name: CI changes
description: Decide which CI jobs a change needs. See .github/scripts/ci-changes.cjs.
outputs:
  typecheck:
    value: ${{ steps.detect.outputs.typecheck }}
  build:
    value: ${{ steps.detect.outputs.build }}
  test:
    value: ${{ steps.detect.outputs.test }}
  test_packages:
    value: ${{ steps.detect.outputs.test_packages }}
  test_web:
    value: ${{ steps.detect.outputs.test_web }}
  test_server:
    value: ${{ steps.detect.outputs.test_server }}
  rust:
    value: ${{ steps.detect.outputs.rust }}
  release_smoke:
    value: ${{ steps.detect.outputs.release_smoke }}
  mobile_native:
    value: ${{ steps.detect.outputs.mobile_native }}
  linux_arm64_package:
    value: ${{ steps.detect.outputs.linux_arm64_package }}
runs:
  using: composite
  steps:
    - id: detect
      shell: bash
      env:
        EVENT_NAME: ${{ github.event_name }}
        BEFORE_SHA: ${{ github.event.before }}
      run: |
        set -uo pipefail

        decide() {
          node .github/scripts/ci-changes.cjs "$@" | tee -a "$GITHUB_OUTPUT"
          exit "${PIPESTATUS[0]}"
        }

        fail_open() {
          echo "$* Running every job."
          decide
        }

        # Reads the change from git rather than the REST API: every job that
        # runs this shares the repository's 1,000 requests/hour GITHUB_TOKEN quota.
        if [[ "$EVENT_NAME" == pull_request ]]; then
          # A pull request checks out GitHub's merge commit with fetch-depth: 2,
          # so its first parent is the base branch and the diff is the PR's change.
          base=HEAD^1
          mode=()
        else
          base=$BEFORE_SHA
          git fetch --quiet --no-tags --depth=1 --filter=blob:none origin "$base" \
            || fail_open "Could not fetch ${base}."
          # main keeps a full run as the backstop for anything the gate misses.
          mode=(--full)
        fi

        # --no-renames lists a rename as its old and new path: renaming a file out
        # of a package changes that package just like editing it. It also keeps
        # git from fetching file contents to score renames.
        git diff --name-only --no-renames "$base" HEAD > "$RUNNER_TEMP/changed-paths" \
          || fail_open "Could not diff against ${base}."
        decide --paths "$RUNNER_TEMP/changed-paths" "${mode[@]}"