added leaderboard (closes #29)

src/js/levels.js

@@ -7,12 +7,37 @@ const get=async filename => {
 	return cache[filename]=json;
 };
 
+const getInfo=(category, id) => {
+	const cat=levelList[category];
+	id=''+id;
+
+	const displayName=cat.levelDisplay
+		.replace(/<n>/g, id)
+		.replace(/<l>/g, id.toLowerCase());
+	const fileName=cat.levelFilename
+		.replace(/<n>/g, id)
+		.replace(/<l>/g, id.toLowerCase());
+	const levelString=category+'/'+id+'/'+fileName;
+
+	return {
+		displayName,
+		fileName,
+		levelString
+	};
+};
+
+const getRules=async (category, id) => {
+	const {fileName}=getInfo(category, id);
+	const json=await get(fileName);
+	return Object.assign({}, window.levelList[category].rules, json.rules);
+};
+
 const clearCache=() =>
 	Object
 		.keys(cache)
 		.forEach(key => delete cache[key]);
 
 return module.exports={
-	get,
+	get, getRules, getInfo,
 	clearCache
 };