assign-milestone-on-close.yml

name: Assign Milestone on Close

env:
  MILESTONE_ID: ${{ vars.MILESTONE_ID }}

on:
  issues:
    types: [closed]
  pull_request_target:
    types: [closed]

permissions:
  issues: write
  pull-requests: write

jobs:
  assign-milestone:
    runs-on: ubuntu-latest
    steps:
      - name: Check if milestone is set
        id: check-milestone
        uses: actions/github-script@v7
        with:
          github-token: ${{secrets.GITHUB_TOKEN}}
          script: |
            const issueOrPr = context.payload.issue || context.payload.pull_request;
            if (!issueOrPr.milestone) {
              core.setOutput('milestoneNotSet', 'true');
            } else {
              core.setOutput('milestoneNotSet', 'false');
            }

      - name: Check completed or merged
        id: check-done
        uses: actions/github-script@v7
        with:
          github-token: ${{secrets.GITHUB_TOKEN}}
          script: |
            if ((context.payload.issue && context.payload.issue.state_reason === "completed")
                || (context.payload.pull_request && context.payload.pull_request.merged === true)) {
              core.setOutput('isDone', 'true');
            } else {
              core.setOutput('isDone', 'false');
            }

      - name: Assign default milestone
        if: steps.check-milestone.outputs.milestoneNotSet == 'true' && steps.check-done.outputs.isDone == 'true'
        uses: actions/github-script@v7
        with:
          github-token: ${{secrets.GITHUB_TOKEN}}
          script: |
            const issueOrPrNumber = (context.payload.issue || context.payload.pull_request).number;
            const repository = context.repo;
            await github.rest.issues.update({
              ...repository,
              issue_number: issueOrPrNumber,
              milestone: process.env.MILESTONE_ID
            });