gpb-blocklist-modifier.php: Added new snippet.

Author: spivurno

gp-blocklist/gpb-blocklist-modifier.php

@@ -0,0 +1,68 @@
+<?php
+/**
+ * Gravity Forms // Gravity Perks // Add to Block List Modifier
+ * https://gravitywiz.com/documentation/gravity-forms-blocklist/
+ *
+ * This snippet introduces a `:blocklist` merge tag modifier for Gravity Forms.
+ * When applied to any field merge tag, it generates a secure URL that allows 
+ * users to easily add that field's value to WordPress's comment 
+ * disallowed list (formerly the "comment blacklist").
+ *
+ * Tip: This can be used to allow users to prevent their email from being submitted
+ * on any GPB-enabled Gravity Form.
+ *
+ * Usage:
+ *
+ * 1. Use the merge tag with the `:blocklist` modifier in your Gravity Forms notifications 
+ *    or confirmations. For example:
+ *    
+ *    `{Email:1:blocklist}`
+ *    
+ *    This will output a secure URL that, when visited, adds the email address to the 
+ *    WordPress blocklist.
+ *
+ * 2. Users clicking the generated link will automatically append the field's value to the 
+ *    WordPress disallowed comment list.
+ *
+ * Instructions:
+ *
+ * 1. Install the snippet.
+ *    https://gravitywiz.com/documentation/managing-snippets/#where-do-i-put-snippets
+ *
+ * 2. Use the `:blocklist` modifier on any field merge tag.
+ */
+add_filter( 'gform_merge_tag_filter', function ( $value, $merge_tag, $modifier, $field, $raw_value, $format ) {
+	if ( $modifier !== 'blocklist' || empty( $raw_value ) || ! is_email( $raw_value ) ) {
+		return $value;
+	}
+
+	$blocklist_url = add_query_arg([
+		'value'   => $raw_value,
+		'hash'    => wp_hash( $raw_value ),
+	], site_url( '/?gf_blocklist=1' ));
+
+	return esc_url( $blocklist_url );
+}, 10, 6 );
+
+add_action( 'init', function () {
+	if ( empty( $_GET['gf_blocklist'] ) || $_GET['gf_blocklist'] !== '1' ) {
+		return;
+	}
+
+	$value = rgget( 'value' );
+	$hash  = rgget( 'hash' );
+	if ( empty( $value ) || $hash !== wp_hash( $value ) ) {
+		wp_die( 'Invalid value.' );
+	}
+
+	// Retrieve the current comment blocklist
+	$blocklist = get_option( 'disallowed_keys', '' );
+
+	// Append the new email if it's not already in the list
+	if ( stripos( $blocklist, $value ) === false ) {
+		$blocklist .= PHP_EOL . $value;
+		update_option( 'disallowed_keys', trim( $blocklist ) );
+	}
+
+	wp_die( sprintf( '"%s" has been added to the blocklist.', $value ), 'Blocklist', ['response' => 200] );
+});