name: Create Release PR

on:
  workflow_call:
    inputs:
      component-name:
        description: 'Component name'
        required: true
        type: string
      source-branch:
        description: 'Source branch'
        required: true
        type: string
    secrets:
      ci-access-token:
        description: 'CI access token'
        required: true

defaults:
  run:
    shell: bash -euo pipefail {0}

permissions:
  contents: read

jobs:
  create-release-branch:
    runs-on: ubuntu-22.04

    permissions:
      contents: write # for `git push`

    steps:
    - name: Harden the runner (Audit all outbound calls)
      uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
      with:
        egress-policy: audit

    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
      with:
        ref: ${{ inputs.source-branch }}
        fetch-depth: 0

    - name: Set variables
      id: vars
      env:
        COMPONENT_NAME: ${{ inputs.component-name }}
        RELEASE_BRANCH: >-
          ${{
            false
            || inputs.component-name == 'Storage' && 'release'
            || inputs.component-name == 'Proxy' && 'release-proxy'
            || inputs.component-name == 'Compute' && 'release-compute'
          }}
      run: |
        today=$(date +'%Y-%m-%d')
        echo "title=${COMPONENT_NAME} release ${today}" | tee -a ${GITHUB_OUTPUT}
        echo "rc-branch=rc/${RELEASE_BRANCH}/${today}"  | tee -a ${GITHUB_OUTPUT}
        echo "release-branch=${RELEASE_BRANCH}"         | tee -a ${GITHUB_OUTPUT}

    - name: Configure git
      run: |
        git config user.name "github-actions[bot]"
        git config user.email "41898282+github-actions[bot]@users.noreply.github.com"

    - name: Create RC branch
      env:
        RELEASE_BRANCH: ${{ steps.vars.outputs.release-branch }}
        RC_BRANCH: ${{ steps.vars.outputs.rc-branch }}
        TITLE: ${{ steps.vars.outputs.title }}
      run: |
        git switch -c "${RC_BRANCH}"

        # Manually create a merge commit on the current branch, keeping the
        # tree and setting the parents to the current HEAD and the HEAD of the
        # release branch. This commit is what we'll fast-forward the release
        # branch to when merging the release branch.
        # For details on why, look at
        # https://docs.neon.build/overview/repositories/neon.html#background-on-commit-history-of-release-prs
        current_tree=$(git rev-parse 'HEAD^{tree}')
        release_head=$(git rev-parse "origin/${RELEASE_BRANCH}")
        current_head=$(git rev-parse HEAD)
        merge_commit=$(git commit-tree -p "${current_head}" -p "${release_head}" -m "${TITLE}" "${current_tree}")

        # Fast-forward the current branch to the newly created merge_commit
        git merge --ff-only ${merge_commit}

        git push origin "${RC_BRANCH}"

    - name: Create a PR into ${{ steps.vars.outputs.release-branch }}
      env:
        GH_TOKEN: ${{ secrets.ci-access-token }}
        RC_BRANCH: ${{ steps.vars.outputs.rc-branch }}
        RELEASE_BRANCH: ${{ steps.vars.outputs.release-branch }}
        TITLE: ${{ steps.vars.outputs.title }}
      run: |
        gh pr create --title "${TITLE}" \
                     --body "" \
                     --head "${RC_BRANCH}" \
                     --base "${RELEASE_BRANCH}"