name: Promote Dev to Main

# `dev` is the working branch. `main` is a pointer to the same history, moved
# only by this workflow. Merge commits from dev → main are what painted the
# GitHub network graph; this job moves the `main` ref to `dev` instead.
on:
  push:
    branches: [dev]
    tags: ['chore.*']
  workflow_dispatch:

permissions:
  contents: read

concurrency:
  group: promote-dev-to-main
  cancel-in-progress: false

jobs:
  decide:
    runs-on: ubuntu-latest
    outputs:
      run: ${{ steps.check.outputs.run }}
      reason: ${{ steps.check.outputs.reason }}
    steps:
      - name: Decide whether to promote
        id: check
        env:
          EVENT_NAME: ${{ github.event_name }}
          REF: ${{ github.ref }}
          REF_TYPE: ${{ github.ref_type }}
          HEAD_COMMIT_MSG: ${{ github.event.head_commit.message }}
        run: |
          set -euo pipefail
          run='false'
          reason=''

          case "${EVENT_NAME}" in
            workflow_dispatch)
              run='true'
              reason='Manual workflow_dispatch'
              ;;
            push)
              if [ "${REF_TYPE}" = 'tag' ]; then
                run='true'
                reason="Tag push: ${REF}"
              elif [ "${REF}" = 'refs/heads/dev' ]; then
                msg="${HEAD_COMMIT_MSG:-}"
                if printf '%s' "${msg}" | grep -qiE '^\[merge\]|^chore\(release\):'; then
                  run='true'
                  reason='Commit message prefix on dev ([merge] or chore(release):)'
                else
                  reason='Commit on dev without [merge] / chore(release): prefix'
                fi
              else
                reason="Push event on unhandled ref: ${REF}"
              fi
              ;;
            *)
              reason="Unhandled event: ${EVENT_NAME}"
              ;;
          esac

          {
            echo "run=${run}"
            echo "reason=${reason}"
          } >> "${GITHUB_OUTPUT}"

          {
            echo "## Promote decision"
            echo
            echo "| Key | Value |"
            echo "| --- | --- |"
            echo "| Event | \`${EVENT_NAME}\` |"
            echo "| Ref | \`${REF}\` |"
            echo "| Run | \`${run}\` |"
            echo "| Reason | ${reason} |"
          } >> "${GITHUB_STEP_SUMMARY}"

  promote:
    needs: decide
    if: needs.decide.outputs.run == 'true'
    runs-on: ubuntu-latest
    steps:
      - name: Validate GitHub App credentials
        env:
          APP_ID: ${{ secrets.SNOWLUMA_BOT_APP_ID }}
          PRIVATE_KEY: ${{ secrets.SNOWLUMA_BOT_PRIVATE_KEY }}
        run: |
          if [ -z "${APP_ID}" ] || [ -z "${PRIVATE_KEY}" ]; then
            echo 'Missing SNOWLUMA_BOT_APP_ID and/or SNOWLUMA_BOT_PRIVATE_KEY secrets.' >&2
            echo 'Configure the same GitHub App used by the nnphook native PR flow.' >&2
            exit 1
          fi

      - name: Mint GitHub App installation token
        id: app-token
        uses: actions/create-github-app-token@v2
        with:
          app-id: ${{ secrets.SNOWLUMA_BOT_APP_ID }}
          private-key: ${{ secrets.SNOWLUMA_BOT_PRIVATE_KEY }}
          owner: ${{ github.repository_owner }}
          repositories: ${{ github.event.repository.name }}

      - name: Checkout
        uses: actions/checkout@v6
        with:
          ref: dev
          fetch-depth: 0
          token: ${{ steps.app-token.outputs.token }}

      - name: Point main at dev
        env:
          REASON: ${{ needs.decide.outputs.reason }}
          RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
        run: |
          set -euo pipefail
          git fetch origin dev main
          dev_sha="$(git rev-parse origin/dev)"
          main_sha="$(git rev-parse origin/main)"
          dev_short="$(git rev-parse --short origin/dev)"
          main_short="$(git rev-parse --short origin/main)"

          if [ "${dev_sha}" = "${main_sha}" ]; then
            echo "::notice::main already equals dev @ ${dev_short}; nothing to promote."
            {
              echo "main already equals dev @ ${dev_short}"
            } >> "${GITHUB_STEP_SUMMARY}"
            exit 0
          fi

          unique="$(git cherry origin/dev origin/main | awk '/^\+/ { print $2 }' || true)"
          if [ -n "${unique}" ]; then
            echo '::error::main has unique commits that dev does not. Cherry-pick them onto dev first.' >&2
            git log --oneline --no-walk ${unique}
            exit 1
          fi

          git push --force-with-lease="refs/heads/main:${main_sha}" origin "origin/dev:refs/heads/main"
          echo "::notice::Updated main ${main_short} → dev@${dev_short}"
          {
            echo "## Promote"
            echo
            echo "| Key | Value |"
            echo "| --- | --- |"
            echo "| \`main\` was | \`${main_sha}\` |"
            echo "| \`main\` now | \`dev\` @ \`${dev_sha}\` |"
            echo "| Reason | ${REASON} |"
            echo "| Workflow run | ${RUN_URL} |"
          } >> "${GITHUB_STEP_SUMMARY}"