PostPasswords.php

<?php
/**
 * Optionally disable post password protection
 *
 * @package  10up-experience
 */

namespace TenUpExperience\PostPasswords;

use TenUpExperience\Singleton;

/**
 * Post passwords class
 */
class PostPasswords {

	use Singleton;

	/**
	 * Setup module
	 *
	 * @since 1.7
	 */
	public function setup() {
		add_action( 'admin_init', [ $this, 'password_protection_setting' ] );
		add_action( 'admin_print_footer_scripts', [ $this, 'print_admin_css' ] );
	}

	/**
	 * Register setting.
	 */
	public function password_protection_setting() {

		$settings_args = array(
			'type'              => 'integer',
			'sanitize_callback' => 'intval',
		);

		register_setting( 'writing', 'tenup_password_protect', $settings_args );

		add_settings_field(
			'tenup_password_protect',
			esc_html__( 'Enable Password Protected Content', 'tenup' ),
			[ $this, 'settings_ui' ],
			'writing',
			'default',
			array(
				'label_for' => 'password-protect',
			)
		);
	}

	/**
	 * Display UI the setting.
	 *
	 * @return void
	 */
	public function settings_ui() {
		$password_protect = get_option( 'tenup_password_protect', 0 );

		?>
		<fieldset>
			<legend class="screen-reader-text"><?php esc_html_e( 'Password Protected Content', 'tenup' ); ?></legend>
			<p>
				<input id="password-protect" name="tenup_password_protect" type="checkbox" value="1" <?php checked( $password_protect, 1 ); ?> />
			</p>
			<p class="description"><?php esc_html_e( 'Enables password protected content. WordPress default password protected post functionality is insecure and does not work with page caching.', 'tenup' ); ?></p>
		</fieldset>
		<?php
	}

	/**
	 * Disable password protect optionally
	 */
	public function print_admin_css() {
		global $pagenow, $post;

		if ( empty( $pagenow ) || ( 'post.php' !== $pagenow && 'post-new.php' !== $pagenow ) ) {
			return;
		}

		$password_protect = (bool) get_option( 'tenup_password_protect', 0 );

		if ( ! empty( $password_protect ) || ! empty( $post->post_password ) ) {
			return;
		}

		?>
		<style type="text/css">
		#visibility-radio-password,
		label[for="visibility-radio-password"] {
			display: none;
		}

		#editor-post-password-0,
		label[for="editor-post-password-0"],
		#editor-post-password-0-description,
		#editor-post-password-1,
		label[for="editor-post-password-1"],
		#editor-post-password-1-description {
			display: none;
		}
		</style>
		<?php
	}
}