Code block: add function to truncate content

The code was duplicated in each of the format message functions. The
function also ensures content is truncated to 10 lines. Previously, code
could have skipped truncating by being 100 lines long but under 204
characters in length.

1 files changed, 16 insertions, 21 deletions

diff --git a/bot/cogs/codeblock/cog.py b/bot/cogs/codeblock/cog.py
index 970cbd63d..c5704b730 100644
--- a/bot/cogs/codeblock/cog.py
+++ b/bot/cogs/codeblock/cog.py
@@ -153,16 +153,7 @@ class CodeBlockCog(Cog, name="Code Block"):
         else:
             content = content[0]
 
-        space_left = 204
-        if len(content) >= space_left:
-            current_length = 0
-            lines_walked = 0
-            for line in content.splitlines(keepends=True):
-                if current_length + len(line) > space_left or lines_walked == 10:
-                    break
-                current_length += len(line)
-                lines_walked += 1
-            content = content[:current_length] + "#..."
+        content = self.truncate(content)
         content_escaped_markdown = RE_MARKDOWN.sub(r'\\\1', content)
 
         return (
@@ -190,22 +181,12 @@ class CodeBlockCog(Cog, name="Code Block"):
         # This check is to avoid all nodes being parsed as expressions.
         # (e.g. words over multiple lines)
         if not all(isinstance(node, ast.Expr) for node in tree.body) or repl_code:
-            # Shorten the code to 10 lines and/or 204 characters.
-            space_left = 204
             if content and repl_code:
                 content = content[1]
             else:
                 content = content[0]
 
-            if len(content) >= space_left:
-                current_length = 0
-                lines_walked = 0
-                for line in content.splitlines(keepends=True):
-                    if current_length + len(line) > space_left or lines_walked == 10:
-                        break
-                    current_length += len(line)
-                    lines_walked += 1
-                content = content[:current_length] + "#..."
+            content = self.truncate(content)
 
             log.debug(
                 f"{message.author} posted something that needed to be put inside python code "
@@ -364,6 +345,20 @@ class CodeBlockCog(Cog, name="Code Block"):
             and not TokenRemover.find_token_in_message(message)
         )
 
+    @staticmethod
+    def truncate(content: str, max_chars: int = 204, max_lines: int = 10) -> str:
+        """Return `content` truncated to be at most `max_chars` or `max_lines` in length."""
+        current_length = 0
+        lines_walked = 0
+
+        for line in content.splitlines(keepends=True):
+            if current_length + len(line) > max_chars or lines_walked == max_lines:
+                break
+            current_length += len(line)
+            lines_walked += 1
+
+        return content[:current_length] + "#..."
+
     @Cog.listener()
     async def on_message(self, msg: Message) -> None:
         """