index.js

const core = require("@actions/core");
const github = require("@actions/github");

const [owner, repo] = process.env.GITHUB_REPOSITORY.split("/");

async function run() {
  try {
    const fromBranch = core.getInput("FROM_BRANCH", { required: true });
    const toBranch = core.getInput("TO_BRANCH", { required: true });
    const githubToken = core.getInput("GITHUB_TOKEN", { required: true });
    const pullRequestTitle = core.getInput("PULL_REQUEST_TITLE");
    const pullRequestBody = core.getInput("PULL_REQUEST_BODY");
    const pullRequestIsDraft =
      core.getInput("PULL_REQUEST_IS_DRAFT").toLowerCase() === "true";
    const contentComparison =
      core.getInput("CONTENT_COMPARISON").toLowerCase() === "true";
    const reviewers = JSON.parse(core.getInput("REVIEWERS"));
    const team_reviewers = JSON.parse(core.getInput("TEAM_REVIEWERS"));

    console.log(
      `Should a pull request to ${toBranch} from ${fromBranch} be created?`
    );
    
    const octokit = new github.getOctokit(githubToken);

    const { data: currentPulls } = await octokit.rest.pulls.list({
      owner,
      repo,
    });

    const currentPull = currentPulls.find((pull) => {
      return pull.head.ref === fromBranch && pull.base.ref === toBranch;
    });

    if (!currentPull) {
      let shouldCreatePullRequest = true;
      if (contentComparison) {
        shouldCreatePullRequest = await hasContentDifference(
          octokit,
          fromBranch,
          toBranch
        );
      }

      if (shouldCreatePullRequest) {
        const { data: pullRequest } = await octokit.rest.pulls.create({
          owner,
          repo,
          head: fromBranch,
          base: toBranch,
          title: pullRequestTitle
            ? pullRequestTitle
            : `sync: ${fromBranch} to ${toBranch}`,
          body: pullRequestBody
            ? pullRequestBody
            : `sync-branches: New code has just landed in ${fromBranch}, so let's bring ${toBranch} up to speed!`,
          draft: pullRequestIsDraft,
        });

        if (reviewers.length > 0 || team_reviewers.length > 0) {
          octokit.rest.pulls.requestReviewers({
            owner,
            repo,
            pull_number: pullRequest.number,
            reviewers,
            team_reviewers,
          });
        }

        console.log(
          `Pull request (${pullRequest.number}) successful! You can view it here: ${pullRequest.url}`
        );

        core.setOutput("PULL_REQUEST_URL", pullRequest.url.toString());
        core.setOutput("PULL_REQUEST_NUMBER", pullRequest.number.toString());
      } else {
        console.log(
          `There is no content difference between ${fromBranch} and ${toBranch}.`
        );
      }
    } else {
      console.log(
        `There is already a pull request (${currentPull.number}) to ${toBranch} from ${fromBranch}.`,
        `You can view it here: ${currentPull.url}`
      );

      core.setOutput("PULL_REQUEST_URL", currentPull.url.toString());
      core.setOutput("PULL_REQUEST_NUMBER", currentPull.number.toString());
    }
  } catch (error) {
    console.error(error);
    core.setFailed(error.message);
  }
}

async function hasContentDifference(octokit, fromBranch, toBranch) {
  const { data: response } = await octokit.rest.repos.compareCommits({
    owner,
    repo,
    base: toBranch,
    head: fromBranch,
    page: 1,
    per_page: 1,
  });
  return response.files.length > 0;
}

run();