From abb5a809e3ec387f46898817c15a2d3137aee819 Mon Sep 17 00:00:00 2001
From: Ilya Konstantinov <ilya.konstantinov@gmail.com>
Date: Fri, 18 Nov 2022 00:32:19 -0500
Subject: [PATCH] mypy_primer: truncate per-project output (#14091)

Closes #14059
---
 .github/workflows/mypy_primer_comment.yml | 24 ++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/mypy_primer_comment.yml b/.github/workflows/mypy_primer_comment.yml
index 2056fc5a40c0f..b20eaf471c9a3 100644
--- a/.github/workflows/mypy_primer_comment.yml
+++ b/.github/workflows/mypy_primer_comment.yml
@@ -48,15 +48,29 @@ jobs:
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           script: |
+            const MAX_CHARACTERS = 30000
+            const MAX_CHARACTERS_PER_PROJECT = MAX_CHARACTERS / 3
+
             const fs = require('fs')
             let data = fs.readFileSync('fulldiff.txt', { encoding: 'utf8' })
-            // posting comment fails if too long, so truncate
-            if (data.length > 30000) {
-              let truncated_data = data.substring(0, 30000)
-              let lines_truncated = data.split('\n').length - truncated_data.split('\n').length
-              data = truncated_data + `\n\n... (truncated ${lines_truncated} lines) ...\n`
+
+            function truncateIfNeeded(original, maxLength) {
+              if (original.length <= maxLength) {
+                return original
+              }
+              let truncated = original.substring(0, maxLength)
+              // further, remove last line that might be truncated
+              truncated = truncated.substring(0, truncated.lastIndexOf('\n'))
+              let lines_truncated = original.split('\n').length - truncated.split('\n').length
+              return `${truncated}\n\n... (truncated ${lines_truncated} lines) ...`
             }
 
+            const projects = data.split('\n\n')
+            // don't let one project dominate
+            data = projects.map(project => truncateIfNeeded(project, MAX_CHARACTERS_PER_PROJECT)).join('\n\n')
+            // posting comment fails if too long, so truncate
+            data = truncateIfNeeded(data, MAX_CHARACTERS)
+
             console.log("Diff from mypy_primer:")
             console.log(data)