class-wp-style-engine.php

<?php
/**
 * WP_Style_Engine
 *
 * Generates classnames and block styles.
 *
 * @package Gutenberg
 */

if ( ! class_exists( 'WP_Style_Engine' ) ) {

	/**
	 * Class WP_Style_Engine.
	 *
	 * The Style Engine aims to provide a consistent API for rendering styling for blocks across both client-side and server-side applications.
	 *
	 * This class is for internal Core usage and is not supposed to be used by extenders (plugins and/or themes).
	 * This class is final and should not be extended.
	 * This is a low-level API that may need to do breaking changes. Please, use wp_style_engine_get_styles instead.
	 *
	 * @access private
	 */
	final class WP_Style_Engine {
		/**
		 * Style definitions that contain the instructions to parse/output valid Gutenberg styles from a block's attributes.
		 *
		 * For every style definition, the following properties are valid:
		 *
		 *  - classnames    => (array) an array of classnames to be returned for block styles. The key is a classname or pattern.
		 *                    A value of `true` means the classname should be applied always. Otherwise, a valid CSS property (string)
		 *                    to match the incoming value, e.g., "color" to match var:preset|color|somePresetSlug.
		 *  - css_vars      => (array) an array of key value pairs used to generate CSS var values.
		 *                     The key should be the CSS property name that matches the second element of the preset string value,
		 *                     i.e., "color" in var:preset|color|somePresetSlug. The value is a CSS var pattern (e.g. `--wp--preset--color--$slug`),
		 *                     whose `$slug` fragment will be replaced with the preset slug, which is the third element of the preset string value,
		 *                     i.e., `somePresetSlug` in var:preset|color|somePresetSlug.
		 *  - property_keys => (array) array of keys whose values represent a valid CSS property, e.g., "margin" or "border".
		 *  - path          => (array) a path that accesses the corresponding style value in the block style object.
		 *  - value_func    => (string) the name of a function to generate a CSS definition array for a particular style object. The output of this function should be `array( "$property" => "$value", ... )`.
		 *
		 * @var array
		 */
		const BLOCK_STYLE_DEFINITIONS_METADATA = array(
			'background' => array(
				'backgroundImage'      => array(
					'property_keys' => array(
						'default' => 'background-image',
					),
					'value_func'    => array( self::class, 'get_url_or_value_css_declaration' ),
					'path'          => array( 'background', 'backgroundImage' ),
				),
				'backgroundPosition'   => array(
					'property_keys' => array(
						'default' => 'background-position',
					),
					'path'          => array( 'background', 'backgroundPosition' ),
				),
				'backgroundRepeat'     => array(
					'property_keys' => array(
						'default' => 'background-repeat',
					),
					'path'          => array( 'background', 'backgroundRepeat' ),
				),
				'backgroundSize'       => array(
					'property_keys' => array(
						'default' => 'background-size',
					),
					'path'          => array( 'background', 'backgroundSize' ),
				),
				'backgroundAttachment' => array(
					'property_keys' => array(
						'default' => 'background-attachment',
					),
					'path'          => array( 'background', 'backgroundAttachment' ),
				),
			),
			'color'      => array(
				'text'       => array(
					'property_keys' => array(
						'default' => 'color',
					),
					'path'          => array( 'color', 'text' ),
					'css_vars'      => array(
						'color' => '--wp--preset--color--$slug',
					),
					'classnames'    => array(
						'has-text-color'  => true,
						'has-$slug-color' => 'color',
					),
				),
				'background' => array(
					'property_keys' => array(
						'default' => 'background-color',
					),
					'path'          => array( 'color', 'background' ),
					'css_vars'      => array(
						'color' => '--wp--preset--color--$slug',
					),
					'classnames'    => array(
						'has-background'             => true,
						'has-$slug-background-color' => 'color',
					),
				),
				'gradient'   => array(
					'property_keys' => array(
						'default' => 'background',
					),
					'css_vars'      => array(
						'gradient' => '--wp--preset--gradient--$slug',
					),
					'path'          => array( 'color', 'gradient' ),
					'classnames'    => array(
						'has-background'                => true,
						'has-$slug-gradient-background' => 'gradient',
					),
				),
			),
			'border'     => array(
				'color'  => array(
					'property_keys' => array(
						'default'    => 'border-color',
						'individual' => 'border-%s-color',
					),
					'path'          => array( 'border', 'color' ),
					'classnames'    => array(
						'has-border-color'       => true,
						'has-$slug-border-color' => 'color',
					),
				),
				'radius' => array(
					'property_keys' => array(
						'default'    => 'border-radius',
						'individual' => 'border-%s-radius',
					),
					'path'          => array( 'border', 'radius' ),
				),
				'style'  => array(
					'property_keys' => array(
						'default'    => 'border-style',
						'individual' => 'border-%s-style',
					),
					'path'          => array( 'border', 'style' ),
				),
				'width'  => array(
					'property_keys' => array(
						'default'    => 'border-width',
						'individual' => 'border-%s-width',
					),
					'path'          => array( 'border', 'width' ),
				),
				'top'    => array(
					'value_func' => array( self::class, 'get_individual_property_css_declarations' ),
					'path'       => array( 'border', 'top' ),
					'css_vars'   => array(
						'color' => '--wp--preset--color--$slug',
					),
				),
				'right'  => array(
					'value_func' => array( self::class, 'get_individual_property_css_declarations' ),
					'path'       => array( 'border', 'right' ),
					'css_vars'   => array(
						'color' => '--wp--preset--color--$slug',
					),
				),
				'bottom' => array(
					'value_func' => array( self::class, 'get_individual_property_css_declarations' ),
					'path'       => array( 'border', 'bottom' ),
					'css_vars'   => array(
						'color' => '--wp--preset--color--$slug',
					),
				),
				'left'   => array(
					'value_func' => array( self::class, 'get_individual_property_css_declarations' ),
					'path'       => array( 'border', 'left' ),
					'css_vars'   => array(
						'color' => '--wp--preset--color--$slug',
					),
				),
			),
			'shadow'     => array(
				'shadow' => array(
					'property_keys' => array(
						'default' => 'box-shadow',
					),
					'path'          => array( 'shadow' ),
					'css_vars'      => array(
						'shadow' => '--wp--preset--shadow--$slug',
					),
				),
			),
			'dimensions' => array(
				'aspectRatio' => array(
					'property_keys' => array(
						'default' => 'aspect-ratio',
					),
					'path'          => array( 'dimensions', 'aspectRatio' ),
					'classnames'    => array(
						'has-aspect-ratio' => true,
					),
				),
				'minHeight'   => array(
					'property_keys' => array(
						'default' => 'min-height',
					),
					'path'          => array( 'dimensions', 'minHeight' ),
					'css_vars'      => array(
						'spacing' => '--wp--preset--spacing--$slug',
					),
				),
			),
			'spacing'    => array(
				'padding' => array(
					'property_keys' => array(
						'default'    => 'padding',
						'individual' => 'padding-%s',
					),
					'path'          => array( 'spacing', 'padding' ),
					'css_vars'      => array(
						'spacing' => '--wp--preset--spacing--$slug',
					),
				),
				'margin'  => array(
					'property_keys' => array(
						'default'    => 'margin',
						'individual' => 'margin-%s',
					),
					'path'          => array( 'spacing', 'margin' ),
					'css_vars'      => array(
						'spacing' => '--wp--preset--spacing--$slug',
					),
				),
			),
			'typography' => array(
				'fontSize'       => array(
					'property_keys' => array(
						'default' => 'font-size',
					),
					'css_vars'      => array(
						'font-size' => '--wp--preset--font-size--$slug',
					),
					'path'          => array( 'typography', 'fontSize' ),
					'classnames'    => array(
						'has-$slug-font-size' => 'font-size',
					),
				),
				'fontFamily'     => array(
					'property_keys' => array(
						'default' => 'font-family',
					),
					'css_vars'      => array(
						'font-family' => '--wp--preset--font-family--$slug',
					),
					'path'          => array( 'typography', 'fontFamily' ),
					'classnames'    => array(
						'has-$slug-font-family' => 'font-family',
					),
				),
				'fontStyle'      => array(
					'property_keys' => array(
						'default' => 'font-style',
					),
					'path'          => array( 'typography', 'fontStyle' ),
				),
				'fontWeight'     => array(
					'property_keys' => array(
						'default' => 'font-weight',
					),
					'path'          => array( 'typography', 'fontWeight' ),
				),
				'lineHeight'     => array(
					'property_keys' => array(
						'default' => 'line-height',
					),
					'path'          => array( 'typography', 'lineHeight' ),
				),
				'textColumns'    => array(
					'property_keys' => array(
						'default' => 'column-count',
					),
					'path'          => array( 'typography', 'textColumns' ),
				),
				'textDecoration' => array(
					'property_keys' => array(
						'default' => 'text-decoration',
					),
					'path'          => array( 'typography', 'textDecoration' ),
				),
				'textTransform'  => array(
					'property_keys' => array(
						'default' => 'text-transform',
					),
					'path'          => array( 'typography', 'textTransform' ),
				),
				'letterSpacing'  => array(
					'property_keys' => array(
						'default' => 'letter-spacing',
					),
					'path'          => array( 'typography', 'letterSpacing' ),
				),
				'writingMode'    => array(
					'property_keys' => array(
						'default' => 'writing-mode',
					),
					'path'          => array( 'typography', 'writingMode' ),
				),
			),
		);

		/**
		 * Util: Extracts the slug in kebab case from a preset string, e.g., "heavenly-blue" from 'var:preset|color|heavenlyBlue'.
		 *
		 * @param string $style_value  A single CSS preset value.
		 * @param string $property_key The CSS property that is the second element of the preset string. Used for matching.
		 *
		 * @return string The slug, or empty string if not found.
		 */
		protected static function get_slug_from_preset_value( $style_value, $property_key ) {
			if ( is_string( $style_value ) && is_string( $property_key ) && str_contains( $style_value, "var:preset|{$property_key}|" ) ) {
				$index_to_splice = strrpos( $style_value, '|' ) + 1;
				return _wp_to_kebab_case( substr( $style_value, $index_to_splice ) );
			}
			return '';
		}

		/**
		 * Util: Generates a CSS var string, e.g., var(--wp--preset--color--background) from a preset string such as `var:preset|space|50`.
		 *
		 * @param string   $style_value  A single CSS preset value.
		 * @param string[] $css_vars     An associate array of CSS var patterns used to generate the var string.
		 *
		 * @return string The css var, or an empty string if no match for slug found.
		 */
		protected static function get_css_var_value( $style_value, $css_vars ) {
			foreach ( $css_vars as  $property_key => $css_var_pattern ) {
				$slug = static::get_slug_from_preset_value( $style_value, $property_key );
				if ( static::is_valid_style_value( $slug ) ) {
					$var = strtr(
						$css_var_pattern,
						array( '$slug' => $slug )
					);
					return "var($var)";
				}
			}
			return '';
		}

		/**
		 * Util: Checks whether an incoming block style value is valid.
		 *
		 * @param string? $style_value  A single css preset value.
		 *
		 * @return bool
		 */
		protected static function is_valid_style_value( $style_value ) {
			return '0' === $style_value || ! empty( $style_value );
		}

		/**
		 * Stores a CSS rule using the provided CSS selector and CSS declarations.
		 *
		 * @param string   $store_name       A valid store key.
		 * @param string   $css_selector     When a selector is passed, the function will return a full CSS rule `$selector { ...rules }`, otherwise a concatenated string of properties and values.
		 * @param string[] $css_declarations An associative array of CSS definitions, e.g., array( "$property" => "$value", "$property" => "$value" ).
		 * @param string $rules_group        Optional. A parent CSS selector in the case of nested CSS, or a CSS nested @rule, such as `@media (min-width: 80rem)` or `@layer module`.
		 *
		 * @return void.
		 */
		public static function store_css_rule( $store_name, $css_selector, $css_declarations, $rules_group = '' ) {
			if ( empty( $store_name ) || empty( $css_selector ) || empty( $css_declarations ) ) {
				return;
			}
			static::get_store( $store_name )->add_rule( $css_selector, $rules_group )->add_declarations( $css_declarations );
		}

		/**
		 * Returns a store by store key.
		 *
		 * @param string $store_name A store key.
		 *
		 * @return WP_Style_Engine_CSS_Rules_Store
		 */
		public static function get_store( $store_name ) {
			return WP_Style_Engine_CSS_Rules_Store::get_store( $store_name );
		}

		/**
		 * Returns classnames and CSS based on the values in a styles object.
		 * Return values are parsed based on the instructions in BLOCK_STYLE_DEFINITIONS_METADATA.
		 *
		 * @since 6.1.0
		 *
		 * @param array $block_styles The style object.
		 * @param array $options      {
		 *     Optional. An array of options. Default empty array.
		 *
		 *     @type bool        $convert_vars_to_classnames Whether to skip converting incoming CSS var patterns, e.g., `var:preset|<PRESET_TYPE>|<PRESET_SLUG>`, to var( --wp--preset--* ) values. Default `false`.
		 *     @type string      $selector                   Optional. When a selector is passed, the value of `$css` in the return value will comprise a full CSS rule `$selector { ...$css_declarations }`,
		 *                                                   otherwise, the value will be a concatenated string of CSS declarations.
		 * }
		 *
		 * @return array {
		 *     @type string   $classnames   Classnames separated by a space.
		 *     @type string[] $declarations An associative array of CSS definitions, e.g., array( "$property" => "$value", "$property" => "$value" ).
		 * }
		 */
		public static function parse_block_styles( $block_styles, $options ) {
			$parsed_styles = array(
				'classnames'   => array(),
				'declarations' => array(),
			);
			if ( empty( $block_styles ) || ! is_array( $block_styles ) ) {
				return $parsed_styles;
			}

			// Collect CSS and classnames.
			foreach ( static::BLOCK_STYLE_DEFINITIONS_METADATA as $definition_group_key => $definition_group_style ) {
				if ( empty( $block_styles[ $definition_group_key ] ) ) {
					continue;
				}
				foreach ( $definition_group_style as $style_definition ) {
					$style_value = _wp_array_get( $block_styles, $style_definition['path'], null );

					if ( ! static::is_valid_style_value( $style_value ) ) {
						continue;
					}

					$parsed_styles['classnames']   = array_merge( $parsed_styles['classnames'], static::get_classnames( $style_value, $style_definition ) );
					$parsed_styles['declarations'] = array_merge( $parsed_styles['declarations'], static::get_css_declarations( $style_value, $style_definition, $options ) );
				}
			}

			return $parsed_styles;
		}

		/**
		 * Returns classnames, and generates classname(s) from a CSS preset property pattern, e.g., '`var:preset|<PRESET_TYPE>|<PRESET_SLUG>`'.
		 *
		 * @param array $style_value      A single raw style value or css preset property from the $block_styles array.
		 * @param array $style_definition A single style definition from BLOCK_STYLE_DEFINITIONS_METADATA.
		 *
		 * @return array|string[] An array of CSS classnames, or empty array.
		 */
		protected static function get_classnames( $style_value, $style_definition ) {
			if ( empty( $style_value ) ) {
				return array();
			}

			$classnames = array();
			if ( ! empty( $style_definition['classnames'] ) ) {
				foreach ( $style_definition['classnames'] as $classname => $property_key ) {
					if ( true === $property_key ) {
						$classnames[] = $classname;
						continue;
					}

					$slug = static::get_slug_from_preset_value( $style_value, $property_key );

					if ( $slug ) {
						/*
						* Right now we expect a classname pattern to be stored in BLOCK_STYLE_DEFINITIONS_METADATA.
						* One day, if there are no stored schemata, we could allow custom patterns or
						* generate classnames based on other properties
						* such as a path or a value or a prefix passed in options.
						*/
						$classnames[] = strtr( $classname, array( '$slug' => $slug ) );
					}
				}
			}

			return $classnames;
		}

		/**
		 * Returns an array of CSS declarations based on valid block style values.
		 *
		 * @since 6.1.0
		 *
		 * @param array $style_value      A single raw style value from $block_styles array.
		 * @param array $style_definition A single style definition from BLOCK_STYLE_DEFINITIONS_METADATA.
		 * @param array $options          {
		 *     Optional. An array of options. Default empty array.
		 *
		 *     @type bool $convert_vars_to_classnames Whether to skip converting incoming CSS var patterns, e.g., `var:preset|<PRESET_TYPE>|<PRESET_SLUG>`, to var( --wp--preset--* ) values. Default `false`.
		 * }
		 *
		 * @return string[] An associative array of CSS definitions, e.g., array( "$property" => "$value", "$property" => "$value" ).
		 */
		protected static function get_css_declarations( $style_value, $style_definition, $options = array() ) {
			if ( isset( $style_definition['value_func'] ) && is_callable( $style_definition['value_func'] ) ) {
				return call_user_func( $style_definition['value_func'], $style_value, $style_definition, $options );
			}

			$css_declarations     = array();
			$style_property_keys  = $style_definition['property_keys'];
			$should_skip_css_vars = isset( $options['convert_vars_to_classnames'] ) && true === $options['convert_vars_to_classnames'];

			/*
			* Build CSS var values from `var:preset|<PRESET_TYPE>|<PRESET_SLUG>` values, e.g, `var(--wp--css--rule-slug )`.
			* Check if the value is a CSS preset and there's a corresponding css_var pattern in the style definition.
			*/
			if ( is_string( $style_value ) && str_contains( $style_value, 'var:' ) ) {
				if ( ! $should_skip_css_vars && ! empty( $style_definition['css_vars'] ) ) {
					$css_var = static::get_css_var_value( $style_value, $style_definition['css_vars'] );
					if ( static::is_valid_style_value( $css_var ) ) {
						$css_declarations[ $style_property_keys['default'] ] = $css_var;
					}
				}
				return $css_declarations;
			}

			/*
			* Default rule builder.
			* If the input contains an array, assume box model-like properties
			* for styles such as margins and padding.
			*/
			if ( is_array( $style_value ) ) {
				// Bail out early if the `'individual'` property is not defined.
				if ( ! isset( $style_property_keys['individual'] ) ) {
					return $css_declarations;
				}

				foreach ( $style_value as $key => $value ) {
					if ( is_string( $value ) && str_contains( $value, 'var:' ) && ! $should_skip_css_vars && ! empty( $style_definition['css_vars'] ) ) {
						$value = static::get_css_var_value( $value, $style_definition['css_vars'] );
					}

					$individual_property = sprintf( $style_property_keys['individual'], _wp_to_kebab_case( $key ) );

					if ( $individual_property && static::is_valid_style_value( $value ) ) {
						$css_declarations[ $individual_property ] = $value;
					}
				}

				return $css_declarations;
			}

			$css_declarations[ $style_property_keys['default'] ] = $style_value;
			return $css_declarations;
		}

		/**
		 * Style value parser that returns a CSS definition array comprising style properties
		 * that have keys representing individual style properties, otherwise known as longhand CSS properties.
		 * e.g., "$style_property-$individual_feature: $value;", which could represent the following:
		 * "border-{top|right|bottom|left}-{color|width|style}: {value};" or,
		 * "border-image-{outset|source|width|repeat|slice}: {value};"
		 *
		 * @param array $style_value                    A single raw style value from $block_styles array.
		 * @param array $individual_property_definition A single style definition from BLOCK_STYLE_DEFINITIONS_METADATA representing an individual property of a CSS property, e.g., 'top' in 'border-top'.
		 * @param array $options                        {
		 *     Optional. An array of options. Default empty array.
		 *
		 *     @type bool $convert_vars_to_classnames Whether to skip converting incoming CSS var patterns, e.g., `var:preset|<PRESET_TYPE>|<PRESET_SLUG>`, to var( --wp--preset--* ) values. Default `false`.
		 * }
		 *
		 * @return string[] An associative array of CSS definitions, e.g., array( "$property" => "$value", "$property" => "$value" ).
		 */
		protected static function get_individual_property_css_declarations( $style_value, $individual_property_definition, $options = array() ) {
			if ( ! is_array( $style_value ) || empty( $style_value ) || empty( $individual_property_definition['path'] ) ) {
				return array();
			}

			/*
			* The first item in $individual_property_definition['path'] array tells us the style property, e.g., "border".
			* We use this to get a corresponding CSS style definition such as "color" or "width" from the same group.
			* The second item in $individual_property_definition['path'] array refers to the individual property marker, e.g., "top".
			*/
			$definition_group_key    = $individual_property_definition['path'][0];
			$individual_property_key = $individual_property_definition['path'][1];
			$should_skip_css_vars    = isset( $options['convert_vars_to_classnames'] ) && true === $options['convert_vars_to_classnames'];
			$css_declarations        = array();

			foreach ( $style_value as $css_property => $value ) {
				if ( empty( $value ) ) {
					continue;
				}

				// Build a path to the individual rules in definitions.
				$style_definition_path = array( $definition_group_key, $css_property );
				$style_definition      = _wp_array_get( static::BLOCK_STYLE_DEFINITIONS_METADATA, $style_definition_path, null );

				if ( $style_definition && isset( $style_definition['property_keys']['individual'] ) ) {
					// Set a CSS var if there is a valid preset value.
					if ( is_string( $value ) && str_contains( $value, 'var:' ) && ! $should_skip_css_vars && ! empty( $individual_property_definition['css_vars'] ) ) {
						$value = static::get_css_var_value( $value, $individual_property_definition['css_vars'] );
					}
					$individual_css_property                      = sprintf( $style_definition['property_keys']['individual'], $individual_property_key );
					$css_declarations[ $individual_css_property ] = $value;
				}
			}
			return $css_declarations;
		}

		/**
		 * Style value parser that constructs a CSS definition array comprising a single CSS property and value.
		 * If the provided value is an array containing a `url` property, the function will return a CSS definition array
		 * with a single property and value, with `url` escaped and injected into a CSS `url()` function,
		 * e.g., array( 'background-image' => "url( '...' )" ).
		 *
		 * @param array $style_value      A single raw style value from $block_styles array.
		 * @param array $style_definition A single style definition from BLOCK_STYLE_DEFINITIONS_METADATA.
		 *
		 * @return string[] An associative array of CSS definitions, e.g., array( "$property" => "$value", "$property" => "$value" ).
		 */
		protected static function get_url_or_value_css_declaration( $style_value, $style_definition ) {
			if ( empty( $style_value ) ) {
				return array();
			}

			$css_declarations = array();

			if ( isset( $style_definition['property_keys']['default'] ) ) {
				$value = null;

				if ( ! empty( $style_value['url'] ) ) {
					$value = "url('" . $style_value['url'] . "')";
				} elseif ( is_string( $style_value ) ) {
					$value = $style_value;
				}

				if ( null !== $value ) {
					$css_declarations[ $style_definition['property_keys']['default'] ] = $value;
				}
			}

			return $css_declarations;
		}

		/**
		 * Returns compiled CSS from css_declarations.
		 *
		 * @param string[] $css_declarations An associative array of CSS definitions, e.g., array( "$property" => "$value", "$property" => "$value" ).
		 * @param string   $css_selector     When a selector is passed, the function will return a full CSS rule `$selector { ...rules }`, otherwise a concatenated string of properties and values.
		 *
		 * @return string A compiled CSS string.
		 */
		public static function compile_css( $css_declarations, $css_selector ) {
			if ( empty( $css_declarations ) || ! is_array( $css_declarations ) ) {
				return '';
			}

			// Return an entire rule if there is a selector.
			if ( $css_selector ) {
				$css_rule = new WP_Style_Engine_CSS_Rule( $css_selector, $css_declarations );
				return $css_rule->get_css();
			}

			$css_declarations = new WP_Style_Engine_CSS_Declarations( $css_declarations );
			return $css_declarations->get_declarations_string();
		}

		/**
		 * Returns a compiled stylesheet from stored CSS rules.
		 *
		 * @param WP_Style_Engine_CSS_Rule[] $css_rules An array of WP_Style_Engine_CSS_Rule objects from a store or otherwise.
		 * @param array                      $options   {
		 *     Optional. An array of options. Default empty array.
		 *
		 *     @type bool $optimize Whether to optimize the CSS output, e.g., combine rules. Default is `false`.
		 *     @type bool $prettify Whether to add new lines and indents to output. Default is the test of whether the global constant `SCRIPT_DEBUG` is defined.
		 * }
		 *
		 * @return string A compiled stylesheet from stored CSS rules.
		 */
		public static function compile_stylesheet_from_css_rules( $css_rules, $options = array() ) {
			$processor = new WP_Style_Engine_Processor();
			$processor->add_rules( $css_rules );
			return $processor->get_css( $options );
		}
	}
}