Adds option to write summary into a pr comment

src/comment-pr.ts

@@ -0,0 +1,84 @@
+import * as github from '@actions/github'
+import * as core from '@actions/core'
+import * as githubUtils from '@actions/github/lib/utils'
+import * as retry from '@octokit/plugin-retry'
+import {RequestError} from '@octokit/request-error'
+
+const retryingOctokit = githubUtils.GitHub.plugin(retry.retry)
+const octo = new retryingOctokit(
+  githubUtils.getOctokitOptions(core.getInput('repo-token', {required: true}))
+)
+
+// Comment Marker to identify an existing comment to update, so we don't spam the PR with comments
+const COMMENT_MARKER = '<!-- dependency-review-pr-comment-marker -->'
+
+export async function commentPr(summary: typeof core.summary): Promise<void> {
+  if (!github.context.payload.pull_request) {
+    core.warning(
+      'Not in the context of a pull request. Skipping comment creation.'
+    )
+    return
+  }
+
+  const commentBody = `${summary.stringify()}\n\n${COMMENT_MARKER}`
+
+  try {
+    const existingCommentId = await findCommentByMarker(COMMENT_MARKER)
+
+    if (existingCommentId) {
+      await octo.rest.issues.updateComment({
+        owner: github.context.repo.owner,
+        repo: github.context.repo.repo,
+        comment_id: existingCommentId,
+        body: commentBody
+      })
+    } else {
+      await octo.rest.issues.createComment({
+        owner: github.context.repo.owner,
+        repo: github.context.repo.repo,
+        issue_number: github.context.payload.pull_request.number,
+        body: commentBody
+      })
+    }
+  } catch (error) {
+    if (error instanceof RequestError && error.status === 403) {
+      core.warning(
+        `Unable to write summary to pull-request. Make sure you are giving this workflow the permission 'pull-requests: write'.`
+      )
+    } else {
+      if (error instanceof Error) {
+        core.warning(
+          `Unable to comment summary to pull-request, received error: ${error.message}`
+        )
+      } else {
+        core.warning(
+          'Unable to comment summary to pull-request: Unexpected fatal error'
+        )
+      }
+    }
+  }
+}
+
+async function findCommentByMarker(
+  commentBodyIncludes: string
+): Promise<number | undefined> {
+  const commentsIterator = octo.paginate.iterator(
+    octo.rest.issues.listComments,
+    {
+      owner: github.context.repo.owner,
+      repo: github.context.repo.repo,
+      // We are already checking if we are in the context of a pull request in the caller
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      issue_number: github.context.payload.pull_request!.number
+    }
+  )
+
+  for await (const {data: comments} of commentsIterator) {
+    const existingComment = comments.find(comment =>
+      comment.body?.includes(commentBodyIncludes)
+    )
+    if (existingComment) return existingComment.id
+  }
+
+  return undefined
+}