cherry-pick-ladybird-pr.sh

#!/bin/bash

# Assumes:
# * you have a remote 'ladybird' pointing to 
#   https://github.com/LadybirdBrowser/ladybird.git"
# * both origin/master and ladybird/master are up-to-date
# * you're on a branch where you want the cherry-picked commits to appear
#
# Example invocation:
#     Meta/cherry-pick-ladybird-pr.sh 242

set -euo pipefail

if [ $# -eq 0 ]; then
  echo "Usage: $0 <PR number>"
  exit 1
fi

PR_NUMBER=$1

SINCE=$(git merge-base origin/master ladybird/master)

# Approach:
# 1. Use github rest api to get commit hashes and messages of a PR as json
# 2. Use python to print just commit hashes and first commit message lines
# 3. Use `git log --grep` with first line of commit message to get the merged
#    upstream commit hash with that commit message, for each commit
# 4. Cherry-pick that upstream commit, for each commit

curl --silent -L \
  -H "Accept: application/vnd.github+json" \
  -H "X-GitHub-Api-Version: 2022-11-28" \
  https://api.github.com/repos/LadybirdBrowser/ladybird/pulls/$PR_NUMBER/commits \
| python3 -c '
import sys
import json

data = json.load(sys.stdin)

for item in data:
    sha = item["sha"]
    message = item["commit"]["message"]
    print(sha, message.splitlines()[0])
' \
| while IFS= read -r line; do
  COMMIT_HASH=$(echo $line | cut -d ' ' -f 1)
  COMMIT_MESSAGE=$(echo $line | cut -d ' ' -f 2-)

  # Find the commit in the base branch by commit message
  REBASED_COMMIT=$(git log --since="$SINCE" \
                           --pretty=format:"%H %s" \
                           --grep "$COMMIT_MESSAGE" \
                           ladybird/master)

  NUM_HITS=$(echo -n "$REBASED_COMMIT" | grep -c '^')

  if [ "$NUM_HITS" -ne "1" ]; then
    echo "found $NUM_HITS hits for $COMMIT_MESSAGE, exiting"
    exit 1
  fi

  echo "Original commit $COMMIT_HASH maps to $REBASED_COMMIT"

  REBASED_HASH=$(echo "$REBASED_COMMIT" | cut -d ' ' -f 1)
  git cherry-pick -x "$REBASED_HASH"
done