action.yml

name: Trigger CI
description: GitHub Action to find and trigger the appropriate CI workflow

inputs:
  branch:
    type: string
    required: true
  validate_branch:
    type: boolean
    required: false
    default: true

runs:
  using: composite
  steps:

    - name: Validate branch exists
      shell: bash
      if: ${{ inputs.validate_branch == 'true' }}
      env:
        GITHUB_REPOSITORY: ${{ github.repository }}
        BRANCH: ${{ inputs.branch }}
      run: |
        # https://docs.github.com/en/free-pro-team@latest/rest/branches/branches?apiVersion=2022-11-28#list-branches
        RESP_CODE=$(curl -w %{http_code} -s -L -o __branches.json \
          -X GET \
          -H "Accept: application/vnd.github+json" \
          -H "Authorization: Bearer ${{ github.token }}"\
          -H "X-GitHub-Api-Version: 2022-11-28" \
          https://api.github.com/repos/$GITHUB_REPOSITORY/branches?per_page=100 \
        )
        if [[ $RESP_CODE != "200" ]]; then
          echo "Failed to read branches - HTTP response code was $RESP_CODE"
          exit 1
        fi
        if [[ $(cat __branches.json | jq "any(.[]; .name == \"$BRANCH\")") == "false" ]]; then
          echo "Could not find branch $BRANCH"
          exit 1
        fi

    - name: Find workflow
      id: find-workflow
      shell: bash
      env:
        GITHUB_REPOSITORY: ${{ github.repository }}
        BRANCH: ${{ inputs.branch }}
      run: |
        FOUND=0
        # Need to loop specifically in this order to find the right file, this is because:
        # - gha-ci has both a ci.yml file (shared with other workflows) and an action-ci.yml file (the one we want to run)
        # - gha-action-ci has both an action-ci.yml file (shared with other workflows) and an action-ci-self.yml file (the one we want to run)
        FILENAMES='action-ci-self.yml action-ci.yml ci.yml'
        for FILENAME in $FILENAMES; do
          URL=https://raw.githubusercontent.com/$GITHUB_REPOSITORY/$BRANCH/.github/workflows/$FILENAME
          RESP_CODE=$(curl -w %{http_code} -s -L -o /dev/null $URL)
          if [[ $RESP_CODE == "200" ]]; then
            FOUND=1
            echo "FILENAME is $FILENAME"
            echo "filename=$FILENAME" >> $GITHUB_OUTPUT
            break
          elif [[ $RESP_CODE != "404" ]]; then
            echo "Failed to check file $FILENAME - HTTP response code was $RESP_CODE"
            exit 1
          fi
        done
        if [[ $FOUND == 0 ]]; then
          echo "Could not workflow file for branch $BRANCH - tried $FILENAMES"
          # If there's no CI file, then this workflow has worked as expected. Don't mark it as a failure.
          # This allows us to do auto-merge ups for things like developer-docs which don't have CI
          # without adding a dummy CI which could result in a false sense of security when reviewing PRs etc.
          exit 0
        fi

    - name: Send API request
      shell: bash
      env:
        GITHUB_REPOSITORY: ${{ github.repository }}
        BRANCH: ${{ inputs.branch }}
        FILENAME: ${{ steps.find-workflow.outputs.filename }}
      run: |
        # https://docs.github.com/en/rest/actions/workflows?apiVersion=2022-11-28#create-a-workflow-dispatch-event
        RESP_CODE=$(curl -w %{http_code} -s -L -o /dev/null \
          -X POST \
          -H "Accept: application/vnd.github+json" \
          -H "Authorization: Bearer ${{ github.token }}"\
          -H "X-GitHub-Api-Version: 2022-11-28" \
          https://api.github.com/repos/$GITHUB_REPOSITORY/actions/workflows/$FILENAME/dispatches \
          -d "{\"ref\":\"$BRANCH\"}"
        )
        if [[ $RESP_CODE != "204" ]]; then
          echo "Failed to dispatch workflow - HTTP response code was $RESP_CODE"
          exit 1
        fi

    - name: Delete temporary files
      shell: bash
      if: always()
      run: |
        if [[ -f __branches.json ]]; then
          rm __branches.json
        fi