woocommerce-correios-envelope.php

<?php
/**
 * Plugin Name: WooCommerce Correios - Envelope
 * Plugin URI: http://claudiosmweb.com/
 * Description: Este plugin ajuda a usar uma taxa fixa para ser usada como preço de envelope
 * Author: claudiosanches
 * Author URI: http://claudiosmweb.com/
 * Version: 1.0
 * License: GPLv2 or later
 */

/**
 * Register envelope metabox.
 *
 * @return void
 */
function cs_correios_envelope_metabox() {
    add_meta_box(
        'envelope',
        'Correios',
        'cs_correios_envelope_metabox_content',
        'product',
        'side',
        'default'
    );
}

add_action( 'add_meta_boxes', 'cs_correios_envelope_metabox' );

/**
 * Envelope metabox content.
 *
 * @param  object $post Product data.
 *
 * @return string       Metabox HTML.
 */
function cs_correios_envelope_metabox_content( $post ) {
    // Use nonce for verification.
    wp_nonce_field( basename( __FILE__ ), 'cs_correios_is_envelope' );

    $html = '<label for="is_envelope">' . __( 'Produto entregue utilizando envelope:' ) . '</label> ';
    $html .= sprintf( '<input type="checkbox" id="is_envelope" name="is_envelope" value="1"%s />', checked( 1, get_post_meta( $post->ID, 'is_envelope', true ), false ) );

    echo $html;
}

/**
 * Save metabox data.
 *
 * @param  int $post_id Post ID.
 *
 * @return void
 */
function cs_correios_envelope_save_metabox( $post_id ) {
    // Verify nonce.
    if ( ! isset( $_POST['cs_correios_is_envelope'] ) || ! wp_verify_nonce( $_POST['cs_correios_is_envelope'], basename( __FILE__ ) ) ) {
        return $post_id;
    }

    // Verify if this is an auto save routine.
    if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
        return $post_id;
    }

    // Check permissions.
    if ( 'product' == $_POST['post_type'] ) {
        if ( ! current_user_can( 'edit_page', $post_id ) ) {
            return $post_id;
        }
    } elseif ( ! current_user_can( 'edit_post', $post_id ) ) {
        return $post_id;
    }

    if ( isset( $_POST['is_envelope'] ) ) {
        update_post_meta( $post_id, 'is_envelope', $_POST['is_envelope'] );
    } else {
        delete_post_meta( $post_id, 'is_envelope' );
    }
}

add_action( 'save_post', 'cs_correios_envelope_save_metabox' );

/**
 * Verifies that there products are not envelopes.
 *
 * @param  array  $available_methods Available shipping methods.
 *
 * @return array                     New rates.
 */
function cs_correios_checks_if_exist_envelope( $available_methods ) {
    global $woocommerce;

    if ( isset( $available_methods['flat_rate'] ) ) {
        foreach ( $woocommerce->cart->cart_contents as $item_id => $values ) {
            if ( ! get_post_meta( $values['product_id'], 'is_envelope', true ) ) {
                unset( $available_methods['flat_rate'] );

                break;
            }
        }
    }

    return $available_methods;
}

add_filter( 'woocommerce_available_shipping_methods', 'cs_correios_checks_if_exist_envelope' );