Discover Web App Manifest in HTML

... and return a hash of the JSON data.

lib/manifique/web_client.rb

@@ -13,8 +13,25 @@ module Manifique
     end
 
     def fetch_web_manifest
-      do_get_request @url
-      # binding.pry
+      res = do_get_request @url
+      links = parse_http_link_header(res)
+      doc = Nokogiri::HTML(res.body)
+      manifest_url = discover_web_manifest_url(links, doc)
+
+      unless manifest_url.match(/^https?\:\/\//)
+        # Link is just the manifest path, not an absolute URL
+        manifest_url = @url + manifest_url
+      end
+
+      res = do_get_request manifest_url
+
+      begin
+        manifest_data = JSON.parse(res.body)
+      rescue
+        manifest_data = false
+      end
+
+      manifest_data
     end
 
     private
@@ -31,5 +48,20 @@ module Manifique
         res
       end
     end
+
+    def parse_http_link_header(response)
+      link_parser = Nitlink::Parser.new
+      link_parser.parse(response)
+    end
+
+    def discover_web_manifest_url(links, doc)
+      # TODO implement/test link header discovery
+      # if url = links.by_rel('manifest').target.to_s or
+      if url = doc.at_css("link[rel=manifest]").attributes["href"].value
+        return url
+      else
+        raise "No Web App Manifest found on #{@url}"
+      end
+    end
   end
 end