# 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 using a modified version of repository B. This
  modified version could be a pull request, a branch or a reference.

  In the simplest case `cascading-pr` runs a workflow in `destination-repo`
  that uses `origin-ref` and blocks until it completes.

  As an example, when a tag is set in Forgejo and builds a new release,
  it is concluded by a call to `cascading-pr` that runs
  [end-to-end](https://code.forgejo.org/forgejo/end-to-end/) tests on
  the newly built release to verify it works as expected.

  When used in a workflow triggered by a PR event in `origin-repo`,
  `cascading-pr` will create, update and close a matching PR in the
  `destination-repo`. When the PR is updated, `cascading-pr` will
  update the matching PR. It waits for the workflow triggered by these
  updates in `destination-repo` to complete. If fails, `cascading-pr`,
  also fails.

  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 and `cascading-pr` waits until the CI in
  `actions/setup-forgejo` is successful.

  The `update` script is expected to be found in `origin-repo` and is
  given the following arguments:

    * A directory path in which the `destination-branch` of `destination-repo`
      (or a fork) is checked-out.
    * The path to a JSON file describing the pull request in `destination-repo`.
    * A directory path in which the head of `origin-repo` is checked-out at:
      * if `origin-pr` is specified, the head branch of `origin-pr`
      * otherwise `origin-ref`
    * Information about the `origin-repo`
      * if `origin-pr` is specified, the path to a JSON file desccribing
        the pull request in `origin-repo`
      * otherwise `origin-ref`

  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 in the `destination-repo`.

  `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` (or `destination-fork-repo`) and 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 in the `destination-repo` is from a forked repository,
  the `update` script is run from the default branch of
  `destination-repo` instead of the head of the PR which is a branch
  in destination-fork-repo.  The PR author must not be trusted and it
  is imperative that the `update` script never runs anything found in
  the head branch of the PR.

  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}, mutually exclusive with {origin-ref}'
  origin-ref:
    description: 'reference in {orign-repo}, mutually exclusive with {origin-pr}'
  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 branch from which the cascading PR is created on {destination-repo} or {destination-fork-repo} (default to {origin-repo})'
  close:
    description: 'if true the cascading PR will be closed and the branch deleted when (i) the {origin-pr} is merged or (ii) when the cascading PR status is success if {origin-ref} is set'
    default: false
  verbose:
    description: 'if true print verbose information'
    default: false
  debug:
    description: 'if true print debug information'
    default: false

runs:
  using: "composite"
  steps:
    - 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 "${{ inputs.origin-pr }}" \
                        --origin-ref "${{ inputs.origin-ref }}" \
                        --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 "${{ inputs.prefix }}" \
                        --close "${{ inputs.close }}" \
                        run