new example: randpic.py

bin/handlers/README.md

@@ -21,6 +21,7 @@ each plugin must define a `main()` which takes 3 arguments;
 ## on404
 
 * [redirect.py](redirect.py) sends an HTTP 301 or 302, redirecting the client to another page/file
+* [randpic.py](randpic.py) redirects `/foo/bar/randpic.jpg` to a random pic in `/foo/bar/`
 * [sorry.py](answer.py) replies with a custom message instead of the usual 404
 * [nooo.py](nooo.py) replies with an endless noooooooooooooo
 * [never404.py](never404.py) 100% guarantee that 404 will never be a thing again as it automatically creates dummy files whenever necessary

bin/handlers/randpic.py

@@ -0,0 +1,35 @@
+import os
+import random
+from urllib.parse import quote
+
+
+# assuming /foo/bar/ is a valid URL but /foo/bar/randpic.png does not exist,
+# hijack the 404 with a redirect to a random pic in that folder
+#
+# thx to lia & kipu for the idea
+
+
+def main(cli, vn, rem):
+    req_fn = rem.split("/")[-1]
+    if not cli.can_read or not req_fn.startswith("randpic"):
+        return
+
+    req_abspath = vn.canonical(rem)
+    req_ap_dir = os.path.dirname(req_abspath)
+    files_in_dir = os.listdir(req_ap_dir)
+
+    if "." in req_fn:
+        file_ext = "." + req_fn.split(".")[-1]
+        files_in_dir = [x for x in files_in_dir if x.lower().endswith(file_ext)]
+
+    if not files_in_dir:
+        return
+
+    selected_file = random.choice(files_in_dir)
+
+    req_url = "/".join([vn.vpath, rem]).strip("/")
+    req_dir = req_url.rsplit("/", 1)[0]
+    new_url = "/".join([req_dir, quote(selected_file)]).strip("/")
+
+    cli.reply(b"redirecting...", 302, headers={"Location": "/" + new_url})
+    return "true"