Proof of concept: Web Fonts API as an extension of WP_Dependencies

lib/experimental/class-old-wp-webfonts.php

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+<?php
+/**
+ * Webfonts API class.
+ *
+ * @package    WordPress
+ * @subpackage WebFonts
+ * @since      6.0.0
+ */
+
+if ( class_exists( 'WP_Webfonts' ) ) {
+	return;
+}
+
+/**
+ * Class WP_Webfonts
+ *
+ * @since 6.0.0
+ */
+class WP_Webfonts {
+
+	/**
+	 * An array of registered webfonts.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @var array[]
+	 */
+	private $registered_webfonts = array();
+
+	/**
+	 * An array of enqueued webfonts.
+	 *
+	 * @var array[]
+	 */
+	private $enqueued_webfonts = array();
+
+	/**
+	 * An array of registered providers.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @var array
+	 */
+	private $providers = array();
+
+	/**
+	 * Stylesheet handle.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @var string
+	 */
+	private $stylesheet_handle = '';
+
+	/**
+	 * Init.
+	 *
+	 * @since 6.0.0
+	 */
+	public function init() {
+		// Register default providers.
+		$this->register_provider( 'local', 'WP_Webfonts_Provider_Local' );
+
+		// Register callback to generate and enqueue styles.
+		if ( did_action( 'wp_enqueue_scripts' ) ) {
+			$this->stylesheet_handle = 'webfonts-footer';
+			$hook                    = 'wp_print_footer_scripts';
+		} else {
+			$this->stylesheet_handle = 'webfonts';
+			$hook                    = 'wp_enqueue_scripts';
+		}
+		add_action( $hook, array( $this, 'generate_and_enqueue_styles' ) );
+
+		// Enqueue webfonts in the block editor.
+		add_action( 'admin_init', array( $this, 'generate_and_enqueue_editor_styles' ) );
+	}
+
+	/**
+	 * Get the list of all fonts.
+	 *
+	 * @return array[]
+	 */
+	public function get_all_webfonts() {
+		return array_merge( $this->get_registered_webfonts(), $this->get_enqueued_webfonts() );
+	}
+
+	/**
+	 * Get the list of providers.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @return WP_Webfonts_Provider[] All registered providers, each keyed by their unique ID.
+	 */
+	public function get_providers() {
+		return $this->providers;
+	}
+
+	/**
+	 * Register a webfont.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @param array $webfont Webfont to be registered.
+	 * @return string|false The font family slug if successfully registered, else false.
+	 */
+	public function register_webfont( array $webfont ) {
+		$webfont = $this->validate_webfont( $webfont );
+
+		// If not valid, bail out.
+		if ( ! $webfont ) {
+			return false;
+		}
+
+		$slug = $this->get_font_slug( $webfont );
+
+		// Initialize a new font-family collection.
+		if ( ! isset( $this->registered_webfonts[ $slug ] ) ) {
+			$this->registered_webfonts[ $slug ] = array();
+		}
+
+		$this->registered_webfonts[ $slug ][] = $webfont;
+		return $slug;
+	}
+
+	/**
+	 * Enqueue a font-family that has been already registered.
+	 *
+	 * @param string $font_family_name The font family name to be enqueued.
+	 * @return bool True if successfully enqueued, else false.
+	 */
+	public function enqueue_webfont( $font_family_name ) {
+		$slug = $this->get_font_slug( $font_family_name );
+
+		if ( isset( $this->enqueued_webfonts[ $slug ] ) ) {
+			return true;
+		}
+
+		if ( ! isset( $this->registered_webfonts[ $slug ] ) ) {
+			/* translators: %s unique slug to identify the font family of the webfont */
+			_doing_it_wrong( __METHOD__, sprintf( __( 'The "%s" font family is not registered.', 'gutenberg' ), $slug ), '6.0.0' );
+
+			return false;
+		}
+
+		$this->enqueued_webfonts[ $slug ] = $this->registered_webfonts[ $slug ];
+		unset( $this->registered_webfonts[ $slug ] );
+		return true;
+	}
+
+	/**
+	 * Get the font slug.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @param array|string $to_convert The value to convert into a slug. Expected as the web font's array
+	 *                                 or a font-family as a string.
+	 * @return string|false The font slug on success, or false if the font-family cannot be determined.
+	 */
+	public static function get_font_slug( $to_convert ) {
+		if ( is_array( $to_convert ) ) {
+			if ( isset( $to_convert['font-family'] ) ) {
+				$to_convert = $to_convert['font-family'];
+			} elseif ( isset( $to_convert['fontFamily'] ) ) {
+				$to_convert = $to_convert['fontFamily'];
+			} else {
+				_doing_it_wrong( __METHOD__, __( 'Could not determine the font family name.', 'gutenberg' ), '6.0.0' );
+				return false;
+			}
+		}
+
+		return sanitize_title( $to_convert );
+	}
+
+	/**
+	 * Validate a webfont.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @param array $webfont The webfont arguments.
+	 *
+	 * @return array|false The validated webfont arguments, or false if the webfont is invalid.
+	 */
+	public function validate_webfont( $webfont ) {
+		$webfont = wp_parse_args(
+			$webfont,
+			array(
+				'provider'     => 'local',
+				'font-family'  => '',
+				'font-style'   => 'normal',
+				'font-weight'  => '400',
+				'font-display' => 'fallback',
+			)
+		);
+
+		// Check the font-family.
+		if ( empty( $webfont['font-family'] ) || ! is_string( $webfont['font-family'] ) ) {
+			trigger_error( __( 'Webfont font family must be a non-empty string.', 'gutenberg' ) );
+			return false;
+		}
+
+		// Local fonts need a "src".
+		if ( 'local' === $webfont['provider'] ) {
+			// Make sure that local fonts have 'src' defined.
+			if ( empty( $webfont['src'] ) || ( ! is_string( $webfont['src'] ) && ! is_array( $webfont['src'] ) ) ) {
+				trigger_error( __( 'Webfont src must be a non-empty string or an array of strings.', 'gutenberg' ) );
+				return false;
+			}
+		}
+
+		// Validate the 'src' property.
+		if ( ! empty( $webfont['src'] ) ) {
+			foreach ( (array) $webfont['src'] as $src ) {
+				if ( empty( $src ) || ! is_string( $src ) ) {
+					trigger_error( __( 'Each webfont src must be a non-empty string.', 'gutenberg' ) );
+					return false;
+				}
+			}
+		}
+
+		// Check the font-weight.
+		if ( ! is_string( $webfont['font-weight'] ) && ! is_int( $webfont['font-weight'] ) ) {
+			trigger_error( __( 'Webfont font weight must be a properly formatted string or integer.', 'gutenberg' ) );
+			return false;
+		}
+
+		// Check the font-display.
+		if ( ! in_array( $webfont['font-display'], array( 'auto', 'block', 'fallback', 'swap' ), true ) ) {
+			$webfont['font-display'] = 'fallback';
+		}
+
+		$valid_props = array(
+			'ascend-override',
+			'descend-override',
+			'font-display',
+			'font-family',
+			'font-stretch',
+			'font-style',
+			'font-weight',
+			'font-variant',
+			'font-feature-settings',
+			'font-variation-settings',
+			'line-gap-override',
+			'size-adjust',
+			'src',
+			'unicode-range',
+
+			// Exceptions.
+			'provider',
+		);
+
+		foreach ( $webfont as $prop => $value ) {
+			if ( ! in_array( $prop, $valid_props, true ) ) {
+				unset( $webfont[ $prop ] );
+			}
+		}
+
+		return $webfont;
+	}
+
+	/**
+	 * Register a provider.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @param string $provider The provider name.
+	 * @param string $class    The provider class name.
+	 * @return bool True if successfully registered, else false.
+	 */
+	public function register_provider( $provider, $class ) {
+		if ( empty( $provider ) || empty( $class ) ) {
+			return false;
+		}
+		$this->providers[ $provider ] = $class;
+		return true;
+	}
+
+	/**
+	 * Generate and enqueue webfonts styles.
+	 *
+	 * @since 6.0.0
+	 */
+	public function generate_and_enqueue_styles() {
+		// Generate the styles.
+		$webfonts = $this->get_webfonts_by_provider( $this->get_enqueued_webfonts() );
+		$styles   = $this->generate_styles( $webfonts );
+
+		// Bail out if there are no styles to enqueue.
+		if ( '' === $styles ) {
+			return;
+		}
+
+		// Enqueue the stylesheet.
+		wp_register_style( $this->stylesheet_handle, '' );
+		wp_enqueue_style( $this->stylesheet_handle );
+
+		// Add the styles to the stylesheet.
+		wp_add_inline_style( $this->stylesheet_handle, $styles );
+	}
+
+	/**
+	 * Generate and enqueue editor styles.
+	 *
+	 * @since 6.0.0
+	 */
+	public function generate_and_enqueue_editor_styles() {
+		// Generate the styles.
+		$webfonts = $this->get_webfonts_by_provider( $this->get_all_webfonts() );
+		$styles   = $this->generate_styles( $webfonts );
+
+		// Bail out if there are no styles to enqueue.
+		if ( '' === $styles ) {
+			return;
+		}
+
+		wp_enqueue_style( 'wp-block-library' );
+		wp_add_inline_style( 'wp-block-library', $styles );
+	}
+
+	/**
+	 * Generate styles for webfonts.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @param array[] $webfonts_by_provider Webfonts organized by provider.
+	 * @return string $styles Generated styles.
+	 */
+	private function generate_styles( array $webfonts_by_provider ) {
+		$styles    = '';
+		$providers = $this->get_providers();
+
+		/*
+		 * Loop through each of the providers to get the CSS for their respective webfonts
+		 * to incrementally generate the collective styles for all of them.
+		 */
+		foreach ( $providers as $provider_id => $provider_class ) {
+
+			// Bail out if the provider class does not exist.
+			if ( ! class_exists( $provider_class ) ) {
+				/* translators: %s is the provider name. */
+				trigger_error( sprintf( __( 'Webfont provider "%s" is not registered.', 'gutenberg' ), $provider_id ) );
+				continue;
+			}
+
+			$provider_webfonts = isset( $webfonts_by_provider[ $provider_id ] )
+				? $webfonts_by_provider[ $provider_id ]
+				: array();
+
+			// If there are no registered webfonts for this provider, skip it.
+			if ( empty( $provider_webfonts ) ) {
+				continue;
+			}
+
+			/*
+			 * Process the webfonts by first passing them to the provider via `set_webfonts()`
+			 * and then getting the CSS from the provider.
+			 */
+			$provider = new $provider_class();
+			$provider->set_webfonts( $provider_webfonts );
+			$styles .= $provider->get_css();
+		}
+
+		return $styles;
+	}
+
+
+	/**
+	 * Reorganizes webfonts grouped by font-family into grouped by provider.
+	 *
+	 * @param array[] $font_families Font families and each of their webfonts.
+	 * @return array[] Webfonts organized by providers.
+	 */
+	private function get_webfonts_by_provider( array $font_families ) {
+		$providers            = $this->get_providers();
+		$webfonts_by_provider = array();
+
+		foreach ( $font_families as $webfonts ) {
+			foreach ( $webfonts as $webfont ) {
+				$provider = $webfont['provider'];
+
+				// Skip if the provider is not registered.
+				if ( ! isset( $providers[ $provider ] ) ) {
+					/* translators: %s is the provider name. */
+					trigger_error( sprintf( __( 'Webfont provider "%s" is not registered.', 'gutenberg' ), $provider ) );
+					continue;
+				}
+
+				// Initialize a new provider collection.
+				if ( ! isset( $webfonts_by_provider[ $provider ] ) ) {
+					$webfonts_by_provider[ $provider ] = array();
+				}
+				$webfonts_by_provider[ $provider ][] = $webfont;
+			}
+		}
+
+		return $webfonts_by_provider;
+	}
+}