name: Revert PR

on:
  pull_request_target:
    # Safe because we only checkout the trusted 'master' branch from the flutteractionsbot/flutter repository
    # to execute reverts of merged pull request commits. It does not execute arbitrary user-controlled code.
    types: [labeled] # zizmor: ignore[dangerous-triggers]

permissions:
  contents: read

jobs:
  revert:
    name: Revert PR
    runs-on: ubuntu-latest
    if: github.event.label.name == 'revert'
    steps:
      - name: Handle Not Merged PR
        if: github.event.pull_request.merged != true
        run: |
          gh pr comment "$PR_NUMBER" -R flutter/flutter -b "Only merged pull requests can be reverted."
          gh pr edit "$PR_NUMBER" -R "$REPO" --remove-label "revert"

          # Cancel the workflow and poll the API with a 5-minute safety timeout to prevent infinite runner hanging
          gh run cancel ${{ github.run_id }} || true
          for i in {1..60}; do
            echo "Waiting for cancellation signal... [$i/60]"
            sleep 5
          done
          echo "Cancellation signal timeout reached. Forcing failure."
          exit 1
        env:
          GH_TOKEN: ${{ secrets.FLUTTERACTIONSBOT_CP_TOKEN }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
          REPO: ${{ github.repository }}

      - name: Verify Reason and Fetch PR Details
        run: |
          # Fetch body, comments, and reviews in a single consolidated API call
          gh pr view "$PR_NUMBER" -R "$REPO" --json body,comments,reviews > pr_details.json

          # Parse the revert reason case-insensitively and robustly, while allowing the latest "revert" reason to win.
          jq -r '.comments // [] | .[] | .body | select(test("^reason for revert:"; "i")) | sub("^reason for revert:\\s*"; ""; "i")' pr_details.json | tail -n 1 > reason.txt

          if [ ! -s reason.txt ]; then
            gh pr comment "$PR_NUMBER" -R flutter/flutter -b "A reason for requesting a revert of $REPO/$PR_NUMBER could not be found or the reason was not properly formatted. Begin a comment with **'Reason for revert:'** to tell the bot why this issue is being reverted."
            gh pr edit "$PR_NUMBER" -R "$REPO" --remove-label "revert"
            exit 1
          fi

          # Extract reviewer and original body with null safety to avoid subsequent API requests
          REVIEWER=$(jq -r '[.reviews // [] | .[] | select(.state == "APPROVED")] | .[0].author.login' pr_details.json)
          if [ -z "$REVIEWER" ] || [ "$REVIEWER" = "null" ]; then
            echo "None" > reviewer.txt
          else
            echo "@$REVIEWER" > reviewer.txt
          fi

          jq -r '.body // ""' pr_details.json > original_body.txt
        env:
          GH_TOKEN: ${{ secrets.FLUTTERACTIONSBOT_CP_TOKEN }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
          REPO: ${{ github.repository }}

      - name: Checkout Fork
        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0
        with:
          repository: flutteractionsbot/flutter
          path: flutter
          ref: master
          token: ${{ secrets.FLUTTERACTIONSBOT_CP_TOKEN }}
          fetch-depth: 0
          persist-credentials: false

      - name: Configure git
        run: |
          gh auth setup-git
          git config --global user.name "flutteractionsbot"
          git config --global user.email "<flutter-actions-bot@google.com>"
        env:
          GH_TOKEN: ${{ secrets.FLUTTERACTIONSBOT_CP_TOKEN }}

      - name: Prepare working folder
        working-directory: ./flutter
        run: |
          git remote add upstream https://github.com/flutter/flutter.git
          git fetch upstream master
          git checkout -b "revert-$PR_NUMBER-$(date +%s)" upstream/master
        env:
          GH_TOKEN: ${{ secrets.FLUTTERACTIONSBOT_CP_TOKEN }}
          PR_NUMBER: ${{ github.event.pull_request.number }}

      - name: Revert Commit
        working-directory: ./flutter
        run: |
          if ! git revert "$MERGE_COMMIT" --no-edit; then
            gh pr comment "$PR_NUMBER" -R flutter/flutter -b "Failed to revert commit $MERGE_COMMIT cleanly. Please resolve conflicts manually."
            gh pr edit "$PR_NUMBER" -R "$REPO" --remove-label "revert"
            exit 1
          fi
        env:
          GH_TOKEN: ${{ secrets.FLUTTERACTIONSBOT_CP_TOKEN }}
          MERGE_COMMIT: ${{ github.event.pull_request.merge_commit_sha }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
          REPO: ${{ github.repository }}

      - name: Push and Create PR
        working-directory: ./flutter
        run: |
          BRANCH_NAME=$(git branch --show-current)
          REVIEWER_NAME=$(cat ../reviewer.txt)
          REVIEW_LINE="Reviewed By: $REVIEWER_NAME"

          git push origin "$BRANCH_NAME"

          PR_LINK="https://github.com/flutter/flutter/pull/$PR_NUMBER"

          {
            echo "Reverts: [$PR_TITLE]($PR_LINK)"
            echo ""
            echo "Initiated by: @$INITIATOR"
            echo ""
            echo "Reason for reverting: $(cat ../reason.txt)"
            echo ""
            echo "Original PR Author: @$ORIGINAL_AUTHOR"
            echo ""
            echo "$REVIEW_LINE"
            echo ""
            echo "The original PR description is provided below:"
            echo ""
            cat ../original_body.txt
          } > ../pr_body.txt

          NEW_PR_URL=$(gh pr create \
            --title "Revert: $PR_TITLE" \
            --body-file ../pr_body.txt \
            --repo flutter/flutter \
            --base master \
            --head "flutteractionsbot:$BRANCH_NAME")

          gh pr comment "$PR_NUMBER" -R flutter/flutter -b "Successfully created revert PR: $NEW_PR_URL"
          gh pr edit "$PR_NUMBER" -R "$REPO" --remove-label "revert"
        env:
          GH_TOKEN: ${{ secrets.FLUTTERACTIONSBOT_CP_TOKEN }}
          INITIATOR: ${{ github.event.sender.login }}
          ORIGINAL_AUTHOR: ${{ github.event.pull_request.user.login }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
          PR_TITLE: ${{ github.event.pull_request.title }}
          REPO: ${{ github.repository }}