Shared Delete Branch

name: Shared - Delete Merged Branch

on:
  workflow_call:
    inputs:
      branch_name:
        description: 'Branch name to delete (if empty, detects from merge commit)'
        required: false
        type: string
        default: ''
      dry_run:
        description: 'Only log what would be deleted, do not actually delete'
        required: false
        type: boolean
        default: false
      fail_on_protected:
        description: 'Hard-fail when target branch is protected (develop/main/master/release/*). Default true for explicit branch_name inputs.'
        required: false
        type: boolean
        default: true

    outputs:
      deleted_branch:
        description: 'Name of deleted branch (empty if not deleted)'
        value: ${{ jobs.delete.outputs.branch }}
      status:
        description: 'Status: deleted, skipped, protected, not_found'
        value: ${{ jobs.delete.outputs.status }}

jobs:
  delete:
    name: Delete Branch
    runs-on: ubuntu-latest

    outputs:
      branch: ${{ steps.delete.outputs.branch }}
      status: ${{ steps.delete.outputs.status }}

    steps:
      - name: Checkout
        uses: actions/checkout@v5
        with:
          fetch-depth: 0

      - name: Detect and delete branch
        id: delete
        env:
          GH_TOKEN: ${{ github.token }}
          INPUT_BRANCH: ${{ inputs.branch_name }}
          DRY_RUN: ${{ inputs.dry_run }}
          FAIL_ON_PROTECTED: ${{ inputs.fail_on_protected }}
        run: |
          # Protected branches - never delete
          PROTECTED_BRANCHES="main master develop"

          # Determine branch to delete
          EXPLICIT_INPUT=false
          if [ -n "$INPUT_BRANCH" ]; then
            BRANCH="$INPUT_BRANCH"
            EXPLICIT_INPUT=true
          else
            COMMIT_SHA=$(git rev-parse HEAD)
            COMMIT_MSG=$(git log -1 --pretty=%B)

            # Method 1: Merge commit message
            if echo "$COMMIT_MSG" | grep -q "Merge pull request"; then
              BRANCH=$(echo "$COMMIT_MSG" | grep -oP "from [^/]+/\K[^\s]+" | head -1)
            elif echo "$COMMIT_MSG" | grep -q "Merge branch"; then
              BRANCH=$(echo "$COMMIT_MSG" | grep -oP "Merge branch '\K[^']+" | head -1)
            fi

            # Method 2: GitHub API (handles squash merges)
            if [ -z "$BRANCH" ]; then
              echo "Trying GitHub API to find PR for commit $COMMIT_SHA"
              BRANCH=$(gh api "repos/${{ github.repository }}/commits/${COMMIT_SHA}/pulls" \
                --jq '.[0].head.ref // empty' 2>/dev/null || echo "")
            fi

            if [ -z "$BRANCH" ]; then
              echo "Could not detect source branch from commit"
              echo "status=not_found" >> $GITHUB_OUTPUT
              echo "branch=" >> $GITHUB_OUTPUT
              exit 0
            fi
          fi

          echo "Detected branch: $BRANCH"

          # Check if branch is protected
          IS_PROTECTED=false
          for protected in $PROTECTED_BRANCHES; do
            if [ "$BRANCH" = "$protected" ]; then
              IS_PROTECTED=true
              break
            fi
          done
          if echo "$BRANCH" | grep -q "^release/"; then
            IS_PROTECTED=true
          fi

          if [ "$IS_PROTECTED" = "true" ]; then
            echo "::warning::Branch '$BRANCH' is protected (main/master/develop/release/*) — refusing to delete."
            echo "status=protected" >> $GITHUB_OUTPUT
            echo "branch=$BRANCH" >> $GITHUB_OUTPUT
            if [ "$EXPLICIT_INPUT" = "true" ] && [ "$FAIL_ON_PROTECTED" = "true" ]; then
              echo "::error::Refusing to delete protected branch '$BRANCH' (explicit input + fail_on_protected=true)."
              exit 1
            fi
            exit 0
          fi

          # Check if branch exists
          if ! git ls-remote --heads origin "$BRANCH" | grep -q .; then
            echo "Branch '$BRANCH' does not exist on remote"
            echo "status=not_found" >> $GITHUB_OUTPUT
            echo "branch=$BRANCH" >> $GITHUB_OUTPUT
            exit 0
          fi

          # Delete branch
          if [ "$DRY_RUN" = "true" ]; then
            echo "[DRY RUN] Would delete branch: $BRANCH"
            echo "status=skipped" >> $GITHUB_OUTPUT
          else
            echo "Deleting branch: $BRANCH"
            gh api -X DELETE "repos/${{ github.repository }}/git/refs/heads/$BRANCH" || true
            echo "status=deleted" >> $GITHUB_OUTPUT
          fi

          echo "branch=$BRANCH" >> $GITHUB_OUTPUT

          # Summary
          echo "### Branch Cleanup" >> $GITHUB_STEP_SUMMARY
          echo "" >> $GITHUB_STEP_SUMMARY
          if [ "$DRY_RUN" = "true" ]; then
            echo "**[DRY RUN]** Would delete: \`$BRANCH\`" >> $GITHUB_STEP_SUMMARY
          else
            echo "Deleted branch: \`$BRANCH\`" >> $GITHUB_STEP_SUMMARY
          fi