defmodule LivebookWeb.PathSelectComponent do
  use LivebookWeb, :live_component

  # The component expects:
  #
  # * `path` - the currently entered path
  # * `running_paths` - the list of notebook paths that are already linked to running sessions
  # * `extnames` - a list of file extensions that should be shown
  # * `phx_target` - id of the component to send update events to or nil to send to the parent LV
  # * `phx_submit` - the event name sent on form submission, use `nil` for no action
  #
  # The target receives `set_path` events with `%{"path" => path}` payload.
  #
  # Optionally inner block may be passed (e.g. with action buttons)
  # and it's rendered next to the text input.
  #
  # To force the component refetch the displayed files
  # you can `send_update` with `force_reload: true` to the component.

  @impl true
  def mount(socket) do
    {:ok,
     socket
     |> assign_new(:inner_block, fn -> nil end)
     |> assign(
       current_dir: nil,
       new_directory_name: nil,
       deleting_path: nil,
       renaming_path: nil,
       renamed_name: ""
     )}
  end

  @impl true
  def update(assigns, socket) do
    {force_reload?, assigns} = Map.pop(assigns, :force_reload, false)

    socket =
      socket
      |> assign(assigns)
      |> update_files(force_reload?)

    {:ok, socket}
  end

  defp update_files(%{assigns: assigns} = socket, force_reload?) do
    {dir, basename} = split_path(assigns.path)
    dir = Path.expand(dir)

    files =
      if assigns.current_dir != dir or force_reload? do
        list_files(dir, assigns.extnames, assigns.running_paths)
      else
        assigns.files
      end

    assign(socket, files: annotate_matching(files, basename), current_dir: dir)
  end

  @impl true
  def render(assigns) do
    ~H"""
    <div class="h-full flex flex-col">
      <div class="flex space-x-3 items-center mb-4">
        <form class="flex-grow"
          phx-change="set_path"
          phx-submit={@phx_submit}
          onsubmit={unless(@phx_submit, do: "return false")}
          phx-target={@phx_target}>
          <input class="input"
            id="input-path"
            phx-hook="FocusOnUpdate"
            type="text"
            name="path"
            placeholder="File"
            value={@path}
            spellcheck="false"
            autocomplete="off" />
        </form>
        <div class="relative" id="path-selector-menu" phx-hook="Menu" data-element="menu">
          <button class="icon-button" data-toggle tabindex="-1">
            <.remix_icon icon="more-2-fill" class="text-xl" />
          </button>
          <div class="menu" data-content>
            <button class="menu__item text-gray-500" phx-click="new_directory" phx-target={@myself}>
              <.remix_icon icon="folder-add-fill" class="text-gray-400" />
              <span class="font-medium">New directory</span>
            </button>
          </div>
        </div>
        <%= if @inner_block do %>
          <div>
            <%= render_block(@inner_block) %>
          </div>
        <% end %>
      </div>
      <%= if @deleting_path do %>
        <div class="mb-4 px-4 py-3 flex space-x-4 items-center border border-gray-200 rounded-lg">
          <p class="flex-grow text-gray-700 text-sm">
            Are you sure you want to irreversibly delete
            <span class="font-semibold"><%= @deleting_path %></span>?
          </p>
          <div class="flex space-x-4">
            <button class="text-red-600 font-medium text-sm whitespace-nowrap"
              phx-click="do_delete_file"
              phx-target={@myself}>
              <.remix_icon icon="delete-bin-6-line" class="align-middle mr-1" />
              Delete
            </button>
            <button class="text-gray-600 font-medium text-sm"
              phx-click="cancel_delete_file"
              phx-target={@myself}>
              Cancel
            </button>
          </div>
        </div>
      <% end %>
      <div class="flex-grow -m-1 p-1 overflow-y-auto tiny-scrollbar" tabindex="-1">
        <%= if @new_directory_name do %>
          <div class="grid grid-cols-2 sm:grid-cols-3 lg:grid-cols-4 gap-2 border-b border-dashed border-grey-200 mb-2 pb-2">
            <div class="flex space-x-2 items-center p-2 rounded-lg">
              <span class="block">
                <.remix_icon icon="folder-add-fill" class="text-xl align-middle text-gray-400" />
              </span>
              <span class="flex font-medium text-gray-500">
                <div
                  phx-window-keydown="cancel_new_directory"
                  phx-key="escape"
                  phx-target={@myself}>
                  <input
                    type="text"
                    value={@new_directory_name}
                    autofocus
                    spellcheck="false"
                    autocomplete="off"
                    phx-blur="cancel_new_directory"
                    phx-window-keydown="create_directory"
                    phx-key="enter"
                    phx-target={@myself} />
                </div>
              </span>
            </div>
          </div>
        <% end %>

        <%= if highlighting?(@files) do %>
          <div class="grid grid-cols-2 sm:grid-cols-3 lg:grid-cols-4 gap-2 border-b border-dashed border-grey-200 mb-2 pb-2">
            <%= for file <- @files, file.highlighted != "" do %>
              <.file
                file={file}
                phx_target={@phx_target}
                myself={@myself}
                renaming_path={@renaming_path}
                renamed_name={@renamed_name} />
            <% end %>
          </div>
        <% end %>

        <div class="grid grid-cols-2 sm:grid-cols-3 lg:grid-cols-4 gap-2">
          <%= for file <- @files, file.highlighted == "" do %>
            <.file
              file={file}
              phx_target={@phx_target}
              myself={@myself}
              renaming_path={@renaming_path}
              renamed_name={@renamed_name} />
          <% end %>
        </div>
      </div>
    </div>
    """
  end

  defp highlighting?(files) do
    Enum.any?(files, &(&1.highlighted != ""))
  end

  defp file(%{file: %{path: path}, renaming_path: path} = assigns) do
    ~H"""
    <div class="flex space-x-2 items-center p-2 rounded-lg">
      <span class="block">
        <.remix_icon icon="edit-line" class="text-xl align-middle text-gray-400" />
      </span>
      <span class="flex font-medium text-gray-500">
        <div
          phx-window-keydown="cancel_rename_file"
          phx-key="escape"
          phx-target={@myself}>
          <input class="w-full"
            type="text"
            value={@renamed_name}
            autofocus
            spellcheck="false"
            autocomplete="off"
            phx-blur="cancel_rename_file"
            phx-window-keydown="do_rename_file"
            phx-key="enter"
            phx-target={@myself} />
        </div>
      </span>
    </div>
    """
  end

  defp file(assigns) do
    icon =
      case assigns.file do
        %{is_running: true} -> "play-circle-line"
        %{is_dir: true} -> "folder-fill"
        _ -> "file-code-line"
      end

    assigns = assign(assigns, :icon, icon)

    ~H"""
    <div class="relative"
      id={"file-menu-#{@file.path}"}
      phx-hook="Menu"
      data-primary="false"
      data-element="menu">
      <button class="w-full flex space-x-2 items-center p-2 rounded-lg hover:bg-gray-100 focus:ring-1 focus:ring-gray-400"
        data-toggle
        phx-click="set_path"
        phx-value-path={@file.path}
        phx-target={@phx_target}>
        <span class="block">
          <.remix_icon icon={@icon} class={"text-xl align-middle #{if(@file.is_running, do: "text-green-300", else: "text-gray-400")}"} />
        </span>
        <span class={"flex font-medium overflow-hidden whitespace-nowrap #{if(@file.is_running, do: "text-green-300", else: "text-gray-500")}"}>
          <%= if @file.highlighted != "" do %>
            <span class={"font-medium #{if(@file.is_running, do: "text-green-400", else: "text-gray-900")}"}>
              <%= @file.highlighted %>
            </span>
          <% end %>
          <span class="overflow-hidden overflow-ellipsis">
            <%= @file.unhighlighted %>
          </span>
        </span>
      </button>
      <div class="menu" data-content>
        <button class="menu__item text-gray-500"
          phx-click="rename_file"
          phx-target={@myself}
          phx-value-path={@file.path}>
          <.remix_icon icon="edit-line" />
          <span class="font-medium">Rename</span>
        </button>
        <button class="menu__item text-red-600"
          phx-click="delete_file"
          phx-target={@myself}
          phx-value-path={@file.path}>
          <.remix_icon icon="delete-bin-6-line" />
          <span class="font-medium">Delete</span>
        </button>
      </div>
    </div>
    """
  end

  defp annotate_matching(files, prefix) do
    for %{name: name} = file <- files do
      if String.starts_with?(name, prefix) do
        %{file | highlighted: prefix, unhighlighted: String.replace_prefix(name, prefix, "")}
      else
        %{file | highlighted: "", unhighlighted: name}
      end
    end
  end

  defp list_files(dir, extnames, running_paths) do
    if File.exists?(dir) do
      file_names =
        case File.ls(dir) do
          {:ok, names} -> names
          {:error, _} -> []
        end

      file_infos =
        file_names
        |> Enum.map(fn name ->
          file_info(name, Path.join(dir, name), running_paths)
        end)
        |> Enum.filter(fn file ->
          not hidden?(file.name) and (file.is_dir or valid_extension?(file.name, extnames))
        end)

      parent = Path.dirname(dir)

      file_infos =
        if parent == dir do
          file_infos
        else
          [file_info("..", parent, running_paths) | file_infos]
        end

      Enum.sort_by(file_infos, fn file -> {!file.is_dir, file.name} end)
    else
      []
    end
  end

  defp file_info(name, path, running_paths) do
    is_dir = File.dir?(path)

    %{
      name: name,
      highlighted: "",
      unhighlighted: name,
      path: if(is_dir, do: ensure_trailing_slash(path), else: path),
      is_dir: is_dir,
      is_running: path in running_paths
    }
  end

  defp hidden?(filename) do
    String.starts_with?(filename, ".")
  end

  defp valid_extension?(filename, extnames) do
    Path.extname(filename) in extnames
  end

  # Note: to provide an intuitive behavior when typing the path
  # we enter a new directory when it has a trailing slash,
  # so given "/foo/bar" we list files in "foo" and given "/foo/bar/
  # we list files in "bar".
  #
  # The basename is kinda like search within the current directory,
  # so we highlight files starting with that string.
  defp split_path(path) do
    if String.ends_with?(path, "/") do
      {path, ""}
    else
      {Path.dirname(path), Path.basename(path)}
    end
  end

  defp ensure_trailing_slash(path) do
    if String.ends_with?(path, "/") do
      path
    else
      path <> "/"
    end
  end

  @impl true
  def handle_event("new_directory", %{}, socket) do
    {:noreply, assign(socket, new_directory_name: "")}
  end

  def handle_event("cancel_new_directory", %{}, socket) do
    {:noreply, assign(socket, new_directory_name: nil)}
  end

  def handle_event("create_directory", %{"value" => name}, socket) do
    socket =
      case create_directory(socket.assigns.current_dir, name) do
        :ok ->
          socket
          |> assign(new_directory_name: nil)
          |> update_files(true)

        _ ->
          assign(socket, new_directory_name: name)
      end

    {:noreply, socket}
  end

  def handle_event("delete_file", %{"path" => path}, socket) do
    {:noreply, assign(socket, deleting_path: path)}
  end

  def handle_event("cancel_delete_file", %{}, socket) do
    {:noreply, assign(socket, deleting_path: nil)}
  end

  def handle_event("do_delete_file", %{}, socket) do
    socket =
      case delete_file(socket.assigns.deleting_path) do
        :ok ->
          socket
          |> assign(deleting_path: nil)
          |> update_files(true)

        _ ->
          socket
      end

    {:noreply, socket}
  end

  def handle_event("rename_file", %{"path" => path}, socket) do
    {_, name} = path |> Path.expand() |> split_path()
    {:noreply, assign(socket, renaming_path: path, renamed_name: name)}
  end

  def handle_event("cancel_rename_file", %{}, socket) do
    {:noreply, assign(socket, renaming_path: nil)}
  end

  def handle_event("do_rename_file", %{"value" => name}, socket) do
    socket =
      case rename_file(socket.assigns.renaming_path, name) do
        :ok ->
          socket
          |> assign(renaming_path: nil)
          |> update_files(true)

        _ ->
          assign(socket, renamed_name: name)
      end

    {:noreply, socket}
  end

  defp create_directory(_parent_dir, ""), do: {:error, :empty}

  defp create_directory(parent_dir, name) do
    new_dir = Path.join(parent_dir, name)
    File.mkdir(new_dir)
  end

  defp delete_file(path) do
    with {:ok, _paths} <- File.rm_rf(path) do
      :ok
    end
  end

  defp rename_file(_path, ""), do: {:error, :empty}

  defp rename_file(path, name) do
    dir = path |> Path.expand() |> Path.dirname()
    new_path = Path.join(dir, name)
    File.rename(path, new_path)
  end
end