defmodule LivebookWeb.HomeLive do
  use LivebookWeb, :live_view

  import LivebookWeb.UserHelpers
  import LivebookWeb.SessionHelpers

  alias LivebookWeb.{SidebarHelpers, ExploreHelpers}
  alias Livebook.{SessionSupervisor, Session, LiveMarkdown, Notebook}

  @impl true
  def mount(_params, %{"current_user_id" => current_user_id} = session, socket) do
    if connected?(socket) do
      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions")
      Phoenix.PubSub.subscribe(Livebook.PubSub, "users:#{current_user_id}")
    end

    current_user = build_current_user(session, socket)
    session_summaries = sort_session_summaries(SessionSupervisor.get_session_summaries())
    notebook_infos = Notebook.Explore.notebook_infos() |> Enum.take(3)

    {:ok,
     assign(socket,
       current_user: current_user,
       path: default_path(),
       session_summaries: session_summaries,
       notebook_infos: notebook_infos
     )}
  end

  @impl true
  def render(assigns) do
    ~H"""
    <div class="flex flex-grow h-full">
      <SidebarHelpers.sidebar>
        <SidebarHelpers.break_item />
        <SidebarHelpers.user_item current_user={@current_user} path={Routes.home_path(@socket, :user)} />
      </SidebarHelpers.sidebar>
      <div class="flex-grow px-6 py-8 overflow-y-auto">
        <div class="max-w-screen-lg w-full mx-auto px-4 pb-8 space-y-4">
          <div class="flex flex-col space-y-2 items-center pb-4 border-b border-gray-200
                      sm:flex-row sm:space-y-0 sm:justify-between">
            <div class="text-2xl text-gray-800 font-semibold">
              <img src="/images/logo-with-text.png" class="h-[50px]" alt="Livebook" />
            </div>
            <div class="flex space-x-2 pt-2">
              <%= live_patch "Import",
                    to: Routes.home_path(@socket, :import, "url"),
                    class: "button button-outlined-gray whitespace-nowrap" %>
              <button class="button button-blue" phx-click="new">
                New notebook
              </button>
            </div>
          </div>

          <div class="h-80">
            <%= live_component LivebookWeb.PathSelectComponent,
                  id: "path_select",
                  path: @path,
                  extnames: [LiveMarkdown.extension()],
                  running_paths: paths(@session_summaries),
                  phx_target: nil,
                  phx_submit: nil do %>
              <div class="flex justify-end space-x-2">
                <button class="button button-outlined-gray whitespace-nowrap"
                  phx-click="fork"
                  disabled={not path_forkable?(@path)}>
                  <.remix_icon icon="git-branch-line" class="align-middle mr-1" />
                  <span>Fork</span>
                </button>
                <%= if path_running?(@path, @session_summaries) do %>
                  <%= live_redirect "Join session",
                        to: Routes.session_path(@socket, :page, session_id_by_path(@path, @session_summaries)),
                        class: "button button-blue" %>
                <% else %>
                  <span {open_button_tooltip_attrs(@path)}>
                    <button class="button button-blue"
                      phx-click="open"
                      disabled={not path_openable?(@path, @session_summaries)}>
                      Open
                    </button>
                  </span>
                <% end %>
              </div>
            <% end %>
          </div>

          <div class="py-12">
            <div class="mb-4 flex justify-between items-center">
              <h2 class="text-xl font-semibold text-gray-800">
                Explore
              </h2>
              <%= live_redirect to: Routes.explore_path(@socket, :page),
                    class: "flex items-center text-blue-600" do %>
                <span class="font-semibold">See all</span>
                <.remix_icon icon="arrow-right-line" class="align-middle ml-1" />
              <% end %>
            </div>
            <div class="grid grid-cols-1 md:grid-cols-3 gap-4">
              <%# Note: it's fine to use stateless components in this comprehension,
                  because @notebook_infos never change %>
              <%= for info <- @notebook_infos do %>
                <ExploreHelpers.notebook_card notebook_info={info} socket={@socket} />
              <% end %>
            </div>
          </div>

          <div class="py-12">
            <h2 class="mb-4 text-xl font-semibold text-gray-800">
              Running sessions
            </h2>
            <.sessions_list session_summaries={@session_summaries} socket={@socket} />
          </div>
        </div>
      </div>
    </div>

    <%= if @live_action == :user do %>
      <%= live_modal LivebookWeb.UserComponent,
            id: "user",
            modal_class: "w-full max-w-sm",
            user: @current_user,
            return_to: Routes.home_path(@socket, :page) %>
    <% end %>

    <%= if @live_action == :close_session do %>
      <%= live_modal LivebookWeb.HomeLive.CloseSessionComponent,
            id: "close-session",
            modal_class: "w-full max-w-xl",
            return_to: Routes.home_path(@socket, :page),
            session_summary: @session_summary %>
    <% end %>

    <%= if @live_action == :import do %>
      <%= live_modal LivebookWeb.HomeLive.ImportComponent,
            id: "import",
            modal_class: "w-full max-w-xl",
            return_to: Routes.home_path(@socket, :page),
            tab: @tab %>
    <% end %>
    """
  end

  defp open_button_tooltip_attrs(path) do
    if File.regular?(path) and not file_writable?(path) do
      [class: "tooltip top", aria_label: "This file is write-protected, please fork instead"]
    else
      []
    end
  end

  defp sessions_list(%{session_summaries: []} = assigns) do
    ~H"""
    <div class="p-5 flex space-x-4 items-center border border-gray-200 rounded-lg">
      <div>
        <.remix_icon icon="windy-line" class="text-gray-400 text-xl" />
      </div>
      <div class="text-gray-600">
        You do not have any running sessions.
        <br>
        Please create a new one by clicking <span class="font-semibold">“New notebook”</span>
      </div>
    </div>
    """
  end

  defp sessions_list(assigns) do
    ~H"""
    <div class="flex flex-col space-y-4">
      <%= for summary <- @session_summaries do %>
        <div class="p-5 flex items-center border border-gray-200 rounded-lg"
          data-test-session-id={summary.session_id}>
          <div class="flex-grow flex flex-col space-y-1">
            <%= live_redirect summary.notebook_name,
                  to: Routes.session_path(@socket, :page, summary.session_id),
                  class: "font-semibold text-gray-800 hover:text-gray-900" %>
            <div class="text-gray-600 text-sm">
              <%= summary.path || "No file" %>
            </div>
          </div>
          <div class="relative" id={"session-#{summary.session_id}-menu"} phx-hook="Menu" data-element="menu">
            <button class="icon-button" data-toggle>
              <.remix_icon icon="more-2-fill" class="text-xl" />
            </button>
            <div class="menu" data-content>
              <button class="menu__item text-gray-500"
                phx-click="fork_session"
                phx-value-id={summary.session_id}>
                <.remix_icon icon="git-branch-line" />
                <span class="font-medium">Fork</span>
              </button>
              <a class="menu__item text-gray-500"
                href={live_dashboard_process_path(@socket, summary.pid)}
                target="_blank">
                <.remix_icon icon="dashboard-2-line" />
                <span class="font-medium">See on Dashboard</span>
              </a>
              <%= live_patch to: Routes.home_path(@socket, :close_session, summary.session_id),
                    class: "menu__item text-red-600" do %>
                <.remix_icon icon="close-circle-line" />
                <span class="font-medium">Close</span>
              <% end %>
            </div>
          </div>
        </div>
      <% end %>
    </div>
    """
  end

  @impl true
  def handle_params(%{"session_id" => session_id}, _url, socket) do
    session_summary = Enum.find(socket.assigns.session_summaries, &(&1.session_id == session_id))
    {:noreply, assign(socket, session_summary: session_summary)}
  end

  def handle_params(%{"tab" => tab}, _url, socket) do
    {:noreply, assign(socket, tab: tab)}
  end

  def handle_params(_params, _url, socket), do: {:noreply, socket}

  @impl true
  def handle_event("set_path", %{"path" => path}, socket) do
    {:noreply, assign(socket, path: path)}
  end

  def handle_event("new", %{}, socket) do
    {:noreply, create_session(socket)}
  end

  def handle_event("fork", %{}, socket) do
    path = socket.assigns.path
    {notebook, messages} = import_notebook(path)
    socket = put_import_flash_messages(socket, messages)
    notebook = Notebook.forked(notebook)
    images_dir = Session.images_dir_for_notebook(path)

    {:noreply,
     create_session(socket,
       notebook: notebook,
       copy_images_from: images_dir,
       origin_url: "file://" <> path
     )}
  end

  def handle_event("open", %{}, socket) do
    path = socket.assigns.path
    {notebook, messages} = import_notebook(path)
    socket = put_import_flash_messages(socket, messages)

    {:noreply,
     create_session(socket, notebook: notebook, path: path, origin_url: "file://" <> path)}
  end

  def handle_event("fork_session", %{"id" => session_id}, socket) do
    data = Session.get_data(session_id)
    notebook = Notebook.forked(data.notebook)
    %{images_dir: images_dir} = Session.get_summary(session_id)

    origin_url =
      if data.path do
        "file://" <> data.path
      else
        data.origin_url
      end

    {:noreply,
     create_session(socket,
       notebook: notebook,
       copy_images_from: images_dir,
       origin_url: origin_url
     )}
  end

  @impl true
  def handle_info({:session_created, id}, socket) do
    summary = Session.get_summary(id)
    session_summaries = sort_session_summaries([summary | socket.assigns.session_summaries])
    {:noreply, assign(socket, session_summaries: session_summaries)}
  end

  def handle_info({:session_closed, id}, socket) do
    session_summaries = Enum.reject(socket.assigns.session_summaries, &(&1.session_id == id))
    {:noreply, assign(socket, session_summaries: session_summaries)}
  end

  def handle_info({:import_content, content, session_opts}, socket) do
    {notebook, messages} = Livebook.LiveMarkdown.Import.notebook_from_markdown(content)
    socket = put_import_flash_messages(socket, messages)
    session_opts = Keyword.merge(session_opts, notebook: notebook)
    {:noreply, create_session(socket, session_opts)}
  end

  def handle_info(
        {:user_change, %{id: id} = user},
        %{assigns: %{current_user: %{id: id}}} = socket
      ) do
    {:noreply, assign(socket, :current_user, user)}
  end

  def handle_info(_message, socket), do: {:noreply, socket}

  defp default_path(), do: Livebook.Config.root_path() <> "/"

  defp sort_session_summaries(session_summaries) do
    Enum.sort_by(session_summaries, & &1.notebook_name)
  end

  defp paths(session_summaries) do
    Enum.map(session_summaries, & &1.path)
  end

  defp path_forkable?(path) do
    File.regular?(path)
  end

  defp path_openable?(path, session_summaries) do
    File.regular?(path) and not path_running?(path, session_summaries) and file_writable?(path)
  end

  defp path_running?(path, session_summaries) do
    running_paths = paths(session_summaries)
    path in running_paths
  end

  defp file_writable?(path) do
    case File.stat(path) do
      {:ok, stat} -> stat.access in [:read_write, :write]
      {:error, _} -> false
    end
  end

  defp import_notebook(path) do
    content = File.read!(path)
    LiveMarkdown.Import.notebook_from_markdown(content)
  end

  defp session_id_by_path(path, session_summaries) do
    summary = Enum.find(session_summaries, &(&1.path == path))
    summary.session_id
  end
end