nix: bring back local release pin to update.py

Revert "nix: remove unused code from update.py"

This reverts commit 48dfd73c91.

nix: update local release pin function in update.py

contrib/package/nix/copyparty/update.py

@@ -2,18 +2,23 @@
 
 # Update the Nix package pin
 #
-# Usage: ./update.sh
+# Usage: ./update.sh [PATH]
+# When the [PATH] is not set, it will fetch the latest release from the repo.
+# With [PATH] set, it will hash the given file and generate the URL,
+# base on the version contained within the file
 
 import base64
 import json
 import hashlib
 import sys
+import tarfile
 from pathlib import Path
 
 OUTPUT_FILE = Path("pin.json")
 TARGET_ASSET = lambda version: f"copyparty-{version}.tar.gz"
 HASH_TYPE = "sha256"
 LATEST_RELEASE_URL = "https://api.github.com/repos/9001/copyparty/releases/latest"
+DOWNLOAD_URL = lambda version: f"https://github.com/9001/copyparty/releases/download/v{version}/{TARGET_ASSET(version)}"
 
 
 def get_formatted_hash(binary):
@@ -24,6 +29,16 @@ def get_formatted_hash(binary):
     return f"{HASH_TYPE}-{encoded_hash}"
 
 
+def version_from_tar_gz(path):
+    with tarfile.open(path) as tarball:
+        release_name = tarball.getmembers()[0].name
+        prefix = "copyparty-"
+
+        if release_name.startswith(prefix):
+            return release_name.replace(prefix, "")
+    raise ValueError("version not found in provided file")
+
+
 def remote_release_pin():
     import requests
 
@@ -38,7 +53,20 @@ def remote_release_pin():
     return result
 
 
+def local_release_pin(path):
+    version = version_from_tar_gz(path)
+    download_url = DOWNLOAD_URL(version)
+    formatted_hash = get_formatted_hash(path.read_bytes())
+
+    result = {"url": download_url, "version": version, "hash": formatted_hash}
+    return result
+
+
 def main():
+    if len(sys.argv) > 1:
+        asset_path = Path(sys.argv[1])
+        result = local_release_pin(asset_path)
+    else:
         result = remote_release_pin()
 
     print(result)