From a19abb1836d920b869091c4b0b8f169973d2ba01 Mon Sep 17 00:00:00 2001
From: Tomas Slusny <slusnucky@gmail.com>
Date: Fri, 12 Sep 2025 10:02:56 +0200
Subject: [PATCH] perf(chat): simplify last line/column calculation

Replaces Chat:last() method with a standalone last() function for
retrieving the last line and column of the chat buffer. Updates
references to use the new function and removes redundant logic.
This improves code clarity and maintainability.
---
 lua/CopilotChat/ui/chat.lua | 41 +++++++++++++++----------------------
 1 file changed, 17 insertions(+), 24 deletions(-)

diff --git a/lua/CopilotChat/ui/chat.lua b/lua/CopilotChat/ui/chat.lua
index 2f97fe74..4681779b 100644
--- a/lua/CopilotChat/ui/chat.lua
+++ b/lua/CopilotChat/ui/chat.lua
@@ -52,6 +52,21 @@ local function match_block_header(header)
   end
 end
 
+--- Get the last line and column of the chat window.
+---@param bufnr number
+---@return number, number
+---@protected
+local function last(bufnr)
+  local line_count = vim.api.nvim_buf_line_count(bufnr)
+  if line_count == 0 then
+    return 0, 0
+  end
+  local last_line = line_count - 1
+  local last_line_content = vim.api.nvim_buf_get_lines(bufnr, last_line, last_line + 1, false)
+  local last_column = last_line_content[1] and #last_line_content[1] or 0
+  return last_line, last_column
+end
+
 ---@class CopilotChat.ui.chat.Header
 ---@field filename string
 ---@field start_line number
@@ -426,11 +441,7 @@ function Chat:follow()
     return
   end
 
-  local last_line, last_column, line_count = self:last()
-  if line_count == 0 then
-    return
-  end
-
+  local last_line, last_column = last(self.bufnr)
   vim.api.nvim_win_set_cursor(self.winnr, { last_line + 1, last_column })
 end
 
@@ -557,7 +568,7 @@ function Chat:append(str)
     should_follow_cursor = current_pos[1] >= line_count - 1
   end
 
-  local last_line, last_column, _ = self:last()
+  local last_line, last_column, _ = last(self.bufnr)
 
   local modifiable = vim.bo[self.bufnr].modifiable
   vim.bo[self.bufnr].modifiable = true
@@ -884,22 +895,4 @@ function Chat:render()
   end
 end
 
---- Get the last line and column of the chat window.
----@return number, number, number
----@protected
-function Chat:last()
-  self:validate()
-  local line_count = vim.api.nvim_buf_line_count(self.bufnr)
-  local last_line = line_count - 1
-  if last_line < 0 then
-    return 0, 0, line_count
-  end
-  local last_line_content = vim.api.nvim_buf_get_lines(self.bufnr, -2, -1, false)
-  if not last_line_content or #last_line_content == 0 then
-    return last_line, 0, line_count
-  end
-  local last_column = #last_line_content[1]
-  return last_line, last_column, line_count
-end
-
 return Chat