Refactor PR comment handling in check.go to support chunked posting of comments, ensuring compliance with GitHub's comment body limit. Enhance markdown processing by introducing chunkMarkdownByURL function and updating upsertPRComments to delete existing comments before posting new ones.

cmd/check.go

@@ -245,29 +245,33 @@ func init() {
 			// Ensure we have a markdown file if needed for PR comment
 			mdPath := mdOut
 			ghRepo, ghPR, ghToken, ghOK := detectGitHubPR()
+			var finalMDPath string
 			if strings.TrimSpace(mdPath) != "" {
 				if _, err := report.WriteMarkdown(mdPath, failedResults, summary); err != nil {
 					return err
 				}
+				finalMDPath = mdPath
 			} else if ghOK {
 				p, err := report.WriteMarkdown("", failedResults, summary)
 				if err != nil {
 					return err
 				}
-				mdPath = p
+				finalMDPath = p
 			}
 
-			if shouldDebug() {
+			// If running on a PR, post or update the comment(s), chunking as needed
-				fmt.Printf("::debug:: Running Environment: repo=%s pr=%d token=%s mdPath=%s\n", ghRepo, ghPR, ghToken, mdPath)
+			if ghOK && strings.TrimSpace(finalMDPath) != "" {
-			}
+				b, rerr := os.ReadFile(finalMDPath)
-
-			// If running on a PR, post or update the comment
-			if ghOK && strings.TrimSpace(mdPath) != "" {
-				b, rerr := os.ReadFile(mdPath)
 				if rerr == nil {
-					body := string(b)
+					full := string(b)
-					body = fmt.Sprintf("%s\n%s", "<!-- slinky-report -->", body)
+					if shouldDebug() {
-					_ = upsertPRComment(ghRepo, ghPR, ghToken, body)
+						fmt.Printf("::debug:: Report size (chars): %d\n", len(full))
+					}
+					chunks := chunkMarkdownByURL(full)
+					if shouldDebug() {
+						fmt.Printf("::debug:: Posting %d chunk(s)\n", len(chunks))
+					}
+					_ = upsertPRComments(ghRepo, ghPR, ghToken, chunks)
 				}
 			}
 
@@ -327,12 +331,6 @@ func detectGitHubPR() (repo string, prNumber int, token string, ok bool) {
 	repo = os.Getenv("GITHUB_REPOSITORY")
 	token = os.Getenv("GITHUB_TOKEN")
 	eventPath := os.Getenv("GITHUB_EVENT_PATH")
-	ref := os.Getenv("GITHUB_REF")
-
-	if shouldDebug() {
-		fmt.Printf("::debug:: Detected Environment: repo=%s eventPath=%s ref=%s\n", repo, eventPath, ref)
-	}
-
 	if repo == "" || eventPath == "" || token == "" {
 		return "", 0, "", false
 	}
@@ -346,18 +344,88 @@ func detectGitHubPR() (repo string, prNumber int, token string, ok bool) {
 		} `json:"pull_request"`
 	}
 	_ = json.Unmarshal(data, &ev)
-
-	if shouldDebug() {
-		fmt.Printf("::debug:: Detected Pull Request: number=%d\n", ev.PullRequest.Number)
-	}
-
 	if ev.PullRequest.Number == 0 {
 		return "", 0, "", false
 	}
 	return repo, ev.PullRequest.Number, token, true
 }
 
-func upsertPRComment(repo string, prNumber int, token string, body string) error {
+// chunkMarkdownByURL splits markdown into chunks under GitHub's comment body limit,
+// keeping whole URL entries together. Only the first chunk includes the original
+// header and the "Failures by URL" section header. Subsequent chunks have no headers.
+func chunkMarkdownByURL(body string) []string {
+	const maxBody = 65000
+	lines := strings.Split(body, "\n")
+	// locate failures header
+	failIdx := -1
+	for i, ln := range lines {
+		if strings.TrimSpace(ln) == "### Failures by URL" {
+			failIdx = i
+			break
+		}
+	}
+	if failIdx < 0 {
+		// no failures section; return as single chunk
+		return []string{body}
+	}
+	preamble := strings.Join(lines[:failIdx+1], "\n") + "\n"
+	entryLines := lines[failIdx+1:]
+
+	// build entries by URL block, starting at lines with "- " at column 0
+	type entry struct {
+		text   string
+		length int
+	}
+	var entries []entry
+	for i := 0; i < len(entryLines); {
+		// skip leading blank lines
+		for i < len(entryLines) && strings.TrimSpace(entryLines[i]) == "" {
+			i++
+		}
+		if i >= len(entryLines) {
+			break
+		}
+		if !strings.HasPrefix(entryLines[i], "- ") {
+			// if unexpected, include line as is
+			entries = append(entries, entry{text: entryLines[i] + "\n", length: len(entryLines[i]) + 1})
+			i++
+			continue
+		}
+		start := i
+		i++
+		for i < len(entryLines) && !strings.HasPrefix(entryLines[i], "- ") {
+			i++
+		}
+		block := strings.Join(entryLines[start:i], "\n") + "\n\n"
+		entries = append(entries, entry{text: block, length: len(block)})
+	}
+
+	var chunks []string
+	// start first chunk with full preamble
+	cur := preamble
+	curLen := len(cur)
+	for _, e := range entries {
+		if curLen+e.length > maxBody && curLen > len(preamble) {
+			// flush current chunk, start new without headers
+			chunks = append(chunks, cur)
+			cur = ""
+			curLen = 0
+		}
+		// if new chunk and would still exceed, force place the single large entry
+		if curLen == 0 && e.length > maxBody {
+			// fallback: include as is; GitHub will still likely accept since entries are typically smaller
+		}
+		cur += e.text
+		curLen += e.length
+	}
+	if strings.TrimSpace(cur) != "" {
+		chunks = append(chunks, cur)
+	}
+	return chunks
+}
+
+// upsertPRComments deletes any existing slinky comments and posts the new chunked comments in order.
+func upsertPRComments(repo string, prNumber int, token string, chunks []string) error {
 	apiBase := "https://api.github.com"
 	listURL := fmt.Sprintf("%s/repos/%s/issues/%d/comments?per_page=100", apiBase, repo, prNumber)
 	req, _ := http.NewRequest(http.MethodGet, listURL, nil)
@@ -374,49 +442,31 @@ func upsertPRComment(repo string, prNumber int, token string, body string) error
 	}
 	b, _ := io.ReadAll(resp.Body)
 	_ = json.Unmarshal(b, &comments)
-	var existingID int
+
+	// Delete all existing slinky-report comments to avoid stale entries
 	for _, c := range comments {
 		if strings.Contains(c.Body, "<!-- slinky-report -->") {
-			existingID = c.ID
+			delURL := fmt.Sprintf("%s/repos/%s/issues/comments/%d", apiBase, repo, c.ID)
-			break
+			dReq, _ := http.NewRequest(http.MethodDelete, delURL, nil)
+			dReq.Header.Set("Authorization", "Bearer "+token)
+			dReq.Header.Set("Accept", "application/vnd.github+json")
+			_, _ = http.DefaultClient.Do(dReq)
 		}
 	}
 
-	payload, _ := json.Marshal(map[string]string{"body": body})
+	// Post new comments in order
-	if existingID > 0 {
+	for idx, chunk := range chunks {
+		body := fmt.Sprintf("%s\n%s", "<!-- slinky-report -->", chunk)
+		postURL := fmt.Sprintf("%s/repos/%s/issues/%d/comments", apiBase, repo, prNumber)
+		payload, _ := json.Marshal(map[string]string{"body": body})
+		req, _ = http.NewRequest(http.MethodPost, postURL, bytes.NewReader(payload))
+		req.Header.Set("Authorization", "Bearer "+token)
+		req.Header.Set("Accept", "application/vnd.github+json")
+		req.Header.Set("Content-Type", "application/json")
+		res, _ := http.DefaultClient.Do(req)
 		if shouldDebug() {
-			fmt.Printf("::debug:: Updating existing comment: %d\n", existingID)
+			fmt.Printf("::debug:: Posted chunk %d/%d: %v\n", idx+1, len(chunks), res)
 		}
-
-		u := fmt.Sprintf("%s/repos/%s/issues/comments/%d", apiBase, repo, existingID)
-		req, _ = http.NewRequest(http.MethodPatch, u, bytes.NewReader(payload))
-	} else {
-		if shouldDebug() {
-			fmt.Printf("::debug:: Creating new comment\n")
-		}
-
-		u := fmt.Sprintf("%s/repos/%s/issues/%d/comments", apiBase, repo, prNumber)
-		req, _ = http.NewRequest(http.MethodPost, u, bytes.NewReader(payload))
-	}
-	req.Header.Set("Authorization", "Bearer "+token)
-	req.Header.Set("Accept", "application/vnd.github+json")
-	req.Header.Set("Content-Type", "application/json")
-	upsertResp, err := http.DefaultClient.Do(req)
-	if err != nil {
-		return err
-	}
-	defer upsertResp.Body.Close()
-	upsertRespBody, _ := io.ReadAll(upsertResp.Body)
-	upsertRespUnmarshalErr := json.Unmarshal(upsertRespBody, &upsertResp)
-	if upsertRespUnmarshalErr != nil {
-		return fmt.Errorf("failed to unmarshal upsert response: %s", upsertRespUnmarshalErr)
-	}
-	if shouldDebug() {
-		fmt.Printf("::debug:: Comment upserted Response: %s\n%s", upsertResp.Status, string(upsertRespBody))
-		fmt.Printf("::debug:: Comment upserted: %+v\n", upsertResp)
-	}
-	if upsertResp.StatusCode != http.StatusOK {
-		return fmt.Errorf("failed to upsert comment: %s", upsertResp.Status)
 	}
 	return nil
 }