Set ada configuration file dynamically on startup

lua/lspconfiguration.lua

@@ -60,10 +60,34 @@ require("lspconfig").verible.setup({
 	cmd = { "verible-verilog-ls", "--rules_config_search" },
 })
 
+-- @name file_exists
+-- @param (name
+-- @short Check if a file does exists (i. e. an ada project file)
+local function file_exists(name)
+	local f = io.open(name, "r")
+	return f ~= nil and io.close(f)
+end
+
 -- @name get_config_file
 -- @param
 -- @short Get the configuration file.
-local function get_config_file() end
+local function get_config_file()
+	local filename = vim.api.nvim_buf_get_name(0)
+	local basedirectory = filename:gsub("/[^%/]-$", "")
+	local currentdirectory = filename:match("[^%/]-$")
+
+	if file_exists(basedirectory .. currentdirectory .. ".gpr") then
+		return basedirectory .. currentdirectory .. ".gpr"
+	else
+		basedirectory = basedirectory:gsub("/[^%/]-$", "")
+		currentdirectory = filename:match("[^%/]-$")
+		if file_exists(basedirectory .. currentdirectory .. ".gpr") then
+			return basedirectory .. currentdirectory .. ".gpr"
+		else
+			return "default.gpr"
+		end
+	end
+end
 
 require("lspconfig").als.setup({
 	settings = {