From d2cdf0a2cb3e1520598bb7c92da33d834699cde6 Mon Sep 17 00:00:00 2001
From: gpopides <46693847+gpopides@users.noreply.github.com>
Date: Sun, 10 Oct 2021 12:29:45 +0200
Subject: [PATCH] Display creation date of a session in home (#593)
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* add created_at to Session struct

* test + doc enhcncement

* change format creation date function name

* use helper function to format created_at

* use mix format

* apply review suggested  changes and 2 more tests

* Store creation time in session state and sort by date by default

Co-authored-by: Jonatan Kłosko <jonatanklosko@gmail.com>
---
 lib/livebook/session.ex               | 10 +++++++---
 lib/livebook_web/live/home_live.ex    | 10 +++++++++-
 lib/livebook_web/live/session_live.ex |  3 ++-
 test/livebook/session_test.exs        | 12 ++++++++++++
 4 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/lib/livebook/session.ex b/lib/livebook/session.ex
index 264a53bfa..0e5e67835 100644
--- a/lib/livebook/session.ex
+++ b/lib/livebook/session.ex
@@ -46,7 +46,7 @@ defmodule Livebook.Session do
   # The struct holds the basic session information that we track
   # and pass around. The notebook and evaluation state is kept
   # within the process state.
-  defstruct [:id, :pid, :origin, :notebook_name, :file, :images_dir]
+  defstruct [:id, :pid, :origin, :notebook_name, :file, :images_dir, :created_at]
 
   use GenServer, restart: :temporary
 
@@ -61,12 +61,14 @@ defmodule Livebook.Session do
           origin: {:file, FileSystem.File.t()} | {:url, String.t()} | nil,
           notebook_name: String.t(),
           file: FileSystem.File.t() | nil,
-          images_dir: FileSystem.File.t()
+          images_dir: FileSystem.File.t(),
+          created_at: DateTime.t()
         }
 
   @type state :: %{
           session_id: id(),
           data: Data.t(),
+          created_at: DateTime.t(),
           runtime_monitor_ref: reference() | nil,
           autosave_timer_ref: reference() | nil,
           save_task_pid: pid() | nil
@@ -378,6 +380,7 @@ defmodule Livebook.Session do
       state = %{
         session_id: id,
         data: data,
+        created_at: DateTime.utc_now(),
         runtime_monitor_ref: nil,
         autosave_timer_ref: nil,
         save_task_pid: nil
@@ -691,7 +694,8 @@ defmodule Livebook.Session do
       origin: state.data.origin,
       notebook_name: state.data.notebook.name,
       file: state.data.file,
-      images_dir: images_dir_from_state(state)
+      images_dir: images_dir_from_state(state),
+      created_at: state.created_at
     }
   end
 
diff --git a/lib/livebook_web/live/home_live.ex b/lib/livebook_web/live/home_live.ex
index da6057ae0..8da48ab7b 100644
--- a/lib/livebook_web/live/home_live.ex
+++ b/lib/livebook_web/live/home_live.ex
@@ -180,6 +180,9 @@ defmodule LivebookWeb.HomeLive do
             <div class="text-gray-600 text-sm">
               <%= if session.file, do: session.file.path, else: "No file" %>
             </div>
+            <div class="text-gray-600 text-sm">
+              Created <%= format_creation_date(session.created_at) %>
+            </div>
           </div>
           <div class="relative" id={"session-#{session.id}-menu"} phx-hook="Menu" data-element="menu">
             <button class="icon-button" data-toggle>
@@ -344,7 +347,7 @@ defmodule LivebookWeb.HomeLive do
   def handle_info(_message, socket), do: {:noreply, socket}
 
   defp sort_sessions(sessions) do
-    Enum.sort_by(sessions, & &1.notebook_name)
+    Enum.sort_by(sessions, & &1.created_at, {:desc, DateTime})
   end
 
   defp files(sessions) do
@@ -383,4 +386,9 @@ defmodule LivebookWeb.HomeLive do
     session = Enum.find(sessions, &(&1.file == file))
     session.id
   end
+
+  def format_creation_date(created_at) do
+    time_words = created_at |> DateTime.to_naive() |> Livebook.Utils.Time.time_ago_in_words()
+    time_words <> " ago"
+  end
 end
diff --git a/lib/livebook_web/live/session_live.ex b/lib/livebook_web/live/session_live.ex
index c134e0643..097c84ba7 100644
--- a/lib/livebook_web/live/session_live.ex
+++ b/lib/livebook_web/live/session_live.ex
@@ -1149,7 +1149,8 @@ defmodule LivebookWeb.SessionLive do
         |> Enum.map(fn {client_pid, user_id} -> {client_pid, data.users_map[user_id]} end)
         |> Enum.sort_by(fn {_client_pid, user} -> user.name end),
       section_views: section_views(data.notebook.sections, data),
-      bin_entries: data.bin_entries
+      bin_entries: data.bin_entries,
+      created_at: DateTime.now!("Etc/UTC")
     }
   end
 
diff --git a/test/livebook/session_test.exs b/test/livebook/session_test.exs
index 0a2a94ced..1a9fab7aa 100644
--- a/test/livebook/session_test.exs
+++ b/test/livebook/session_test.exs
@@ -614,6 +614,18 @@ defmodule Livebook.SessionTest do
     end
   end
 
+  test "session has created_at attribute when it is created", %{session: session} do
+    assert Map.has_key?(session, :created_at)
+  end
+
+  test "session created_at attribute is a date time", %{session: session} do
+    assert %DateTime{} = session.created_at
+  end
+
+  test "session created_at is before now", %{session: session} do
+    assert session.created_at < DateTime.utc_now()
+  end
+
   defp start_session(opts \\ []) do
     session_id = Utils.random_id()
     {:ok, pid} = Session.start_link(Keyword.merge([id: session_id], opts))