refactor yewtu.be URL generation into a js library

1 files changed, 57 insertions, 0 deletions

diff --git a/content/syewtube_urls/yewtube_urls.js b/content/syewtube_urls/yewtube_urls.js
new file mode 100644
index 0000000..b013132
--- /dev/null
+++ b/content/syewtube_urls/yewtube_urls.js
@@ -0,0 +1,57 @@
+/**
+ * Copyright (C) 2021, Wojtek Kosior
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the CC0 1.0 Universal License as published by
+ * the Creative Commons Corporation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * CC0 1.0 Universal License for more details.
+ * Available under the terms of Creative Commons Zero.
+ */
+
+/* Library to convert youtube.com URLs to yewtu.be URLs. */
+
+function decode_query_options(url)
+{
+    const query_options = {};
+    const match = /^[^?]*\?(.*)/.exec(url);
+    if (!match)
+	return query_options;
+
+    for (const opt of match[1].split("&")) {
+	const [key, val] =
+	      /^([^=]*)=?(.*)/.exec(opt).splice(1, 2).map(decodeURIComponent);
+	query_options[key] = val;
+    }
+
+    return query_options;
+}
+
+function encode_query_options(query_options)
+{
+    return Object.entries(query_options)
+	.map(ar => ar.map(encodeURIComponent).join("=")).join("&");
+}
+
+function make_yewtube_url(youtube_url)
+{
+    const query_options = decode_query_options(youtube_url);
+
+    let endpoint = "";
+
+    const match = /^(?:(?:https?:)?\/\/)?[^/]*\/([^?]*)/.exec(youtube_url);
+    if (match)
+	endpoint = match[1];
+
+    if (/^embed\//.test(query_options.v))
+	endpoint = query_options.v;
+
+    if (/^embed\/.+/.test(endpoint))
+	delete query_options.v
+
+    const encoded_options = encode_query_options(query_options);
+    return `https://yewtu.be/${endpoint}?${encoded_options}`;
+}