modified-customer-purchased-product.php

<?php
function olivier_customer_bought_product( $customer_email, $user_id, $product_id ) {
    global $wpdb;

    $transient_name = 'wc_cbp_' . md5( $customer_email . $user_id . WC_Cache_Helper::get_transient_version( 'orders' ) );

    if ( false === ( $result = get_transient( $transient_name ) ) ) {
        $customer_data = array( $user_id );

        if ( $user_id ) {
            $user = get_user_by( 'id', $user_id );

            if ( isset( $user->user_email ) ) {
                $customer_data[] = $user->user_email;
            }
        }

        if ( is_email( $customer_email ) ) {
            $customer_data[] = $customer_email;
        }

        $customer_data = array_map( 'esc_sql', array_filter( array_unique( $customer_data ) ) );

        if ( sizeof( $customer_data ) == 0 ) {
            return false;
        }

        $result = $wpdb->get_col( "
            SELECT im.meta_value FROM {$wpdb->posts} AS p
            INNER JOIN {$wpdb->postmeta} AS pm ON p.ID = pm.post_id
            INNER JOIN {$wpdb->prefix}woocommerce_order_items AS i ON p.ID = i.order_id
            INNER JOIN {$wpdb->prefix}woocommerce_order_itemmeta AS im ON i.order_item_id = im.order_item_id
            WHERE p.post_status IN ( 'wc-completed', 'wc-processing', 'mobile-access' )
            AND pm.meta_key IN ( '_billing_email', '_customer_user' )
            AND im.meta_key IN ( '_product_id', '_variation_id' )
            AND im.meta_value != 0
            AND pm.meta_value IN ( '" . implode( "','", $customer_data ) . "' )
        " );
        $result = array_map( 'absint', $result );

        set_transient( $transient_name, $result, DAY_IN_SECONDS * 30 );
    }
    return in_array( absint( $product_id ), $result );
}