defmodule LivebookWeb.HomeLive do
  use LivebookWeb, :live_view

  import LivebookWeb.UserHelpers
  import LivebookWeb.SessionHelpers

  alias Livebook.{SessionSupervisor, Session, LiveMarkdown, Notebook}

  @impl true
  def mount(_params, %{"current_user_id" => current_user_id}, 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(current_user_id, 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
    ~L"""
    <div class="flex flex-grow h-full">
    <%= live_component LivebookWeb.SidebarComponent,
          id: :sidebar,
          items: [
            %{type: :break},
            %{type: :user, current_user: @current_user, path: Routes.home_path(@socket, :user)}
          ] %>
      <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 sm:flex-row sm:space-y-0 sm:justify-between sm:pb-4 pb-8 border-b border-gray-200">
            <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 to: Routes.home_path(@socket, :import, "url"),
                    class: "button button-outlined-gray whitespace-nowrap" do %>
                Import
              <% end %>
              <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">
                <%= content_tag :button,
                  class: "button button-outlined-gray whitespace-nowrap",
                  phx_click: "fork",
                  disabled: not path_forkable?(@path) do %>
                  <%= remix_icon("git-branch-line", class: "align-middle mr-1") %>
                  <span>Fork</span>
                <% end %>
                <%= 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 %>
                  <%= tag :span, if(File.regular?(@path) and not file_writable?(@path),
                        do: [class: "tooltip top", aria_label: "This file is write-protected, please fork instead"],
                        else: []
                      ) %>
                    <%= content_tag :button, "Open",
                      class: "button button-blue",
                      phx_click: "open",
                      disabled: not path_openable?(@path, @session_summaries) %>
                  </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("arrow-right-line", class: "align-middle ml-1") %>
              <% end %>
            </div>
            <div class="grid grid-cols-1 md:grid-cols-3 gap-4">
              <%= for {info, idx} <- Enum.with_index(@notebook_infos) do %>
                <%= live_component LivebookWeb.NotebookCardComponent,
                      id: "notebook-card-#{idx}",
                      notebook_info: info %>
              <% end %>
            </div>
          </div>
          <div class="py-12">
            <h2 class="mb-4 text-xl font-semibold text-gray-800">
              Running sessions
            </h2>
            <%= if @session_summaries == [] do %>
              <div class="p-5 flex space-x-4 items-center border border-gray-200 rounded-lg">
                <div>
                  <%= remix_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>
            <% else %>
              <%= live_component LivebookWeb.HomeLive.SessionsComponent,
                id: "sessions_list",
                session_summaries: @session_summaries %>
            <% end %>
          </div>
        </div>
      </div>
    </div>

    <%= if @live_action == :user do %>
      <%= live_modal LivebookWeb.UserComponent,
            id: :user_modal,
            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,
            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,
            modal_class: "w-full max-w-xl",
            return_to: Routes.home_path(@socket, :page),
            tab: @tab %>
    <% end %>
    """
  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
    {notebook, messages} = import_notebook(socket.assigns.path)
    socket = put_import_flash_messages(socket, messages)
    notebook = Notebook.forked(notebook)
    images_dir = Session.images_dir_for_notebook(socket.assigns.path)
    {:noreply, create_session(socket, notebook: notebook, copy_images_from: images_dir)}
  end

  def handle_event("open", %{}, socket) do
    {notebook, messages} = import_notebook(socket.assigns.path)
    socket = put_import_flash_messages(socket, messages)
    {:noreply, create_session(socket, notebook: notebook, path: socket.assigns.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)
    {:noreply, create_session(socket, notebook: notebook, copy_images_from: images_dir)}
  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}, socket) do
    {notebook, messages} = Livebook.LiveMarkdown.Import.notebook_from_markdown(content)
    socket = put_import_flash_messages(socket, messages)
    {:noreply, create_session(socket, notebook: notebook)}
  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 put_import_flash_messages(socket, []), do: socket

  defp put_import_flash_messages(socket, messages) do
    list =
      messages
      |> Enum.map(fn message -> ["- ", message] end)
      |> Enum.intersperse("\n")

    flash =
      IO.iodata_to_binary([
        "We found problems while importing the file and tried to autofix them:\n" | list
      ])

    put_flash(socket, :info, flash)
  end

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