Add items sync endpoint

lib/frenzy_web/controllers/fervor/items_controller.ex

@@ -1,12 +1,12 @@
 defmodule FrenzyWeb.Fervor.ItemsController do
   use FrenzyWeb, :controller
-  alias Frenzy.{Repo, Item}
+  alias Frenzy.{Repo, Item, Group, Feed}
   import Ecto.Query
   alias FrenzyWeb.Fervor.Paginator
 
   plug :get_specific_item
 
-  def get_specific_item(%Plug.Conn{path_params: %{"id" => id}} = conn, _opts) do
+  def get_specific_item(%Plug.Conn{path_params: %{"id" => id}} = conn, _opts) when id != "sync" do
     user = conn.assigns[:user] |> Repo.preload(:feeds)
 
     item = Repo.get(Item, id)
@@ -119,4 +119,42 @@ defmodule FrenzyWeb.Fervor.ItemsController do
   def unread_multiple(conn, params) do
     mark_multiple_items(conn, params, %{read: false})
   end
+
+  def sync(conn, params) do
+    sync_timestamp = Timex.now()
+
+    feed_ids =
+      Group
+      |> where([g], g.user_id == ^conn.assigns.user.id)
+      |> join(:inner, [g], f in Feed, on: f.group_id == g.id)
+      |> select([g, f], f.id)
+      |> Repo.all()
+
+    last_sync =
+      Map.get(params, "last_sync")
+      |> case do
+        s when is_binary(s) -> Timex.parse!(s, "{ISO:Extended:Z}")
+        _ -> nil
+      end
+
+    {deleted_ids, upserted} =
+      case last_sync do
+        nil ->
+          items = Repo.all(from i in Item, where: not i.tombstone and i.feed_id in ^feed_ids)
+          {[], items}
+
+        _ ->
+          all_items =
+            Repo.all(from i in Item, where: i.feed_id in ^feed_ids and i.updated_at >= ^last_sync)
+
+          {tombstones, rest} = Enum.split_with(all_items, & &1.tombstone)
+          {Enum.map(tombstones, & &1.id), rest}
+      end
+
+    json(conn, %{
+      sync_timestamp: Timex.format!(sync_timestamp, "{ISO:Extended:Z}"),
+      delete: Enum.map(deleted_ids, &to_string/1),
+      upsert: Enum.map(upserted, &Item.to_fervor/1)
+    })
+  end
 end

lib/frenzy_web/router.ex

@@ -99,6 +99,7 @@ defmodule FrenzyWeb.Router do
     post "/api/v1/feeds/:id/delete", FeedsController, :delete
 
     get "/api/v1/items", ItemsController, :items_list
+    get "/api/v1/items/sync", ItemsController, :sync
     get "/api/v1/items/:id", ItemsController, :specific_item
     post "/api/v1/items/:id/read", ItemsController, :read_specific_item
     post "/api/v1/items/:id/unread", ItemsController, :unread_specific_item