refactor: move utility functions to utils module

Moves uuid, machine_id and quick_hash functions from copilot.lua to utils.lua
module. Also improves type annotations and documentation for the moved
functions. Removes unused table_equals function and renames
blend_color_with_neovim_bg to blend_color for better clarity.

lua/CopilotChat/copilot.lua

@@ -36,6 +36,8 @@ local tiktoken = require('CopilotChat.tiktoken')
 local utils = require('CopilotChat.utils')
 local class = utils.class
 local temp_file = utils.temp_file
+
+--- Constants
 local context_format = '[#file:%s](#file:%s-context)\n'
 local big_file_threshold = 2000
 local timeout = 30000
@@ -81,31 +83,8 @@ local tiktoken_load = async.wrap(function(tokenizer, callback)
   tiktoken.load(tokenizer, callback)
 end, 2)
 
-local function uuid()
-  local template = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'
-  return (
-    string.gsub(template, '[xy]', function(c)
-      local v = (c == 'x') and math.random(0, 0xf) or math.random(8, 0xb)
-      return string.format('%x', v)
-    end)
-  )
-end
-
-local function machine_id()
-  local length = 65
-  local hex_chars = '0123456789abcdef'
-  local hex = ''
-  for _ = 1, length do
-    local index = math.random(1, #hex_chars)
-    hex = hex .. hex_chars:sub(index, index)
-  end
-  return hex
-end
-
-local function quick_hash(str)
-  return #str .. str:sub(1, 32) .. str:sub(-32)
-end
-
+--- Get the github oauth cached token
+---@return string|nil
 local function get_cached_token()
   -- loading token from the environment only in GitHub Codespaces
   local token = os.getenv('GITHUB_TOKEN')
@@ -140,6 +119,10 @@ local function get_cached_token()
   return nil
 end
 
+--- Generate line numbers for the given content
+---@param content string: The content to generate line numbers for
+---@param start_line number|nil: The starting line number
+---@return string
 local function generate_line_numbers(content, start_line)
   local lines = vim.split(content, '\n')
   local truncated = false
@@ -348,21 +331,13 @@ local function generate_embedding_request(inputs, model)
   }
 end
 
-local function count_history_tokens(history)
-  local count = 0
-  for _, msg in ipairs(history) do
-    count = count + tiktoken.count(msg.content)
-  end
-  return count
-end
-
 local Copilot = class(function(self, proxy, allow_insecure)
   self.history = {}
   self.embedding_cache = {}
   self.github_token = nil
   self.token = nil
   self.sessionid = nil
-  self.machineid = machine_id()
+  self.machineid = utils.machine_id()
   self.models = nil
   self.agents = nil
   self.claude_enabled = false
@@ -404,7 +379,7 @@ function Copilot:authenticate()
   if
     not self.token or (self.token.expires_at and self.token.expires_at <= math.floor(os.time()))
   then
-    local sessionid = uuid() .. tostring(math.floor(os.time() * 1000))
+    local sessionid = utils.uuid() .. tostring(math.floor(os.time() * 1000))
     local headers = {
       ['authorization'] = 'token ' .. self.github_token,
       ['accept'] = 'application/json',
@@ -434,7 +409,7 @@ function Copilot:authenticate()
 
   local headers = {
     ['authorization'] = 'Bearer ' .. self.token.token,
-    ['x-request-id'] = uuid(),
+    ['x-request-id'] = utils.uuid(),
     ['vscode-sessionid'] = self.sessionid,
     ['vscode-machineid'] = self.machineid,
     ['copilot-integration-id'] = 'vscode-chat',
@@ -570,7 +545,7 @@ function Copilot:ask(prompt, opts)
   local temperature = opts.temperature or 0.1
   local no_history = opts.no_history or false
   local on_progress = opts.on_progress
-  local job_id = uuid()
+  local job_id = utils.uuid()
   self.current_job = job_id
 
   log.trace('System prompt: ' .. system_prompt)
@@ -622,7 +597,10 @@ function Copilot:ask(prompt, opts)
 
   -- Calculate how many tokens we can use for history
   local history_limit = max_tokens - required_tokens - reserved_tokens
-  local history_tokens = count_history_tokens(history)
+  local history_tokens = 0
+  for _, msg in ipairs(history) do
+    history_tokens = history_tokens + tiktoken.count(msg.content)
+  end
 
   -- If we're over history limit, truncate history from the beginning
   while history_tokens > history_limit and #history > 0 do
@@ -914,7 +892,7 @@ function Copilot:embed(inputs, opts)
     embed.filetype = embed.filetype or 'text'
 
     if embed.content then
-      local key = embed.filename .. quick_hash(embed.content)
+      local key = embed.filename .. utils.quick_hash(embed.content)
       if self.embedding_cache[key] then
         table.insert(cached_embeddings, self.embedding_cache[key])
       else
@@ -977,7 +955,7 @@ function Copilot:embed(inputs, opts)
   -- Cache embeddings
   for _, embedding in ipairs(out) do
     if embedding.content then
-      local key = embedding.filename .. quick_hash(embedding.content)
+      local key = embedding.filename .. utils.quick_hash(embedding.content)
       self.embedding_cache[key] = embedding
     end
   end

lua/CopilotChat/diff.lua

@@ -20,21 +20,9 @@ local class = utils.class
 
 local Diff = class(function(self, help, on_buf_create)
   self.hl_ns = vim.api.nvim_create_namespace('copilot-chat-highlights')
-  vim.api.nvim_set_hl(
-    self.hl_ns,
-    '@diff.plus',
-    { bg = utils.blend_color_with_neovim_bg('DiffAdd', 20) }
-  )
-  vim.api.nvim_set_hl(
-    self.hl_ns,
-    '@diff.minus',
-    { bg = utils.blend_color_with_neovim_bg('DiffDelete', 20) }
-  )
-  vim.api.nvim_set_hl(
-    self.hl_ns,
-    '@diff.delta',
-    { bg = utils.blend_color_with_neovim_bg('DiffChange', 20) }
-  )
+  vim.api.nvim_set_hl(self.hl_ns, '@diff.plus', { bg = utils.blend_color('DiffAdd', 20) })
+  vim.api.nvim_set_hl(self.hl_ns, '@diff.minus', { bg = utils.blend_color('DiffDelete', 20) })
+  vim.api.nvim_set_hl(self.hl_ns, '@diff.delta', { bg = utils.blend_color('DiffChange', 20) })
 
   self.name = 'copilot-diff'
   self.help = help

lua/CopilotChat/utils.lua

@@ -69,32 +69,11 @@ function M.config_path()
   end
 end
 
---- Check if a table is equal to another table
----@param a table The first table
----@param b table The second table
----@return boolean
-function M.table_equals(a, b)
-  if type(a) ~= type(b) then
-    return false
-  end
-  if type(a) ~= 'table' then
-    return a == b
-  end
-  for k, v in pairs(a) do
-    if not M.table_equals(v, b[k]) then
-      return false
-    end
-  end
-  for k, v in pairs(b) do
-    if not M.table_equals(v, a[k]) then
-      return false
-    end
-  end
-  return true
-end
-
 --- Blend a color with the neovim background
-function M.blend_color_with_neovim_bg(color_name, blend)
+---@param color_name string The color name
+---@param blend number The blend percentage
+---@return string?
+function M.blend_color(color_name, blend)
   local color_int = vim.api.nvim_get_hl(0, { name = color_name }).fg
   local bg_int = vim.api.nvim_get_hl(0, { name = 'Normal' }).bg
 
@@ -207,4 +186,36 @@ function M.filename_same(file1, file2)
   return vim.fn.fnamemodify(file1, ':p') == vim.fn.fnamemodify(file2, ':p')
 end
 
+--- Generate a UUID
+---@return string
+function M.uuid()
+  local template = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'
+  return (
+    string.gsub(template, '[xy]', function(c)
+      local v = (c == 'x') and math.random(0, 0xf) or math.random(8, 0xb)
+      return string.format('%x', v)
+    end)
+  )
+end
+
+--- Generate machine id
+---@return string
+function M.machine_id()
+  local length = 65
+  local hex_chars = '0123456789abcdef'
+  local hex = ''
+  for _ = 1, length do
+    local index = math.random(1, #hex_chars)
+    hex = hex .. hex_chars:sub(index, index)
+  end
+  return hex
+end
+
+--- Generate a quick hash
+---@param str string The string to hash
+---@return string
+function M.quick_hash(str)
+  return #str .. str:sub(1, 32) .. str:sub(-32)
+end
+
 return M