name: CI

on:
  pull_request:
  push:

jobs:
  verify:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Set up Go
        uses: actions/setup-go@v5
        with:
          go-version-file: go.mod
          cache: true

      - name: Install tooling
        run: |
          echo "$(go env GOPATH)/bin" >> "$GITHUB_PATH"
          go install github.com/magefile/mage@v1.15.0
          go install github.com/golangci/golangci-lint/cmd/golangci-lint@v1.64.8

      - name: Gate vet
        run: mage vet

      - name: Gate lint
        env:
          PR_BASE_SHA: ${{ github.event.pull_request.base.sha }}
          PUSH_BEFORE_SHA: ${{ github.event.before }}
          DEFAULT_BRANCH: ${{ github.event.repository.default_branch }}
        run: |
          is_usable_rev() {
            local rev="$1"
            [ -n "$rev" ] &&
              [ "$rev" != "0000000000000000000000000000000000000000" ] &&
              git rev-parse --verify "${rev}^{commit}" >/dev/null 2>&1 &&
              git merge-base --is-ancestor "$rev" HEAD >/dev/null 2>&1
          }

          BASE_SHA="${PR_BASE_SHA:-$PUSH_BEFORE_SHA}"

          if ! is_usable_rev "$BASE_SHA"; then
            BASE_SHA=""
          fi

          if [ -z "$BASE_SHA" ] && [ -n "$DEFAULT_BRANCH" ]; then
            DEFAULT_REF="origin/$DEFAULT_BRANCH"

            if ! git rev-parse --verify "${DEFAULT_REF}^{commit}" >/dev/null 2>&1; then
              git fetch --no-tags --depth=1 origin \
                "$DEFAULT_BRANCH:refs/remotes/origin/$DEFAULT_BRANCH" \
                >/dev/null 2>&1 || true
            fi

            if git rev-parse --verify "${DEFAULT_REF}^{commit}" >/dev/null 2>&1; then
              MERGE_BASE="$(git merge-base HEAD "$DEFAULT_REF" 2>/dev/null || true)"
              if is_usable_rev "$MERGE_BASE"; then
                BASE_SHA="$MERGE_BASE"
              fi
            fi
          fi

          if [ -z "$BASE_SHA" ]; then
            if git rev-parse --verify HEAD~1 >/dev/null 2>&1; then
              BASE_SHA="$(git rev-parse HEAD~1)"
            else
              BASE_SHA="$(git rev-list --max-parents=0 HEAD)"
            fi
          fi

          echo "Lint baseline: $BASE_SHA"
          golangci-lint run --new-from-rev="$BASE_SHA"

      - name: Gate tests
        run: mage test