Add script to generate changelogs (#2920)

* Add script to generate changelogs from PR labels

* Improve PR template

* Better categorization

scripts/generate_changelog.py

@@ -0,0 +1,187 @@
+#!/usr/bin/env python3
+
+"""
+Summarizes recent PRs based on their GitHub labels.
+
+The result can be copy-pasted into CHANGELOG.md, though it often needs some manual editing too.
+"""
+
+import multiprocessing
+import re
+import sys
+from dataclasses import dataclass
+from typing import Any, List, Optional
+
+import requests
+from git import Repo  # pip install GitPython
+from tqdm import tqdm
+
+OWNER = "emilk"
+REPO = "egui"
+COMMIT_RANGE = "latest..HEAD"
+INCLUDE_LABELS = False  # It adds quite a bit of visual noise
+OFFICIAL_DEVS = [
+    "emilk",
+]
+
+
+@dataclass
+class PrInfo:
+    gh_user_name: str
+    pr_title: str
+    labels: List[str]
+
+
+@dataclass
+class CommitInfo:
+    hexsha: str
+    title: str
+    pr_number: Optional[int]
+
+
+def get_github_token() -> str:
+    import os
+
+    token = os.environ.get("GH_ACCESS_TOKEN", "")
+    if token != "":
+        return token
+
+    home_dir = os.path.expanduser("~")
+    token_file = os.path.join(home_dir, ".githubtoken")
+
+    try:
+        with open(token_file, "r") as f:
+            token = f.read().strip()
+        return token
+    except Exception:
+        pass
+
+    print("ERROR: expected a GitHub token in the environment variable GH_ACCESS_TOKEN or in ~/.githubtoken")
+    sys.exit(1)
+
+
+# Slow
+def fetch_pr_info_from_commit_info(commit_info: CommitInfo) -> Optional[PrInfo]:
+    if commit_info.pr_number is None:
+        return None
+    else:
+        return fetch_pr_info(commit_info.pr_number)
+
+
+# Slow
+def fetch_pr_info(pr_number: int) -> Optional[PrInfo]:
+    url = f"https://api.github.com/repos/{OWNER}/{REPO}/pulls/{pr_number}"
+    gh_access_token = get_github_token()
+    headers = {"Authorization": f"Token {gh_access_token}"}
+    response = requests.get(url, headers=headers)
+    json = response.json()
+
+    # Check if the request was successful (status code 200)
+    if response.status_code == 200:
+        labels = [label["name"] for label in json["labels"]]
+        gh_user_name = json["user"]["login"]
+        return PrInfo(gh_user_name=gh_user_name, pr_title=json["title"], labels=labels)
+    else:
+        print(f"ERROR {url}: {response.status_code} - {json['message']}")
+        return None
+
+
+def get_commit_info(commit: Any) -> CommitInfo:
+    match = re.match(r"(.*) \(#(\d+)\)", commit.summary)
+    if match:
+        return CommitInfo(hexsha=commit.hexsha, title=str(match.group(1)), pr_number=int(match.group(2)))
+    else:
+        return CommitInfo(hexsha=commit.hexsha, title=commit.summary, pr_number=None)
+
+
+def remove_prefix(text, prefix):
+    if text.startswith(prefix):
+        return text[len(prefix):]
+    return text  # or whatever
+
+
+def print_section(crate: str, items: List[str]) -> None:
+    if 0 < len(items):
+        print(f"#### {crate}")
+        for line in items:
+            line = remove_prefix(line, f"{crate}: ")
+            line = remove_prefix(line, f"[{crate}] ")
+            print(f"- {line}")
+    print()
+
+
+def main() -> None:
+    repo = Repo(".")
+    commits = list(repo.iter_commits(COMMIT_RANGE))
+    commits.reverse()  # Most recent last
+    commit_infos = list(map(get_commit_info, commits))
+
+    pool = multiprocessing.Pool()
+    pr_infos = list(
+        tqdm(
+            pool.imap(fetch_pr_info_from_commit_info, commit_infos),
+            total=len(commit_infos),
+            desc="Fetch PR info commits",
+        )
+    )
+
+    ignore_labels = ["CI", "dependencies"]
+
+    crate_names = [
+        "ecolor",
+        "eframe",
+        "egui_extras",
+        "egui_glow",
+        "egui-wgpu",
+        "egui-winit",
+        "egui",
+        "epaint",
+    ]
+    sections = {}
+    unsorted_prs = []
+    unsorted_commits = []
+
+    for commit_info, pr_info in zip(commit_infos, pr_infos):
+        hexsha = commit_info.hexsha
+        title = commit_info.title
+        pr_number = commit_info.pr_number
+
+        if pr_number is None:
+            # Someone committed straight to main:
+            summary = f"{title} [{hexsha}](https://github.com/{OWNER}/{REPO}/commit/{hexsha})"
+            unsorted_commits.append(summary)
+        else:
+            title = pr_info.pr_title if pr_info else title  # We prefer the PR title if available
+            labels = pr_info.labels if pr_info else []
+
+            summary = f"{title} [#{pr_number}](https://github.com/{OWNER}/{REPO}/pull/{pr_number})"
+
+            if INCLUDE_LABELS and 0 < len(labels):
+                summary += f" ({', '.join(labels)})"
+
+            if pr_info is not None:
+                gh_user_name = pr_info.gh_user_name
+                if gh_user_name not in OFFICIAL_DEVS:
+                    summary += f" (thanks [@{gh_user_name}](https://github.com/{gh_user_name})!)"
+
+            added = False
+            for crate in crate_names:
+                if crate in labels:
+                    sections.setdefault(crate, []).append(summary)
+                    added = True
+
+            if not added:
+                if not any(label in labels for label in ignore_labels):
+                    unsorted_prs.append(summary)
+
+    print()
+    for crate in crate_names:
+        if crate in sections:
+            summary = sections[crate]
+            print_section(crate, summary)
+    print_section("Unsorted PRs", unsorted_prs)
+    print_section("Unsorted commits", unsorted_commits)
+
+
+if __name__ == "__main__":
+    main()