feat: change contest file naming

* Update filesystem.lua 

Add helper function inside Filesystem:save to convert the filename from PascalCase to Capitalised_Snake_Case

* Update filesystem.lua

Fix to_snake_case function to handle consecutive capital letters

* Update filesystem.lua

Fix `to_snake_case` function to handle spaces and numbers

* Update filesystem.lua

* Fix the formatting using stylua lua --config-path=./.stylua.toml

Author: nathy-cpu

lua/assistant/core/filesystem.lua

@@ -83,18 +83,32 @@ end
 
 ---@param chunk string
 function FileSystem:save(chunk)
+  -- Helper function to convert to snake_case
+  local function to_snake_case(str)
+    -- Convert spaces to underscores and handle camel-case and consecutive capital letters
+    local result = str:gsub("(%s)", "_"):gsub("(%u%l)", "_%1"):gsub("(%l)(%u)", "%1_%2"):gsub("^_", "")
+    return result
+      :gsub("^%s*(.-)%s*$", "%1")
+      :gsub("%s+", "_")
+      :gsub("(%l)(%u)", "%1_%2")
+      :gsub("(%l)(%d)", "%1_%2")
+      :gsub("(%d)(%l)", "%1_%2")
+      :gsub("(%d)(%u)", "%1_%2")
+  end
+
   self.__init__()
   chunk = string.match(chunk, "^.+\r\n(.+)$")
   local data = vim.json.decode(chunk)
 
   if data.languages.java.taskClass then
     vim.schedule(function()
       local filtered_data = self.filter(chunk)
-      local filepath = string.format("%s/.ast/%s.json", vim.fn.expand("%:p:h"), data.languages.java.taskClass)
+      local task_class_snake = to_snake_case(data.languages.java.taskClass) -- Convert to snake_case
+      local filepath = string.format("%s/.ast/%s.json", vim.fn.expand("%:p:h"), task_class_snake)
 
       if filtered_data then
         self:write(filepath, vim.json.encode(filtered_data))
-        self.create(data.languages.java.taskClass)
+        self.create(task_class_snake)
       end
     end)
   end