cherry-pick-rc-to-develop.yml

# GitHub Action: Cherry-pick from `release/candidate` to `TARGET_BRANCH`
#
# This action automates the process of cherry-picking merged PRs from `release/candidate` branch to `TARGET_BRANCH`.
# It is triggered whenever a pull request is merged into `release/candidate`.
#
# The action performs the following steps:
# 1. Checkout the merged PR.
# 2. If changes are made outside the specified submodule or no submodule is specified, the action proceeds.
# 3. If a submodule name is provided in the `SUBMODULE_NAME` environment variable:
#    a. The action creates a temporary branch.
#    b. Updates the submodule to its latest version from `develop`.
#    c. Commits the submodule updates.
# 4. Squashes the commit with the commit message of the merged PR (if a submodule was updated).
# 5. Cherry-picks the squashed (or original if no squashing occurred) commit to a new branch based on `develop`.
# 6. If any conflicts arise during the cherry-pick, they are committed.
# 7. The branch with the cherry-picked changes is pushed.
# 8. A new pull request is created against `develop` with the cherry-picked changes.
#
# Note: Ensure you add a "cherry-pick" label to your project. This label is required for the creation of cherry-picked PRs.
# If needed, you can also set the `TARGET_BRANCH` environment variable to specify a different target branch for the cherry-pick.
# By default, it's set to `develop`.

name: "Cherry-pick from rc to develop"

on:
    pull_request:
        branches:
            - release/candidate
        types:
            - closed

env:
    TARGET_BRANCH: develop
    SUBMODULE_NAME: kalium

jobs:
    cherry-pick:
        runs-on: ubuntu-latest
        if: github.event.pull_request.merged == true

        env:
            GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

        steps:
            - name: Checkout
              uses: actions/checkout@v4
              with:
                  fetch-depth: 0
                  submodules: recursive

            - name: Append -cherry-pick to branch name
              id: extract
              run: |
                  PR_BRANCH="${{ github.event.pull_request.head.ref }}"
                  NEW_BRANCH_NAME="${PR_BRANCH}-cherry-pick"
                  echo "New branch name: $NEW_BRANCH_NAME"
                  echo "newBranchName=$NEW_BRANCH_NAME" >> $GITHUB_ENV

            - name: Check for changes excluding submodule
              id: check_changes
              run: |
                  if [[ -n "${{ env.SUBMODULE_NAME }}" ]]; then
                    # If SUBMODULE_NAME is set
                    NUM_CHANGES=$(git diff origin/${{ env.TARGET_BRANCH }} --name-only | grep -v "^${{ env.SUBMODULE_NAME }}/" | wc -l)
                  else
                    # If SUBMODULE_NAME is not set
                    NUM_CHANGES=$(git diff origin/${{ env.TARGET_BRANCH }} --name-only | wc -l)
                  fi
                  if [ "$NUM_CHANGES" -gt 0 ]; then
                       echo "shouldCherryPick=true" >> $GITHUB_ENV
                  else
                    if [[ -n "${{ env.SUBMODULE_NAME }}" ]]; then
                      echo "No changes outside of ${{ env.SUBMODULE_NAME }} submodule, skipping cherry-pick"
                    else
                      echo "No changes detected, skipping cherry-pick"
                    fi
                    echo "shouldCherryPick=false" >> $GITHUB_ENV
                  fi

            - uses: fregante/setup-git-user@v2

            - name: Update submodule
              if: env.SUBMODULE_NAME && env.shouldCherryPick == 'true'
              run: |
                  set -x
                  # Create a temporary branch and get the last commit message
                  git checkout -b temp-branch-for-cherry-pick
                  LAST_COMMIT_MESSAGE=$(git log --format=%B -n 1 ${{ github.event.pull_request.merge_commit_sha }})
                  cd ${{ env.SUBMODULE_NAME }}
                  git checkout ${{ env.TARGET_BRANCH }}
                  git pull origin ${{ env.TARGET_BRANCH }}
                  cd ..
                  git add ${{ env.SUBMODULE_NAME }}
                  git commit -m "Update submodule ${{ env.SUBMODULE_NAME }} to latest from ${{ env.TARGET_BRANCH }}"
                  # Base64 encode the commit message to avoid issues with newlines and special characters
                  echo "lastCommitMessageBase64=$(echo "$LAST_COMMIT_MESSAGE" | base64 -w 0 )" >> $GITHUB_ENV

            - name: Get Cherry-pick commit
              id: get-cherry
              if: env.shouldCherryPick == 'true'
              run: |
                  if [[ -n "${{ env.SUBMODULE_NAME }}" ]]; then
                    # If SUBMODULE_NAME is set
                    git reset --soft HEAD~2
                    # Decode the base64-encoded string
                    LAST_COMMIT_MESSAGE=$(echo "${{ env.lastCommitMessageBase64 }}" | base64 --decode)
                    git commit -m "$LAST_COMMIT_MESSAGE"
                  fi
                  
                  # Get the SHA of the current commit (either squashed or not based on the condition above)
                  CHERRY_PICK_COMMIT=$(git rev-parse HEAD)
                  echo "cherryPickCommit=$CHERRY_PICK_COMMIT" >> $GITHUB_ENV

            - name: Get Original Author
              id: get-author
              if: env.shouldCherryPick == 'true'
              run: |
                  ORIGINAL_AUTHOR=$(git log -1 --pretty=format:'%an <%ae>' ${{ github.event.pull_request.merge_commit_sha }})
                  echo "Original author: $ORIGINAL_AUTHOR"
                  echo "originalAuthor=$ORIGINAL_AUTHOR" >> $GITHUB_ENV

            - name: Cherry-pick commits
              id: commit-cherry-pick
              if: env.shouldCherryPick == 'true'
              run: |
                  # Checkout the desired branch and cherry-pick the commit  
                  git checkout ${{ env.TARGET_BRANCH }}
                  git checkout -b ${{ env.newBranchName }}
                  OUTPUT=$(git cherry-pick ${{ env.cherryPickCommit }} || true)
                  
                  # Handle conflicts
                  CONFLICTED_FILES=$(git diff --name-only --diff-filter=U | awk 'ORS="\\\\n"' | sed 's/\\\\n$/\\n/')
                  echo "Captured conflicted files: $CONFLICTED_FILES"
                  if [[ "$OUTPUT" == *"CONFLICT"* ]]; then
                      # Commit the remaining conflicts
                      git add .
                      git commit --author "${{ env.originalAuthor }}" -am "Commit with unresolved merge conflicts outside of ${{ env.SUBMODULE_NAME }}"
                  else
                      git commit --author "${{ env.originalAuthor }}" --amend --no-edit
                  fi
                  
                  # Push branch and remove temp
                  git push origin ${{ env.newBranchName }} || (echo "Failed to push to origin" && exit 1)
                  echo "conflictedFiles=$CONFLICTED_FILES" >> $GITHUB_ENV
                  if [[ -n "${{ env.SUBMODULE_NAME }}" ]]; then
                  git branch -D temp-branch-for-cherry-pick
                  fi

            - name: Create PR
              if: env.shouldCherryPick == 'true'
              env:
                  GITHUB_TOKEN: ${{ secrets.ANDROID_BOB_GH_TOKEN }}
                  PR_TITLE: ${{ github.event.pull_request.title }}
                  PR_BRANCH: ${{ env.newBranchName }}
                  PR_ASSIGNEE: ${{ github.event.pull_request.user.login }}
              run: |
                  PR_BODY=$(echo -e "Cherry pick from the original PR: \n- #${{ github.event.pull_request.number }}\n\n---- \n\n ⚠️ Conflicts during cherry-pick:\n${{ env.conflictedFiles }}\n\n${{ github.event.pull_request.body }}")
                  gh pr create --title "$PR_TITLE" --body "$PR_BODY" --base ${{ env.TARGET_BRANCH }} --head "$PR_BRANCH" --label "cherry-pick" --assignee "$PR_ASSIGNEE"