[gnome-maps/wip/mlundblad/wikidata: 7/10] WIP: wikipedia: Add function to fetch Wikidata tag for an article

[Marcus Lundblad <mlundblad src gnome org>]

commit 28ec83a987cd4db8f7cdf1d1890c83aa6796ef58
Author: Marcus Lundblad <ml dfupdate se>
Date:   Tue Oct 11 23:09:16 2022 +0200

    WIP: wikipedia: Add function to fetch Wikidata tag for an article

 src/wikipedia.js | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
---
diff --git a/src/wikipedia.js b/src/wikipedia.js
index b5f17a15..5530d246 100644
--- a/src/wikipedia.js
+++ b/src/wikipedia.js
@@ -225,6 +225,34 @@ export function fetchArticleInfoForWikidata(wikidata, defaultArticle,
     });
 }
 
+export function fetchWikidataForArticle(wiki, cancellable, callback) {
+    let lang = getLanguage(wiki);
+    let title = getHtmlEntityEncodedArticle(wiki);
+    let uri = 'https://www.wikidata.org/w/api.php';
+    let encodedForm = Soup.form_encode_hash({ action: 'wbgetentities',
+                                              sites:  lang + 'wiki',
+                                              titles:  title,
+                                              format: 'json' });
+    let msg = Soup.Message.new_from_encoded_form('GET', uri, encodedForm);
+    let session = _getSoupSession();
+
+    session.send_and_read_async(msg, GLib.PRIORIRY_DEFAULT, cancellable,
+                                     (source, res) => {
+        if (msg.get_status() !== Soup.Status.OK) {
+            log("Failed to request Wikidata entities: " + msg.reason_phrase);
+            callback(null);
+            return;
+        }
+
+        let buffer = session.send_and_read_finish(res).get_data();
+        let response = JSON.parse(Utils.getBufferText(buffer));
+        Utils.debug('response: ' + JSON.stringify(response, '', 2));
+        let id = Object.values(response.entities ?? [])?.[0]?.id;
+
+        callback(id);
+    });
+}
+
 function _onWikidataFetched(wikidata, defaultArticle, response, size,
                             metadataCb, thumbnailCb) {
     let sitelinks = response?.entities?.[wikidata]?.sitelinks;