KAFKA-19013 Reformat PR body to 72 characters (apache#19242)

Parse the body of a PR and re-format it to a text wrap of 72 characters.
Since GitHub will do this automatically when merging PRs with the merge
queue, we should do our best to pre-format the commit message.

Reviewers: Chia-Ping Tsai <[email protected]>

Author: mumrah

.github/scripts/pr-format.py

@@ -22,9 +22,9 @@
 import shlex
 import sys
 import tempfile
+import textwrap
 from typing import Dict, Optional, TextIO
 
-
 logger = logging.getLogger()
 logger.setLevel(logging.DEBUG)
 handler = logging.StreamHandler(sys.stderr)
@@ -61,6 +61,7 @@ def write_commit(io: TextIO, title: str, body: str):
     io.write(body.encode())
     io.flush()
 
+
 def parse_trailers(title, body) -> Dict:
     trailers = defaultdict(list)
 
@@ -77,6 +78,29 @@ def parse_trailers(title, body) -> Dict:
     return trailers
 
 
+def split_paragraphs(text: str):
+    """
+    Split the given text into a generator of paragraph lines and a boolean "markdown" flag.
+
+    If any line of a paragraph starts with a markdown character, we will assume the whole paragraph
+    contains markdown.
+    """
+    lines = text.splitlines(keepends=True)
+    paragraph = []
+    markdown = False
+    for line in lines:
+        if line.strip() == "":
+            if len(paragraph) > 0:
+                yield paragraph, markdown
+                paragraph.clear()
+                markdown = False
+        else:
+            if line[0] in ("#", "*", "-", "=") or line[0].isdigit():
+                markdown = True
+            paragraph.append(line)
+    yield paragraph, markdown
+
+
 if __name__ == "__main__":
     """
     This script performs some basic linting of our PR titles and body. The PR number is read from the PR_NUMBER
@@ -96,10 +120,6 @@ def parse_trailers(title, body) -> Dict:
     * Has "Reviewers:" trailer if the PR is approved
     """
 
-    if not get_env("GITHUB_ACTIONS"):
-        print("This script is intended to by run by GitHub Actions.")
-        exit(1)
-
     pr_number = get_env("PR_NUMBER")
     cmd = f"gh pr view {pr_number} --json 'title,body,reviews'"
     p = subprocess.run(shlex.split(cmd), capture_output=True)
@@ -132,6 +152,32 @@ def check(positive_assertion, ok_msg, err_msg):
     check("Delete this text and replace" not in body, "PR template text not present", "PR template text should be removed")
     check("Committer Checklist" not in body, "PR template text not present", "Old PR template text should be removed")
 
+    paragraph_iter = split_paragraphs(body)
+    new_paragraphs = []
+    for p, markdown in paragraph_iter:
+        if markdown:
+            # If a paragraph looks like it has markdown in it, wrap each line separately.
+            new_lines = []
+            for line in p:
+                new_lines.append(textwrap.fill(line, width=72, break_long_words=False, break_on_hyphens=False, replace_whitespace=False))
+            rewrapped_p = "\n".join(new_lines)
+        else:
+            rewrapped_p = textwrap.fill("".join(p), width=72, break_long_words=False, break_on_hyphens=False, replace_whitespace=True)
+        new_paragraphs.append(rewrapped_p + "\n")
+    body = "\n".join(new_paragraphs)
+
+    if get_env("GITHUB_ACTIONS"):
+        with tempfile.NamedTemporaryFile() as fp:
+            fp.write(body.encode())
+            fp.flush()
+            cmd = f"gh pr edit {pr_number} --body-file {fp.name}"
+            p = subprocess.run(shlex.split(cmd), capture_output=True)
+            fp.close()
+            if p.returncode != 0:
+                logger.error(f"Could not update PR {pr_number}. STDOUT: {p.stdout.decode()}")
+    else:
+        logger.info(f"Not reformatting {pr_number} since this is not running on GitHub Actions.")
+
     # Check for Reviewers
     approved = has_approval(reviews)
     if approved:
@@ -143,12 +189,13 @@ def check(positive_assertion, ok_msg, err_msg):
                 logger.debug(reviewer_in_body)
 
     logger.debug("Commit will look like:\n")
-    logger.debug("```")
+    logger.debug("<pre>")
     io = BytesIO()
+    title += f" (#{pr_number})"
     write_commit(io, title, body)
     io.seek(0)
     logger.debug(io.read().decode())
-    logger.debug("```\n")
+    logger.debug("</pre>\n")
 
     exit_code = 0
     logger.debug("Validation results:")