# SPDX-License-Identifier: MIT
name: 'Cascading PR'
author: 'Forgejo authors'
description: |

  If repository A depends on repository B, `cascadinging-pr` can be
  used by a workflow in repository B to trigger the CI on repository A
  and verify it passes when it will upgrade with the proposed change
  from repository B.

  When used in a workflow triggered by a PR event in `origin-repo`,
  `cascading-pr` will create, update and close a matching PR in
  another repository (`destination-repo`). When the PR is updated,
  `cascading-pr` subsequently will update the matching PR. The
  worfklows in `origin-repo` will wait for the workflow in
  `destination-repo` to complete. If the workflow in
  `destination-repo` fails, the workflow in `origin-repo` will also
  fail.

  As an example, when a PR is created in
  [`forgejo/runner`](https://code.forgejo.org/forgejo/runner/), a
  matching PR is created in
  [`actions/setup-forgejo`](https://code.forgejo.org/actions/setup-forgejo/)
  with the proposed change. `cascading-pr` will wait until the CI in
  `actions/setup-forgejo` is successful.

  The `update` script is expected to be found in the origin repository
  running the PR. It is given four arguments:

    * A directory in which the destination repository (or a fork) is checked-out
      on the base branch
    * A file with the JSON describing the pull request in the
      destination repository
    * A directory in which the origin repository is checked-out
      on the head branch
    * A file with the JSON describing the pull request in the
      origin repository

  If changes are found in the destination repository directory after the `update` script runs,
  they will be pushed as a new commit in the PR.

  `origin-token` is used when accessing `origin-repo` and needs the
  `read:user`, `read:repository` and `write:issue` scopes.

  `destination-token` is used to push the branch that contains an
  update to `destination-repo` and to open a pull request. It needs
  the `read:user`, `write:repository` and `write:issue` scopes.

  It is recommended that a dedicated user is used to create
  `destination-token` and that `destination-fork-repo` is always used
  unless the users who are able to create pull requests are trusted.

  When the PR is from a forked repository, the `update` script is run
  from the default branch of the base repository instead of the head
  branch of the fork. The pull request author must not be trusted
  and it is imperative that the `update` script never runs anything
  found in the head branch of the pull request.

  If the fork of the destination repository is specified and it does
  not exist, it is created.

inputs:
  origin-url:
    description: 'URL of the Forgejo instance where the PR that triggers the action is located (e.g. https://code.forgejo.org)'
    required: true
  origin-repo:
    description: 'the repository in which the PR was created'
    required: true
  origin-token:
    description: 'a token with write permission on origin-repo'
    required: true
  origin-pr:
    description: 'number of the PR in {orign-repo}'
    required: true
  destination-url:
    description: 'URL of the Forgejo instance where the cascading PR is created or updated (e.g. https://code.forgejo.org)'
    required: true
  destination-repo:
    description: 'the repository in which the cascading PR is created or updated'
    required: true
  destination-fork-repo:
    description: 'the fork of {destination-repo} in which the {destination-branch} will be created or updated'
  destination-branch:
    description: 'the base branch of the destination repository for the cascading PR'
    required: true
  destination-token:
    description: 'a token with write permission on destination-repo'
    required: true
  update:
    description: 'path to the script to update the content of the cascading PR'
    required: true
  prefix:
    description: 'prefix of the cascading PR created on destination-repo (default to {origin-repo})'
  close-merge:
    description: 'if true the cascading PR will be closed and the branch deleted when the PR is merged'
    default: false
  verbose:
    description: 'if true print verbose information'
    default: false
  debug:
    description: 'if true print debug information'
    default: false

runs:
  using: "composite"
  steps:
    - uses: actions/checkout@v4
    - run: |
        export PATH=${{ github.action_path }}:$PATH

        if "${{ inputs.verbose }}"; then
          verbosity="$verbosity --verbose"
        fi
        if "${{ inputs.debug }}"; then
          verbosity="$verbosity --debug"
        fi

        origin_token=$(pwd)/origin.token
        echo -n ${{ inputs.origin-token }} > $origin_token
        destination_token=$(pwd)/destination.token
        echo -n ${{ inputs.destination-token }} > $destination_token

        cascading-pr.sh $verbosity \
                        --origin-url "${{ inputs.origin-url }}" \
                        --origin-repo "${{ inputs.origin-repo }}" \
                        --origin-token "@$origin_token" \
                        --origin-pr "${{ inputs.origin-pr }}" \
                        --destination-url "${{ inputs.destination-url }}" \
                        --destination-repo "${{ inputs.destination-repo }}" \
                        --destination-fork-repo "${{ inputs.destination-fork-repo }}" \
                        --destination-token "@$destination_token" \
                        --destination-branch "${{ inputs.destination-branch }}" \
                        --update "${{ inputs.update }}" \
                        --prefix "${{ inputs.prefix }}" \
                        --close-merge "${{ inputs.close-merge }}" \
                        run