name: Release sweep

# Keeps v1 from lagging main when ci.yaml's release-tag job defers or never
# runs. Each tick either finds v1 already covering main's tip and exits, or
# gates the tip exactly as ci.yaml's selftest job does and moves v1 to it. A
# red run here means v1 is behind a main that fails its gate.
#
# Gitea registers schedules from the default branch only, so this fires once
# it is on main.
on:
  schedule:
    - cron: '*/15 * * * *'

# A tick that arrives while another is still gating waits behind it rather
# than gating the same tip twice.
concurrency:
  group: release-sweep
  cancel-in-progress: false

jobs:
  sweep:
    name: move v1 to main if it lags
    runs-on: ubuntu-latest
    timeout-minutes: 25
    permissions:
      contents: write
    steps:
      - uses: actions/checkout@v4
        with:
          token: ${{ secrets.GITHUB_TOKEN }}
          fetch-depth: 0

      # A scheduled run's github.sha is main as of the last push, not
      # necessarily its tip, so the tip is read here instead.
      - name: Check whether v1 lags main
        id: check
        run: bash scripts/release-v1.sh sweep-check

      # Everything below runs only when v1 lags, and gates the tip itself,
      # not the commit this run was created from.
      - name: Check out main's tip
        if: steps.check.outputs.needed == 'true'
        run: git checkout -q --detach "${{ steps.check.outputs.tip }}"

      - name: Install shellcheck
        if: steps.check.outputs.needed == 'true'
        uses: taiki-e/install-action@v2
        with:
          tool: shellcheck

      # Same toolchains, same order, as ci.yaml's selftest job.
      - name: Install Rust nightly
        if: steps.check.outputs.needed == 'true'
        uses: dtolnay/rust-toolchain@nightly
      - name: Install Rust toolchain
        if: steps.check.outputs.needed == 'true'
        uses: dtolnay/rust-toolchain@stable

      - name: shellcheck
        if: steps.check.outputs.needed == 'true'
        run: shellcheck -x --source-path=scripts scripts/*.sh

      - name: Selftests
        if: steps.check.outputs.needed == 'true'
        run: bash scripts/selftest.sh

      - name: Move v1 to the gated tip
        if: steps.check.outputs.needed == 'true'
        run: bash scripts/release-v1.sh push "${{ steps.check.outputs.tip }}" "${{ steps.check.outputs.v1 }}"