<?php
/**
 * Main file for styles manager
 *
 * @package EditorPlus
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

require_once EDPL_EDITORPLUS_PLUGIN_DIR . 'includes/class-editorplus-styles-generator.php';

/**
 * Main class for handling editorplus stylings
 */
class EditorPlus_Styles_Manager {

	/**
	 * Editorplus styles generator.
	 *
	 * @var EditorPlus_Styles_Generator
	 */
	private $generator;

	/**
	 * Contructor.
	 *
	 * @return void
	 */
	public function __construct() {

		$this->generator = new EditorPlus_Styles_Generator();

		add_action( 'wp_head', array( $this, 'render_styles' ) );
		add_action( 'body_class', array( $this, 'insert_editorplus_body_class' ) );
		add_action( 'editor_plus_css_code', array( $this, 'merge_global_styles' ) );
		add_action( 'init', array( $this, 'register' ) );
		add_filter( 'render_block', array( $this, 'prepare_blocks_for_styles' ), 10, 2 );
	}

	/**
	 * Will prepare each block for styling by assigning them unique classes.
	 *
	 * @param string $block_content - Block inner content.
	 * @param array  $block - Parsed block.
	 *
	 * @return string - Block content with unique class assigned.
	 */
	public function prepare_blocks_for_styles( $block_content, $block ) {

		$slug = $block['blockName'];

		// Excluding unsupported blocks.
		if ( ! editorplus_is_supported_block( $slug ) || ! editorplus_has_block_styles( $block ) ) {
			return $block_content;
		}

		libxml_use_internal_errors( true ); // For surpressing any document error.

		$document = new DOMDocument();

		if ( '' === $block_content ) {
			return $block_content;
		}

		$document->loadHTML( '<?xml encoding="utf-8" ?>' . $block_content );

		$finder = new DOMXPath( $document );

		$selector = $block['attrs']['epGeneratedClass'] ?? '';

		if ( '' === $selector ) {
			return $block_content;
		}

		$block_element = $finder->query( "//*[contains(@class, '$selector')]" )->item( 0 );

		if ( is_null( $block_element ) ) {
			return $block_content;
		}

		$classlist = explode( ' ', $block_element->getAttribute( 'class' ) ?? '' );

		$classlist[] = 'eplus-styles-uid-' . editorplus_generate_unique_uid_for_block( $block );

		if ( ! is_null( $block_element ) ) {
			$block_element->setAttribute(
				'class',
				join( ' ', $classlist )
			);
		}

		libxml_clear_errors();

		return $document->saveHTML( $document->getElementsByTagName( 'body' )->item( 0 )->firstChild );
	}

	/**
	 * All registerations should be done here.
	 *
	 * @return void
	 */
	public function register() {

		$post_types = get_post_types(
			array(
				'_builtin' => false,
			),
			'names',
			'and'
		);

		$post_types['post'] = 'post';

		foreach ( $post_types as $post_type ) {

			// TODO: "copy styling feature" is still using metadata, refactor the client script to utilize state for this.
			register_meta(
				$post_type,
				'editor_plus_copied_stylings',
				array(
					'show_in_rest' => true,
					'single'       => true,
					'type'         => 'string',
					'default'      => '{}',
				)
			);
		}

	}

	/**
	 * Will insert editorplus body class.
	 *
	 * @param array $classes - Body classes.
	 * @return array - body classes merged with editorplus class.
	 */
	public function insert_editorplus_body_class( $classes ) {
		$classes['editorplus_styles'] = 'eplus_styles';
		return $classes;
	}

	/**
	 * Will merge global styles to the given css code.
	 *
	 * @param string $css_code - CSS Code.
	 * @return string - CSS Code with global styles merged.
	 */
	public function merge_global_styles( $css_code = '' ) {

		$css_code .= get_option( 'ep_custom_global_css', '' );

		return $css_code;

	}

	/**
	 * This method is responsible to output editorplus styles, scoped to a post.
	 *
	 * @return void
	 */
	public function render_styles() {

		$current_post_id = get_the_ID();
		$current_post    = get_post( $current_post_id );

		if ( is_null( $current_post ) ) {
			return;
		}

		$generated_editorplus_styles = '';

		// Generating styles specifically for post content.
		$current_post_content = $current_post->post_content;

		$parsed_blocks = parse_blocks( $current_post_content );

		$generated_editorplus_styles .= $this->generator->generate_styles_from_blocks( $parsed_blocks );

		$generated_editorplus_styles = apply_filters( 'editor_plus_css_code', $generated_editorplus_styles );

		/**
		 * The generated CSS should not contain any html markup.
		 * Using regex to match and strip these html tags.
		 *
		 * WordPress is also using some regex to validate the CSS output.
		 *
		 * @see https://github.com/WordPress/WordPress/blob/56c162fbc9867f923862f64f1b4570d885f1ff03/wp-includes/customize/class-wp-customize-custom-css-setting.php#L157-L168
		 */
		if ( preg_match( '#</?\w+#', $generated_editorplus_styles ) ) {

			// Replacing all the matched tags.
			$generated_editorplus_styles = preg_replace( '#</?\w+#', '', $generated_editorplus_styles );

		}

		if ( '' !== $generated_editorplus_styles ) {
			?>
				<style id="editorplus-generated-styles">  
					<?php echo $generated_editorplus_styles; ?>
				</style>
			<?php
		}

	}

}