ) {
				continue;
			}
			
			
			$local = get_date_from_gmt( (string) $ts ); 
			$h     = (int) substr( $local, 11, 2 );
			if ( $h >= 0 && $h <= 23 ) {
				$hist[ $h ]++;
			}
		}
		$best = 0;
		$max  = -1;
		foreach ( $hist as $h => $n ) {
			if ( $n > $max ) {
				$max  = $n;
				$best = $h;
			}
		}
		return ( $max >= 1 ) ? (int) $best : null;
	}

	
	public static function delay_to_hour( $best_hour ) {
		$best = max( 0, min( 23, (int) $best_hour ) );
		
		if ( $best === (int) wp_date( 'G' ) ) {
			return 0;
		}
		
		
		
		try {
			$tz  = wp_timezone();
			$now = new \DateTime( 'now', $tz );
			$tgt = clone $now;
			$tgt->setTime( $best, 0, 0 );
			if ( $tgt <= $now ) {
				$tgt->modify( '+1 day' );
			}
			return max( 0, $tgt->getTimestamp() - $now->getTimestamp() );
		} catch ( \Throwable $e ) {
			$now_h = (int) wp_date( 'G' );
			return ( $best === $now_h ) ? 0 : ( ( ( $best - $now_h + 24 ) % 24 ) * HOUR_IN_SECONDS );
		}
	}
}