assign-reviewer.yml

name: Assign Unique Reviewer

on:
  pull_request:
    types: [opened, synchronize]

permissions:
  issues: write
  pull-requests: write

jobs:
  assign:
    runs-on: ubuntu-latest
    steps:
      - name: Check out repository
        uses: actions/checkout@v2

      - name: Fetch repository collaborators
        id: fetch-collaborators
        run: |
          RESPONSE=$(curl -s -H "Authorization: token ${{ secrets.ACTION_TOKEN }}" \
            "https://api.github.com/repos/${{ github.repository }}/collaborators")
          COLLABORATORS=$(echo "$RESPONSE" | jq -r '.[].login' | tr '\n' ' ')
          echo "COLLABORATORS=$COLLABORATORS" >> $GITHUB_ENV

      - name: Fetch existing PR reviewers
        id: fetch-pr-reviewers
        run: |
          RESPONSE=$(curl -s -H "Authorization: token ${{ secrets.ACTION_TOKEN }}" \
            "https://api.github.com/repos/${{ github.repository }}/pulls/${{ github.event.pull_request.number }}/requested_reviewers")
          EXISTING_REVIEWERS=$(echo "$RESPONSE" | jq -r '.users[].login' | sort | uniq | tr '\n' ' ')
          echo "EXISTING_REVIEWERS=$EXISTING_REVIEWERS" >> $GITHUB_ENV

      - name: Select random collaborator
        id: select-random
        run: |
          # Convert collaborators to array
          COLLABORATORS_ARRAY=($COLLABORATORS)

          # Convert existing reviewers to array
          EXISTING_REVIEWERS_ARRAY=($EXISTING_REVIEWERS)

          # Remove PR author from collaborators
          PR_AUTHOR=${{ github.event.pull_request.user.login }}
          FILTERED_COLLABORATORS=()
          for collaborator in "${COLLABORATORS_ARRAY[@]}"; do
            if [[ "$collaborator" != "$PR_AUTHOR" && ! " ${EXISTING_REVIEWERS_ARRAY[@]} " =~ " ${collaborator} " ]]; then
              FILTERED_COLLABORATORS+=($collaborator)
            fi
          done

          # Check if there are any eligible collaborators left
          if [ ${#FILTERED_COLLABORATORS[@]} -eq 0 ]; then
            echo "No eligible collaborators to assign"
            exit 1
          fi

          # Select a random collaborator from filtered collaborators
          RANDOM_COLLABORATOR=${FILTERED_COLLABORATORS[$RANDOM % ${#FILTERED_COLLABORATORS[@]}]}
          echo "SELECTED_COLLABORATOR=$RANDOM_COLLABORATOR" >> $GITHUB_ENV

      - name: Assign PR to selected reviewer
        run: |
          curl -X POST \
            -H "Accept: application/vnd.github.v3+json" \
            -H "Authorization: token ${{ secrets.ACTION_TOKEN }}" \
            -d '{"reviewers":["${{ env.SELECTED_COLLABORATOR }}"]}' \
            "https://api.github.com/repos/${{ github.repository }}/pulls/${{ github.event.pull_request.number }}/requested_reviewers"