use matching tag only

src/index.ts

@@ -32,7 +32,7 @@ export class PicSourceInstance extends PicSource {
     const page = this.nextPage();
     const data = await this.ctx.http.get<PicInfo[]>(this.config.endpoint, {
       params: {
-        tags: picTags.join('+'),
+        tags: picTags.length ? picTags.join('+') : undefined,
         limit: 1000,
         page: page,
       },
@@ -47,6 +47,12 @@ export class PicSourceInstance extends PicSource {
       this.page = 1;
       return this.randomPic(picTags);
     }
+    const matchingData = picTags.length
+      ? data.filter((d) => d.tags.split(' ').some((t) => picTags.includes(t)))
+      : data;
+    if (!matchingData.length) {
+      return;
+    }
     const pic = Random.pick(data);
     return {
       url: this.config.useOriginal ? pic.file_url : pic.sample_url,