add script to make release tags

Now that the changelog entry is also include in the tag message, this
script makes sure that happens, and the entry also ends up in CHANGELOG.md

tools/make-release-tag.py

@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+
+"""A script to check everything is in order, then make the release tag."""
+
+import git
+import re
+import sys
+
+from pathlib import Path
+
+
+def main():
+    project_dir = Path(__file__).parent.parent
+
+    for line in (project_dir / 'app/build.gradle.kts').open():
+        m = re.search(r"""versionName\s*=\s*["']([^"']+)["']""", line)
+        if m:
+            current_version = m.group(1)
+            break
+
+    changelog_file = project_dir / "CHANGELOG.md"
+    changelog = changelog_file.read_text()
+    versions = list()
+    entries = dict()
+    for entry in changelog.split('###'):
+        if not entry:
+            continue
+        m = re.match(r" *(\S+) *\([0-9-]+\)\n(.*)", entry, flags=re.DOTALL)
+        if not m:
+            print('ERROR: broken entry format in CHANGELOG.md:', entry)
+            sys.exit(1)
+        version = m.group(1)
+        versions.append(version)
+        entries[version] = m.group(2).strip()
+
+    if current_version not in versions:
+        print(f"ERROR: CHANGELOG.md missing entry for {current_version}")
+        sys.exit(1)
+
+    repo = git.Repo(project_dir)
+    for tag in sorted(
+        repo.tags,
+        key=lambda t: t.tag.tagged_date if t.tag is not None else 0,
+        reverse=True,
+    ):
+        if tag.name == current_version:
+            print(f"ERROR: current version {tag.name} tag exists at {tag.commit}")
+            sys.exit(1)
+
+    message = entries[current_version]
+    repo.create_tag(current_version, message=message, sign=True)
+    print(f'Tagged current version {current_version} with changelog entry:\n\n{message}')
+
+
+if __name__ == "__main__":
+    main()