Warn when a commit message isn't wrapped

Git tools assume the commit message is well structured according to
the standard convention of a subject line, blank line, and the body.
They also assume the message has been manually line wrapped at
shorter than 70 characters, so the message still fits on an 80
character wide terminal.

Encourage this formatting by warning users when a commit they are
uploading for review doesn't meet this criteria.

Change-Id: I6015a7a72e73f9bfffb239f2c6fb34a83352c0a7
Signed-off-by: Shawn O. Pearce <sop@google.com>

gerrit-server/src/main/java/com/google/gerrit/server/git/ReceiveCommits.java

@@ -775,6 +775,7 @@ public class ReceiveCommits implements PreReceiveHook, PostReceiveHook {
   private void createChange(final RevWalk walk, final RevCommit c)
       throws OrmException, IOException {
     walk.parseBody(c);
+    warnMalformedMessage(c);
 
     final Account.Id me = currentUser.getAccountId();
     Change.Key changeKey = new Change.Key("I" + c.name());
@@ -900,6 +901,7 @@ public class ReceiveCommits implements PreReceiveHook, PostReceiveHook {
       throws IOException, OrmException {
     final RevCommit c = request.newCommit;
     rp.getRevWalk().parseBody(c);
+    warnMalformedMessage(c);
 
     final Account.Id me = currentUser.getAccountId();
     final Set<Account.Id> reviewers = new HashSet<Account.Id>(reviewerId);
@@ -992,7 +994,7 @@ public class ReceiveCommits implements PreReceiveHook, PostReceiveHook {
             reject(request.cmd, "no changes made");
             return null;
           } else {
-            rp.sendMessage("warning: " + change.getKey().abbreviate() + ": " //
+            rp.sendMessage("(W) " + c.abbreviate(repo, 6).name() + ":" //
                 + " no files changed, but" //
                 + (!messageEq ? " message updated" : "") //
                 + (!messageEq && !parentsEq ? " and" : "") //
@@ -1325,6 +1327,28 @@ public class ReceiveCommits implements PreReceiveHook, PostReceiveHook {
     return true;
   }
 
+  private void warnMalformedMessage(RevCommit c) {
+    if (65 < c.getShortMessage().length()) {
+      rp.sendMessage("(W) " + c.abbreviate(repo, 6).name()
+          + ": commit subject >65 characters; use shorter first paragraph");
+    }
+
+    int longLineCnt = 0, nonEmptyCnt = 0;
+    for (String line : c.getFullMessage().split("\n")) {
+      if (!line.trim().isEmpty()) {
+        nonEmptyCnt++;
+      }
+      if (70 < line.length()) {
+        longLineCnt++;
+      }
+    }
+
+    if (0 < longLineCnt && 33 < longLineCnt * 100 / nonEmptyCnt) {
+      rp.sendMessage("(W) " + c.abbreviate(repo, 6).name()
+          + ": commit message lines >70 characters; manually wrap lines");
+    }
+  }
+
   private void autoCloseChanges(final ReceiveCommand cmd) {
     final RevWalk rw = rp.getRevWalk();
     try {