<?php
/**
 * Table styles: the same styles inside the editor and on the page, a scrollable frame around styled tables, so
 * wide tables never widen the page on phones, cell labels for the card layout on phones and sorting on request.
 * The style itself is chosen in the "Table style" dialog (assets/js/table-dialog.js).
 *
 * Only tables with the class threece-table are touched; the styles load only on pages that have one.
 *
 * @package ThreeCE
 */

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

/**
 * Tables.
 */
class ThreeCE_Tables {

	const CLASS_NAME = 'threece-table';

	/**
	 * Hooks.
	 */
	public static function init(): void {
		add_filter( 'tiny_mce_before_init', array( __CLASS__, 'editor_settings' ) );
		add_filter( 'mce_css', array( __CLASS__, 'editor_css' ) );
		add_filter( 'the_content', array( __CLASS__, 'frame' ), 20 );
		add_action( 'init', array( __CLASS__, 'register' ) );
	}

	/**
	 * Sorting script, enqueued only for sortable tables.
	 */
	public static function register(): void {
		wp_register_script_module( 'threece-table-sort', THREECE_URL . 'assets/js/table-sort.js', array(), THREECE_VERSION );
	}

	/**
	 * New tables get no border or width attributes, the style does that. The class list of the TinyMCE table
	 * dialog stays off: it would overwrite our classes on save; the "Table style" button sets them instead.
	 *
	 * @param mixed $settings TinyMCE settings.
	 * @return mixed
	 */
	public static function editor_settings( $settings ) {
		if ( ! is_array( $settings ) ) {
			return $settings;
		}
		$settings['table_default_attributes'] = '{}';
		$settings['table_default_styles']     = '{}';
		return $settings;
	}

	/**
	 * Our element styles inside the editor as well, after the theme's editor styles.
	 *
	 * @param mixed $css Comma separated style sheet addresses.
	 * @return mixed
	 */
	public static function editor_css( $css ) {
		if ( ! is_string( $css ) ) {
			return $css;
		}
		$own = THREECE_URL . 'assets/css/elements.css?ver=' . rawurlencode( THREECE_VERSION );
		return '' === $css ? $own : $css . ',' . $own;
	}

	/**
	 * Puts a scrollable frame around every outermost table with our class. The frame is a labelled region that
	 * takes keyboard focus, so keyboard users can scroll it (WCAG 2.1.1).
	 *
	 * @param mixed $content Post content.
	 * @return mixed
	 */
	public static function frame( $content ) {
		if ( ! is_string( $content ) || false === stripos( $content, '<table' ) ) {
			return $content;
		}
		if ( ! preg_match_all( '#<table\b[^>]*>|</table\s*>#i', $content, $tags, PREG_OFFSET_CAPTURE ) ) {
			return $content;
		}
		$result = '';
		$last   = 0;
		$depth  = 0;
		$start  = null;
		$found  = false;
		foreach ( $tags[0] as $tag ) {
			$is_open = '/' !== $tag[0][1];
			if ( $is_open && 0 === $depth ) {
				$start = self::is_ours( $tag[0] ) && ! self::framed( $content, $tag[1] ) ? $tag[1] : null;
			}
			$depth += $is_open ? 1 : -1;
			if ( 0 === $depth && null !== $start ) {
				$end     = $tag[1] + strlen( $tag[0] );
				$table   = substr( $content, $start, $end - $start );
				$result .= substr( $content, $last, $start - $last ) . self::wrap( $table );
				$last    = $end;
				$start   = null;
				$found   = true;
			}
			$depth = max( 0, $depth );
		}
		if ( ! $found ) {
			return $content;
		}
		wp_enqueue_style( 'threece-elements' );
		return $result . substr( $content, $last );
	}

	/**
	 * The table tag carries our class as a whole word.
	 *
	 * @param string $tag Opening table tag.
	 */
	private static function is_ours( $tag ): bool {
		return (bool) preg_match( '#\sclass\s*=\s*(["\'])(?:[^"\']*\s)?' . self::CLASS_NAME . '(?:\s[^"\']*)?\1#i', $tag );
	}

	/**
	 * The opening tag of the table carries one of our modifier classes.
	 *
	 * @param string $table    Table HTML.
	 * @param string $modifier Modifier without prefix, e.g. stack.
	 */
	private static function has_class( $table, $modifier ): bool {
		return (bool) preg_match( '#^<table\b[^>]*\sclass\s*=\s*(["\'])(?:[^"\']*\s)?' . self::CLASS_NAME . '--' . preg_quote( $modifier, '#' ) . '(?:\s[^"\']*)?\1#i', $table );
	}

	/**
	 * Card layout on phones: every body cell gets the text of its column header as data-label. Header from thead or
	 * from a first row of th cells, column spans counted. Tables with row spans get no labels, they would be wrong.
	 *
	 * @param string $table Table HTML.
	 */
	private static function cell_labels( $table ): string {
		if ( preg_match( '#\srowspan\s*=#i', $table ) || ! class_exists( 'DOMDocument' ) ) {
			return $table;
		}
		$doc      = new DOMDocument();
		$previous = libxml_use_internal_errors( true );
		$loaded   = $doc->loadHTML( '<?xml encoding="utf-8"?><div>' . $table . '</div>', LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD );
		libxml_clear_errors();
		libxml_use_internal_errors( $previous );
		$xp  = new DOMXPath( $doc );
		$box = $doc->getElementsByTagName( 'div' )->item( 0 );
		$tbl = $doc->getElementsByTagName( 'table' )->item( 0 );
		if ( ! $loaded || ! $box || ! $tbl ) {
			return $table;
		}
		// Rows of this table only, not of tables nested in its cells.
		$rows = $xp->query( './tr | ./thead/tr | ./tbody/tr | ./tfoot/tr', $tbl );
		$head = $xp->query( './thead/tr[1]', $tbl )->item( 0 );
		if ( ! $head && $rows && $rows->length ) {
			$first = $rows->item( 0 );
			$head  = $first && 0.0 === $xp->evaluate( 'count(./td)', $first ) && $xp->evaluate( 'count(./th)', $first ) > 0 ? $first : null;
		}
		if ( ! $head || ! $rows ) {
			return $table;
		}
		$labels = array();
		foreach ( $xp->query( './th | ./td', $head ) as $cell ) {
			if ( ! $cell instanceof DOMElement ) {
				continue;
			}
			$text   = (string) $xp->evaluate( 'normalize-space(.)', $cell );
			$labels = array_merge( $labels, array_fill( 0, max( 1, (int) $cell->getAttribute( 'colspan' ) ), $text ) );
		}
		foreach ( $rows as $tr ) {
			if ( $tr === $head ) {
				continue;
			}
			$column = 0;
			foreach ( $xp->query( './th | ./td', $tr ) as $cell ) {
				if ( ! $cell instanceof DOMElement ) {
					continue;
				}
				if ( isset( $labels[ $column ] ) && '' !== $labels[ $column ] ) {
					$cell->setAttribute( 'data-label', $labels[ $column ] );
				}
				$column += max( 1, (int) $cell->getAttribute( 'colspan' ) );
			}
		}
		$html = '';
		foreach ( $xp->query( './node()', $box ) as $node ) {
			$html .= $doc->saveHTML( $node );
		}
		return $html;
	}

	/**
	 * The table already sits right inside our frame (content filtered twice).
	 *
	 * @param string $content Content.
	 * @param int    $offset  Position of the table tag.
	 */
	private static function framed( $content, $offset ): bool {
		return (bool) preg_match( '#<div class="threece-table-scroll"[^>]*>\s*$#', substr( $content, max( 0, $offset - 300 ), min( 300, $offset ) ) );
	}

	/**
	 * Frame around one table, labelled with its caption or "Table".
	 *
	 * @param string $table Table HTML.
	 */
	private static function wrap( $table ): string {
		if ( self::has_class( $table, 'stack' ) ) {
			$table = self::cell_labels( $table );
		}
		if ( self::has_class( $table, 'sortable' ) ) {
			wp_enqueue_script_module( 'threece-table-sort' );
		}
		$label = __( 'Table', '3task-toolbar-for-classic-editor' );
		if ( preg_match( '#<caption\b[^>]*>(.*?)</caption>#is', $table, $caption ) ) {
			$text  = trim( (string) preg_replace( '#\s+#', ' ', wp_strip_all_tags( $caption[1] ) ) );
			$label = '' !== $text ? $text : $label;
		}
		return '<div class="threece-table-scroll" role="region" tabindex="0" aria-label="' . esc_attr( $label ) . '">' . $table . '</div>';
	}
}