Applies a tag after a user has visited a post or page more than X times

wpf-apply-tags-based-on-visit.php

<?php
/**
 * Track visits to a specific post or page and apply a tag with WP Fusion if the visit count exceeds 5.
 */

function wpf_track_post_visits() {

	// Replace with the IDs of the posts or pages you want to track
	$target_post_ids = array( 123, 456 );

	// Replace with the WP Fusion tag name you want to apply
	$wp_fusion_tag = 'Example Tag Name';

	// Replace with how many visits should apply the tag
	$target_visit_count = 5;

	//
	// Don't edit after here:
	//

	$wp_fusion_tag = wpf_get_tag_id( $wp_fusion_tag );

	// Ensure user is logged in
	if ( ! is_user_logged_in() ) {
		return;
	}

	// Ensure we're on either a post or page
	if ( ! is_singular( 'post' ) && ! is_singular( 'page' ) ) {
		return;
	}

	// Ensure we're on the right post or page ID
	if ( ! in_array( get_the_ID(), $target_post_ids ) ) {
		return;
	}

	$user_id     = get_current_user_id();
	$meta_key    = 'post_visit_count_' . get_the_ID();
	$visit_count = (int) get_user_meta( $user_id, $meta_key, true );

	// Increment visit count
	++$visit_count;
	update_user_meta( $user_id, $meta_key, $visit_count );

	// Apply WP Fusion tag if visit count exceeds 5 and tag hasn't been applied yet
	if ( $visit_count > $target_visit_count ) {
		wp_fusion()->user->apply_tags( array( $wp_fusion_tag ), $user_id );
	}
}

add_action( 'wp', 'wpf_track_post_visits' );