Add changelog diff extraction script

changelog-diff.py

@@ -0,0 +1,53 @@
+#!/usr/bin/env python
+#
+# Script for retrieving a condensed changelog between two revisions
+#
+# 2021 (c) Marcel Kapfer <opensource@mmk2410.org>
+# Licensed under the MIT/Expat License
+#
+# NOTES:
+#
+# - This is a draft! It may burn your house, delete your harddrive
+#   and/or kill your kitten.
+
+import sys
+import subprocess
+
+
+def changelog_diff(old, new, changelog_file = "./CHANGELOG.md"):
+    raw_diff = subprocess.run(["git", "diff", "--unified=0",
+                               "{}..{}".format(old, new), changelog_file],
+                              stdout=subprocess.PIPE)
+    last_block_start = 0
+    diff = []
+    for line in raw_diff.stdout.decode('utf-8').splitlines()[4::]:
+        if line.startswith("@@ ") and line.endswith(" @@"):
+            if last_block_start == 2:
+                diff.pop()
+            last_block_start = 1
+        elif line.startswith("+"):
+            last_block_start = last_block_start + 1
+            diff.append(line[1::])
+        else:
+            last_block_start = last_block_start + 1
+    return diff
+
+
+def main():
+    help_str = "Must be: ./changelog-diff old-revision new-revision [changelog file]"
+    # Check for correct amount of arguments
+    if len(sys.argv) < 3:
+        print("[ERROR] Not enough arguments. {}".format(help_str))
+        sys.exit(1)
+    elif len(sys.argv) == 3:
+        diff = changelog_diff(sys.argv[1], sys.argv[2])
+    elif len(sys.argv) == 4:
+        diff = changelog_diff(sys.argv[1], sys.argv[2], sys.argv[3])
+    else:
+        print("[ERROR] Two much arguments. {}".format(help_str))
+        sys.exit(1)
+    print("\n".join(diff))
+
+
+if __name__ == "__main__":
+    main()