verilator/.github/workflows/pr-automation.yml

---
# DESCRIPTION: Github actions config
# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0

# Drives the automation of a pull request.

name: Maintenance - PR automation

on:
  pull_request_target:  # 'pull_request' can have no write permissions
    types: [opened, synchronize, reopened, closed]
  workflow_run:  # To react to the result of a workflow on a pull request
    workflows: ["Code coverage", "Regression"]
    types: [completed]

permissions:
  actions: read  # To download the artifacts of the triggering run
  pull-requests: write

defaults:
  run:
    shell: bash

# One job per event source, to avoid startup churn. Use separate gated steps for actions
jobs:
  pr-event:
    name: PR event
    if: ${{ github.event_name == 'pull_request_target' }}
    runs-on: ubuntu-slim
    env:
      GH_TOKEN: ${{ github.token }}
    steps:
      - name: "Add 'pr: regression' label on open"
        if: ${{ github.event.action == 'opened' || github.event.action == 'reopened' }}
        run: |-
          gh pr edit "${{ github.event.number }}" \
            --repo "${{ github.repository }}" \
            --add-label 'pr: regression'

      - name: "Optionally add 'pr: dev-coverage' label on open"
        if: ${{ github.event.action == 'opened' || github.event.action == 'reopened' }}
        run: |-
          # Grab changed files
          FILES=$(gh api --paginate \
            "repos/${{ github.repository }}/pulls/${{ github.event.number }}/files" \
            --jq '.[].filename')
          echo "Files changed:"
          echo "${FILES}"
          # Add label if src or include chagned
          if grep -q -E '^(src|include)/' <<< "${FILES}"; then
            gh pr edit "${{ github.event.number }}" \
              --repo "${{ github.repository }}" \
              --add-label 'pr: dev-coverage'
          fi

      - name: "Remove all 'pr*' labels on close"
        if: ${{ github.event.action == 'closed' }}
        run: |-
          # Filter in 'jq', so an empty result is not an error, as it is with 'grep'
          LABELS=$(gh api \
            "repos/${{ github.repository }}/issues/${{ github.event.number }}/labels?per_page=100" \
            --jq '[.[].name | select(startswith("pr"))] | join(",")')
          if [ -n "${LABELS}" ]; then
            echo "Removing labels: ${LABELS}"
            gh pr edit "${{ github.event.number }}" \
              --repo "${{ github.repository }}" \
              --remove-label "${LABELS}"
          fi

  regression-complete:
    name: Regression complete
    if: |
      github.event_name == 'workflow_run'
      && github.event.workflow_run.name == 'Regression'
      && github.event.workflow_run.event == 'pull_request'
      && (github.event.workflow_run.conclusion == 'success'
          || github.event.workflow_run.conclusion == 'failure')
    runs-on: ubuntu-slim
    env:
      GH_TOKEN: ${{ github.token }}
    steps:
      - name: "Set the 'pr-blocked: fix-regression' label from the result"
        env:
          SHA: ${{ github.event.workflow_run.head_sha }}
          LABEL: "pr-blocked: fix-regression"
          FAILED: ${{ github.event.workflow_run.conclusion == 'failure' }}
        run: |-
          # The run tells us which pull request it was for
          if ! gh run download "${{ github.event.workflow_run.id }}" --name pr-number; then
            echo "Run has no 'pr-number' artifact"
            exit 0
          fi
          PR=$(cat pr-number.txt)
          # Its state and head as they are now, and whether it carries the
          # label already
          read -r STATE HEAD LABELLED < <(gh pr view "${PR}" \
            --repo "${{ github.repository }}" \
            --json state,headRefOid,labels \
            --jq '"\(.state) \(.headRefOid) \(any(.labels[]; .name == env.LABEL))"')
          # Only act on a change, so a run does not reapply what is already set
          if [ "${STATE}" != OPEN ]; then
            # Closing removes all 'pr*' labels, do not put one back on
            echo "PR #${PR} is ${STATE}"
          elif [ "${HEAD}" != "${SHA}" ]; then
            # Pushed to since, so this result is stale and a new run will decide
            echo "PR #${PR} has moved on from ${SHA}"
          elif [ "${FAILED}" = true ] && [ "${LABELLED}" = false ]; then
            echo "Regression failed, blocking PR #${PR}"
            gh pr edit "${PR}" --repo "${{ github.repository }}" --add-label "${LABEL}"
          elif [ "${FAILED}" = false ] && [ "${LABELLED}" = true ]; then
            echo "Regression succeeded, unblocking PR #${PR}"
            gh pr edit "${PR}" --repo "${{ github.repository }}" --remove-label "${LABEL}"
          else
            echo "No change to PR #${PR}"
          fi

  coverage-complete:
    name: Coverage complete
    if: |
      github.event_name == 'workflow_run'
      && github.event.workflow_run.name == 'Code coverage'
      && github.event.workflow_run.event == 'pull_request'
      && github.event.workflow_run.conclusion == 'success'
    runs-on: ubuntu-slim
    env:
      GH_TOKEN: ${{ github.token }}
    steps:
      - name: "Set the 'pr-blocked: improve-coverage' label from the result"
        env:
          SHA: ${{ github.event.workflow_run.head_sha }}
          LABEL: "pr-blocked: improve-coverage"
        run: |-
          # The run tells us which pull request it was for, and whether every
          # line its patch touches is covered
          if ! gh run download "${{ github.event.workflow_run.id }}" --name coverage-status; then
            echo "Run has no 'coverage-status' artifact"
            exit 0
          fi
          STATUS=$(cat coverage-status.txt)
          PR=${STATUS%% *}
          COVERED=${STATUS##* }
          # Its state and head as they are now, and whether it carries the
          # label already
          read -r STATE HEAD LABELLED < <(gh pr view "${PR}" \
            --repo "${{ github.repository }}" \
            --json state,headRefOid,labels \
            --jq '"\(.state) \(.headRefOid) \(any(.labels[]; .name == env.LABEL))"')
          # Only act on a change, so a run does not reapply what is already set
          if [ "${STATE}" != OPEN ]; then
            # Closing removes all 'pr*' labels, do not put one back on
            echo "PR #${PR} is ${STATE}"
          elif [ "${HEAD}" != "${SHA}" ]; then
            # Pushed to since, so this result is stale and a new run will decide
            echo "PR #${PR} has moved on from ${SHA}"
          elif [ "${COVERED}" = false ] && [ "${LABELLED}" = false ]; then
            echo "Line coverage incomplete, blocking PR #${PR}"
            gh pr edit "${PR}" --repo "${{ github.repository }}" --add-label "${LABEL}"
          elif [ "${COVERED}" = true ] && [ "${LABELLED}" = true ]; then
            echo "Line coverage complete, unblocking PR #${PR}"
            gh pr edit "${PR}" --repo "${{ github.repository }}" --remove-label "${LABEL}"
          else
            echo "No change to PR #${PR}"
          fi