Add Elixir source export (#476)

lib/livebook/notebook/export/elixir.ex

@@ -0,0 +1,80 @@
+defmodule Livebook.Notebook.Export.Elixir do
+  alias Livebook.Notebook
+  alias Livebook.Notebook.Cell
+
+  @doc """
+  Converts the given notebook into a Elixir source code.
+  """
+  @spec notebook_to_elixir(Notebook.t()) :: String.t()
+  def notebook_to_elixir(notebook) do
+    iodata = render_notebook(notebook)
+    # Add trailing newline
+    IO.iodata_to_binary([iodata, "\n"])
+  end
+
+  defp render_notebook(notebook) do
+    name = ["# Title: ", notebook.name]
+    sections = Enum.map(notebook.sections, &render_section(&1, notebook))
+
+    [name | sections]
+    |> Enum.intersperse("\n\n")
+  end
+
+  defp render_section(section, notebook) do
+    name = ["# ── ", section.name, " ──"]
+
+    name =
+      if section.parent_id do
+        {:ok, parent} = Notebook.fetch_section(notebook, section.parent_id)
+        [name, " (⎇ from ", parent.name, ")"]
+      else
+        name
+      end
+
+    cells =
+      section.cells
+      |> Enum.map(&render_cell(&1, section))
+      |> Enum.reject(&(&1 == []))
+
+    [name | cells]
+    |> Enum.intersperse("\n\n")
+  end
+
+  defp render_cell(%Cell.Markdown{} = cell, _section) do
+    cell.source
+    |> Livebook.LiveMarkdown.MarkdownHelpers.reformat()
+    |> String.split("\n")
+    |> Enum.map_intersperse("\n", &comment_out/1)
+  end
+
+  defp render_cell(%Cell.Elixir{} = cell, section) do
+    code = get_elixir_cell_code(cell)
+
+    if section.parent_id do
+      code
+      |> IO.iodata_to_binary()
+      |> String.split("\n")
+      |> Enum.map_intersperse("\n", &comment_out/1)
+    else
+      code
+    end
+  end
+
+  defp render_cell(_cell, _section), do: []
+
+  defp comment_out(""), do: ""
+  defp comment_out(line), do: ["# ", line]
+
+  defp get_elixir_cell_code(%{source: source, metadata: %{"disable_formatting" => true}}),
+    do: source
+
+  defp get_elixir_cell_code(%{source: source}), do: format_code(source)
+
+  defp format_code(code) do
+    try do
+      Code.format_string!(code)
+    rescue
+      _ -> code
+    end
+  end
+end

lib/livebook_web/controllers/session_controller.ex

@@ -14,20 +14,38 @@ defmodule LivebookWeb.SessionController do
     end
   end
 
-  def download_source(conn, %{"id" => id}) do
+  def download_source(conn, %{"id" => id, "format" => format}) do
     if SessionSupervisor.session_exists?(id) do
       notebook = Session.get_notebook(id)
-      source = Livebook.LiveMarkdown.Export.notebook_to_markdown(notebook)
 
-      send_download(conn, {:binary, source},
+      send_notebook_source(conn, notebook, format)
-        filename: "notebook.livemd",
-        content_type: "text/plain"
-      )
     else
       send_resp(conn, 404, "Not found")
     end
   end
 
+  defp send_notebook_source(conn, notebook, "livemd") do
+    source = Livebook.LiveMarkdown.Export.notebook_to_markdown(notebook)
+
+    send_download(conn, {:binary, source},
+      filename: "notebook.livemd",
+      content_type: "text/plain"
+    )
+  end
+
+  defp send_notebook_source(conn, notebook, "exs") do
+    source = Livebook.Notebook.Export.Elixir.notebook_to_elixir(notebook)
+
+    send_download(conn, {:binary, source},
+      filename: "notebook.exs",
+      content_type: "text/plain"
+    )
+  end
+
+  defp send_notebook_source(conn, _notebook, _format) do
+    send_resp(conn, 400, "Invalid format, supported formats: livemd, exs")
+  end
+
   defp serve_static(conn, path) do
     case put_cache_header(conn, path) do
       {:stale, conn} ->

lib/livebook_web/live/session_live.ex

@@ -202,7 +202,7 @@ defmodule LivebookWeb.SessionLive do
                   <.remix_icon icon="dashboard-2-line" />
                   <span class="font-medium">See on Dashboard</span>
                 </a>
-                <%= live_patch to: Routes.session_path(@socket, :export, @session_id),
+                <%= live_patch to: Routes.session_path(@socket, :export, @session_id, "livemd"),
                       class: "menu__item text-gray-500" do %>
                   <.remix_icon icon="download-2-line" />
                   <span class="font-medium">Export</span>
@@ -323,6 +323,7 @@ defmodule LivebookWeb.SessionLive do
             id: "export",
             modal_class: "w-full max-w-4xl",
             session_id: @session_id,
+            tab: @tab,
             return_to: Routes.session_path(@socket, :page, @session_id) %>
     <% end %>
     """
@@ -361,6 +362,10 @@ defmodule LivebookWeb.SessionLive do
     {:noreply, handle_relative_path(socket, path)}
   end
 
+  def handle_params(%{"tab" => tab}, _url, socket) do
+    {:noreply, assign(socket, tab: tab)}
+  end
+
   def handle_params(_params, _url, socket) do
     {:noreply, socket}
   end

lib/livebook_web/live/session_live/export_component.ex

@@ -8,14 +8,13 @@ defmodule LivebookWeb.SessionLive.ExportComponent do
     socket = assign(socket, assigns)
 
     socket =
-      if socket.assigns[:source] do
+      if socket.assigns[:notebook] do
         socket
       else
         # Note: we need to load the notebook, because the local data
         # has cell contents stripped out
         notebook = Session.get_notebook(socket.assigns.session_id)
-        source = Livebook.LiveMarkdown.Export.notebook_to_markdown(notebook)
+        assign(socket, :notebook, notebook)
-        assign(socket, :source, source)
       end
 
     {:ok, socket}
@@ -32,38 +31,30 @@ defmodule LivebookWeb.SessionLive.ExportComponent do
         <p class="text-gray-700">
           Here you can preview and directly export the notebook source.
         </p>
-        <div class="flex flex-col space-y-1">
+        <div class="tabs">
-          <div class="flex justify-between items-center">
+          <%= live_patch to: Routes.session_path(@socket, :export, @session_id, "livemd"),
-            <span class="text-sm text-gray-700 font-semibold">
+                class: "tab #{if(@tab == "livemd", do: "active")}" do %>
-              .livemd
+            <span class="font-medium">
+              Live Markdown
             </span>
-            <div class="flex justify-end space-x-2">
+          <% end %>
-              <span class="tooltip left" aria-label="Copy source">
+          <%= live_patch to: Routes.session_path(@socket, :export, @session_id, "exs"),
-                <button class="icon-button"
+                class: "tab #{if(@tab == "exs", do: "active")}" do %>
-                  id="export-notebook-source-clipcopy"
+            <span class="font-medium">
-                  phx-hook="ClipCopy"
+              Elixir Script
-                  data-target-id="export-notebook-source">
+            </span>
-                  <.remix_icon icon="clipboard-line" class="text-lg" />
+          <% end %>
-                </button>
-              </span>
-              <span class="tooltip left" aria-label="Download source">
-                <a class="icon-button"
-                  href={Routes.session_path(@socket, :download_source, @session_id)}>
-                  <.remix_icon icon="download-2-line" class="text-lg" />
-                </a>
-              </span>
-            </div>
-          </div>
-          <div class="markdown">
-            <pre><code
-              class="tiny-scrollbar"
-              id="export-notebook-source"
-              phx-hook="Highlight"
-              data-language="markdown"><%= @source %></code></pre>
-          </div>
         </div>
+        <div>
+        <%= live_component component_for_tab(@tab),
+              session_id: @session_id,
+              notebook: @notebook %>
+      </div>
       </div>
     </div>
     """
   end
+
+  defp component_for_tab("livemd"), do: LivebookWeb.SessionLive.ExportLiveMarkdownComponent
+  defp component_for_tab("exs"), do: LivebookWeb.SessionLive.ExportElixirComponent
 end

lib/livebook_web/live/session_live/export_elixir_component.ex

@@ -0,0 +1,61 @@
+defmodule LivebookWeb.SessionLive.ExportElixirComponent do
+  use LivebookWeb, :live_component
+
+  @impl true
+  def update(assigns, socket) do
+    socket = assign(socket, assigns)
+
+    source = Livebook.Notebook.Export.Elixir.notebook_to_elixir(socket.assigns.notebook)
+    socket = assign(socket, :source, source)
+
+    {:ok, socket}
+  end
+
+  @impl true
+  def render(assigns) do
+    ~H"""
+    <div class="flex flex-col space-y-3">
+      <p class="text-gray-700">
+        <span class="font-semibold">Note:</span>
+        the script export is available as a convenience, rather than
+        an exact reproduction of the notebook and in some cases it may
+        not even compile. For example, if you define a macro in one cell
+        and import it in another cell, it works fine in Livebook,
+        because each cell is compiled separately. However, when running
+        the script it gets compiled as a whole and consequently doing so
+        doesn't work. Additionally, branching sections are commented out.
+      </p>
+      <div class="flex flex-col space-y-1">
+        <div class="flex justify-between items-center">
+          <span class="text-sm text-gray-700 font-semibold">
+            .exs
+          </span>
+          <div class="flex justify-end space-x-2">
+            <span class="tooltip left" aria-label="Copy source">
+              <button class="icon-button"
+                id="export-notebook-source-clipcopy"
+                phx-hook="ClipCopy"
+                data-target-id="export-notebook-source">
+                <.remix_icon icon="clipboard-line" class="text-lg" />
+              </button>
+            </span>
+            <span class="tooltip left" aria-label="Download source">
+              <a class="icon-button"
+                href={Routes.session_path(@socket, :download_source, @session_id, "exs")}>
+                <.remix_icon icon="download-2-line" class="text-lg" />
+              </a>
+            </span>
+          </div>
+        </div>
+        <div class="markdown">
+          <pre><code
+            class="tiny-scrollbar"
+            id="export-notebook-source"
+            phx-hook="Highlight"
+            data-language="elixir"><%= @source %></code></pre>
+        </div>
+      </div>
+    </div>
+    """
+  end
+end

lib/livebook_web/live/session_live/export_live_markdown_component.ex

@@ -0,0 +1,49 @@
+defmodule LivebookWeb.SessionLive.ExportLiveMarkdownComponent do
+  use LivebookWeb, :live_component
+
+  @impl true
+  def update(assigns, socket) do
+    socket = assign(socket, assigns)
+
+    source = Livebook.LiveMarkdown.Export.notebook_to_markdown(socket.assigns.notebook)
+    socket = assign(socket, :source, source)
+
+    {:ok, socket}
+  end
+
+  @impl true
+  def render(assigns) do
+    ~H"""
+    <div class="flex flex-col space-y-1">
+      <div class="flex justify-between items-center">
+        <span class="text-sm text-gray-700 font-semibold">
+          .livemd
+        </span>
+        <div class="flex justify-end space-x-2">
+          <span class="tooltip left" aria-label="Copy source">
+            <button class="icon-button"
+              id="export-notebook-source-clipcopy"
+              phx-hook="ClipCopy"
+              data-target-id="export-notebook-source">
+              <.remix_icon icon="clipboard-line" class="text-lg" />
+            </button>
+          </span>
+          <span class="tooltip left" aria-label="Download source">
+            <a class="icon-button"
+              href={Routes.session_path(@socket, :download_source, @session_id, "livemd")}>
+              <.remix_icon icon="download-2-line" class="text-lg" />
+            </a>
+          </span>
+        </div>
+      </div>
+      <div class="markdown">
+        <pre><code
+          class="tiny-scrollbar"
+          id="export-notebook-source"
+          phx-hook="Highlight"
+          data-language="markdown"><%= @source %></code></pre>
+      </div>
+    </div>
+    """
+  end
+end

lib/livebook_web/router.ex

@@ -34,8 +34,8 @@ defmodule LivebookWeb.Router do
     live "/sessions/:id/settings/runtime", SessionLive, :runtime_settings
     live "/sessions/:id/settings/file", SessionLive, :file_settings
     live "/sessions/:id/bin", SessionLive, :bin
-    live "/sessions/:id/export", SessionLive, :export
+    get "/sessions/:id/export/download/:format", SessionController, :download_source
-    get "/sessions/:id/export/download", SessionController, :download_source
+    live "/sessions/:id/export/:tab", SessionLive, :export
     live "/sessions/:id/cell-settings/:cell_id", SessionLive, :cell_settings
     live "/sessions/:id/cell-upload/:cell_id", SessionLive, :cell_upload
     live "/sessions/:id/delete-section/:section_id", SessionLive, :delete_section

test/livebook/notebook/export/elixir_test.exs

@@ -0,0 +1,120 @@
+defmodule Livebook.Notebook.Export.ElixirTest do
+  use ExUnit.Case, async: true
+
+  alias Livebook.Notebook.Export
+  alias Livebook.Notebook
+
+  test "acceptance" do
+    notebook = %{
+      Notebook.new()
+      | name: "My Notebook",
+        metadata: %{"author" => "Sherlock Holmes"},
+        sections: [
+          %{
+            Notebook.Section.new()
+            | name: "Section 1",
+              metadata: %{"created_at" => "2021-02-15"},
+              cells: [
+                %{
+                  Notebook.Cell.new(:markdown)
+                  | metadata: %{"updated_at" => "2021-02-15"},
+                    source: """
+                    Make sure to install:
+
+                    * Erlang
+                    * Elixir
+                    * PostgreSQL\
+                    """
+                },
+                %{
+                  Notebook.Cell.new(:elixir)
+                  | metadata: %{"readonly" => true},
+                    source: """
+                    Enum.to_list(1..10)\
+                    """
+                },
+                %{
+                  Notebook.Cell.new(:markdown)
+                  | metadata: %{},
+                    source: """
+                    This is it for this section.\
+                    """
+                }
+              ]
+          },
+          %{
+            Notebook.Section.new()
+            | id: "s2",
+              name: "Section 2",
+              metadata: %{},
+              cells: [
+                %{
+                  Notebook.Cell.new(:input)
+                  | type: :text,
+                    name: "length",
+                    value: "100",
+                    reactive: true
+                },
+                %{
+                  Notebook.Cell.new(:elixir)
+                  | metadata: %{},
+                    source: """
+                    IO.gets("length: ")\
+                    """
+                },
+                %{
+                  Notebook.Cell.new(:input)
+                  | type: :range,
+                    name: "length",
+                    value: "100",
+                    props: %{min: 50, max: 150, step: 2}
+                }
+              ]
+          },
+          %{
+            Notebook.Section.new()
+            | name: "Section 3",
+              metadata: %{},
+              parent_id: "s2",
+              cells: [
+                %{
+                  Notebook.Cell.new(:elixir)
+                  | metadata: %{},
+                    source: """
+                    Process.info()\
+                    """
+                }
+              ]
+          }
+        ]
+    }
+
+    expected_document = """
+    # Title: My Notebook
+
+    # ── Section 1 ──
+
+    # Make sure to install:
+
+    # * Erlang
+    # * Elixir
+    # * PostgreSQL
+
+    Enum.to_list(1..10)
+
+    # This is it for this section.
+
+    # ── Section 2 ──
+
+    IO.gets("length: ")
+
+    # ── Section 3 ── (⎇ from Section 2)
+
+    # Process.info()
+    """
+
+    document = Export.Elixir.notebook_to_elixir(notebook)
+
+    assert expected_document == document
+  end
+end

test/livebook_web/controllers/session_controller_test.exs

@@ -39,16 +39,25 @@ defmodule LivebookWeb.SessionControllerTest do
 
   describe "download_source" do
     test "returns not found when the given session does not exist", %{conn: conn} do
-      conn = get(conn, Routes.session_path(conn, :download_source, "nonexistent"))
+      conn = get(conn, Routes.session_path(conn, :download_source, "nonexistent", "livemd"))
 
       assert conn.status == 404
       assert conn.resp_body == "Not found"
     end
 
-    test "returns live markdown notebook source", %{conn: conn} do
+    test "returns bad request when given an invalid format", %{conn: conn} do
       {:ok, session_id} = SessionSupervisor.create_session()
 
-      conn = get(conn, Routes.session_path(conn, :download_source, session_id))
+      conn = get(conn, Routes.session_path(conn, :download_source, session_id, "invalid"))
+
+      assert conn.status == 400
+      assert conn.resp_body == "Invalid format, supported formats: livemd, exs"
+    end
+
+    test "handles live markdown notebook source", %{conn: conn} do
+      {:ok, session_id} = SessionSupervisor.create_session()
+
+      conn = get(conn, Routes.session_path(conn, :download_source, session_id, "livemd"))
 
       assert conn.status == 200
       assert get_resp_header(conn, "content-type") == ["text/plain"]
@@ -59,5 +68,20 @@ defmodule LivebookWeb.SessionControllerTest do
 
       SessionSupervisor.close_session(session_id)
     end
+
+    test "handles elixir notebook source", %{conn: conn} do
+      {:ok, session_id} = SessionSupervisor.create_session()
+
+      conn = get(conn, Routes.session_path(conn, :download_source, session_id, "exs"))
+
+      assert conn.status == 200
+      assert get_resp_header(conn, "content-type") == ["text/plain"]
+
+      assert conn.resp_body == """
+             # Title: Untitled notebook
+             """
+
+      SessionSupervisor.close_session(session_id)
+    end
   end
 end