Registers default settings available in WordPress.

The settings registered here are primarily useful for the REST API, so this
does not encompass all settings available in WordPress.

function register_initial_settings() {
	register_setting(
		'general',
		'blogname',
		array(
			'show_in_rest' => array(
				'name' => 'title',
			),
			'type'         => 'string',
			'description'  => __( 'Site title.' ),
		)
	);

	register_setting(
		'general',
		'blogdescription',
		array(
			'show_in_rest' => array(
				'name' => 'description',
			),
			'type'         => 'string',
			'description'  => __( 'Site tagline.' ),
		)
	);

	if ( ! is_multisite() ) {
		register_setting(
			'general',
			'siteurl',
			array(
				'show_in_rest' => array(
					'name'   => 'url',
					'schema' => array(
						'format' => 'uri',
					),
				),
				'type'         => 'string',
				'description'  => __( 'Site URL.' ),
			)
		);
	}

	if ( ! is_multisite() ) {
		register_setting(
			'general',
			'admin_email',
			array(
				'show_in_rest' => array(
					'name'   => 'email',
					'schema' => array(
						'format' => 'email',
					),
				),
				'type'         => 'string',
				'description'  => __( 'This address is used for admin purposes, like new user notification.' ),
			)
		);
	}

	register_setting(
		'general',
		'timezone_string',
		array(
			'show_in_rest' => array(
				'name' => 'timezone',
			),
			'type'         => 'string',
			'description'  => __( 'A city in the same timezone as you.' ),
		)
	);

	register_setting(
		'general',
		'date_format',
		array(
			'show_in_rest' => true,
			'type'         => 'string',
			'description'  => __( 'A date format for all date strings.' ),
		)
	);

	register_setting(
		'general',
		'time_format',
		array(
			'show_in_rest' => true,
			'type'         => 'string',
			'description'  => __( 'A time format for all time strings.' ),
		)
	);

	register_setting(
		'general',
		'start_of_week',
		array(
			'show_in_rest' => true,
			'type'         => 'integer',
			'description'  => __( 'A day number of the week that the week should start on.' ),
		)
	);

	register_setting(
		'general',
		'WPLANG',
		array(
			'show_in_rest' => array(
				'name' => 'language',
			),
			'type'         => 'string',
			'description'  => __( 'WordPress locale code.' ),
			'default'      => 'en_US',
		)
	);

	register_setting(
		'writing',
		'use_smilies',
		array(
			'show_in_rest' => true,
			'type'         => 'boolean',
			'description'  => __( 'Convert emoticons like :-) and :-P to graphics on display.' ),
			'default'      => true,
		)
	);

	register_setting(
		'writing',
		'default_category',
		array(
			'show_in_rest' => true,
			'type'         => 'integer',
			'description'  => __( 'Default post category.' ),
		)
	);

	register_setting(
		'writing',
		'default_post_format',
		array(
			'show_in_rest' => true,
			'type'         => 'string',
			'description'  => __( 'Default post format.' ),
		)
	);

	register_setting(
		'reading',
		'posts_per_page',
		array(
			'show_in_rest' => true,
			'type'         => 'integer',
			'description'  => __( 'Blog pages show at most.' ),
			'default'      => 10,
		)
	);

	register_setting(
		'reading',
		'show_on_front',
		array(
			'show_in_rest' => true,
			'type'         => 'string',
			'description'  => __( 'What to show on the front page' ),
		)
	);

	register_setting(
		'reading',
		'page_on_front',
		array(
			'show_in_rest' => true,
			'type'         => 'integer',
			'description'  => __( 'The ID of the page that should be displayed on the front page' ),
		)
	);

	register_setting(
		'reading',
		'page_for_posts',
		array(
			'show_in_rest' => true,
			'type'         => 'integer',
			'description'  => __( 'The ID of the page that should display the latest posts' ),
		)
	);

	register_setting(
		'discussion',
		'default_ping_status',
		array(
			'show_in_rest' => array(
				'schema' => array(
					'enum' => array( 'open', 'closed' ),
				),
			),
			'type'         => 'string',
			'description'  => __( 'Allow link notifications from other blogs (pingbacks and trackbacks) on new articles.' ),
		)
	);

	register_setting(
		'discussion',
		'default_comment_status',
		array(
			'show_in_rest' => array(
				'schema' => array(
					'enum' => array( 'open', 'closed' ),
				),
			),
			'type'         => 'string',
			'description'  => __( 'Allow people to submit comments on new posts.' ),
		)
	);
}