static page versions

lib/philomena/static_pages/version.ex

@@ -0,0 +1,27 @@
+defmodule Philomena.StaticPages.Version do
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  alias Philomena.StaticPages.StaticPage
+  alias Philomena.Users.User
+
+  schema "static_page_versions" do
+    belongs_to :static_page, StaticPage
+    belongs_to :user, User
+
+    field :title, :string
+    field :slug, :string
+    field :body, :string
+
+    field :difference, :any, virtual: true
+
+    timestamps(inserted_at: :created_at)
+  end
+
+  @doc false
+  def changeset(version, attrs) do
+    version
+    |> cast(attrs, [])
+    |> validate_required([])
+  end
+end

lib/philomena_web/controllers/page/history_controller.ex

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+defmodule PhilomenaWeb.Page.HistoryController do
+  use PhilomenaWeb, :controller
+
+  alias Philomena.StaticPages.StaticPage
+  alias Philomena.StaticPages.Version
+  alias Philomena.Repo
+  import Ecto.Query
+
+  plug :load_resource, model: StaticPage, id_field: "slug", persisted: true
+
+  def index(conn, _params) do
+    page = conn.assigns.static_page
+
+    versions =
+      Version
+      |> where(static_page_id: ^page.id)
+      |> preload(:user)
+      |> order_by(desc: :created_at)
+      |> Repo.all()
+      |> generate_differences(page.body)
+
+    render(conn, "index.html", layout_class: "layout--wide", versions: versions)
+  end
+
+  defp generate_differences(pages, current_body) do
+    Enum.map_reduce(pages, current_body, fn page, previous_body ->
+      difference = List.myers_difference(split(previous_body), split(page.body))
+
+      %{page | difference: difference}
+    end)
+  end
+
+  defp split(nil), do: ""
+  defp split(body), do: String.split(body, "\n")
+end

lib/philomena_web/templates/page/history/index.html.slime

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+h1
+  ' Revision history for
+  = link @static_page.title, to: Routes.page_path(@conn, :show, @static_page)
+
+table.table
+  thead
+    tr
+      th User
+      th Date
+      th Body
+
+  tbody
+    = for version <- @versions do
+      tr
+        td = link version.user.name, to: Routes.profile_path(@conn, :show,  version.user)
+        td = pretty_time(version.created_at)
+        td.static-page__diff
+          = for diff <- version.difference do
+            = case diff do
+              - {:eq, lines} ->
+                = for line <- lines do
+                  = line
+                  = "\n"
+
+              - {:ins, lines} ->
+                ins.differ
+                  = for line <- lines do
+                    = line
+                    = "\n"
+
+              - {:del, lines} ->
+                del.differ
+                  = for line <- lines do
+                    = line
+                    = "\n"

lib/philomena_web/views/page/history_view.ex

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+defmodule PhilomenaWeb.Page.HistoryView do
+  use PhilomenaWeb, :view
+end