force-admin-color-scheme.php

<?php
/**
 * Plugin Name: Force Admin Color Scheme
 * Version:     2.0.3
 * Plugin URI:  https://coffee2code.com/wp-plugins/force-admin-color-scheme/
 * Author:      Scott Reilly
 * Author URI:  https://coffee2code.com/
 * Text Domain: force-admin-color-scheme
 * License:     GPLv2 or later
 * License URI: https://www.gnu.org/licenses/gpl-2.0.html
 * Description: Force a single admin color scheme for all users of the site.
 *
 * Compatible with WordPress 4.1 through 5.8+.
 *
 * =>> Read the accompanying readme.txt file for instructions and documentation.
 * =>> Also, visit the plugin's homepage for additional information and updates.
 * =>> Or visit: https://wordpress.org/plugins/force-admin-color-scheme/
 *
 * @package Force_Admin_Color_Scheme
 * @author  Scott Reilly
 * @version 2.0.3
 */

/*
	Copyright (c) 2014-2021 by Scott Reilly (aka coffee2code)

	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/

defined( 'ABSPATH' ) or die();

if ( ! class_exists( 'c2c_ForceAdminColorScheme' ) ) :

class c2c_ForceAdminColorScheme {

	/**
	 * Name of plugin's setting.
	 *
	 * @access private
	 * @var string
	 */
	private static $setting = 'c2c_forced_admin_color';

	/**
	 * Returns version of the plugin.
	 *
	 * @since 1.0
	 */
	public static function version() {
		return '2.0.3';
	}

	/**
	 * Hooks actions and filters.
	 *
	 * @since 1.0
	 */
	public static function init() {
		if ( ! is_admin() ) {
			return;
		}

		register_activation_hook( __FILE__, array( __CLASS__, 'activation' ) );

		add_action( 'admin_init', array( __CLASS__, 'do_init' ) );
	}

	/**
	 * Handles activation tasks, such as registering the uninstall hook.
	 *
	 * @since 1.1
	 */
	public static function activation() {
		register_uninstall_hook( __FILE__, array( __CLASS__, 'uninstall' ) );
	}

	/**
	 * Handles uninstallation tasks, such as deleting plugin options.
	 *
	 * @since 1.1
	 */
	public static function uninstall() {
		delete_option( self::get_setting_name() );
	}

	/**
	 * Performs initializations on the 'init' action.
	 *
	 * @since 1.0
	 */
	public static function do_init() {
		// Load textdomain.
		load_plugin_textdomain( 'force-admin-color-scheme' );

		/*
		 * Register hooks
		 */

		// Override the user's admin color scheme.
		add_filter( 'get_user_option_admin_color', array( __CLASS__, 'force_color_scheme'          ) );

		// Add checked for setting the forced admin color scheme.
		add_action( 'admin_color_scheme_picker',   array( __CLASS__, 'add_checkbox'                ), 20 );

		// Save the checkbox value for forcing admin color scheme.
		add_action( 'personal_options_update',     array( __CLASS__, 'save_setting'                ) );

		// Hide the Admin Color Scheme field from users who can't set a forced color scheme.
		add_action( 'admin_color_scheme_picker',   array( __CLASS__, 'hide_admin_color_scheme_picker' ), 8 );

		// Output CSS.
		add_action( 'load-profile.php',            array( __CLASS__, 'register_css'                ) );

		/*
		 * Note: not bothering with preventing users from being able to save a value for admin_color
		 * since it's not really a big deal if they do.
		 */
	}

	/**
	 * Returns the name of the setting that stores the forced admin color scheme.
	 *
	 * @since 1.1
	 *
	 * @return string
	 */
	public static function get_setting_name() {
		return self::$setting;
	}

	/**
	 * Determines if the constant is being used to set a forced admin color
	 * scheme
	 *
	 * @since 2.0
	 *
	 * @return bool True if the constant is being used, else false.
	 */
	public static function is_constant_set() {
		return defined( 'C2C_FORCE_ADMIN_COLOR_SCHEME' ) && ! empty( C2C_FORCE_ADMIN_COLOR_SCHEME );
	}

	/**
	 * Returns the forced admin color scheme.
	 *
	 * Forced admin color scheme is determined in this order:
	 * - The value of the constant `C2C_FORCE_ADMIN_COLOR_SCHEME`, if set and valid.
	 * - The return value of the filter `c2c_force_admin_color_scheme`, if set and valid.
	 * - The configured value previously saved by the plugin, if still valid.
	 * - An empty string to indicate no admin color scheme is being forced.
	 *
	 * The admin color scheme is checked for validity. If the color scheme is
	 * not valid (e.g. it does not currently exist), then the color scheme is
	 * not returned.
	 *
	 * @since 1.1
	 * @since 2.0 Added support for constant and filter. Renamed from `get_forced_color_scheme()`.
	 *
	 * @return string The admin color scheme or empty string if color scheme was
	 *                not set or is currently invalid.
	 */
	public static function get_forced_color_scheme() {
		// Constant takes precedence.
		$color_scheme = self::get_color_scheme_via_constant();
		if ( ! self::is_valid_color_scheme( $color_scheme ) ) {
			$color_scheme = '';
		}

		// If constant not defined or invalid, then filter current valie.
		if ( ! $color_scheme ) {
			$color_scheme = self::get_filtered_color_scheme();
			if ( ! self::is_valid_color_scheme( $color_scheme ) ) {
				$color_scheme = '';
			}
		}

		// If filtered value is not defined or invalid, then use current valie.
		if ( ! $color_scheme ) {
			$color_scheme = get_option( self::get_setting_name() );
			if ( ! self::is_valid_color_scheme( $color_scheme ) ) {
				$color_scheme = '';
			}
		}

		return $color_scheme;
	}

	/**
	 * Sets the forced admin color scheme.
	 *
	 * NOTE: Does not perform any capability checks.
	 * NOTE: Does not prevent setting admin color when constant is in use.
	 *
	 * @since 1.1
	 * @since 2.0 Renamed from `set_forced_color_scheme()`.
	 *
	 * @param  string $color_scheme The color scheme name.
	 * @return string The admin color scheme or empty string if color scheme was
	 *                invalid and thus not saved.
	 */
	public static function set_forced_color_scheme( $color_scheme ) {
		$color_scheme = strtolower( $color_scheme );

		if ( ! $color_scheme ) {
			delete_option( self::get_setting_name() );
		} elseif ( ! self::is_valid_color_scheme( $color_scheme ) ) {
			$color_scheme = '';
		} else {
			update_option( self::get_setting_name(), $color_scheme );
		}

		return $color_scheme;
	}

	/**
	 * Returns the filtered admin color scheme.
	 *
	 * Note: Does not validate whether the returned filter value corresponds to
	 * an actual admin color scheme.
	 *
	 * @since 2.0
	 *
	 * @return string The filtered admin color scheme. A blank string indicates
	 *                that no filtering took place. The color scheme is not
	 *                verified as being a legitimate admin color scheme.
	 */
	public static function get_filtered_color_scheme() {
		/**
		 * Filters the forced admin color scheme.
		 *
		 * If an empty string is returned, then it's as if the filter had
		 * not been hooked.
		 *
		 * @since 2.0
		 *
		 * @param string $new_color_scheme Empty string.
		 * @param string $cur_color_scheme The currently configured forced admin color scheme.
		 */
		$filtered_color_scheme = apply_filters( 'c2c_force_admin_color_scheme', '', get_option( self::get_setting_name(), '' ) );

		return is_string( $filtered_color_scheme ) ? strtolower( $filtered_color_scheme ) : '';
	}

	/**
	 * Returns the admin color scheme as set via constant.
	 *
	 * Note: Does not validate whether the value corresponds to a legitimate
	 * admin color scheme.
	 *
	 * @since 2.0
	 *
	 * @return string The admin color scheme. A blank string indicates
	 *                that no color scheme was defined. The color scheme is not
	 *                verified as being a legitimate admin color scheme.
	 */
	public static function get_color_scheme_via_constant() {
		$color_scheme = self::is_constant_set() ? C2C_FORCE_ADMIN_COLOR_SCHEME : '';

		return is_string( $color_scheme ) ? strtolower( $color_scheme ) : '';
	}

	/**
	 * Determines if the given admin color scheme exists.
	 *
	 * Note: This only returns a valid determination in the admin area and only
	 * when not running a '-src' version of WordPress.
	 *
	 * @since 2.0
	 *
	 * @return bool True if the color scheme exists, false otherwise.
	 */
	public static function is_valid_color_scheme( $color_scheme ) {
		global $_wp_admin_css_colors;

		return isset( $_wp_admin_css_colors[ $color_scheme ] );
	}

	/**
	 * Overrides the user's admin color scheme with the forced admin color
	 * scheme, if set.
	 *
	 * The admin color scheme is checked for validity. If the color scheme does
	 * not currently exist, then the color scheme is not overridden.
	 *
	 * @since 1.0
	 * @since 2.0 Rename from `force_admin_color()`.
	 *
	 * @param  string $admin_color_scheme The admin color scheme.
	 * @return string
	 */
	public static function force_color_scheme( $admin_color_scheme ) {
		// If a forced admin color has been configured and it is valid, use it.
		if ( $forced = self::get_forced_color_scheme() ) {
			$admin_color_scheme = $forced;
		}

		return $admin_color_scheme;
	}

	/**
	 * Outputs the checkbox for forcing the admin color scheme.
	 *
	 * @since 1.0
	 */
	public static function add_checkbox() {
		if ( ! current_user_can( 'manage_options' ) ) {
			return;
		}

		$forced_admin_color = self::get_forced_color_scheme();
		$constant_color_scheme = self::get_color_scheme_via_constant();
		$filtered_color_scheme = self::get_filtered_color_scheme();

		$setting = self::get_setting_name();

		// Output a message to admin user indicating the constant is being used.
		if ( $constant_color_scheme && $forced_admin_color === $constant_color_scheme ) {
			printf(
				'<em class="%s notice notice-info">%s</em>',
				esc_attr( $setting ),
				sprintf(
					/* translators: 1: name of constant, 2: name of forced admin color scheme. */
					__( 'Currently forced admin color scheme (via the constant %1$s, and thus cannot be changed above): %2$s', 'force-admin-color-scheme' ),
					'<strong><code>C2C_FORCE_ADMIN_COLOR_SCHEME</code></strong>',
					'<strong>' . ucfirst( $forced_admin_color ) . '</strong>'
				)
			);

			return;
		}

		// Output a message to admin user indicating the filter is being used.
		if ( $filtered_color_scheme && $forced_admin_color === $filtered_color_scheme ) {
			printf(
				'<em class="%s notice notice-info">%s</em>',
				esc_attr( $setting ),
				sprintf(
					/* translators: 1: name of filter, 2: name of forced admin color scheme. */
					__( 'Currently forced admin color scheme (via the filter %1$s, and thus cannot be changed above): %2$s', 'force-admin-color-scheme' ),
					'<strong><code>c2c_force_admin_color_scheme</code></strong>',
					'<strong>' . ucfirst( $forced_admin_color ) . '</strong>'
				)
			);

			return;
		}

		printf(
			'<label for="%s"><input name="%s" type="checkbox" id="%s" value="true"%s /> %s</label>',
			esc_attr( $setting ),
			esc_attr( $setting ),
			esc_attr( $setting ),
			checked( ! empty( $forced_admin_color ), true, false ),
			__( 'Force this admin color scheme on all users?', 'force-admin-color-scheme' )
		);

		// Output notice about currently forced admin color scheme.
		if ( $forced_admin_color ) {
			printf(
				'<em class="%s notice notice-info">%s</em>',
				esc_attr( $setting ),
				sprintf(
					__( 'Currently forced admin color scheme: %s', 'force-admin-color-scheme' ),
					'<strong>' . ucfirst( $forced_admin_color ) . '</strong>'
				)
			);
		}

		// Output notice if constant was defined but with an invalid admin color scheme.
		if ( $constant_color_scheme && $forced_admin_color !== $constant_color_scheme ) {
			printf(
				'<em class="%s notice notice-warning">%s</em>',
				esc_attr( $setting ),
				sprintf(
					/* translators: 1: name of constant, 2: name of forced admin color scheme. */
					__( '<strong>Notice:</strong> The constant %1$s is defined with an invalid color scheme (%2$s) and is being ignored.', 'force-admin-color-scheme' ),
					'<strong><code>C2C_FORCE_ADMIN_COLOR_SCHEME</code></strong>',
					'<strong>' . esc_html( $constant_color_scheme ) . '</strong>'
				)
			);
		}

		// Output notice if filter was hooked but returns an invalid admin color scheme.
		if ( $forced_admin_color && $filtered_color_scheme && ( $forced_admin_color !== $filtered_color_scheme ) ) {
			printf(
				'<em class="%s notice notice-warning">%s</em>',
				esc_attr( $setting ),
				sprintf(
					/* translators: 1: name of filter, 2: name of forced admin color scheme. */
					__( '<strong>Notice:</strong> The filter %1$s is hooked and returns an invalid color scheme (%2$s) and is being ignored.', 'force-admin-color-scheme' ),
					'<strong><code>c2c_force_admin_color_scheme</code></strong>',
					'<strong>' . esc_html( $filtered_color_scheme ) . '</strong>'
				)
			);
		}
	}

	/**
	 * Saves the admin user's admin color scheme as the forced admin color
	 * scheme if the checkbox is checked.
	 *
	 * Note: Does not save value if the constant is in use.
	 *
	 * @since 1.0
	 *
	 * @param  $user_id The user ID.
	 */
	public static function save_setting( $user_id ) {
		if ( current_user_can( 'manage_options' ) && ! self::is_constant_set() ) {
			// Unset the forced admin color if the checkbox is unchecked or no color was
			// specified.
			$new_color = empty( $_POST[ self::get_setting_name() ] ) || empty( $_POST['admin_color'] )
				? ''
				: $_POST['admin_color'];
			self::set_forced_color_scheme( $new_color );
		}
	}

	/**
	 * Hides the Admin Color Scheme input and label when appropriate.
	 *
	 * The input is hidden for users who do not have the capability to set the
	 * forced admin color scheme *and* when an admin color scheme hasn't been
	 * forced yet (so that users can still choose until a forced admin color
	 * scheme is chosen).
	 *
	 * @since 1.1
	 * @since 2.0 Renamed from `hide_admin_color_input()`.
	 */
	public static function hide_admin_color_scheme_picker() {
		if ( ! current_user_can( 'manage_options' ) && self::get_forced_color_scheme() ) {
			remove_action( 'admin_color_scheme_picker', 'admin_color_scheme_picker' );
		}
	}

	/**
	 * Registers hook for outputting CSS on the profile page.
	 *
	 * @since 1.0
	 */
	public static function register_css() {
		add_action( 'admin_head', array( __CLASS__, 'output_css' ) );
	}

	/**
	 * Outputs the CSS for hiding the label associated with the admin color picker.
	 *
	 * @since 1.0
	 */
	public static function output_css() {
		$css = '';

		// Admins need CSS to align checkbox with admin color picker.
		if ( current_user_can( 'manage_options' ) ) {
			$class = esc_attr( self::get_setting_name() );
			$css = "label[for=\"{$class}\"], .{$class} { display: block; padding-left: 15px; margin-top: 10px; }";
		}
		// Non-admins need CSS to hide admin color label if a color is being forced.
		elseif ( self::get_forced_color_scheme() ) {
			$css = '.user-admin-color-wrap { display: none; }';
		}

		if ( $css ) {
			$css .= "\n.wrap .c2c_forced_admin_color.notice { line-height: 2em; margin-left: 15px; margin-top: 15px; margin-bottom: 0; }";

			echo "<style>{$css}</style>\n";
		}
	}

} // end c2c_ForceAdminColorScheme

add_action( 'plugins_loaded', array( 'c2c_ForceAdminColorScheme', 'init' ) );

endif; // end if !class_exists()