chore: Add changelog-helper script

Since we now use Conventional Commits we can create our Changelog
semi-automatically.

Signed-off-by: Michael Vetter <jubalh@iodoru.org>

scripts/changelog-helper.py

@@ -0,0 +1,165 @@
+#!/usr/bin/env python3
+
+# Since we use Conventional Commits
+# we can now create our Changelog semi-automatically
+
+import subprocess
+import sys
+import re
+import argparse
+from collections import defaultdict
+
+# Configuration for sections and their order
+SECTION_CONFIG = [
+    ("fix", "Bug Fixes"),
+    ("feat", "Features"),
+    ("build", "Build System"),
+    ("ci", "CI"),
+    ("docs", "Documentation"),
+    ("perf", "Performance Improvements"),
+    ("refactor", "Refactorings"),
+    ("cleanup", "Cleanup"),
+    ("style", "Style"),
+    ("tests", "Tests"),
+    ("chore", "Chores"),
+]
+SECTIONS = dict(SECTION_CONFIG)
+TYPE_ORDER = [t for t, _ in SECTION_CONFIG]
+
+CORRECTIONS = {
+    "ests": "tests",
+    "wleanup": "cleanup",
+}
+
+def git_run(args):
+    """Run a git command and return stripped output lines."""
+    try:
+        result = subprocess.run(["git"] + args, capture_output=True, text=True, check=True)
+        return [line for line in result.stdout.strip().split('\n') if line]
+    except subprocess.CalledProcessError:
+        return []
+
+def get_last_tag():
+    output = git_run(["describe", "--tags", "--abbrev=0"])
+    return output[0] if output else None
+
+def get_commits(revision_range):
+    """Get list of (hash, subject) tuples."""
+    lines = git_run(["log", revision_range, "--format=%H %s"])
+    commits = []
+    for line in lines:
+        parts = line.split(' ', 1)
+        if len(parts) == 2:
+            commits.append(parts)
+    return commits
+
+def get_pr_mappings(revision_range):
+    """Map commit hashes to PR numbers found in merge commits."""
+    merge_commits = git_run(["log", revision_range, "--merges", "--format=%H %s"])
+    pr_map = {}
+    pr_re = re.compile(r'Merge pull request #(\d+)')
+
+    for line in merge_commits:
+        parts = line.split(' ', 1)
+        if len(parts) < 2:
+            continue
+        m_hash, m_subject = parts
+        match = pr_re.search(m_subject)
+        if match:
+            pr_num = match.group(1)
+            # Find all commits that are part of this merge branch
+            branch_commits = git_run(["rev-list", f"{m_hash}^1..{m_hash}^2"])
+            for b_hash in branch_commits:
+                pr_map[b_hash] = pr_num
+    return pr_map
+
+def get_contributors(revision_range):
+    """Get sorted list of all unique contributors."""
+    cmd = ["log", revision_range, "--format=%an%n%(trailers:key=Co-authored-by,valueonly=true)"]
+    output = git_run(cmd)
+    
+    contributors = set()
+    for line in output:
+        # Remove email part if present: "Name <email@example.com>" -> "Name"
+        name = line.split('<')[0].strip()
+        if name:
+            contributors.add(name)
+    
+    return sorted(list(contributors))
+
+def format_description(description):
+    """Capitalize first letter of description."""
+    description = description.strip()
+    if description and description[0].islower():
+        return description[0].upper() + description[1:]
+    return description
+
+def main():
+    parser = argparse.ArgumentParser(description="Generate a sorted changelog from git commits.")
+    parser.add_argument("--pr", action="store_true", help="Append PR number to each commit.")
+    args = parser.parse_args()
+
+    last_tag = get_last_tag()
+    if not last_tag:
+        print("No tags found in the repository.", file=sys.stderr)
+    
+    revision_range = f"{last_tag}..HEAD" if last_tag else "HEAD"
+    
+    commits = get_commits(revision_range)
+    if not commits:
+        print(f"No commits found since {last_tag if last_tag else 'the beginning'}.")
+        return
+
+    pr_map = get_pr_mappings(revision_range) if args.pr else {}
+
+    # Conventional Commit regex: type(scope): description
+    commit_re = re.compile(r'^(\w+)(?:\(([^)]+)\))?:\s*(.*)$')
+
+    grouped = defaultdict(list)
+    others = []
+
+    for c_hash, c_subject in commits:
+        # Skip merge commits in the output
+        if c_subject.startswith(("Merge pull request", "Merge branch")):
+            continue
+
+        pr_suffix = f" (#{pr_map[c_hash]})" if c_hash in pr_map else ""
+        match = commit_re.match(c_subject)
+
+        if match:
+            ctype = match.group(1).lower()
+            ctype = CORRECTIONS.get(ctype, ctype)
+            description = format_description(match.group(3))
+            grouped[ctype].append(f"{description}{pr_suffix}")
+        else:
+            others.append(f"{c_subject}{pr_suffix}")
+
+    # Output sections in ordered priority
+    all_types = TYPE_ORDER + sorted([t for t in grouped if t not in TYPE_ORDER])
+    first = True
+    for ctype in all_types:
+        if ctype in grouped:
+            if not first:
+                print()
+            section_name = SECTIONS.get(ctype, ctype.capitalize())
+            print(f"{section_name}:")
+            for msg in sorted(grouped[ctype]):
+                print(f"- {msg}")
+            first = False
+
+    if others:
+        if not first:
+            print()
+        print("Others:")
+        for msg in sorted(others):
+            print(f"- {msg}")
+
+    # Contributors section
+    contributors = get_contributors(revision_range)
+    if contributors:
+        print("\nContributors:")
+        for i, name in enumerate(contributors, 1):
+            print(f"{i}. {name}")
+
+if __name__ == "__main__":
+    main()