fix: More accurate results for URL on HN

Similar behavior to Lemmy and Lobsters: when query is URL, try to
match URL of post source.

hackernews.go

@@ -30,9 +30,17 @@ type HackerNewsResponse struct {
 //
 // See: https://hn.algolia.com/api
 func SearchHackerNews(ctx context.Context, client http.Client, query string) ([]Discussion, error) {
-	searchURL := "http://hn.algolia.com/api/v1/search?tags=story&query="
+	searchURL := "http://hn.algolia.com/api/v1/search?"
 	discussions := make([]Discussion, 0)
 
+	_, err := url.Parse(query)
+	switch {
+	case err == nil:
+		searchURL += "restrictSearchableAttributes=url&query="
+	default:
+		searchURL += "tags=story&query="
+	}
+
 	r, err := client.Get(ctx, searchURL+url.QueryEscape(query))
 	if err != nil {
 		return discussions, err

hackernews_test.go

@@ -10,7 +10,7 @@ import (
 
 func ExampleSearchHackerNews() {
 	client := http.Client{}
-	query := "grugbrain.dev"
+	query := "https://grugbrain.dev"
 
 	opinions := ensure.MustReturn(SearchHackerNews(context.TODO(), client, query))