comment_build.yml

name: Post build links to pull request
on:
  workflow_run:
    workflows: ['Create a test build']
    types: [completed]

permissions:
  actions: write
  contents: write
  pull-requests: write
jobs:
  pr_comment:
    if: github.event.workflow_run.event == 'pull_request' && github.event.workflow_run.conclusion == 'success'
    runs-on: ubuntu-latest
    steps:
      - uses: actions/github-script@v7
        with:
          # This snippet is public-domain, combined from
          # https://github.com/oprypin/nightly.link/blob/master/.github/workflows/pr-comment.yml
          # https://github.com/AKSW/submission.d2r2.aksw.org/blob/main/.github/workflows/pr-comment.yml
          script: |
            // Function Definitions

            /**
             * Fetch PR details for a given commit SHA.
             * @returns {Object} PR details containing prNumber, prRef, prRepoId.
             * @throws {Error} If no matching PR is found.
             */
            async function fetchPRDetails() {
              const iterator = github.paginate.iterator(github.rest.pulls.list, {
                owner: context.repo.owner,
                repo: context.repo.repo,
              });
              for await (const { data } of iterator) {
                for (const pull of data) {
                  if (pull.head.sha === '${{github.event.workflow_run.head_sha}}') {
                    return {
                      prNumber: pull.number,
                      prRef: pull.head.ref,
                      prRepoId: pull.head.repo.id
                    };
                  }
                }
              }
              throw new Error("No matching PR found for the commit SHA");
            }

            /**
             * Fetch all artifacts for a given workflow run.
             * @returns {Object} All artifacts data.
             * @throws {Error} If no artifacts are found.
             */
            async function fetchAllArtifacts() {
              const artifactsResponse = await github.rest.actions.listWorkflowRunArtifacts({
                owner: context.repo.owner,
                repo: context.repo.repo,
                run_id: context.payload.workflow_run.id,
              });
              if (!(artifactsResponse.data && artifactsResponse.data.artifacts && artifactsResponse.data.artifacts.length)) {
                throw new Error("No artifacts found for the workflow run");
              }
              return artifactsResponse.data.artifacts;
            }

            /**
             * Create or update a comment on the PR.
             * @param {number} prNumber - The PR number.
             * @param {string} purpose - The purpose of the comment.
             * @param {string} body - The comment body.
             * @throws {Error} If the comment creation or update fails.
             */
            async function upsertComment(prNumber, purpose, body) {
              const { data: comments } = await github.rest.issues.listComments({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: prNumber,
              });
              const marker = `<!-- bot: ${purpose} -->`;
              body = marker + "\n" + body;

              const existing = comments.filter(c => c.body.includes(marker));
              if (existing.length > 0) {
                const last = existing[existing.length - 1];
                core.info(`Updating comment ${last.id}`);
                await github.rest.issues.updateComment({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  body: body,
                  comment_id: last.id,
                });
              } else {
                core.info(`Creating a comment in PR #${prNumber}`);
                await github.rest.issues.createComment({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  body: body,
                  issue_number: prNumber,
                });
              }
            }

            /**
             * Handle and log errors with detailed context and exit the process.
             * @param {Error} error - The error object.
             * @param {string} description - Description of the context where the error occurred.
             */
            function handleError(error, description, prNumber) {
              core.error(`Failed to ${description}`);
              core.error(`Message: ${error.message}`);
              core.error(`Stack Trace: ${error.stack || 'No stack trace available'}`);
              if (prNumber) {
                core.error(`PR Number: ${prNumber}`);
              }
              core.error(`PRs: https://api.github.com/repos/${context.repo.owner}/${context.repo.repo}/pulls`);
              core.error(`SHA: ${{github.event.workflow_run.head_sha}}`);
              process.exit(1);
            }

            // Main Code Execution

            let prNumber, prRef, prRepoId;

            // Fetch PR details
            try {
              ({ prNumber, prRef, prRepoId } = await fetchPRDetails());
              core.info(`Found PR: #${prNumber}, Ref: ${prRef}, Repo ID: ${prRepoId}`);
            } catch (error) {
              handleError(error, 'fetch PR details', undefined);
            }

            // Fetch all artifacts
            let allArtifacts;
            try {
              allArtifacts = await fetchAllArtifacts();
              core.info(`Artifacts fetched successfully`);
            } catch (error) {
              handleError(error, 'fetch artifacts', prNumber);
            }

            // Construct the comment body
            let body = allArtifacts.reduce((acc, item) => {
              if (item.name === "assets") return acc;
              acc += `\n* [${item.name}.zip](https://nightly.link/${context.repo.owner}/${context.repo.repo}/actions/artifacts/${item.id}.zip)`;
              return acc;
            }, 'Download the built assets for this pull request:\n');

            // Upsert the comment on the PR
            try {
              await upsertComment(prNumber, "nightly-link", body);
              core.info("Comment created/updated successfully");
            } catch (error) {
              handleError(error, 'create/update comment', prNumber);
            }