auto-update-base.yaml

name: Auto-Update PR Base

on:
  push:
    branches:
      - main

jobs:
  auto-update-base:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.ROBOT_TOKEN }}
          script: |
            let retriesNeeded = true;
            let attemptCount = 0;
            const maxAttempts = 10;  // Set a limit for the maximum number of attempts
            let errorEncountered = false; // Track if any errors occur

            while (retriesNeeded && attemptCount < maxAttempts) {
              retriesNeeded = false;  // Assume no retries needed, unless 'unknown' state is found.
              attemptCount += 1;

              try {
                const { data: pulls } = await github.rest.pulls.list({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  state: "open",
                });

                for (const pull of pulls) {
                  const hasAutoUpdateLabel = pull.labels.some(label => label.name === "auto-update-base");

                  if (!hasAutoUpdateLabel) {
                    continue;
                  }

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

                    switch (pr.mergeable) {
                      case null:
                        console.log(`[INFO] PR #${pull.number}: "${pull.title}" - GitHub is still computing the mergeability. Will retry later.`);
                        retriesNeeded = true;
                        break;
                      case false:
                        console.log(`[INFO] PR #${pull.number}: "${pull.title}" - Skipping update due to merge conflict.`);
                        break;
                      case true:
                        try {
                          const { data: baseBranch } = await github.rest.repos.getBranch({
                            owner: context.repo.owner,
                            repo: context.repo.repo,
                            branch: pr.base.ref,
                          });

                          if (pr.base.sha === baseBranch.commit.sha) {
                            console.log(`[INFO] PR #${pull.number}: "${pull.title}" - Base branch is already up-to-date.`);
                            break;
                          }

                          console.log(`[UPDATE] PR #${pull.number}: "${pull.title}" - Updating base branch...`);
                          try {
                            await github.rest.pulls.updateBranch({
                              owner: context.repo.owner,
                              repo: context.repo.repo,
                              pull_number: pull.number,
                            });
                            console.log(`[SUCCESS] PR #${pull.number}: "${pull.title}" - Base branch updated.`);
                          } catch (updateError) {
                            console.error(`[ERROR] PR #${pull.number}: Failed to update base branch - ${updateError.message}`);
                            errorEncountered = true;
                          }

                          break;
                        } catch (baseError) {
                          console.error(`[ERROR] PR #${pull.number}: Failed to get base branch - ${baseError.message}`);
                          errorEncountered = true;
                          break;
                        }
                    }
                  } catch (prError) {
                    console.error(`[ERROR] Failed to get PR #${pull.number} - ${prError.message}`);
                    errorEncountered = true;
                  }
                }
              } catch (error) {
                console.error(`[ERROR] Failed to list pull requests - ${error.message}`);
                errorEncountered = true;
              }

              if (retriesNeeded && attemptCount < maxAttempts) {
                console.log(`[INFO] Retrying for PRs with 'unknown' mergeable state (Attempt ${attemptCount}/${maxAttempts})...`);
                await new Promise(resolve => setTimeout(resolve, 5000));
              }
            }

            if (attemptCount >= maxAttempts) {
              console.error(`[ERROR] Maximum attempts (${maxAttempts}) reached. Some PRs may still have 'unknown' mergeable state.`);
              errorEncountered = true;
            }

            if (errorEncountered) {
              core.setFailed(`[ERROR] Some PRs failed to update base branch.`);
            } else {
              console.log(`[INFO] All PRs with 'auto-update-base' label have been processed.`);
            }