<?php
/**
 * Handles lazyloading of images
 *
 * @package RocketLazyload
 */

namespace RocketLazyload;

/**
 * A class to provide the methods needed to lazyload images in WP Rocket and Lazyload by WP Rocket
 */
class Image {

	/**
	 * Finds the images to be lazyloaded and call the callback method to replace them.
	 *
	 * @param string $html   Original HTML.
	 * @param string $buffer Content to parse.
	 * @return string
	 */
	public function lazyloadImages( $html, $buffer ) {
		$clean_buffer = preg_replace( '/<script\b(?:[^>]*)>(?:.+)?<\/script>/Umsi', '', $html );
		$clean_buffer = preg_replace( '#<noscript>(?:.+)</noscript>#Umsi', '', $clean_buffer );
		if (! preg_match_all('#<img(?<atts>\s.+)\s?/?>#iUs', $clean_buffer, $images, PREG_SET_ORDER)) {
			return $html;
		}

		$images = array_unique( $images, SORT_REGULAR );

		foreach ( $images as $image ) {
			$image = $this->canLazyload( $image );

			if ( ! $image ) {
				continue;
			}

			$image_lazyload  = $this->replaceImage( $image );
			$image_lazyload .= $this->noscript( $image[0] );
			$html            = str_replace( $image[0], $image_lazyload, $html );

			unset( $image_lazyload );
		}

		return $html;
	}

	/**
	 * Applies lazyload on background images defined in style attributes
	 *
	 * @param string $html   Original HTML.
	 * @param string $buffer Content to parse.
	 * @return string
	 */
	public function lazyloadBackgroundImages( $html, $buffer ) {
		if ( ! preg_match_all( '#<(?<tag>div|figure|section|span|li|a)\s+(?<before>[^>]+[\'"\s])?style\s*=\s*([\'"])(?<styles>.*?)\3(?<after>[^>]*)>#is', $buffer, $elements, PREG_SET_ORDER ) ) {
			return $html;
		}

		foreach ( $elements as $element ) {
			if ( $this->isExcluded( $element['before'] . $element['after'], $this->getExcludedAttributes() ) ) {
				continue;
			}

			if ( ! preg_match( '#background-image\s*:\s*(?<attr>\s*url\s*\((?<url>[^)]+)\))\s*;?#is', $element['styles'], $url ) ) {
				continue;
			}

			$url['url'] = esc_url(
				trim(
					strip_tags(
						html_entity_decode(
							$url['url'], ENT_QUOTES|ENT_HTML5
						)
					), '\'" '
				)
			);

			if ( $this->isExcluded( $url['url'], $this->getExcludedSrc() ) ) {
				continue;
			}

			$lazy_bg = $this->addLazyCLass( $element[0] );
			$lazy_bg = str_replace( $url[0], '', $lazy_bg );
			$lazy_bg = str_replace( '<' . $element['tag'], '<' . $element['tag'] . ' data-bg="' . esc_attr( $url['url'] ) . '"', $lazy_bg );

			$html = str_replace( $element[0], $lazy_bg, $html );
			unset( $lazy_bg );
		}

		return $html;
	}

	/**
	 * Add the identifier class to the element
	 *
	 * @param string $element Element to add the class to.
	 * @return string
	 */
	private function addLazyClass( $element ) {
		$class = $this->getClasses( $element );
		if ( empty( $class )  ) {
			return preg_replace( '#<(img|div|figure|section|li|span|a)([^>]*)>#is', '<\1 class="rocket-lazyload"\2>', $element );
		}

		if ( empty( $class['attribute'] ) || empty( $class['classes'] ) ) {
			return str_replace( $class['attribute'], 'class="rocket-lazyload"', $element );
		}

		$quotes  = $this->getAttributeQuotes( $class['classes'] );
		$classes = $this->trimOuterQuotes( $class['classes'], $quotes );

		if ( empty( $classes ) ) {
			return str_replace( $class['attribute'], 'class="rocket-lazyload"', $element );
		}

		$classes .= ' rocket-lazyload';

		return str_replace(
			$class['attribute'],
			'class=' . $this->normalizeClasses( $classes, $quotes ),
			$element
		);
	}

	/**
	 * Gets the attribute value's outer quotation mark, if one exists, i.e. " or '.
	 *
	 * @param string $attribute_value The target attribute's value.
	 *
	 * @return bool|string quotation character; else false when no quotation mark.
	 */
	private function getAttributeQuotes( $attribute_value ) {
		$attribute_value = trim( $attribute_value );
		$first_char = $attribute_value[0];

		if ( '"' === $first_char || "'" === $first_char ) {
			return $first_char;
		}

		return false;
	}

	/**
	 * Gets the class attribute and values from the given element, if it exists.
	 *
	 * @param string $element Given HTML element to extract classes from.
	 *
	 * @return bool|string[] {
	 *      @type string $attribute Class attribute and value, e.g. class="value"
	 *      @type string $classes   String of class attribute's value(s)
	 * }; else, false when no class attribute exists.
	 */
	private function getClasses( $element ) {
		if ( ! preg_match( '#class\s*=\s*(?<classes>["\'].*?["\']|[^\s]+)#is', $element, $class ) ) {
			return false;
		}

		if ( empty( $class ) ) {
			return false;
		}

		if ( ! isset( $class['classes'] ) ) {
			return false;
		}

		return [
			'attribute' => $class[0],
			'classes'   => $class['classes'],
		];
	}

	/**
	 * Removes outer single or double quotations.
	 *
	 * @param string $string String to strip quotes from.
	 * @param string $quotes The outer quotes to remove.
	 *
	 * @return string string without quotes.
	 */
	private function trimOuterQuotes( $string, $quotes ) {
		$string = trim( $string );
		if ( empty( $string ) ) {
			return '';
		}

		if ( empty( $quotes ) ) {
			return $string;
		}

		$string = ltrim( $string, $quotes );
		$string = rtrim( $string, $quotes );
		return trim( $string );
	}

	/**
	 * Normalizes the class attribute values to ensure well-formed.
	 *
	 * @param string      $classes String of class attribute value(s).
	 * @param string|bool $quotes  Optional. Quotation mark to wrap around the classes.
	 *
	 * @return string well-formed class attributes.
	 */
	private function normalizeClasses( $classes, $quotes = '"' ) {
		$array_of_classes = $this->stringToArray( $classes );
		$classes          = implode( ' ', $array_of_classes );

		if ( false === $quotes ) {
			$quotes = '"';
		}

		return $quotes . $classes . $quotes;
	}

	/**
	 * Converts the given string into an array of strings.
	 *
	 * Note:
	 *  1. Removes empties.
	 *  2. Trims each string.
	 *
	 * @param string $string    The target string to convert.
	 * @param string $delimiter Optional. Default: ' ' empty string.
	 *
	 * @return array An array of trimmed strings.
	 */
	private function stringToArray( $string, $delimiter = ' ' ) {
		if ( empty( $string ) ) {
			return [];
		}

		$array = explode( $delimiter, $string );
		$array = array_map('trim', $array );

		// Remove empties.
		return array_filter( $array );
	}

	/**
	 * Applies lazyload on picture elements found in the HTML.
	 *
	 * @param string $html   Original HTML.
	 * @param string $buffer Content to parse.
	 * @return string
	 */
	public function lazyloadPictures( $html, $buffer ) {
		if ( ! preg_match_all( '#<picture(?:.*)?>(?<sources>.*)</picture>#iUs', $buffer, $pictures, PREG_SET_ORDER ) ) {
			return $html;
		}

		$pictures = array_unique( $pictures, SORT_REGULAR );
		$excluded = array_merge( $this->getExcludedAttributes(), $this->getExcludedSrc() );

		foreach ( $pictures as $picture ) {
			if ( $this->isExcluded( $picture[0], $excluded ) ) {
				continue;
			}

			if ( preg_match_all( '#<source(?<atts>\s.+)>#iUs', $picture['sources'], $sources, PREG_SET_ORDER ) ) {
				$sources = array_unique( $sources, SORT_REGULAR );

				$lazy_sources = 0;

				foreach ( $sources as $source ) {
					$lazyload_srcset = preg_replace( '/([\s"\'])srcset/i', '\1data-lazy-srcset', $source[0] );
					$html            = str_replace( $source[0], $lazyload_srcset, $html );

					unset( $lazyload_srcset );
					$lazy_sources++;
				}
			}

			if ( 0 === $lazy_sources ) {
				continue;
			}

			if ( ! preg_match( '#<img(?<atts>\s.+)\s?/?>#iUs', $picture[0], $img ) ) {
				continue;
			}

			$img = $this->canLazyload( $img );

			if ( ! $img ) {
				continue;
			}

			$img_lazy  = $this->replaceImage( $img );
			$img_lazy .= $this->noscript( $img[0] );
			$safe_img = str_replace('/', '\/', preg_quote( $img[0], '#' ));
			$html      = preg_replace( '#<noscript[^>]*>.*' . $safe_img . '.*<\/noscript>(*SKIP)(*FAIL)|' . $safe_img . '#iU', $img_lazy, $html );

			unset( $img_lazy );
		}

		return $html;
	}

	/**
	 * Checks if the image can be lazyloaded
	 *
	 * @param Array $image Array of image data coming from Regex.
	 * @return bool|Array
	 */
	private function canLazyload( $image ) {
		if ( $this->isExcluded( $image['atts'], $this->getExcludedAttributes() ) ) {
			return false;
		}

		// Given the previous regex pattern, $image['atts'] starts with a whitespace character.
		if ( ! preg_match( '@\ssrc\s*=\s*(\'|")(?<src>.*)\1@iUs', $image['atts'], $atts ) ) {
			return false;
		}

		$image['src'] = trim( $atts['src'] );

		if ( '' === $image['src'] ) {
			return false;
		}

		if ( $this->isExcluded( $image['src'], $this->getExcludedSrc() ) ) {
			return false;
		}

		// Don't apply LazyLoad on images from WP Retina x2.
		if ( function_exists( 'wr2x_picture_rewrite' ) ) {
			if ( wr2x_get_retina( trailingslashit( ABSPATH ) . wr2x_get_pathinfo_from_image_src( trim( $image['src'], '"' ) ) ) ) {
				return false;
			}
		}

		return $image;
	}

	/**
	 * Checks if the provided string matches with the provided excluded patterns
	 *
	 * @param string $string          String to check.
	 * @param array  $excluded_values Patterns to match against.
	 * @return boolean
	 */
	public function isExcluded( $string, $excluded_values ) {
		if ( ! is_array( $excluded_values ) ) {
			(array) $excluded_values;
		}

		if ( empty( $excluded_values ) ) {
			return false;
		}

		foreach ( $excluded_values as $excluded_value ) {
			if ( strpos( $string, $excluded_value ) !== false ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Returns the list of excluded attributes
	 *
	 * @return array
	 */
	public function getExcludedAttributes() {
		/**
		 * Filters the attributes used to prevent lazylad from being applied
		 *
		 * @since 1.0
		 * @author Remy Perona
		 *
		 * @param array $excluded_attributes An array of excluded attributes.
		 */
		return apply_filters(
			'rocket_lazyload_excluded_attributes',
			[
				'data-src=',
				'data-no-lazy=',
				'data-lazy-original=',
				'data-lazy-src=',
				'data-lazysrc=',
				'data-lazyload=',
				'data-bgposition=',
				'data-envira-src=',
				'fullurl=',
				'lazy-slider-img=',
				'data-srcset=',
				'class="ls-l',
				'class="ls-bg',
				'soliloquy-image',
				'loading="eager"',
				'swatch-img',
				'data-height-percentage',
				'data-large_image',
				'avia-bg-style-fixed',
				'data-skip-lazy',
				'skip-lazy',
			]
		);
	}

	/**
	 * Returns the list of excluded src
	 *
	 * @return array
	 */
	public function getExcludedSrc() {
		/**
		 * Filters the src used to prevent lazylad from being applied
		 *
		 * @since 1.0
		 * @author Remy Perona
		 *
		 * @param array $excluded_src An array of excluded src.
		 */
		return apply_filters(
			'rocket_lazyload_excluded_src',
			[
				'/wpcf7_captcha/',
				'timthumb.php?src',
				'woocommerce/assets/images/placeholder.png',
			]
		);
	}

	/**
	 * Replaces the original image by the lazyload one
	 *
	 * @param array $image Array of matches elements.
	 * @return string
	 */
	private function replaceImage( $image ) {
		$width  = 0;
		$height = 0;

		if ( preg_match( '@[\s"\']width\s*=\s*(\'|")(?<width>.*)\1@iUs', $image['atts'], $atts ) ) {
			$width = absint( $atts['width'] );
		}

		if ( preg_match( '@[\s"\']height\s*=\s*(\'|")(?<height>.*)\1@iUs', $image['atts'], $atts ) ) {
			$height = absint( $atts['height'] );
		}

		$placeholder_atts = preg_replace( '@\ssrc\s*=\s*(\'|")(?<src>.*)\1@iUs', ' src="' . $this->getPlaceholder( $width, $height ) . '"', $image['atts'] );

		$image_lazyload = str_replace( $image['atts'], $placeholder_atts . ' data-lazy-src="' . $image['src'] . '"', $image[0] );

		if ( ! preg_match( '@\sloading\s*=\s*(\'|")(?:lazy|auto)\1@i', $image_lazyload ) && apply_filters( 'rocket_use_native_lazyload', false ) ) {
			$image_lazyload = str_replace( '<img', '<img loading="lazy"', $image_lazyload );
		}

		/**
		 * Filter the LazyLoad HTML output
		 *
		 * @since 1.0
		 *
		 * @param string $html Output that will be printed
		 */
		$image_lazyload = apply_filters( 'rocket_lazyload_html', $image_lazyload );

		return $image_lazyload;
	}

	/**
	 * Returns the HTML tag wrapped inside noscript tags
	 *
	 * @param string $element Element to wrap.
	 * @return string
	 */
	private function noscript( $element ) {
		return '<noscript>' . $element . '</noscript>';
	}

	/**
	 * Applies lazyload on srcset and sizes attributes
	 *
	 * @param string $html HTML image tag.
	 * @return string
	 */
	public function lazyloadResponsiveAttributes( $html ) {
		$html = preg_replace( '/[\s|"|\'](srcset)\s*=\s*("|\')([^"|\']+)\2/i', ' data-lazy-$1=$2$3$2', $html );
		$html = preg_replace( '/[\s|"|\'](sizes)\s*=\s*("|\')([^"|\']+)\2/i', ' data-lazy-$1=$2$3$2', $html );

		return $html;
	}

	/**
	 * Finds patterns matching smiley and call the callback method to replace them with the image
	 *
	 * @param string $text Content to search in.
	 * @return string
	 */
	public function convertSmilies( $text ) {
		global $wp_smiliessearch;

		if ( ! get_option( 'use_smilies' ) || empty( $wp_smiliessearch ) ) {
			return $text;
		}

		$output = '';
		// HTML loop taken from texturize function, could possible be consolidated.
		$textarr = preg_split( '/(<.*>)/U', $text, -1, PREG_SPLIT_DELIM_CAPTURE ); // capture the tags as well as in between.
		$stop    = count( $textarr );// loop stuff.

		// Ignore proessing of specific tags.
		$tags_to_ignore       = 'code|pre|style|script|textarea';
		$ignore_block_element = '';

		for ( $i = 0; $i < $stop; $i++ ) {
			$content = $textarr[ $i ];

			// If we're in an ignore block, wait until we find its closing tag.
			if ( '' === $ignore_block_element && preg_match( '/^<(' . $tags_to_ignore . ')>/', $content, $matches ) ) {
				$ignore_block_element = $matches[1];
			}

			// If it's not a tag and not in ignore block.
			if ( '' === $ignore_block_element && strlen( $content ) > 0 && '<' !== $content[0] ) {
				$content = preg_replace_callback( $wp_smiliessearch, [ $this, 'translateSmiley' ], $content );
			}

			// did we exit ignore block.
			if ( '' !== $ignore_block_element && '</' . $ignore_block_element . '>' === $content ) {
				$ignore_block_element = '';
			}

			$output .= $content;
		}

		return $output;
	}

	/**
	 * Replace matches by smiley image, lazyloaded
	 *
	 * @param array $matches Array of matches.
	 * @return string
	 */
	private function translateSmiley( $matches ) {
		global $wpsmiliestrans;

		if ( count( $matches ) === 0 ) {
			return '';
		}

		$smiley = trim( reset( $matches ) );
		$img    = $wpsmiliestrans[ $smiley ];

		$matches    = [];
		$ext        = preg_match( '/\.([^.]+)$/', $img, $matches ) ? strtolower( $matches[1] ) : false;
		$image_exts = [ 'jpg', 'jpeg', 'jpe', 'gif', 'png' ];

		// Don't convert smilies that aren't images - they're probably emoji.
		if ( ! in_array( $ext, $image_exts, true ) ) {
			return $img;
		}

		/**
		 * Filter the Smiley image URL before it's used in the image element.
		 *
		 * @since 2.9.0
		 *
		 * @param string $smiley_url URL for the smiley image.
		 * @param string $img        Filename for the smiley image.
		 * @param string $site_url   Site URL, as returned by site_url().
		 */
		$src_url = apply_filters( 'smilies_src', includes_url( "images/smilies/$img" ), $img, site_url() );

		// Don't LazyLoad if process is stopped for these reasons.
		if ( is_feed() || is_preview() ) {
			return sprintf( ' <img src="%s" alt="%s" class="wp-smiley" /> ', esc_url( $src_url ), esc_attr( $smiley ) );
		}

		return sprintf( ' <img src="%s" data-lazy-src="%s" alt="%s" class="wp-smiley" /> ', $this->getPlaceholder(), esc_url( $src_url ), esc_attr( $smiley ) );
	}

	/**
	 * Returns the placeholder for the src attribute
	 *
	 * @since 1.2
	 * @author Remy Perona
	 *
	 * @param int $width  Width of the placeholder image. Default 0.
	 * @param int $height Height of the placeholder image. Default 0.
	 * @return string
	 */
	public function getPlaceholder( $width = 0, $height = 0 ) {
		$width  = 0 === $width ? 0 : absint( $width );
		$height = 0 === $height ? 0 : absint( $height );

		$placeholder = str_replace( ' ', '%20', "data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 $width $height'%3E%3C/svg%3E" );
		/**
		 * Filter the image lazyLoad placeholder on src attribute
		 *
		 * @since 1.1
		 *
		 * @param string $placeholder Placeholder that will be printed.
		 * @param int    $width Placeholder width.
		 * @param int    $height Placeholder height.
		 */
		return apply_filters( 'rocket_lazyload_placeholder', $placeholder, $width, $height );
	}
}
