<?php
/**
 * Plugin Name: H5P core version reconciliation
 * Description: Reconciles H5PCore's static properties with the h5p-php-library actually installed, which Pressbooks' vendored h5p-core 1.27 misreports.
 *
 * Pressbooks pins h5p/h5p-core 1.27.0, and that package declares its classes under
 * Composer's autoload.files, so h5p.classes.php is eagerly required when Pressbooks'
 * autoloader boots. The H5P WordPress plugin registers the same classes through a lazy
 * spl_autoload_register classmap (h5p/autoloader.php) and never requires the file
 * directly. Eager autoload wins, the plugin's autoloader never fires, and no redeclare
 * fatal occurs — so H5PCore silently describes 1.27 while the library actually installed,
 * executed and served to browsers is the H5P plugin's 1.28 at a different path.
 *
 * Two symptoms follow, both fixed here by reconciling the statics with what is on disk:
 *
 * 1. $styles omits three stylesheets 1.28 ships. add_core_assets() resolves the 1.27 list
 *    against plugins_url('h5p/h5p-php-library'), so the content iframe is built without
 *    the icon @font-face (action bar renders as tofu) and without the theme layer that
 *    1.28-era libraries depend on (content collapses — see PB_H5P_RESTORE_STYLES).
 *
 * 2. $coreApi reports 1.27. H5PValidator::isValidH5pData() compares an imported package's
 *    declared coreApi against it, so importing an .h5p archive containing a library that
 *    requires 1.28 fails with "requires a newer version of the H5P plugin ... currently
 *    running version 1.27". Authoring new content is unaffected, because the editor never
 *    runs the package validator.
 *
 * Reporting the shipped values is accurate, not a workaround: coreApi describes the
 * client-side H5P core JS, and the JS actually served is the shipped one. The PHP delta
 * between 1.27 and 1.28 is confined to Hub endpoints and one sanitization fix, with no
 * change to content validation or storage.
 *
 * Remove this once Pressbooks' vendored h5p-core catches up with the H5P plugin's
 * h5p-php-library. Removing the file is a complete rollback: nothing here is persisted
 * beyond a cache of values read from disk.
 */

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

/**
 * Stylesheets 1.28 ships that 1.27's $styles omits, used as a fallback if the shipped
 * $styles array can't be parsed.
 *
 * h5p-fonts.css carries the icon @font-face. The other two carry H5P's 1.28 theme layer:
 * h5p-theme-variables.css defines ~82 --h5p-theme-* custom properties, and h5p-theme.css
 * consumes them. Libraries built against 1.28 — H5P.Components, and current builds of the
 * shared H5P.Question / H5P.JoubelUI / H5P.DragText — reference those variables heavily,
 * and without the definitions every reference resolves to an empty string and the content
 * collapses. Importing any recent .h5p package upgrades those shared libraries site-wide,
 * so this is not opt-in.
 *
 * Restoring all three is safe for older content: h5p-theme.css is scoped entirely to
 * .h5p-theme / .h5p-content:has(.h5p-theme), which only 1.28-era libraries apply to
 * themselves, and h5p-theme-variables.css just declares custom properties on :root and
 * .h5peditor. Neither affects a library that does not reference them.
 */
const PB_H5P_RESTORE_STYLES = [
	'styles/h5p-fonts.css',
	'styles/h5p-theme.css',
	'styles/h5p-theme-variables.css',
];

/**
 * Read the coreApi version and core stylesheet list declared by the h5p-php-library on
 * disk.
 *
 * Parsed rather than hardcoded so this keeps telling the truth across H5P plugin updates,
 * and so the stylesheet list keeps upstream's ordering by construction. Cached against the
 * file's mtime. Either value may come back null, in which case callers fall back.
 *
 * @param string $classes_file Absolute path to the shipped h5p.classes.php.
 * @return array{coreApi:?array,styles:?array}
 */
function pb_h5p_shipped_core_values( $classes_file ) {
	$mtime  = @filemtime( $classes_file );
	$cached = get_site_transient( 'pb_h5p_shipped_core_values' );

	if ( is_array( $cached ) && isset( $cached['mtime'] ) && $cached['mtime'] === $mtime ) {
		return $cached['values'];
	}

	$source = @file_get_contents( $classes_file );
	$values = [ 'coreApi' => null, 'styles' => null ];

	if ( $source ) {
		if ( preg_match(
			'/public\s+static\s+\$coreApi\s*=\s*(?:array\s*\(|\[)\s*'
			. "'majorVersion'\s*=>\s*(\d+)\s*,\s*'minorVersion'\s*=>\s*(\d+)/",
			$source,
			$m
		) ) {
			$values['coreApi'] = [
				'majorVersion' => (int) $m[1],
				'minorVersion' => (int) $m[2],
			];
		}

		if ( preg_match( '/public\s+static\s+\$styles\s*=\s*(?:array\s*\(|\[)(.*?)(?:\)|\])\s*;/s', $source, $m )
			&& preg_match_all( "/'([^']+\.css)'/", $m[1], $found )
		) {
			$values['styles'] = $found[1];
		}
	}

	set_site_transient(
		'pb_h5p_shipped_core_values',
		[ 'mtime' => $mtime, 'values' => $values ],
		DAY_IN_SECONDS
	);

	return $values;
}

add_action( 'plugins_loaded', function () {
	if ( ! class_exists( 'H5PCore' ) ) {
		return;
	}

	// add_core_assets() resolves style paths against plugins_url('h5p/h5p-php-library').
	$library_dir  = WP_PLUGIN_DIR . '/h5p/h5p-php-library/';
	$classes_file = $library_dir . 'h5p.classes.php';

	if ( ! is_readable( $classes_file ) ) {
		return;
	}

	$shipped = pb_h5p_shipped_core_values( $classes_file );
	$loaded  = H5PCore::$styles;

	// 1. Adopt the shipped stylesheet list, which preserves upstream's ordering — the
	//    theme layer has to load after h5p.css to override it. Only files actually
	//    present are included, and anything the loaded list has that the shipped one
	//    doesn't is kept, so this can only ever add.
	if ( $shipped['styles'] ) {
		$styles = array_values( array_filter(
			$shipped['styles'],
			function ( $style ) use ( $library_dir ) {
				return file_exists( $library_dir . $style );
			}
		) );
		H5PCore::$styles = array_merge( $styles, array_values( array_diff( $loaded, $styles ) ) );
	} else {
		// Fallback: prepend whichever known-missing sheets are present.
		$missing = array_values( array_filter(
			PB_H5P_RESTORE_STYLES,
			function ( $style ) use ( $library_dir, $loaded ) {
				return ! in_array( $style, $loaded, true ) && file_exists( $library_dir . $style );
			}
		) );
		if ( $missing ) {
			H5PCore::$styles = array_merge( $missing, $loaded );
		}
	}

	// 2. Report the coreApi the shipped library actually implements. Only ever raised,
	//    so a future vendor copy that overtakes the H5P plugin is left untouched.
	if ( ! $shipped['coreApi'] ) {
		return;
	}

	$current  = H5PCore::$coreApi;
	$is_newer = $shipped['coreApi']['majorVersion'] > $current['majorVersion']
		|| ( $shipped['coreApi']['majorVersion'] === $current['majorVersion']
			&& $shipped['coreApi']['minorVersion'] > $current['minorVersion'] );

	if ( $is_newer ) {
		H5PCore::$coreApi = $shipped['coreApi'];
	}
}, 100 );