name: Handle Pull Request
on:
  # WARNING: pull_request_target MUST NOT be used if running code under control
  # of the source PR [0], as it could risk leaking the GH_TOKENs.
  #
  # In this case, we do it as the job needs to run within the context of the
  # target repo, so it can get a GH_TOKEN which it can use to comment on and
  # update the PR.
  #
  # Crucially, no external code is loaded or run as part of this workflow.
  #
  # [0] https://docs.github.com/en/actions/reference/workflows-and-actions/events-that-trigger-workflows#pull_request_target:~:text=Warning-,Running,websitehttps://docs.github.com/en/actions/reference/workflows-and-actions/events-that-trigger-workflows#pull_request_target:~:text=Warning-,Running,website
  #
  pull_request_target:
    types: [opened, reopened]


env:
  ALLOWED_TEAM: lando-github-pilot
  ALLOWED_PATHS: |
    gradle/
    mobile/android/android-components
    mobile/android/fenix
    mobile/android/focus-android
    taskcluster/config.yml

  GH_REPO: ${{ github.repository }}
  PR: ${{ github.event.pull_request.number }}

  GH_TOKEN: ${{ github.token }}

jobs:
  handle-pr:
    runs-on: ubuntu-latest
    steps:

      # Workflows don't get access to organisation metadata via the GITHUB_TOKEN.
      # We use the Lando Web App to obtain a token with sufficient permissions.
      - name: Generate a Lando Web token
        id: generate-lando-web-token
        uses: actions/create-github-app-token@v2
        continue-on-error: true
        with:
          app-id: ${{ vars.LANDO_WEB_APP_ID }}
          private-key: ${{ secrets.LANDO_WEB_APP_PRIVATE_KEY }}
          permission-members: read

      - name: Check team membership
        id: team
        continue-on-error: true
        env:
          AUTHOR: ${{ github.actor }}
          GH_ORG: ${{ github.repository_owner }}
          GH_TOKEN: ${{ steps.generate-lando-web-token.outputs.token }}
        run: |
          if gh api "/orgs/${GH_ORG}/teams/${ALLOWED_TEAM}/memberships/${AUTHOR}" --silent; then
            echo "is_member=true" >> $GITHUB_OUTPUT
          else
            echo "is_member=false" >> $GITHUB_OUTPUT
          fi

      - name: Check allowed paths
        id: paths
        continue-on-error: true
        if: steps.team.outputs.is_member == 'true'
        run: |
          PATTERN=$(echo "${ALLOWED_PATHS}" | xargs | tr ' ' '|')
          if gh pr view "${PR}" --json files --jq '.files[].path' | grep -vE "^(${PATTERN})"; then
            echo "only_allowed=false" >> $GITHUB_OUTPUT
          else
            echo "only_allowed=true" >> $GITHUB_OUTPUT
          fi

      - name: Close PR
        if: steps.team.outputs.is_member != 'true' || steps.paths.outputs.only_allowed != 'true'
        run: |
          gh pr close "${PR}" --comment "(Automated Close) Please do not file pull requests here, see https://firefox-source-docs.mozilla.org/contributing/how_to_submit_a_patch.html"
          gh pr lock "${PR}"

      - name: Check PR target
        if: (steps.team.outputs.is_member == 'true' && steps.paths.outputs.only_allowed == 'true') && github.event.action == 'opened' && github.base_ref == 'main'
        run: |
          gh pr comment "${PR}" --body "> [!WARNING]
          The base branch is currently set to \`main\`. Please Edit this PR and set the base to \`autoland\`."

      - name: Add Lando link
        if: (steps.team.outputs.is_member == 'true' && steps.paths.outputs.only_allowed == 'true') && github.event.action == 'opened'
        env:
          #
          # Set the following variables at the repository level [0].
          # [0] https://docs.github.com/en/actions/how-tos/write-workflows/choose-what-workflows-do/use-variables#defining-configuration-variables-for-multiple-workflows
          #
          LANDO_BASE_URL: ${{ vars.LANDO_BASE_URL }}
          LANDO_REPO: ${{ vars.LANDO_REPO }}
          #
          # If they are empty, the following will be used to determine sane defaults.
          #
          DEFAULT_LANDO_BASE_URL: https://lando.moz.tools
          TARGET_BRANCH: ${{ github.base_ref }}
        run: |
          LANDO_BASE_URL="${LANDO_BASE_URL:-${DEFAULT_LANDO_BASE_URL}}"
          # We extract the GitHub repo name and target branch to use as
          # default LANDO_REPO if unspecified.
          LANDO_REPO="${LANDO_REPO:-${GH_REPO/*\//}-${TARGET_BRANCH}}"
          gh pr comment "${PR}" --body "[View this pull request in Lando](${LANDO_BASE_URL}/pulls/${LANDO_REPO}/${PR}) to land it once approved."