Track Views on Posts (firestormforum#86)

lib/firestorm_web/forums/forums.ex

@@ -5,7 +5,14 @@ defmodule FirestormWeb.Forums do
 
   import Ecto.{Query, Changeset}, warn: false
   alias FirestormWeb.{Repo, Notifications}
-  alias FirestormWeb.Forums.{User, Category, Thread, Post, Watch}
+  alias FirestormWeb.Forums.{
+    User,
+    Category,
+    Thread,
+    Post,
+    Watch,
+    View
+  }
 
   @doc """
   Returns the list of users.
@@ -264,10 +271,9 @@ defmodule FirestormWeb.Forums do
       posts_count = length(thread.posts)
       completely_read? =
         if user do
-          # TODO: Return true if the user has completely read this thread -
-          # i.e., if each post has a corresponding view in the database for the
-          # user
-          false
+          # FIXME: This is insanely inefficient, lol?
+          thread.posts
+          |> Enum.all?(fn(post) -> post |> viewed_by?(user) end)
         else
           false
         end
@@ -542,4 +548,52 @@ defmodule FirestormWeb.Forums do
     |> cast(attrs, [:assoc_id, :user_id])
     |> validate_required([:assoc_id, :user_id])
   end
+
+  @doc """
+  Indicate a user viewed a post:
+
+      iex> %User{} |> view(%Post{})
+      {:ok, %Post{}}
+
+  """
+  def view(%User{} = user, %Post{} = post) do
+    post
+    |> Ecto.build_assoc(:views, %{user_id: user.id})
+    |> view_changeset(%{})
+    |> Repo.insert()
+  end
+
+  @doc """
+  Determine if a user has viewed a given viewable (Post, etc):
+
+      iex> %Post{} |> viewed_by?(%User{})
+      false
+
+  """
+  def viewed_by?(viewable, user = %User{}) do
+    view_count(viewable, user) > 0
+  end
+
+  def view_count(viewable) do
+    viewable
+    |> views()
+    |> Repo.aggregate(:count, :id)
+  end
+  defp view_count(viewable, user = %User{}) do
+    viewable
+    |> views()
+    |> where([f], f.user_id == ^user.id)
+    |> Repo.aggregate(:count, :id)
+  end
+
+  defp views(viewable) do
+    viewable
+    |> Ecto.assoc(:views)
+  end
+
+  defp view_changeset(%View{} = view, attrs) do
+    view
+    |> cast(attrs, [:assoc_id, :user_id])
+    |> validate_required([:assoc_id, :user_id])
+  end
 end

lib/firestorm_web/forums/post.ex

@@ -1,11 +1,13 @@
 defmodule FirestormWeb.Forums.Post do
   use Ecto.Schema
-  alias FirestormWeb.Forums.{User, Thread}
+  alias FirestormWeb.Forums.{User, Thread, View}
 
   schema "forums_posts" do
     field :body, :string
     belongs_to :thread, Thread
     belongs_to :user, User
+    has_many :views, {"forums_posts_views", View}, foreign_key: :assoc_id
+    many_to_many :viewers, User, join_through: "forums_posts_views", join_keys: [assoc_id: :id, user_id: :id]
 
     timestamps()
   end

lib/firestorm_web/forums/view.ex

@@ -0,0 +1,17 @@
+defmodule FirestormWeb.Forums.View do
+  @moduledoc """
+  A `View` is a polymorphic representation that a user viewed a thing in our
+  system at a specified time.
+  """
+
+  use Ecto.Schema
+
+  schema "abstract table: views" do
+    # This will be used by associations on each "concrete" table
+    field :assoc_id, :integer
+    field :user_id, :integer
+
+    timestamps()
+  end
+end
+

lib/firestorm_web/web/controllers/category_controller.ex

@@ -32,7 +32,7 @@ defmodule FirestormWeb.Web.CategoryController do
 
     threads =
       category
-      |> Forums.list_threads()
+      |> Forums.list_threads(current_user(conn))
 
     render(conn, "show.html", category: category, threads: threads)
   end

lib/firestorm_web/web/controllers/thread_controller.ex

@@ -49,6 +49,15 @@ defmodule FirestormWeb.Web.ThreadController do
         false
       end
 
+    # Record a view for each post in this thread
+    if current_user(conn) do
+      for post <- thread.posts do
+        conn
+        |> current_user()
+        |> Forums.view(post)
+      end
+    end
+
     render(conn, "show.html", thread: thread, category: category, first_post: first_post, posts: posts, watched: watched)
   end
 

priv/repo/migrations/20170629061022_add_forums_posts_views.exs

@@ -0,0 +1,11 @@
+defmodule FirestormWeb.Repo.Migrations.AddForumsPostsViews do
+  use Ecto.Migration
+
+  def change do
+    create table(:forums_posts_views) do
+      add :assoc_id, references(:forums_posts)
+      add :user_id, references(:forums_users)
+      timestamps()
+    end
+  end
+end

test/feature/categories_test.exs

@@ -35,11 +35,21 @@ defmodule FirestormWeb.Feature.CategoriesTest do
     {:ok, _post} = Forums.create_post(otp_is_cool, user, %{body: "Yup"})
 
     session
+    |> log_in_as(user)
     |> visit(category_path(Endpoint, :show, elixir.id))
     |> all(threads(1))
     |> List.first()
     |> assert_has(thread_title("OTP is cool"))
     |> assert_has(thread_posts_count(2, completely_read?: false))
+
+    session
+    |> log_in_as(user)
+    |> visit(category_thread_path(Endpoint, :show, elixir.id, otp_is_cool.id))
+    |> visit(category_path(Endpoint, :show, elixir.id))
+    |> all(threads(1))
+    |> List.first()
+    |> assert_has(thread_title("OTP is cool"))
+    |> assert_has(thread_posts_count(2, completely_read?: true))
   end
 
   def create_categories(titles) do

test/feature/threads_test.exs

@@ -77,10 +77,4 @@ defmodule FirestormWeb.Feature.ThreadsTest do
       end
     {:ok, categories}
   end
-
-  defp log_in_as(session, user) do
-    session
-    |> visit("/")
-    |> Browser.set_cookie("current_user", user.id)
-  end
 end

test/forums_test.exs

@@ -239,6 +239,21 @@ defmodule FirestormWeb.ForumsTest do
     end
   end
 
+  describe "viewing a post" do
+    setup [:create_user, :create_category, :create_thread]
+
+    test "viewing a post", %{thread: thread, user: user} do
+      thread =
+        thread
+        |> Repo.preload(:posts)
+
+      [first_post] = thread.posts
+
+      {:ok, _view} = user |> Forums.view(first_post)
+      assert first_post |> Forums.viewed_by?(user)
+    end
+  end
+
   def create_category(_) do
     category = fixture(:category, @create_category_attrs)
     {:ok, category: category}

test/support/feature_case.ex

@@ -1,6 +1,16 @@
 defmodule FirestormWeb.Web.FeatureCase do
   use ExUnit.CaseTemplate
 
+  defmodule Helpers do
+    use Wallaby.DSL
+
+    def log_in_as(session, user) do
+      session
+      |> visit("/")
+      |> Browser.set_cookie("current_user", user.id)
+    end
+  end
+
   using do
     quote do
       use Wallaby.DSL
@@ -11,6 +21,7 @@ defmodule FirestormWeb.Web.FeatureCase do
       import Ecto.Query
 
       import FirestormWeb.Web.Router.Helpers
+      import FirestormWeb.Web.FeatureCase.Helpers
 
       alias FirestormWeb.Forums.{
         User,