feat: provide web app manifest (dynamically geneated)

inc/config_cascade.php

@@ -28,6 +28,10 @@ $config_cascade = array_merge(
             'default'   => array(DOKU_CONF . 'license.php'),
             'local'     => array(DOKU_CONF . 'license.local.php'),
         ),
+        'manifest' => array(
+            'default'   => array(DOKU_CONF . 'manifest.json'),
+            'local'     => array(DOKU_CONF . 'manifest.local.json'),
+        ),
         'mediameta' => array(
             'default'   => array(DOKU_CONF . 'mediameta.php'),
             'local'     => array(DOKU_CONF . 'mediameta.local.php'),

inc/template.php

@@ -242,6 +242,10 @@ function tpl_metaheaders($alt = true) {
         );
     }
 
+    if (actionOK('manifest')) {
+        $head['link'][] = array('rel'=> 'manifest', 'href'=> DOKU_BASE.'lib/exe/manifest.php');
+    }
+
     if($alt) {
         if(actionOK('rss')) {
             $head['link'][] = array(

lib/exe/manifest.php

+<?php
+
+if (!defined('DOKU_INC')) {
+    define('DOKU_INC', __DIR__ . '/../../');
+}
+require_once(DOKU_INC . 'inc/init.php');
+
+class Manifest {
+    public function run() {
+        $manifest = retrieveConfig('manifest', [$this, 'jsonToArray']);
+
+        global $conf;
+
+        if (empty($manifest['name'])) {
+            $manifest['name'] = $conf['title'];
+        }
+
+        if (empty($manifest['short_name'])) {
+            $manifest['short_name'] = $conf['title'];
+        }
+
+        if (empty($manifest['description'])) {
+            $manifest['description'] = $conf['tagline'];
+        }
+
+        if (empty($manifest['start_url'])) {
+            $manifest['start_url'] = DOKU_REL;
+        }
+
+        if (empty($manifest['icons'])) {
+            $manifest['icons'] = [];
+            $look = [
+                ':wiki:logo.png',
+                ':logo.png',
+                'images/logo.png',
+                ':wiki:apple-touch-icon.png',
+                ':apple-touch-icon.png',
+                'images/apple-touch-icon.png',
+                ':wiki:favicon.svg',
+                ':favicon.svg',
+                'images/favicon.svg',
+                ':wiki:favicon.ico',
+                ':favicon.ico',
+                'images/favicon.ico',
+                ':wiki:logo',
+            ];
+
+            $abs = true;
+            foreach($look as $img) {
+                if($img[0] === ':') {
+                    $file    = mediaFN($img);
+                    $ismedia = true;
+                } else {
+                    $file    = tpl_incdir().$img;
+                    $ismedia = false;
+                }
+
+                if (file_exists($file)) {
+                    $imginfo = getimagesize($file);
+                    if($ismedia) {
+                        $url = ml($img, '', true, '', $abs);
+                    } else {
+                        $url = tpl_basedir().$img;
+                        if($abs) $url = DOKU_URL.substr($url, strlen(DOKU_REL));
+                    }
+                    $manifest['icons'][] = [
+                        'src' => $url,
+                        'sizes' => $imginfo[0] . 'x' . $imginfo[1],
+                        'type' => $imginfo['mime'],
+                    ];
+                };
+            }
+        }
+
+        trigger_event('MANIFEST_SEND', $manifest);
+
+        header('Content-Type: application/manifest+json');
+        echo json_encode($manifest);
+    }
+
+    public function jsonToArray($file)
+    {
+        $json = file_get_contents($file);
+
+        $conf = json_decode($json, true);
+
+        $jsonError = json_last_error();
+        if (!is_array($conf) && $jsonError !== JSON_ERROR_NONE) {
+
+            switch ($jsonError) {
+                case JSON_ERROR_DEPTH:
+                    $jsonErrorText = 'The maximum stack depth has been exceeded';
+                    break;
+                case JSON_ERROR_STATE_MISMATCH:
+                    $jsonErrorText = 'Invalid or malformed JSON';
+                    break;
+                case JSON_ERROR_CTRL_CHAR:
+                    $jsonErrorText = 'Control character error, possibly incorrectly encoded';
+                    break;
+                case JSON_ERROR_SYNTAX:
+                    $jsonErrorText = 'Syntax error';
+                    break;
+                case JSON_ERROR_UTF8:
+                    $jsonErrorText = 'Malformed UTF-8 characters, possibly incorrectly encoded';
+                    break;
+                case JSON_ERROR_RECURSION:
+                    $jsonErrorText = 'One or more recursive references in the value to be encoded';
+                    break;
+                case JSON_ERROR_INF_OR_NAN:
+                    $jsonErrorText = 'One or more NAN or INF values in the value to be encoded';
+                    break;
+                case JSON_ERROR_UNSUPPORTED_TYPE:
+                    $jsonErrorText = 'A value of a type that cannot be encoded was given';
+                    break;
+                case JSON_ERROR_INVALID_PROPERTY_NAME:
+                    $jsonErrorText = 'A property name that cannot be encoded was given';
+                    break;
+                case JSON_ERROR_UTF16:
+                    $jsonErrorText = 'Malformed UTF-16 characters, possibly incorrectly encoded';
+                    break;
+                default:
+                    $jsonErrorText = 'Unknown Error Code';
+            }
+
+            trigger_error('JSON decoding error "' . $jsonErrorText . '" for file ' . $file, E_USER_WARNING);
+            return [];
+        }
+
+        return $conf;
+    }
+}
+
+$manifest = new Manifest();
+$manifest->run();