` values, and assigning values to CSS variables.
 *              Added support for `object-fit`, `gap`, `column-gap`, `row-gap`, and `flex-wrap`.
 *              Extended `margin-*` and `padding-*` support for logical properties.
 * @since 6.2.0 Added support for `aspect-ratio`, `position`, `top`, `right`, `bottom`, `left`,
 *              and `z-index` CSS properties.
 * @since 6.3.0 Extended support for `filter` to accept a URL and added support for repeat().
 *              Added support for `box-shadow`.
 * @since 6.4.0 Added support for `writing-mode`.
 * @since 6.5.0 Added support for `background-repeat`.
 *
 * @param string $css        A string of CSS rules.
 * @param string $deprecated Not used.
 * @return string Filtered string of CSS rules.
 */
function safecss_filter_attr( $css, $deprecated = '' ) {
	if ( ! empty( $deprecated ) ) {
		_deprecated_argument( __FUNCTION__, '2.8.1' ); // Never implemented.
	}

	$css = wp_kses_no_null( $css );
	$css = str_replace( array( "\n", "\r", "\t" ), '', $css );

	$allowed_protocols = wp_allowed_protocols();

	$css_array = explode( ';', trim( $css ) );

	/**
	 * Filters the list of allowed CSS attributes.
	 *
	 * @since 2.8.1
	 *
	 * @param string[] $attr Array of allowed CSS attributes.
	 */
	$allowed_attr = apply_filters(
		'safe_style_css',
		array(
			'background',
			'background-color',
			'background-image',
			'background-position',
			'background-repeat',
			'background-size',
			'background-attachment',
			'background-blend-mode',

			'border',
			'border-radius',
			'border-width',
			'border-color',
			'border-style',
			'border-right',
			'border-right-color',
			'border-right-style',
			'border-right-width',
			'border-bottom',
			'border-bottom-color',
			'border-bottom-left-radius',
			'border-bottom-right-radius',
			'border-bottom-style',
			'border-bottom-width',
			'border-bottom-right-radius',
			'border-bottom-left-radius',
			'border-left',
			'border-left-color',
			'border-left-style',
			'border-left-width',
			'border-top',
			'border-top-color',
			'border-top-left-radius',
			'border-top-right-radius',
			'border-top-style',
			'border-top-width',
			'border-top-left-radius',
			'border-top-right-radius',

			'border-spacing',
			'border-collapse',
			'caption-side',

			'columns',
			'column-count',
			'column-fill',
			'column-gap',
			'column-rule',
			'column-span',
			'column-width',

			'color',
			'filter',
			'font',
			'font-family',
			'font-size',
			'font-style',
			'font-variant',
			'font-weight',
			'letter-spacing',
			'line-height',
			'text-align',
			'text-decoration',
			'text-indent',
			'text-transform',

			'height',
			'min-height',
			'max-height',

			'width',
			'min-width',
			'max-width',

			'margin',
			'margin-right',
			'margin-bottom',
			'margin-left',
			'margin-top',
			'margin-block-start',
			'margin-block-end',
			'margin-inline-start',
			'margin-inline-end',

			'padding',
			'padding-right',
			'padding-bottom',
			'padding-left',
			'padding-top',
			'padding-block-start',
			'padding-block-end',
			'padding-inline-start',
			'padding-inline-end',

			'flex',
			'flex-basis',
			'flex-direction',
			'flex-flow',
			'flex-grow',
			'flex-shrink',
			'flex-wrap',

			'gap',
			'column-gap',
			'row-gap',

			'grid-template-columns',
			'grid-auto-columns',
			'grid-column-start',
			'grid-column-end',
			'grid-column-gap',
			'grid-template-rows',
			'grid-auto-rows',
			'grid-row-start',
			'grid-row-end',
			'grid-row-gap',
			'grid-gap',

			'justify-content',
			'justify-items',
			'justify-self',
			'align-content',
			'align-items',
			'align-self',

			'clear',
			'cursor',
			'direction',
			'float',
			'list-style-type',
			'object-fit',
			'object-position',
			'overflow',
			'vertical-align',
			'writing-mode',

			'position',
			'top',
			'right',
			'bottom',
			'left',
			'z-index',
			'box-shadow',
			'aspect-ratio',

			// Custom CSS properties.
			'--*',
		)
	);

	/*
	 * CSS attributes that accept URL data types.
	 *
	 * This is in accordance to the CSS spec and unrelated to
	 * the sub-set of supported attributes above.
	 *
	 * See: https://developer.mozilla.org/en-US/docs/Web/CSS/url
	 */
	$css_url_data_types = array(
		'background',
		'background-image',

		'cursor',
		'filter',

		'list-style',
		'list-style-image',
	);

	/*
	 * CSS attributes that accept gradient data types.
	 *
	 */
	$css_gradient_data_types = array(
		'background',
		'background-image',
	);

	if ( empty( $allowed_attr ) ) {
		return $css;
	}

	$css = '';
	foreach ( $css_array as $css_item ) {
		if ( '' === $css_item ) {
			continue;
		}

		$css_item        = trim( $css_item );
		$css_test_string = $css_item;
		$found           = false;
		$url_attr        = false;
		$gradient_attr   = false;
		$is_custom_var   = false;

		if ( ! str_contains( $css_item, ':' ) ) {
			$found = true;
		} else {
			$parts        = explode( ':', $css_item, 2 );
			$css_selector = trim( $parts[0] );

			// Allow assigning values to CSS variables.
			if ( in_array( '--*', $allowed_attr, true ) && preg_match( '/^--[a-zA-Z0-9-_]+$/', $css_selector ) ) {
				$allowed_attr[] = $css_selector;
				$is_custom_var  = true;
			}

			if ( in_array( $css_selector, $allowed_attr, true ) ) {
				$found         = true;
				$url_attr      = in_array( $css_selector, $css_url_data_types, true );
				$gradient_attr = in_array( $css_selector, $css_gradient_data_types, true );
			}

			if ( $is_custom_var ) {
				$css_value     = trim( $parts[1] );
				$url_attr      = str_starts_with( $css_value, 'url(' );
				$gradient_attr = str_contains( $css_value, '-gradient(' );
			}
		}

		if ( $found && $url_attr ) {
			// Simplified: matches the sequence `url(*)`.
			preg_match_all( '/url\([^)]+\)/', $parts[1], $url_matches );

			foreach ( $url_matches[0] as $url_match ) {
				// Clean up the URL from each of the matches above.
				preg_match( '/^url\(\s*([\'\"]?)(.*)(\g1)\s*\)$/', $url_match, $url_pieces );

				if ( empty( $url_pieces[2] ) ) {
					$found = false;
					break;
				}

				$url = trim( $url_pieces[2] );

				if ( empty( $url ) || wp_kses_bad_protocol( $url, $allowed_protocols ) !== $url ) {
					$found = false;
					break;
				} else {
					// Remove the whole `url(*)` bit that was matched above from the CSS.
					$css_test_string = str_replace( $url_match, '', $css_test_string );
				}
			}
		}

		if ( $found && $gradient_attr ) {
			$css_value = trim( $parts[1] );
			if ( preg_match( '/^(repeating-)?(linear|radial|conic)-gradient\(([^()]|rgb[a]?\([^()]*\))*\)$/', $css_value ) ) {
				// Remove the whole `gradient` bit that was matched above from the CSS.
				$css_test_string = str_replace( $css_value, '', $css_test_string );
			}
		}

		if ( $found ) {
			/*
			 * Allow CSS functions like var(), calc(), etc. by removing them from the test string.
			 * Nested functions and parentheses are also removed, so long as the parentheses are balanced.
			 */
			$css_test_string = preg_replace(
				'/\b(?:var|calc|min|max|minmax|clamp|repeat)(\((?:[^()]|(?1))*\))/',
				'',
				$css_test_string
			);

			/*
			 * Disallow CSS containing \ ( & } = or comments, except for within url(), var(), calc(), etc.
			 * which were removed from the test string above.
			 */
			$allow_css = ! preg_match( '%[\\\(&=}]|/\*%', $css_test_string );

			/**
			 * Filters the check for unsafe CSS in `safecss_filter_attr`.
			 *
			 * Enables developers to determine whether a section of CSS should be allowed or discarded.
			 * By default, the value will be false if the part contains \ ( & } = or comments.
			 * Return true to allow the CSS part to be included in the output.
			 *
			 * @since 5.5.0
			 *
			 * @param bool   $allow_css       Whether the CSS in the test string is considered safe.
			 * @param string $css_test_string The CSS string to test.
			 */
			$allow_css = apply_filters( 'safecss_filter_attr_allow_css', $allow_css, $css_test_string );

			// Only add the CSS part if it passes the regex check.
			if ( $allow_css ) {
				if ( '' !== $css ) {
					$css .= ';';
				}

				$css .= $css_item;
			}
		}
	}

	return $css;
}

/**
 * Helper function to add global attributes to a tag in the allowed HTML list.
 *
 * @since 3.5.0
 * @since 5.0.0 Added support for `data-*` wildcard attributes.
 * @since 6.0.0 Added `dir`, `lang`, and `xml:lang` to global attributes.
 * @since 6.3.0 Added `aria-controls`, `aria-current`, and `aria-expanded` attributes.
 * @since 6.4.0 Added `aria-live` and `hidden` attributes.
 *
 * @access private
 * @ignore
 *
 * @param array $value An array of attributes.
 * @return array The array of attributes with global attributes added.
 */
function _wp_add_global_attributes( $value ) {
	$global_attributes = array(
		'aria-controls'    => true,
		'aria-current'     => true,
		'aria-describedby' => true,
		'aria-details'     => true,
		'aria-expanded'    => true,
		'aria-hidden'      => true,
		'aria-label'       => true,
		'aria-labelledby'  => true,
		'aria-live'        => true,
		'class'            => true,
		'data-*'           => true,
		'dir'              => true,
		'hidden'           => true,
		'id'               => true,
		'lang'             => true,
		'style'            => true,
		'title'            => true,
		'role'             => true,
		'xml:lang'         => true,
	);

	if ( true === $value ) {
		$value = array();
	}

	if ( is_array( $value ) ) {
		return array_merge( $value, $global_attributes );
	}

	return $value;
}

/**
 * Helper function to check if this is a safe PDF URL.
 *
 * @since 5.9.0
 * @access private
 * @ignore
 *
 * @param string $url The URL to check.
 * @return bool True if the URL is safe, false otherwise.
 */
function _wp_kses_allow_pdf_objects( $url ) {
	// We're not interested in URLs that contain query strings or fragments.
	if ( str_contains( $url, '?' ) || str_contains( $url, '#' ) ) {
		return false;
	}

	// If it doesn't have a PDF extension, it's not safe.
	if ( ! str_ends_with( $url, '.pdf' ) ) {
		return false;
	}

	// If the URL host matches the current site's media URL, it's safe.
	$upload_info = wp_upload_dir( null, false );
	$parsed_url  = wp_parse_url( $upload_info['url'] );
	$upload_host = isset( $parsed_url['host'] ) ? $parsed_url['host'] : '';
	$upload_port = isset( $parsed_url['port'] ) ? ':' . $parsed_url['port'] : '';

	if ( str_starts_with( $url, "http://$upload_host$upload_port/" )
		|| str_starts_with( $url, "https://$upload_host$upload_port/" )
	) {
		return true;
	}

	return false;
}
->cap->publish_posts ) ) {
			$rels[] = 'https://api.w.org/action-publish';
		}

		if ( current_user_can( 'unfiltered_html' ) ) {
			$rels[] = 'https://api.w.org/action-unfiltered-html';
		}

		if ( 'post' === $post_type->name ) {
			if ( current_user_can( $post_type->cap->edit_others_posts ) && current_user_can( $post_type->cap->publish_posts ) ) {
				$rels[] = 'https://api.w.org/action-sticky';
			}
		}

		if ( post_type_supports( $post_type->name, 'author' ) ) {
			if ( current_user_can( $post_type->cap->edit_others_posts ) ) {
				$rels[] = 'https://api.w.org/action-assign-author';
			}
		}

		$taxonomies = wp_list_filter( get_object_taxonomies( $this->post_type, 'objects' ), array( 'show_in_rest' => true ) );

		foreach ( $taxonomies as $tax ) {
			$tax_base   = ! empty( $tax->rest_base ) ? $tax->rest_base : $tax->name;
			$create_cap = is_taxonomy_hierarchical( $tax->name ) ? $tax->cap->edit_terms : $tax->cap->assign_terms;

			if ( current_user_can( $create_cap ) ) {
				$rels[] = 'https://api.w.org/action-create-' . $tax_base;
			}

			if ( current_user_can( $tax->cap->assign_terms ) ) {
				$rels[] = 'https://api.w.org/action-assign-' . $tax_base;
			}
		}

		return $rels;
	}

	/**
	 * Retrieves the post's schema, conforming to JSON Schema.
	 *
	 * @since 4.7.0
	 *
	 * @return array Item schema data.
	 */
	public function get_item_schema() {
		if ( $this->schema ) {
			return $this->add_additional_fields_schema( $this->schema );
		}

		$schema = array(
			'$schema'    => 'http://json-schema.org/draft-04/schema#',
			'title'      => $this->post_type,
			'type'       => 'object',
			// Base properties for every Post.
			'properties' => array(
				'date'         => array(
					'description' => __( "The date the post was published, in the site's timezone." ),
					'type'        => array( 'string', 'null' ),
					'format'      => 'date-time',
					'context'     => array( 'view', 'edit', 'embed' ),
				),
				'date_gmt'     => array(
					'description' => __( 'The date the post was published, as GMT.' ),
					'type'        => array( 'string', 'null' ),
					'format'      => 'date-time',
					'context'     => array( 'view', 'edit' ),
				),
				'guid'         => array(
					'description' => __( 'The globally unique identifier for the post.' ),
					'type'        => 'object',
					'context'     => array( 'view', 'edit' ),
					'readonly'    => true,
					'properties'  => array(
						'raw'      => array(
							'description' => __( 'GUID for the post, as it exists in the database.' ),
							'type'        => 'string',
							'context'     => array( 'edit' ),
							'readonly'    => true,
						),
						'rendered' => array(
							'description' => __( 'GUID for the post, transformed for display.' ),
							'type'        => 'string',
							'context'     => array( 'view', 'edit' ),
							'readonly'    => true,
						),
					),
				),
				'id'           => array(
					'description' => __( 'Unique identifier for the post.' ),
					'type'        => 'integer',
					'context'     => array( 'view', 'edit', 'embed' ),
					'readonly'    => true,
				),
				'link'         => array(
					'description' => __( 'URL to the post.' ),
					'type'        => 'string',
					'format'      => 'uri',
					'context'     => array( 'view', 'edit', 'embed' ),
					'readonly'    => true,
				),
				'modified'     => array(
					'description' => __( "The date the post was last modified, in the site's timezone." ),
					'type'        => 'string',
					'format'      => 'date-time',
					'context'     => array( 'view', 'edit' ),
					'readonly'    => true,
				),
				'modified_gmt' => array(
					'description' => __( 'The date the post was last modified, as GMT.' ),
					'type'        => 'string',
					'format'      => 'date-time',
					'context'     => array( 'view', 'edit' ),
					'readonly'    => true,
				),
				'slug'         => array(
					'description' => __( 'An alphanumeric identifier for the post unique to its type.' ),
					'type'        => 'string',
					'context'     => array( 'view', 'edit', 'embed' ),
					'arg_options' => array(
						'sanitize_callback' => array( $this, 'sanitize_slug' ),
					),
				),
				'status'       => array(
					'description' => __( 'A named status for the post.' ),
					'type'        => 'string',
					'enum'        => array_keys( get_post_stati( array( 'internal' => false ) ) ),
					'context'     => array( 'view', 'edit' ),
					'arg_options' => array(
						'validate_callback' => array( $this, 'check_status' ),
					),
				),
				'type'         => array(
					'description' => __( 'Type of post.' ),
					'type'        => 'string',
					'context'     => array( 'view', 'edit', 'embed' ),
					'readonly'    => true,
				),
				'password'     => array(
					'description' => __( 'A password to protect access to the content and excerpt.' ),
					'type'        => 'string',
					'context'     => array( 'edit' ),
				),
			),
		);

		$post_type_obj = get_post_type_object( $this->post_type );
		if ( is_post_type_viewable( $post_type_obj ) && $post_type_obj->public ) {
			$schema['properties']['permalink_template'] = array(
				'description' => __( 'Permalink template for the post.' ),
				'type'        => 'string',
				'context'     => array( 'edit' ),
				'readonly'    => true,
			);

			$schema['properties']['generated_slug'] = array(
				'description' => __( 'Slug automatically generated from the post title.' ),
				'type'        => 'string',
				'context'     => array( 'edit' ),
				'readonly'    => true,
			);
		}

		if ( $post_type_obj->hierarchical ) {
			$schema['properties']['parent'] = array(
				'description' => __( 'The ID for the parent of the post.' ),
				'type'        => 'integer',
				'context'     => array( 'view', 'edit' ),
			);
		}

		$post_type_attributes = array(
			'title',
			'editor',
			'author',
			'excerpt',
			'thumbnail',
			'comments',
			'revisions',
			'page-attributes',
			'post-formats',
			'custom-fields',
		);
		$fixed_schemas        = array(
			'post'       => array(
				'title',
				'editor',
				'author',
				'excerpt',
				'thumbnail',
				'comments',
				'revisions',
				'post-formats',
				'custom-fields',
			),
			'page'       => array(
				'title',
				'editor',
				'author',
				'excerpt',
				'thumbnail',
				'comments',
				'revisions',
				'page-attributes',
				'custom-fields',
			),
			'attachment' => array(
				'title',
				'author',
				'comments',
				'revisions',
				'custom-fields',
				'thumbnail',
			),
		);

		foreach ( $post_type_attributes as $attribute ) {
			if ( isset( $fixed_schemas[ $this->post_type ] ) && ! in_array( $attribute, $fixed_schemas[ $this->post_type ], true ) ) {
				continue;
			} elseif ( ! isset( $fixed_schemas[ $this->post_type ] ) && ! post_type_supports( $this->post_type, $attribute ) ) {
				continue;
			}

			switch ( $attribute ) {

				case 'title':
					$schema['properties']['title'] = array(
						'description' => __( 'The title for the post.' ),
						'type'        => 'object',
						'context'     => array( 'view', 'edit', 'embed' ),
						'arg_options' => array(
							'sanitize_callback' => null, // Note: sanitization implemented in self::prepare_item_for_database().
							'validate_callback' => null, // Note: validation implemented in self::prepare_item_for_database().
						),
						'properties'  => array(
							'raw'      => array(
								'description' => __( 'Title for the post, as it exists in the database.' ),
								'type'        => 'string',
								'context'     => array( 'edit' ),
							),
							'rendered' => array(
								'description' => __( 'HTML title for the post, transformed for display.' ),
								'type'        => 'string',
								'context'     => array( 'view', 'edit', 'embed' ),
								'readonly'    => true,
							),
						),
					);
					break;

				case 'editor':
					$schema['properties']['content'] = array(
						'description' => __( 'The content for the post.' ),
						'type'        => 'object',
						'context'     => array( 'view', 'edit' ),
						'arg_options' => array(
							'sanitize_callback' => null, // Note: sanitization implemented in self::prepare_item_for_database().
							'validate_callback' => null, // Note: validation implemented in self::prepare_item_for_database().
						),
						'properties'  => array(
							'raw'           => array(
								'description' => __( 'Content for the post, as it exists in the database.' ),
								'type'        => 'string',
								'context'     => array( 'edit' ),
							),
							'rendered'      => array(
								'description' => __( 'HTML content for the post, transformed for display.' ),
								'type'        => 'string',
								'context'     => array( 'view', 'edit' ),
								'readonly'    => true,
							),
							'block_version' => array(
								'description' => __( 'Version of the content block format used by the post.' ),
								'type'        => 'integer',
								'context'     => array( 'edit' ),
								'readonly'    => true,
							),
							'protected'     => array(
								'description' => __( 'Whether the content is protected with a password.' ),
								'type'        => 'boolean',
								'context'     => array( 'view', 'edit', 'embed' ),
								'readonly'    => true,
							),
						),
					);
					break;

				case 'author':
					$schema['properties']['author'] = array(
						'description' => __( 'The ID for the author of the post.' ),
						'type'        => 'integer',
						'context'     => array( 'view', 'edit', 'embed' ),
					);
					break;

				case 'excerpt':
					$schema['properties']['excerpt'] = array(
						'description' => __( 'The excerpt for the post.' ),
						'type'        => 'object',
						'context'     => array( 'view', 'edit', 'embed' ),
						'arg_options' => array(
							'sanitize_callback' => null, // Note: sanitization implemented in self::prepare_item_for_database().
							'validate_callback' => null, // Note: validation implemented in self::prepare_item_for_database().
						),
						'properties'  => array(
							'raw'       => array(
								'description' => __( 'Excerpt for the post, as it exists in the database.' ),
								'type'        => 'string',
								'context'     => array( 'edit' ),
							),
							'rendered'  => array(
								'description' => __( 'HTML excerpt for the post, transformed for display.' ),
								'type'        => 'string',
								'context'     => array( 'view', 'edit', 'embed' ),
								'readonly'    => true,
							),
							'protected' => array(
								'description' => __( 'Whether the excerpt is protected with a password.' ),
								'type'        => 'boolean',
								'context'     => array( 'view', 'edit', 'embed' ),
								'readonly'    => true,
							),
						),
					);
					break;

				case 'thumbnail':
					$schema['properties']['featured_media'] = array(
						'description' => __( 'The ID of the featured media for the post.' ),
						'type'        => 'integer',
						'context'     => array( 'view', 'edit', 'embed' ),
					);
					break;

				case 'comments':
					$schema['properties']['comment_status'] = array(
						'description' => __( 'Whether or not comments are open on the post.' ),
						'type'        => 'string',
						'enum'        => array( 'open', 'closed' ),
						'context'     => array( 'view', 'edit' ),
					);
					$schema['properties']['ping_status']    = array(
						'description' => __( 'Whether or not the post can be pinged.' ),
						'type'        => 'string',
						'enum'        => array( 'open', 'closed' ),
						'context'     => array( 'view', 'edit' ),
					);
					break;

				case 'page-attributes':
					$schema['properties']['menu_order'] = array(
						'description' => __( 'The order of the post in relation to other posts.' ),
						'type'        => 'integer',
						'context'     => array( 'view', 'edit' ),
					);
					break;

				case 'post-formats':
					// Get the native post formats and remove the array keys.
					$formats = array_values( get_post_format_slugs() );

					$schema['properties']['format'] = array(
						'description' => __( 'The format for the post.' ),
						'type'        => 'string',
						'enum'        => $formats,
						'context'     => array( 'view', 'edit' ),
					);
					break;

				case 'custom-fields':
					$schema['properties']['meta'] = $this->meta->get_field_schema();
					break;

			}
		}

		if ( 'post' === $this->post_type ) {
			$schema['properties']['sticky'] = array(
				'description' => __( 'Whether or not the post should be treated as sticky.' ),
				'type'        => 'boolean',
				'context'     => array( 'view', 'edit' ),
			);
		}

		$schema['properties']['template'] = array(
			'description' => __( 'The theme file to use to display the post.' ),
			'type'        => 'string',
			'context'     => array( 'view', 'edit' ),
			'arg_options' => array(
				'validate_callback' => array( $this, 'check_template' ),
			),
		);

		$taxonomies = wp_list_filter( get_object_taxonomies( $this->post_type, 'objects' ), array( 'show_in_rest' => true ) );

		foreach ( $taxonomies as $taxonomy ) {
			$base = ! empty( $taxonomy->rest_base ) ? $taxonomy->rest_base : $taxonomy->name;

			if ( array_key_exists( $base, $schema['properties'] ) ) {
				$taxonomy_field_name_with_conflict = ! empty( $taxonomy->rest_base ) ? 'rest_base' : 'name';
				_doing_it_wrong(
					'register_taxonomy',
					sprintf(
						/* translators: 1: The taxonomy name, 2: The property name, either 'rest_base' or 'name', 3: The conflicting value. */
						__( 'The "%1$s" taxonomy "%2$s" property (%3$s) conflicts with an existing property on the REST API Posts Controller. Specify a custom "rest_base" when registering the taxonomy to avoid this error.' ),
						$taxonomy->name,
						$taxonomy_field_name_with_conflict,
						$base
					),
					'5.4.0'
				);
			}

			$schema['properties'][ $base ] = array(
				/* translators: %s: Taxonomy name. */
				'description' => sprintf( __( 'The terms assigned to the post in the %s taxonomy.' ), $taxonomy->name ),
				'type'        => 'array',
				'items'       => array(
					'type' => 'integer',
				),
				'context'     => array( 'view', 'edit' ),
			);
		}

		$schema_links = $this->get_schema_links();

		if ( $schema_links ) {
			$schema['links'] = $schema_links;
		}

		// Take a snapshot of which fields are in the schema pre-filtering.
		$schema_fields = array_keys( $schema['properties'] );

		/**
		 * Filters the post's schema.
		 *
		 * The dynamic portion of the filter, `$this->post_type`, refers to the
		 * post type slug for the controller.
		 *
		 * Possible hook names include:
		 *
		 *  - `rest_post_item_schema`
		 *  - `rest_page_item_schema`
		 *  - `rest_attachment_item_schema`
		 *
		 * @since 5.4.0
		 *
		 * @param array $schema Item schema data.
		 */
		$schema = apply_filters( "rest_{$this->post_type}_item_schema", $schema );

		// Emit a _doing_it_wrong warning if user tries to add new properties using this filter.
		$new_fields = array_diff( array_keys( $schema['properties'] ), $schema_fields );
		if ( count( $new_fields ) > 0 ) {
			_doing_it_wrong(
				__METHOD__,
				sprintf(
					/* translators: %s: register_rest_field */
					__( 'Please use %s to add new schema properties.' ),
					'register_rest_field'
				),
				'5.4.0'
			);
		}

		$this->schema = $schema;

		return $this->add_additional_fields_schema( $this->schema );
	}

	/**
	 * Retrieves Link Description Objects that should be added to the Schema for the posts collection.
	 *
	 * @since 4.9.8
	 *
	 * @return array
	 */
	protected function get_schema_links() {

		$href = rest_url( "{$this->namespace}/{$this->rest_base}/{id}" );

		$links = array();

		if ( 'attachment' !== $this->post_type ) {
			$links[] = array(
				'rel'          => 'https://api.w.org/action-publish',
				'title'        => __( 'The current user can publish this post.' ),
				'href'         => $href,
				'targetSchema' => array(
					'type'       => 'object',
					'properties' => array(
						'status' => array(
							'type' => 'string',
							'enum' => array( 'publish', 'future' ),
						),
					),
				),
			);
		}

		$links[] = array(
			'rel'          => 'https://api.w.org/action-unfiltered-html',
			'title'        => __( 'The current user can post unfiltered HTML markup and JavaScript.' ),
			'href'         => $href,
			'targetSchema' => array(
				'type'       => 'object',
				'properties' => array(
					'content' => array(
						'raw' => array(
							'type' => 'string',
						),
					),
				),
			),
		);

		if ( 'post' === $this->post_type ) {
			$links[] = array(
				'rel'          => 'https://api.w.org/action-sticky',
				'title'        => __( 'The current user can sticky this post.' ),
				'href'         => $href,
				'targetSchema' => array(
					'type'       => 'object',
					'properties' => array(
						'sticky' => array(
							'type' => 'boolean',
						),
					),
				),
			);
		}

		if ( post_type_supports( $this->post_type, 'author' ) ) {
			$links[] = array(
				'rel'          => 'https://api.w.org/action-assign-author',
				'title'        => __( 'The current user can change the author on this post.' ),
				'href'         => $href,
				'targetSchema' => array(
					'type'       => 'object',
					'properties' => array(
						'author' => array(
							'type' => 'integer',
						),
					),
				),
			);
		}

		$taxonomies = wp_list_filter( get_object_taxonomies( $this->post_type, 'objects' ), array( 'show_in_rest' => true ) );

		foreach ( $taxonomies as $tax ) {
			$tax_base = ! empty( $tax->rest_base ) ? $tax->rest_base : $tax->name;

			/* translators: %s: Taxonomy name. */
			$assign_title = sprintf( __( 'The current user can assign terms in the %s taxonomy.' ), $tax->name );
			/* translators: %s: Taxonomy name. */
			$create_title = sprintf( __( 'The current user can create terms in the %s taxonomy.' ), $tax->name );

			$links[] = array(
				'rel'          => 'https://api.w.org/action-assign-' . $tax_base,
				'title'        => $assign_title,
				'href'         => $href,
				'targetSchema' => array(
					'type'       => 'object',
					'properties' => array(
						$tax_base => array(
							'type'  => 'array',
							'items' => array(
								'type' => 'integer',
							),
						),
					),
				),
			);

			$links[] = array(
				'rel'          => 'https://api.w.org/action-create-' . $tax_base,
				'title'        => $create_title,
				'href'         => $href,
				'targetSchema' => array(
					'type'       => 'object',
					'properties' => array(
						$tax_base => array(
							'type'  => 'array',
							'items' => array(
								'type' => 'integer',
							),
						),
					),
				),
			);
		}

		return $links;
	}

	/**
	 * Retrieves the query params for the posts collection.
	 *
	 * @since 4.7.0
	 * @since 5.4.0 The `tax_relation` query parameter was added.
	 * @since 5.7.0 The `modified_after` and `modified_before` query parameters were added.
	 *
	 * @return array Collection parameters.
	 */
	public function get_collection_params() {
		$query_params = parent::get_collection_params();

		$query_params['context']['default'] = 'view';

		$query_params['after'] = array(
			'description' => __( 'Limit response to posts published after a given ISO8601 compliant date.' ),
			'type'        => 'string',
			'format'      => 'date-time',
		);

		$query_params['modified_after'] = array(
			'description' => __( 'Limit response to posts modified after a given ISO8601 compliant date.' ),
			'type'        => 'string',
			'format'      => 'date-time',
		);

		if ( post_type_supports( $this->post_type, 'author' ) ) {
			$query_params['author']         = array(
				'description' => __( 'Limit result set to posts assigned to specific authors.' ),
				'type'        => 'array',
				'items'       => array(
					'type' => 'integer',
				),
				'default'     => array(),
			);
			$query_params['author_exclude'] = array(
				'description' => __( 'Ensure result set excludes posts assigned to specific authors.' ),
				'type'        => 'array',
				'items'       => array(
					'type' => 'integer',
				),
				'default'     => array(),
			);
		}

		$query_params['before'] = array(
			'description' => __( 'Limit response to posts published before a given ISO8601 compliant date.' ),
			'type'        => 'string',
			'format'      => 'date-time',
		);

		$query_params['modified_before'] = array(
			'description' => __( 'Limit response to posts modified before a given ISO8601 compliant date.' ),
			'type'        => 'string',
			'format'      => 'date-time',
		);

		$query_params['exclude'] = array(
			'description' => __( 'Ensure result set excludes specific IDs.' ),
			'type'        => 'array',
			'items'       => array(
				'type' => 'integer',
			),
			'default'     => array(),
		);

		$query_params['include'] = array(
			'description' => __( 'Limit result set to specific IDs.' ),
			'type'        => 'array',
			'items'       => array(
				'type' => 'integer',
			),
			'default'     => array(),
		);

		if ( 'page' === $this->post_type || post_type_supports( $this->post_type, 'page-attributes' ) ) {
			$query_params['menu_order'] = array(
				'description' => __( 'Limit result set to posts with a specific menu_order value.' ),
				'type'        => 'integer',
			);
		}

		$query_params['offset'] = array(
			'description' => __( 'Offset the result set by a specific number of items.' ),
			'type'        => 'integer',
		);

		$query_params['order'] = array(
			'description' => __( 'Order sort attribute ascending or descending.' ),
			'type'        => 'string',
			'default'     => 'desc',
			'enum'        => array( 'asc', 'desc' ),
		);

		$query_params['orderby'] = array(
			'description' => __( 'Sort collection by post attribute.' ),
			'type'        => 'string',
			'default'     => 'date',
			'enum'        => array(
				'author',
				'date',
				'id',
				'include',
				'modified',
				'parent',
				'relevance',
				'slug',
				'include_slugs',
				'title',
			),
		);

		if ( 'page' === $this->post_type || post_type_supports( $this->post_type, 'page-attributes' ) ) {
			$query_params['orderby']['enum'][] = 'menu_order';
		}

		$post_type = get_post_type_object( $this->post_type );

		if ( $post_type->hierarchical || 'attachment' === $this->post_type ) {
			$query_params['parent']         = array(
				'description' => __( 'Limit result set to items with particular parent IDs.' ),
				'type'        => 'array',
				'items'       => array(
					'type' => 'integer',
				),
				'default'     => array(),
			);
			$query_params['parent_exclude'] = array(
				'description' => __( 'Limit result set to all items except those of a particular parent ID.' ),
				'type'        => 'array',
				'items'       => array(
					'type' => 'integer',
				),
				'default'     => array(),
			);
		}

		$query_params['search_columns'] = array(
			'default'     => array(),
			'description' => __( 'Array of column names to be searched.' ),
			'type'        => 'array',
			'items'       => array(
				'enum' => array( 'post_title', 'post_content', 'post_excerpt' ),
				'type' => 'string',
			),
		);

		$query_params['slug'] = array(
			'description' => __( 'Limit result set to posts with one or more specific slugs.' ),
			'type'        => 'array',
			'items'       => array(
				'type' => 'string',
			),
		);

		$query_params['status'] = array(
			'default'           => 'publish',
			'description'       => __( 'Limit result set to posts assigned one or more statuses.' ),
			'type'              => 'array',
			'items'             => array(
				'enum' => array_merge( array_keys( get_post_stati() ), array( 'any' ) ),
				'type' => 'string',
			),
			'sanitize_callback' => array( $this, 'sanitize_post_statuses' ),
		);

		$query_params = $this->prepare_taxonomy_limit_schema( $query_params );

		if ( 'post' === $this->post_type ) {
			$query_params['sticky'] = array(
				'description' => __( 'Limit result set to items that are sticky.' ),
				'type'        => 'boolean',
			);
		}

		/**
		 * Filters collection parameters for the posts controller.
		 *
		 * The dynamic part of the filter `$this->post_type` refers to the post
		 * type slug for the controller.
		 *
		 * This filter registers the collection parameter, but does not map the
		 * collection parameter to an internal WP_Query parameter. Use the
		 * `rest_{$this->post_type}_query` filter to set WP_Query parameters.
		 *
		 * @since 4.7.0
		 *
		 * @param array        $query_params JSON Schema-formatted collection parameters.
		 * @param WP_Post_Type $post_type    Post type object.
		 */
		return apply_filters( "rest_{$this->post_type}_collection_params", $query_params, $post_type );
	}

	/**
	 * Sanitizes and validates the list of post statuses, including whether the
	 * user can query private statuses.
	 *
	 * @since 4.7.0
	 *
	 * @param string|array    $statuses  One or more post statuses.
	 * @param WP_REST_Request $request   Full details about the request.
	 * @param string          $parameter Additional parameter to pass to validation.
	 * @return array|WP_Error A list of valid statuses, otherwise WP_Error object.
	 */
	public function sanitize_post_statuses( $statuses, $request, $parameter ) {
		$statuses = wp_parse_slug_list( $statuses );

		// The default status is different in WP_REST_Attachments_Controller.
		$attributes     = $request->get_attributes();
		$default_status = $attributes['args']['status']['default'];

		foreach ( $statuses as $status ) {
			if ( $status === $default_status ) {
				continue;
			}

			$post_type_obj = get_post_type_object( $this->post_type );

			if ( current_user_can( $post_type_obj->cap->edit_posts ) || 'private' === $status && current_user_can( $post_type_obj->cap->read_private_posts ) ) {
				$result = rest_validate_request_arg( $status, $request, $parameter );
				if ( is_wp_error( $result ) ) {
					return $result;
				}
			} else {
				return new WP_Error(
					'rest_forbidden_status',
					__( 'Status is forbidden.' ),
					array( 'status' => rest_authorization_required_code() )
				);
			}
		}

		return $statuses;
	}

	/**
	 * Prepares the 'tax_query' for a collection of posts.
	 *
	 * @since 5.7.0
	 *
	 * @param array           $args    WP_Query arguments.
	 * @param WP_REST_Request $request Full details about the request.
	 * @return array Updated query arguments.
	 */
	private function prepare_tax_query( array $args, WP_REST_Request $request ) {
		$relation = $request['tax_relation'];

		if ( $relation ) {
			$args['tax_query'] = array( 'relation' => $relation );
		}

		$taxonomies = wp_list_filter(
			get_object_taxonomies( $this->post_type, 'objects' ),
			array( 'show_in_rest' => true )
		);

		foreach ( $taxonomies as $taxonomy ) {
			$base = ! empty( $taxonomy->rest_base ) ? $taxonomy->rest_base : $taxonomy->name;

			$tax_include = $request[ $base ];
			$tax_exclude = $request[ $base . '_exclude' ];

			if ( $tax_include ) {
				$terms            = array();
				$include_children = false;
				$operator         = 'IN';

				if ( rest_is_array( $tax_include ) ) {
					$terms = $tax_include;
				} elseif ( rest_is_object( $tax_include ) ) {
					$terms            = empty( $tax_include['terms'] ) ? array() : $tax_include['terms'];
					$include_children = ! empty( $tax_include['include_children'] );

					if ( isset( $tax_include['operator'] ) && 'AND' === $tax_include['operator'] ) {
						$operator = 'AND';
					}
				}

				if ( $terms ) {
					$args['tax_query'][] = array(
						'taxonomy'         => $taxonomy->name,
						'field'            => 'term_id',
						'terms'            => $terms,
						'include_children' => $include_children,
						'operator'         => $operator,
					);
				}
			}

			if ( $tax_exclude ) {
				$terms            = array();
				$include_children = false;

				if ( rest_is_array( $tax_exclude ) ) {
					$terms = $tax_exclude;
				} elseif ( rest_is_object( $tax_exclude ) ) {
					$terms            = empty( $tax_exclude['terms'] ) ? array() : $tax_exclude['terms'];
					$include_children = ! empty( $tax_exclude['include_children'] );
				}

				if ( $terms ) {
					$args['tax_query'][] = array(
						'taxonomy'         => $taxonomy->name,
						'field'            => 'term_id',
						'terms'            => $terms,
						'include_children' => $include_children,
						'operator'         => 'NOT IN',
					);
				}
			}
		}

		return $args;
	}

	/**
	 * Prepares the collection schema for including and excluding items by terms.
	 *
	 * @since 5.7.0
	 *
	 * @param array $query_params Collection schema.
	 * @return array Updated schema.
	 */
	private function prepare_taxonomy_limit_schema( array $query_params ) {
		$taxonomies = wp_list_filter( get_object_taxonomies( $this->post_type, 'objects' ), array( 'show_in_rest' => true ) );

		if ( ! $taxonomies ) {
			return $query_params;
		}

		$query_params['tax_relation'] = array(
			'description' => __( 'Limit result set based on relationship between multiple taxonomies.' ),
			'type'        => 'string',
			'enum'        => array( 'AND', 'OR' ),
		);

		$limit_schema = array(
			'type'  => array( 'object', 'array' ),
			'oneOf' => array(
				array(
					'title'       => __( 'Term ID List' ),
					'description' => __( 'Match terms with the listed IDs.' ),
					'type'        => 'array',
					'items'       => array(
						'type' => 'integer',
					),
				),
				array(
					'title'                => __( 'Term ID Taxonomy Query' ),
					'description'          => __( 'Perform an advanced term query.' ),
					'type'                 => 'object',
					'properties'           => array(
						'terms'            => array(
							'description' => __( 'Term IDs.' ),
							'type'        => 'array',
							'items'       => array(
								'type' => 'integer',
							),
							'default'     => array(),
						),
						'include_children' => array(
							'description' => __( 'Whether to include child terms in the terms limiting the result set.' ),
							'type'        => 'boolean',
							'default'     => false,
						),
					),
					'additionalProperties' => false,
				),
			),
		);

		$include_schema = array_merge(
			array(
				/* translators: %s: Taxonomy name. */
				'description' => __( 'Limit result set to items with specific terms assigned in the %s taxonomy.' ),
			),
			$limit_schema
		);
		// 'operator' is supported only for 'include' queries.
		$include_schema['oneOf'][1]['properties']['operator'] = array(
			'description' => __( 'Whether items must be assigned all or any of the specified terms.' ),
			'type'        => 'string',
			'enum'        => array( 'AND', 'OR' ),
			'default'     => 'OR',
		);

		$exclude_schema = array_merge(
			array(
				/* translators: %s: Taxonomy name. */
				'description' => __( 'Limit result set to items except those with specific terms assigned in the %s taxonomy.' ),
			),
			$limit_schema
		);

		foreach ( $taxonomies as $taxonomy ) {
			$base         = ! empty( $taxonomy->rest_base ) ? $taxonomy->rest_base : $taxonomy->name;
			$base_exclude = $base . '_exclude';

			$query_params[ $base ]                = $include_schema;
			$query_params[ $base ]['description'] = sprintf( $query_params[ $base ]['description'], $base );

			$query_params[ $base_exclude ]                = $exclude_schema;
			$query_params[ $base_exclude ]['description'] = sprintf( $query_params[ $base_exclude ]['description'], $base );

			if ( ! $taxonomy->hierarchical ) {
				unset( $query_params[ $base ]['oneOf'][1]['properties']['include_children'] );
				unset( $query_params[ $base_exclude ]['oneOf'][1]['properties']['include_children'] );
			}
		}

		return $query_params;
	}
}