Markdown

lib/wiki/accounts/user.ex

@@ -2,6 +2,14 @@ defmodule Wiki.Accounts.User do
   use Ecto.Schema
   import Ecto.Changeset
 
+  @type t() :: %__MODULE__{
+          email: String.t(),
+          password: String.t() | nil,
+          hashed_password: String.t(),
+          confirmed_at: NaiveDateTime.t(),
+          content_encryption_key_salt: String.t()
+        }
+
   @derive {Inspect, except: [:password]}
   schema "users" do
     field :email, :string

lib/wiki/content.ex

@@ -100,7 +100,7 @@ defmodule Wiki.Content do
       %Ecto.Changeset{data: %Page{}}
 
   """
-  def change_page(%Page{} = page, attrs \\ %{}) do
-    Page.changeset(page, attrs)
+  def change_page(%Page{} = page, attrs \\ %{}, options \\ []) do
+    Page.changeset(page, attrs, options)
   end
 end

lib/wiki/content/page.ex

@@ -2,12 +2,24 @@ defmodule Wiki.Content.Page do
   use Ecto.Schema
   import Ecto.Changeset
 
+  @type t() :: %__MODULE__{
+          encrypted_content: binary(),
+          encrypted_content_iv: binary(),
+          encrypted_content_tag: binary(),
+          content: String.t() | nil,
+          content_encryption_key: String.t() | nil,
+          html: String.t() | nil,
+          title: String.t(),
+          user: Wiki.Accounts.User.t()
+        }
+
   schema "pages" do
     field :encrypted_content, :binary
     field :encrypted_content_iv, :binary
     field :encrypted_content_tag, :binary
     field :content, :string, virtual: true
     field :content_encryption_key, :string, virtual: true
+    field :html, :string, virtual: true
     field :title, :string
 
     belongs_to :user, Wiki.Accounts.User
@@ -16,15 +28,21 @@ defmodule Wiki.Content.Page do
   end
 
   @doc false
-  def changeset(page, attrs) do
-    page
-    |> cast(attrs, [
-      :title,
-      :content,
-      :content_encryption_key,
-      :user_id
-    ])
-    |> encrypt_changeset()
+  def changeset(page, attrs, options \\ []) do
+    changeset =
+      page
+      |> cast(attrs, [
+        :title,
+        :content,
+        :content_encryption_key,
+        :user_id
+      ])
+
+    if Keyword.get(options, :encrypt, true) do
+      encrypt_changeset(changeset)
+    else
+      changeset
+    end
     |> validate_required([
       :title,
       :encrypted_content,

lib/wiki/content/renderer.ex

@@ -0,0 +1,47 @@
+defmodule Wiki.Content.Renderer do
+  alias Wiki.Repo
+  alias Wiki.Content.Page
+  alias WikiWeb.Router.Helpers, as: Routes
+  alias WikiWeb.Endpoint
+  import Ecto.Query
+
+  @spec render(Page.t()) :: String.t()
+  def render(page) do
+    page.content
+    |> replace_page_links(page)
+    |> render_markdown()
+  end
+
+  @page_link_regex ~r/\[\[.*?\]\]/
+
+  @spec replace_page_links(content :: String.t(), root_page :: Page.t()) :: String.t()
+  defp replace_page_links(content, root_page) do
+    String.replace(content, @page_link_regex, fn match ->
+      title = String.slice(match, 2..-3)
+      lower_title = String.downcase(title)
+
+      path =
+        from(p in Page)
+        |> where([p], p.user_id == ^root_page.user_id)
+        |> where([p], fragment("lower(?)", p.title) == ^lower_title)
+        |> select([p], p.id)
+        |> Repo.one()
+        |> case do
+          nil ->
+            Routes.page_path(Endpoint, :new, title: title)
+
+          linked_page_id ->
+            Routes.page_path(Endpoint, :show, linked_page_id)
+        end
+
+      # convert link to markdown, because [[title]] -> link transformation happens before markdown parsing
+      "[#{title}](#{path})"
+    end)
+  end
+
+  @spec render_markdown(content :: String.t()) :: String.t()
+  defp render_markdown(content) do
+    {:ok, html, _errors} = Earmark.as_html(content)
+    html
+  end
+end

lib/wiki_web/controllers/page_controller.ex

@@ -34,8 +34,8 @@ defmodule WikiWeb.PageController do
     render(conn, "index.html", pages: pages)
   end
 
-  def new(conn, _params) do
-    changeset = Content.change_page(%Page{})
+  def new(conn, params) do
+    changeset = Content.change_page(%Page{}, params, encrypt: false)
     render(conn, "new.html", changeset: changeset)
   end
 
@@ -59,7 +59,8 @@ defmodule WikiWeb.PageController do
   end
 
   def show(conn, _params) do
-    render(conn, "show.html", page: conn.assigns.page)
+    rendered_content = Content.Renderer.render(conn.assigns.page)
+    render(conn, "show.html", page: conn.assigns.page, content: rendered_content)
   end
 
   def edit(conn, _params) do

lib/wiki_web/templates/page/show.html.eex

@@ -9,7 +9,7 @@
 
   <li>
     <strong>Content:</strong>
-    <%= @page.content %>
+    <%= raw(@content) %>
   </li>
 
 </ul>

priv/repo/migrations/20200726020001_create_pages.exs

@@ -13,5 +13,6 @@ defmodule Wiki.Repo.Migrations.CreatePages do
     end
 
     create index(:pages, [:user_id])
+    create index(:pages, ["(lower(title))"], name: :pages_lowercase_title_index)
   end
 end