$final[ $key ] = $b[ $key ];
				}
			}
		}

		// Finally, we need to merge any keys that exist only in $b.
		foreach ( $b as $key => $value ) {
			if ( ! isset( $final[ $key ] ) ) {
				$final[ $key ] = $value;
			}
		}
	}

	return $final;
}

/**
 * Implode and escape HTML attributes for output.
 *
 * @since 3.3.0
 * @param array $raw_attributes Attribute name value pairs.
 * @return string
 */
function wc_implode_html_attributes( $raw_attributes ) {
	$attributes = array();
	foreach ( $raw_attributes as $name => $value ) {
		$attributes[] = esc_attr( $name ) . '="' . esc_attr( $value ) . '"';
	}
	return implode( ' ', $attributes );
}

/**
 * Escape JSON for use on HTML or attribute text nodes.
 *
 * @since 3.5.5
 * @param string $json JSON to escape.
 * @param bool   $html True if escaping for HTML text node, false for attributes. Determines how quotes are handled.
 * @return string Escaped JSON.
 */
function wc_esc_json( $json, $html = false ) {
	return _wp_specialchars(
		$json,
		$html ? ENT_NOQUOTES : ENT_QUOTES, // Escape quotes in attribute nodes only.
		'UTF-8',                           // json_encode() outputs UTF-8 (really just ASCII), not the blog's charset.
		true                               // Double escape entities: `&` -> `&`.
	);
}

/**
 * Parse a relative date option from the settings API into a standard format.
 *
 * @since 3.4.0
 * @param mixed $raw_value Value stored in DB.
 * @return array Nicely formatted array with number and unit values.
 */
function wc_parse_relative_date_option( $raw_value ) {
	$periods = array(
		'days'   => __( 'Day(s)', 'woocommerce' ),
		'weeks'  => __( 'Week(s)', 'woocommerce' ),
		'months' => __( 'Month(s)', 'woocommerce' ),
		'years'  => __( 'Year(s)', 'woocommerce' ),
	);

	$value = wp_parse_args(
		(array) $raw_value,
		array(
			'number' => '',
			'unit'   => 'days',
		)
	);

	$value['number'] = ! empty( $value['number'] ) ? absint( $value['number'] ) : '';

	if ( ! in_array( $value['unit'], array_keys( $periods ), true ) ) {
		$value['unit'] = 'days';
	}

	return $value;
}

/**
 * Format the endpoint slug, strip out anything not allowed in a url.
 *
 * @since 3.5.0
 * @param string $raw_value The raw value.
 * @return string
 */
function wc_sanitize_endpoint_slug( $raw_value ) {
	return sanitize_title( $raw_value ?? '' );
}

/**
 * Removes useless non-displayable and problematic Unicode characters from a string.
 *
 * This function eliminates characters that can cause formatting issues, invisible text,
 * or unexpected behavior in copy-pasted text. Specifically, it removes:
 *
 * - **Soft hyphen (`U+00AD`)** – Invisible unless text is broken across lines.
 * - **Zero-width spaces & joiners (`U+200B–U+200D`)** – Invisible and can cause copy/paste issues.
 * - **Directional markers (`U+200E–U+200F`, `U+202A–U+202E`)** – Can affect text rendering.
 * - **Byte Order Mark (BOM) (`U+FEFF`)** – Can interfere with encoding.
 * - **Interlinear annotation characters (`U+FFF9–U+FFFB`)** – Rarely used and unnecessary in checkout fields.
 *
 * It does **not** remove:
 *
 * - **Non-breaking space (`U+00A0`)** – Useful for preventing line breaks in addresses.
 * - **Word joiner (`U+2060`)** – Sometimes needed for proper text rendering in certain scripts.
 *
 * @param string $raw_value The input string to sanitize.
 *
 * @return string The sanitized string without problematic characters.
 * @since 9.9.0
 */
function wc_remove_non_displayable_chars( string $raw_value ): string {
	$remove_chars = array(
		"\u{00AD}", // Soft Hyphen.
		"\u{200B}", // Zero Width Space.
		"\u{200C}", // Zero Width Non-Joiner.
		"\u{200D}", // Zero Width Joiner.
		"\u{200E}", // Left-to-Right Mark.
		"\u{200F}", // Right-to-Left Mark.
		"\u{202A}", // Left-to-Right Embedding.
		"\u{202B}", // Right-to-Left Embedding.
		"\u{202C}", // Pop Directional Formatting.
		"\u{202D}", // Left-to-Right Override.
		"\u{202E}", // Right-to-Left Override.
		"\u{FEFF}", // Byte Order Mark (BOM).
		"\u{FFF9}", // Interlinear Annotation Anchor.
		"\u{FFFA}", // Interlinear Annotation Separator.
		"\u{FFFB}", // Interlinear Annotation Terminator.
	);

	return str_replace( $remove_chars, '', $raw_value );
}

add_filter( 'woocommerce_admin_settings_sanitize_option_woocommerce_checkout_pay_endpoint', 'wc_sanitize_endpoint_slug', 10, 1 );
add_filter( 'woocommerce_admin_settings_sanitize_option_woocommerce_checkout_order_received_endpoint', 'wc_sanitize_endpoint_slug', 10, 1 );
add_filter( 'woocommerce_admin_settings_sanitize_option_woocommerce_myaccount_add_payment_method_endpoint', 'wc_sanitize_endpoint_slug', 10, 1 );
add_filter( 'woocommerce_admin_settings_sanitize_option_woocommerce_myaccount_delete_payment_method_endpoint', 'wc_sanitize_endpoint_slug', 10, 1 );
add_filter( 'woocommerce_admin_settings_sanitize_option_woocommerce_myaccount_set_default_payment_method_endpoint', 'wc_sanitize_endpoint_slug', 10, 1 );
add_filter( 'woocommerce_admin_settings_sanitize_option_woocommerce_myaccount_orders_endpoint', 'wc_sanitize_endpoint_slug', 10, 1 );
add_filter( 'woocommerce_admin_settings_sanitize_option_woocommerce_myaccount_view_order_endpoint', 'wc_sanitize_endpoint_slug', 10, 1 );
add_filter( 'woocommerce_admin_settings_sanitize_option_woocommerce_myaccount_downloads_endpoint', 'wc_sanitize_endpoint_slug', 10, 1 );
add_filter( 'woocommerce_admin_settings_sanitize_option_woocommerce_myaccount_edit_account_endpoint', 'wc_sanitize_endpoint_slug', 10, 1 );
add_filter( 'woocommerce_admin_settings_sanitize_option_woocommerce_myaccount_edit_address_endpoint', 'wc_sanitize_endpoint_slug', 10, 1 );
add_filter( 'woocommerce_admin_settings_sanitize_option_woocommerce_myaccount_payment_methods_endpoint', 'wc_sanitize_endpoint_slug', 10, 1 );
add_filter( 'woocommerce_admin_settings_sanitize_option_woocommerce_myaccount_lost_password_endpoint', 'wc_sanitize_endpoint_slug', 10, 1 );
add_filter( 'woocommerce_admin_settings_sanitize_option_woocommerce_logout_endpoint', 'wc_sanitize_endpoint_slug', 10, 1 );