close_pr.yml

name: Label closed PR as merged and leave a comment
on:
  push

permissions:
  contents: read
  pull-requests: write

jobs:
  comment-and-label:
    runs-on: ubuntu-latest
    if: github.repository == 'facebook/react-native'
    steps:
      - uses: actions/github-script@v6
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            if(!context.payload.commits || !context.payload.commits.length) return;
            const sha = context.payload.commits[0].id;

            const {commit, author} = (await github.rest.repos.getCommit({
              ref: sha,
              owner: context.repo.owner,
              repo: context.repo.repo,
            })).data;

            // Looking at the commit message, checks which PR number, if any, was closed by this commit
            const getClosedPrIfExists = (commit) => {
              if(!commit || !commit.message) return;
              const prClosingRegex = /Closes https:\/\/github.com\/facebook\/react-native\/pull\/([0-9]+)|Pull Request resolved: https:\/\/github.com\/facebook\/react-native\/pull\/([0-9]+)/;
              const prClosingMatch = commit.message.match(prClosingRegex);
              if(!prClosingMatch || (!prClosingMatch[1] && ! prClosingMatch[2])) return;
              return prClosingMatch[1] ?? prClosingMatch[2];
            };

            const closedPrNumber = getClosedPrIfExists(commit);
            if(!closedPrNumber) return;

            const pr = (await github.rest.pulls.get({
              pull_number: closedPrNumber,
              owner: context.repo.owner,
              repo: context.repo.repo,
            })).data;

            // If the PR has already been processed (labeled as Merged), skip it
            const mergedLabel = "Merged";
            if(pr.labels && pr.labels.some(label => label.name === mergedLabel)) return;

            const authorName = author?.login ? `@${author.login}` : commit.author.name;

            github.rest.issues.createComment({
              issue_number: closedPrNumber,
              owner: context.repo.owner,
              repo: context.repo.repo,
              body: `This pull request was successfully merged by ${authorName} in **${sha}**.\n\n<sup>[When will my fix make it into a release?](https://github.com/facebook/react-native/wiki/Release-FAQ#when-will-my-fix-make-it-into-a-release) | [Upcoming Releases](https://github.com/reactwg/react-native-releases/discussions/categories/releases)</sup>`
            });

            github.rest.issues.addLabels({
              issue_number: closedPrNumber,
              owner: context.repo.owner,
              repo: context.repo.repo,
              labels: [mergedLabel]
            });