Send a Slack Notification When a Post is Published

/**
 * Send a Slack notification when a post transitions to 'publish' for the first time.
 *
 * Add your Slack webhook URL to wp-config.php:
 *   define( 'WPFOLKS_SLACK_WEBHOOK', 'https://hooks.slack.com/services/XXX/YYY/ZZZ' );
 */

add_action( 'transition_post_status', 'wpfolks_notify_slack_on_publish', 10, 3 );
function wpfolks_notify_slack_on_publish( string $new_status, string $old_status, WP_Post $post ): void {

    // Only fire when transitioning TO publish FROM a non-publish status
    // Prevents firing on every edit of an already-published post
    if ( $new_status !== 'publish' || $old_status === 'publish' ) return;

    // Only notify for standard posts — adjust post types as needed
    if ( ! in_array( $post->post_type, [ 'post', 'project' ], true ) ) return;

    // Skip revisions and autosaves
    if ( wp_is_post_revision( $post->ID ) || wp_is_post_autosave( $post->ID ) ) return;

    if ( ! defined( 'WPFOLKS_SLACK_WEBHOOK' ) || empty( WPFOLKS_SLACK_WEBHOOK ) ) return;

    $author   = get_the_author_meta( 'display_name', $post->post_author );
    $url      = get_permalink( $post->ID );
    $type     = ucfirst( $post->post_type );

    $payload = [
        'text' => sprintf(
            '📝 *New %s Published*: <%s|%s> by %s',
            esc_html( $type ),
            esc_url( $url ),
            esc_html( $post->post_title ),
            esc_html( $author )
        ),
    ];

    wp_remote_post( WPFOLKS_SLACK_WEBHOOK, [
        'headers'   => [ 'Content-Type' => 'application/json' ],
        'body'      => wp_json_encode( $payload ),
        'blocking'  => false, // Non-blocking — doesn't slow down the publish action
        'sslverify' => true,
    ] );
}