name: Chatops Binder
on: [issue_comment] # issues and PRs are equivalent in terms of comments for the GitHub API

jobs:
  trigger-chatops:
    # Make sure the comment is from one in our organization, it's on a PR, and contains the command "/binder"
    if: |
      (
        (github.event.issue.pull_request != null) &&
        contains(github.event.comment.body, '/binder')
      )
    runs-on: ubuntu-latest
    steps:
      # Use the GitHub API to: 
      #  (1) Get the branch name of the PR that has been commented on with "/binder" 
      #  (2) make a comment on the PR with the binder badge
    - name: comment on PR with Binder link
      uses: actions/github-script@v1
      with:
        github-token: ${{secrets.GITHUB_TOKEN}}
        script: |
          // Get the branch name
          github.pulls.get({
            owner: context.repo.owner,
            repo: context.repo.repo,
            pull_number: context.payload.issue.number
          }).then( (pr) => {

            // use the branch name to make a comment  on the PR with a Binder badge
            var BRANCH_NAME = pr.data.head.ref;
            var USER_NAME = pr.data.head.user.login;
            github.issues.createComment({
              issue_number: context.payload.issue.number,
              owner: context.repo.owner,
              repo: context.repo.repo,
              body: `[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/${USER_NAME}/${context.repo.repo}/${BRANCH_NAME}?urlpath=%2Fdesktop) :point_left: Launch a Binder instance on this branch`
            })
          })
