action.yml

name: 'Check force-builds override'
description: >-
  Detects whether the current workflow run should bypass native build reuse
  (both the GHA cache and the cross-run artifact lookup) and always compile
  fresh. The override is honored on `pull_request` events via a `force-builds`
  label OR a `[force-builds]` token in the head commit message. It is
  intentionally ignored on `merge_group` and `push` events so the merge queue
  always uses hash-verified reuse.

inputs:
  github-token:
    description: >-
      GitHub token with `pull-requests: read` (for label lookup) and
      `contents: read` (to fetch the head commit message via the REST API).
    required: true
  label-name:
    description: 'PR label that, when present, forces fresh builds'
    required: false
    default: 'force-builds'
  commit-tag:
    description: 'Case-sensitive substring in the head commit message that forces fresh builds'
    required: false
    default: '[force-builds]'

outputs:
  force:
    description: "'true' when fresh builds should be forced, otherwise 'false'"
    value: ${{ steps.compute.outputs.force }}

runs:
  using: 'composite'
  steps:
    - name: Compute force-builds flag
      id: compute
      shell: bash
      env:
        GH_TOKEN: ${{ inputs.github-token }}
        LABEL_NAME: ${{ inputs.label-name }}
        COMMIT_TAG: ${{ inputs.commit-tag }}
        EVENT_NAME: ${{ github.event_name }}
        HEAD_COMMIT_HASH: ${{ github.event.pull_request.head.sha }}
        PR_NUMBER: ${{ github.event.pull_request.number }}
        REPOSITORY: ${{ github.repository }}
      run: |
        FORCE="false"

        if [[ "$EVENT_NAME" != "pull_request" ]]; then
          echo "Event is $EVENT_NAME; force-builds override is ignored outside pull_request events."
          echo "force=$FORCE" >> "$GITHUB_OUTPUT"
          exit 0
        fi

        # Commit-message tag.
        COMMIT_MESSAGE=""
        if COMMIT_MESSAGE=$(gh api \
            "repos/$REPOSITORY/commits/$HEAD_COMMIT_HASH" \
            --jq '.commit.message' 2>/dev/null); then
          if printf '%s' "$COMMIT_MESSAGE" \
              | grep --fixed-strings --quiet "$COMMIT_TAG"; then
            echo "-> force=true because '$COMMIT_TAG' was found in commit message of $HEAD_COMMIT_HASH"
            FORCE="true"
          fi
        else
          echo "::warning::Failed to fetch commit message for $HEAD_COMMIT_HASH via GitHub API; commit-tag force-builds check skipped for this run (the '$LABEL_NAME' label path still works)."
        fi

        # PR label
        if [[ -n "$PR_NUMBER" ]]; then
          if gh pr view "$PR_NUMBER" --repo "$REPOSITORY" \
              --json labels --jq '.labels[].name' \
              | grep --fixed-strings --line-regexp --quiet "$LABEL_NAME"; then
            echo "-> force=true because '$LABEL_NAME' label is applied to PR #$PR_NUMBER"
            FORCE="true"
          fi
        fi

        if [[ "$FORCE" == "false" ]]; then
          echo "No force-builds override active."
        fi

        echo "force=$FORCE" >> "$GITHUB_OUTPUT"