Feature: mark arguments of callback traces

lib/live_debugger/structs/trace.ex

@@ -94,6 +94,50 @@ defmodule LiveDebugger.Structs.Trace do
     "#{trace.function}/#{trace.arity}"
   end
 
+  @spec arg_name(t(), non_neg_integer()) :: String.t()
+  def arg_name(trace, arg_index)
+
+  # Callbacks common for LiveView and LiveComponent
+  def arg_name(%{function: :handle_async}, 0), do: "name"
+  def arg_name(%{function: :handle_async}, 1), do: "async_fun_result"
+  def arg_name(%{function: :handle_async}, 2), do: "socket"
+
+  def arg_name(%{function: :handle_call}, 0), do: "message"
+  def arg_name(%{function: :handle_call}, 1), do: "from"
+  def arg_name(%{function: :handle_call}, 2), do: "socket"
+
+  def arg_name(%{function: :handle_cast}, 0), do: "message"
+  def arg_name(%{function: :handle_cast}, 1), do: "socket"
+
+  def arg_name(%{function: :handle_event}, 0), do: "event"
+  def arg_name(%{function: :handle_event}, 1), do: "unsigned_params"
+  def arg_name(%{function: :handle_event}, 2), do: "socket"
+
+  def arg_name(%{function: :handle_info}, 0), do: "message"
+  def arg_name(%{function: :handle_info}, 1), do: "socket"
+
+  def arg_name(%{function: :handle_params}, 0), do: "unsigned_params"
+  def arg_name(%{function: :handle_params}, 1), do: "uri"
+  def arg_name(%{function: :handle_params}, 2), do: "socket"
+
+  def arg_name(%{function: :render}, 0), do: "assigns"
+
+  def arg_name(%{function: :terminate}, 0), do: "reason"
+  def arg_name(%{function: :terminate}, 1), do: "socket"
+
+  # LiveView specific
+  def arg_name(%{function: :mount, arity: 3}, 0), do: "params"
+  def arg_name(%{function: :mount, arity: 3}, 1), do: "session"
+  def arg_name(%{function: :mount, arity: 3}, 2), do: "socket"
+
+  # LiveComponent specific
+  def arg_name(%{function: :mount, arity: 1}, 0), do: "socket"
+
+  def arg_name(%{function: :update}, 0), do: "assigns"
+  def arg_name(%{function: :update}, 1), do: "socket"
+
+  def arg_name(%{function: :update_many}, 0), do: "list"
+
   defp get_transport_pid_from_args(args) do
     args
     |> Enum.map(&maybe_get_transport_pid(&1))

lib/live_debugger_web/components/traces.ex

@@ -100,6 +100,8 @@ defmodule LiveDebuggerWeb.Components.Traces do
         <div class="flex flex-col gap-4 overflow-x-auto max-w-full max-h-[30vh] overflow-y-auto p-4">
           <%= if @render_body? do %>
             <%= for {args, index} <- Enum.with_index(@trace.args) do %>
+              <div :if={index > 0} class="border-t border-default-border"></div>
+              <p class="font-semibold">Arg <%= index %> (<%= Trace.arg_name(@trace, index) %>)</p>
               <ElixirDisplay.term
                 id={@id <> "-#{index}"}
                 node={TermParser.term_to_display_tree(args)}
@@ -174,6 +176,10 @@ defmodule LiveDebuggerWeb.Components.Traces do
     <.fullscreen id={@id} title={@callback_name}>
       <div class="w-full flex flex-col gap-4 items-start justify-center">
         <%= for {args, index} <- Enum.with_index(@trace_args) do %>
+          <div :if={index > 0} class="border-t border-default-border w-full"></div>
+          <p class="font-semibold shrink-0">
+            Arg <%= index %> (<%= Trace.arg_name(@trace, index) %>)
+          </p>
           <ElixirDisplay.term
             id={@id <> "-#{index}-fullscreen"}
             node={TermParser.term_to_display_tree(args)}

test/structs/trace_test.exs

@@ -176,6 +176,80 @@ defmodule LiveDebugger.Structs.TraceTest do
     end
   end
 
+  describe "arg_name/2" do
+    test "returns correct args for handle_async/3" do
+      trace = %{function: :handle_async, arity: 3}
+
+      assert args_list(trace) == ["name", "async_fun_result", "socket"]
+    end
+
+    test "returns correct args for handle_call/3" do
+      trace = %{function: :handle_call, arity: 3}
+
+      assert args_list(trace) == ["message", "from", "socket"]
+    end
+
+    test "returns correct args for handle_cast/2" do
+      trace = %{function: :handle_cast, arity: 2}
+
+      assert args_list(trace) == ["message", "socket"]
+    end
+
+    test "returns correct args for handle_event/3" do
+      trace = %{function: :handle_event, arity: 3}
+
+      assert args_list(trace) == ["event", "unsigned_params", "socket"]
+    end
+
+    test "returns correct args for handle_info/2" do
+      trace = %{function: :handle_info, arity: 2}
+
+      assert args_list(trace) == ["message", "socket"]
+    end
+
+    test "returns correct args for handle_params/3" do
+      trace = %{function: :handle_params, arity: 3}
+
+      assert args_list(trace) == ["unsigned_params", "uri", "socket"]
+    end
+
+    test "returns correct args for mount/3" do
+      trace = %{function: :mount, arity: 3}
+
+      assert args_list(trace) == ["params", "session", "socket"]
+    end
+
+    test "returns correct args for mount/1" do
+      trace = %{function: :mount, arity: 1}
+
+      assert args_list(trace) == ["socket"]
+    end
+
+    test "returns correct args for render/1" do
+      trace = %{function: :render, arity: 1}
+
+      assert args_list(trace) == ["assigns"]
+    end
+
+    test "returns correct args for terminate/2" do
+      trace = %{function: :terminate, arity: 2}
+
+      assert args_list(trace) == ["reason", "socket"]
+    end
+
+    test "returns correct args for update/2" do
+      trace = %{function: :update, arity: 2}
+
+      assert args_list(trace) == ["assigns", "socket"]
+    end
+
+    test "returns correct args for update_many/1" do
+      trace = %{function: :update_many, arity: 1}
+
+      assert args_list(trace) == ["list"]
+    end
+  end
+
   test "callback_name/1 returns callback with arity" do
     trace_map = %{
       id: 1,
@@ -208,4 +282,10 @@ defmodule LiveDebugger.Structs.TraceTest do
 
     Trace.new(id, module, function, args, pid, timestamp, opts)
   end
+
+  defp args_list(trace) do
+    for index <- 0..(trace.arity - 1) do
+      Trace.arg_name(trace, index)
+    end
+  end
 end