<?php

/**

 * WP_Font_Face class.

 *

 * @package    WordPress

 * @subpackage Fonts

 * @since      6.4.0

 */

/**

 * Font Face generates and prints `@font-face` styles for given fonts.

 *

 * @since 6.4.0

 */

class WP_Font_Face {

	/**

	 * The font-face property defaults.

	 *

	 * @since 6.4.0

	 *

	 * @var string[]

	 */

	private $font_face_property_defaults = array(

		'font-family'  => '',

		'font-style'   => 'normal',

		'font-weight'  => '400',

		'font-display' => 'fallback',

	);

	/**

	 * Valid font-face property names.

	 *

	 * @since 6.4.0

	 *

	 * @var string[]

	 */

	private $valid_font_face_properties = array(

		'ascent-override',

		'descent-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',

	);

	/**

	 * Valid font-display values.

	 *

	 * @since 6.4.0

	 *

	 * @var string[]

	 */

	private $valid_font_display = array( 'auto', 'block', 'fallback', 'swap', 'optional' );

	/**

	 * Array of font-face style tag's attribute(s)

	 * where the key is the attribute name and the

	 * value is its value.

	 *

	 * @since 6.4.0

	 *

	 * @var string[]

	 */

	private $style_tag_attrs = array();

	/**

	 * Creates and initializes an instance of WP_Font_Face.

	 *

	 * @since 6.4.0

	 */

	public function __construct() {

		if (

			function_exists( 'is_admin' ) && ! is_admin()

			&&

			function_exists( 'current_theme_supports' ) && ! current_theme_supports( 'html5', 'style' )

		) {

			$this->style_tag_attrs = array( 'type' => 'text/css' );

		}

	}

	/**

	 * Generates and prints the `@font-face` styles for the given fonts.

	 *

	 * @since 6.4.0

	 *

	 * @param array[][] $fonts Optional. The font-families and their font variations.

	 *                         See {@see wp_print_font_faces()} for the supported fields.

	 *                         Default empty array.

	 */

	public function generate_and_print( array $fonts ) {

		$fonts = $this->validate_fonts( $fonts );

		// Bail out if there are no fonts are given to process.

		if ( empty( $fonts ) ) {

			return;

		}

		$css = $this->get_css( $fonts );

		/*

		 * The font-face CSS is contained within <style> tags and can only be interpreted

		 * as CSS in the browser. Using wp_strip_all_tags() is sufficient escaping

		 * to avoid malicious attempts to close </style> and open a <script>.

		 */

		$css = wp_strip_all_tags( $css );

		// Bail out if there is no CSS to print.

		if ( empty( $css ) ) {

			return;

		}

		printf( $this->get_style_element(), $css );

	}

	/**

	 * Validates each of the font-face properties.

	 *

	 * @since 6.4.0

	 *

	 * @param array $fonts The fonts to valid.

	 * @return array Prepared font-faces organized by provider and font-family.

	 */

	private function validate_fonts( array $fonts ) {

		$validated_fonts = array();

		foreach ( $fonts as $font_faces ) {

			foreach ( $font_faces as $font_face ) {

				$font_face = $this->validate_font_face_declarations( $font_face );

				// Skip if failed validation.

				if ( false === $font_face ) {

					continue;

				}

				$validated_fonts[] = $font_face;

			}

		}

		return $validated_fonts;

	}

	/**

	 * Validates each font-face declaration (property and value pairing).

	 *

	 * @since 6.4.0

	 *

	 * @param array $font_face Font face property and value pairings to validate.

	 * @return array|false Validated font-face on success, or false on failure.

	 */

	private function validate_font_face_declarations( array $font_face ) {

		$font_face = wp_parse_args( $font_face, $this->font_face_property_defaults );

		// Check the font-family.

		if ( empty( $font_face['font-family'] ) || ! is_string( $font_face['font-family'] ) ) {

			// @todo replace with `wp_trigger_error()`.

			_doing_it_wrong(

				__METHOD__,

				__( 'Font font-family must be a non-empty string.' ),

				'6.4.0'

			);

			return false;

		}

		// Make sure that local fonts have 'src' defined.

		if ( empty( $font_face['src'] ) || ( ! is_string( $font_face['src'] ) && ! is_array( $font_face['src'] ) ) ) {

			// @todo replace with `wp_trigger_error()`.

			_doing_it_wrong(

				__METHOD__,

				__( 'Font src must be a non-empty string or an array of strings.' ),

				'6.4.0'

			);

			return false;

		}

		// Validate the 'src' property.

		foreach ( (array) $font_face['src'] as $src ) {

			if ( empty( $src ) || ! is_string( $src ) ) {

				// @todo replace with `wp_trigger_error()`.

				_doing_it_wrong(

					__METHOD__,

					__( 'Each font src must be a non-empty string.' ),

					'6.4.0'

				);

				return false;

			}

		}

		// Check the font-weight.

		if ( ! is_string( $font_face['font-weight'] ) && ! is_int( $font_face['font-weight'] ) ) {

			// @todo replace with `wp_trigger_error()`.

			_doing_it_wrong(

				__METHOD__,

				__( 'Font font-weight must be a properly formatted string or integer.' ),

				'6.4.0'

			);

			return false;

		}

		// Check the font-display.

		if ( ! in_array( $font_face['font-display'], $this->valid_font_display, true ) ) {

			$font_face['font-display'] = $this->font_face_property_defaults['font-display'];

		}

		// Remove invalid properties.

		foreach ( $font_face as $property => $value ) {

			if ( ! in_array( $property, $this->valid_font_face_properties, true ) ) {

				unset( $font_face[ $property ] );

			}

		}

		return $font_face;

	}

	/**

	 * Gets the style element for wrapping the `@font-face` CSS.

	 *

	 * @since 6.4.0

	 *

	 * @return string The style element.

	 */

	private function get_style_element() {

		$attributes = $this->generate_style_element_attributes();

		return "<style class='wp-fonts-local'{$attributes}>\n%s\n</style>\n";

	}

	/**

	 * Gets the defined <style> element's attributes.

	 *

	 * @since 6.4.0

	 *

	 * @return string A string of attribute=value when defined, else, empty string.

	 */

	private function generate_style_element_attributes() {

		$attributes = '';

		foreach ( $this->style_tag_attrs as $name => $value ) {

			$attributes .= " {$name}='{$value}'";

		}

		return $attributes;

	}

	/**

	 * Gets the `@font-face` CSS styles for locally-hosted font files.

	 *

	 * This method does the following processing tasks:

	 *    1. Orchestrates an optimized `src` (with format) for browser support.

	 *    2. Generates the `@font-face` for all its fonts.

	 *

	 * @since 6.4.0

	 *

	 * @param array[] $font_faces The font-faces to generate @font-face CSS styles.

	 * @return string The `@font-face` CSS styles.

	 */

	private function get_css( $font_faces ) {

		$css = '';

		foreach ( $font_faces as $font_face ) {

				// Order the font's `src` items to optimize for browser support.

				$font_face = $this->order_src( $font_face );

				// Build the @font-face CSS for this font.

				$css .= '@font-face{' . $this->build_font_face_css( $font_face ) . '}' . "\n";

		}

		// Don't print the last newline character.

		return rtrim( $css, "\n" );

	}

	/**

	 * Orders `src` items to optimize for browser support.

	 *

	 * @since 6.4.0

	 *

	 * @param array $font_face Font face to process.

	 * @return array Font-face with ordered src items.

	 */

	private function order_src( array $font_face ) {

		if ( ! is_array( $font_face['src'] ) ) {

			$font_face['src'] = (array) $font_face['src'];

		}

		$src         = array();

		$src_ordered = array();

		foreach ( $font_face['src'] as $url ) {

			// Add data URIs first.

			if ( str_starts_with( trim( $url ), 'data:' ) ) {

				$src_ordered[] = array(

					'url'    => $url,

					'format' => 'data',

				);

				continue;

			}

			$format         = pathinfo( $url, PATHINFO_EXTENSION );

			$src[ $format ] = $url;

		}

		// Add woff2.

		if ( ! empty( $src['woff2'] ) ) {

			$src_ordered[] = array(

				'url'    => $src['woff2'],

				'format' => 'woff2',

			);

		}

		// Add woff.

		if ( ! empty( $src['woff'] ) ) {

			$src_ordered[] = array(

				'url'    => $src['woff'],

				'format' => 'woff',

			);

		}

		// Add ttf.

		if ( ! empty( $src['ttf'] ) ) {

			$src_ordered[] = array(

				'url'    => $src['ttf'],

				'format' => 'truetype',

			);

		}

		// Add eot.

		if ( ! empty( $src['eot'] ) ) {

			$src_ordered[] = array(

				'url'    => $src['eot'],

				'format' => 'embedded-opentype',

			);

		}

		// Add otf.

		if ( ! empty( $src['otf'] ) ) {

			$src_ordered[] = array(

				'url'    => $src['otf'],

				'format' => 'opentype',

			);

		}

		$font_face['src'] = $src_ordered;

		return $font_face;

	}

	/**

	 * Builds the font-family's CSS.

	 *

	 * @since 6.4.0

	 *

	 * @param array $font_face Font face to process.

	 * @return string This font-family's CSS.

	 */

	private function build_font_face_css( array $font_face ) {

		$css = '';

		/*

		 * Wrap font-family in quotes if it contains spaces

		 * and is not already wrapped in quotes.

		 */

		if (

			str_contains( $font_face['font-family'], ' ' ) &&

			! str_contains( $font_face['font-family'], '"' ) &&

			! str_contains( $font_face['font-family'], "'" )

		) {

			$font_face['font-family'] = '"' . $font_face['font-family'] . '"';

		}

		foreach ( $font_face as $key => $value ) {

			// Compile the "src" parameter.

			if ( 'src' === $key ) {

				$value = $this->compile_src( $value );

			}

			// If font-variation-settings is an array, convert it to a string.

			if ( 'font-variation-settings' === $key && is_array( $value ) ) {

				$value = $this->compile_variations( $value );

			}

			if ( ! empty( $value ) ) {

				$css .= "$key:$value;";

			}

		}

		return $css;

	}

	/**

	 * Compiles the `src` into valid CSS.

	 *

	 * @since 6.4.0

	 *

	 * @param array $value Value to process.

	 * @return string The CSS.

	 */

	private function compile_src( array $value ) {

		$src = '';

		foreach ( $value as $item ) {

			$src .= ( 'data' === $item['format'] )

				? ", url({$item['url']})"

				: ", url('{$item['url']}') format('{$item['format']}')";

		}

		$src = ltrim( $src, ', ' );

		return $src;

	}

	/**

	 * Compiles the font variation settings.

	 *

	 * @since 6.4.0

	 *

	 * @param array $font_variation_settings Array of font variation settings.

	 * @return string The CSS.

	 */

	private function compile_variations( array $font_variation_settings ) {

		$variations = '';

		foreach ( $font_variation_settings as $key => $value ) {

			$variations .= "$key $value";

		}

		return $variations;

	}

}