cherry-pick-for

#!/bin/bash

set -euo pipefail

if [ $# -lt 2 ] || [ "$1" = "-h" ] || [ "$1" = "--help" ]; then
  echo "Usage: $0 (--no-checkout-and-pull|BRANCH) (COMMITS...|https://github.com/ORG/REPO/pull/NUMBER)"
  echo "Switches to the given branch, pulls it, cherry-picks all given commits or all commits of the"
  echo "given GitHub PR, and pushes the branch"
  echo "WARNING: Does not work for changes on symbolic links! Cherry pick the PR's commits manually,"
  echo "this helper script is not really needed anymore for change tracking because this is done through"
  echo "files in the changelog/*/ folders now."
  echo "Parameters:"
  echo "  --no-checkout-and-pull: If given instead of a branch, skips switching and pulling but pushes in the end"
  echo "Environment variables:"
  echo "  MERGE_COMMIT: Create a GitHub-style merge commit if a URL is given (defaults to 1)"
  echo "  PUSH: Push the branch to upstream (defaults to 1)"
  echo "  ORIGIN: Remote to use when checking out the tracking branch (defaults to origin)"
  exit 1
fi

PUSH="${PUSH-1}"
MERGE_COMMIT="${MERGE_COMMIT-1}"
ORIGIN="${ORIGIN-origin}"
BRANCH="$1"
COMMITS="${@:2}"

if [ "$BRANCH" = "--no-checkout-and-pull" ]; then
  BRANCH="HEAD"
else
  echo "Checking out $BRANCH"
  git checkout --recurse-submodules "$BRANCH" || git checkout --recurse-submodules --track "$ORIGIN/$BRANCH"
  echo "Pulling $BRANCH"
  git pull --recurse-submodules
fi

# Remove BRANCH from arguments to get the COMMITS to the front
shift

if [ "${COMMITS:0:4}" = http ]; then
  URL="$COMMITS"
  if [[ "$URL" = *" "* ]]; then
    echo "Error: Only one URL supported as argument"
    exit 1
  fi
  echo "Going to merge $URL"
  if [ "$MERGE_COMMIT" = 1 ]; then
    TEMP_BRANCH="pick$RANDOM"
    META="$(curl -s -S -f -L "$URL" | grep '<title>.*GitHub</title>')"
    PR_MSG1="Merge$(echo "$META" | awk -F'·' '{ print $2 }' | tr '[:upper:]' '[:lower:]')"
    PR_MSG2="from$(echo "$META" | awk -F'·' '{ print $3 }')"
    PR_TITLE="$(echo "$META" | awk -F'·' '{ print $1 }' | cut -d '>' -f 2- | rev | cut -d ' ' -f 4- | rev)"
    COMMIT_MSG="$PR_MSG1$PR_MSG2

$PR_TITLE"
    git checkout -b "$TEMP_BRANCH"
  fi
  echo "If you need to resolve conflicts, follow the \"git status\" instructions, then run:"
  if [ "${MERGE_COMMIT}" = 1 ]; then
    echo "  git checkout --recurse-submodules -"
    echo "  git merge --no-ff -m \"$COMMIT_MSG\" $TEMP_BRANCH"
    echo "  git branch -d $TEMP_BRANCH"
  fi
  echo "  git push"
  echo
  curl -s -S -f -L "$URL".patch | git am --3way
  echo "Successfully picked $URL"
  if [ "$MERGE_COMMIT" = 1 ]; then
    git checkout --recurse-submodules -
    git merge --no-ff -m "$COMMIT_MSG" "$TEMP_BRANCH"
    git branch -d "$TEMP_BRANCH"
  fi
else
  echo "Going to pick $COMMITS"
  for COMMIT in $COMMITS; do
    echo "Cherry-picking $COMMIT for $BRANCH"
    # Remove current COMMIT from arguments to get the list of remaining commits
    shift
    if [ $# -gt 0 ]; then
      echo "If you need to resolve conflicts, continue with: $0 --no-checkout-and-pull $@"
    else
      echo "If you need to resolve conflicts, continue with: git push"
    fi
    git cherry-pick "$COMMIT"
  done
  echo "Successfully picked $COMMITS"
fi

if [ "$PUSH" = 1 ]; then
  echo "Pushing changes"
  git push
fi
echo "Done"