name: Merge release to pg

on:
  push:
    branches:
      - release  # Trigger on push to the release branch

jobs:
  merge-release-to-pg:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout release branch
        uses: actions/checkout@v3
        with:
          ref: release  # Checkout the release branch
          fetch-depth: 0

      - name: Set Git config values
        run: |
          git config pull.rebase false
          git config user.email "automated@github.com"
          git config user.name "Automated Github Action"

      - name: Checkout pg branch
        run: git checkout pg

      - name: Merge release to pg
        id: merge_commits
        run: |
          PG_HEAD=$(git rev-parse pg)
          RELEASE_HEAD=$(git rev-parse release)

          echo "PG_HEAD=$PG_HEAD"
          echo "RELEASE_HEAD=$RELEASE_HEAD"

          # Attempt to merge release into pg
          if ! git merge release; then
            echo "Merge conflict detected during merge"

            # Capture the conflicting commit SHAs (both HEAD of pg and the merge commit from release)
            CONFLICTING_COMMIT=$(git log -1 --pretty=format:"%H")
            echo "CONFLICTING_COMMIT=$CONFLICTING_COMMIT" >> $GITHUB_ENV

            echo "MERGE_CONFLICT=true" >> $GITHUB_ENV
          else
            echo "MERGE_CONFLICT=false" >> $GITHUB_ENV
          fi

      - name: Push changes
        if: env.MERGE_CONFLICT == 'false'
        run: |
          git push origin pg

      - name: Notify on merge conflicts
        if: env.MERGE_CONFLICT == 'true'
        env:
          REPOSITORY_URL: ${{ github.repositoryUrl }}
          CONFLICTING_COMMIT: ${{ env.CONFLICTING_COMMIT }}
        run: |
          # Prepare the message for Slack
          message="Merge conflict detected while merging release into pg branch. Conflicted commits:\n"
          commit_url="$REPOSITORY_URL/commit/$CONFLICTING_COMMIT"
          message+="$commit_url\n"

          # Send the message to Slack
          # This unwieldy horror of a sed command, converts standard Markdown links to Slack's unwieldy link syntax.
          slack_message="$(echo "$message" | sed -E 's/\[([^]]+)\]\(([^)]+)\)/<\2|\1>/g')"

          echo "$slack_message"

          # This is the ChannelId of the proj postgres channel.
          body="$(jq -nc \
            --arg channel C06Q3A97USE \
            --arg text "$slack_message" \
            '$ARGS.named'
          )"

          curl --version
          curl -v https://slack.com/api/chat.postMessage \
            --header 'Authorization: Bearer ${{ secrets.SLACK_APPSMITH_ALERTS_TOKEN }}' \
            --header 'Content-Type: application/json; charset=utf-8' \
            --data-raw "$body"