defmodule <%= inspect controller %> do
  @moduledoc """
  Example Phoenix controller demonstrating StarView with Datastar.

  Features:
    - Active search with debounced input
    - Element patching with smart change detection
    - Optimistic client-side filtering with data-show
  """

  use <%= inspect web_module %>, :controller

  @items [
    "Elixir",
    "Phoenix",
    "LiveView",
    "Datastar",
    "SSE",
    "Plug",
    "Ecto",
    "Ash",
    "HEEx",
    "Tailwind"
  ]

  @impl StarView
  def mount(conn, _params) do
    conn
    |> signal(:query, "")
    |> signal(:results, @items)
  end

  @impl StarView
  def render(assigns) do
    ~H"""
    <div class="max-w-xl mx-auto p-6" data-signals={init_signals(@conn)}>
      <h1 class="text-2xl font-bold mb-4">Active Search</h1>
      <.search_form />
      <.item_list results={@results} />
      <.no_results query={@query} />
    </div>
    """
  end

  def search_form(assigns) do
    ~H"""
    <div class="mb-4 flex gap-2">
      <input
        type="text"
        class="input grow"
        placeholder="Search frameworks..."
        data-bind:query
        data-on:input__debounce.200ms={post("search")}
      />
      <button class="btn" data-on:click={post("reset")}>
        Reset
      </button>
    </div>
    """
  end

  attr :query, :string, default: nil

  def no_results(assigns) do
    ~H"""
    <div data-show={query_results("=== 0")}>
      <p class="text-gray-500">
        No results found for "<span data-text="$query">{@query}</span>"
      </p>
    </div>
    """
  end

  attr :results, :list, default: []

  def item_list(assigns) do
    ~H"""
    <ul id="item-list" class="grid gap-2" data-show={query_results("> 0")}>
      <.item :for={item <- @results} item={item} />
    </ul>
    """
  end

  attr :item, :string, required: true

  def item(assigns) do
    ~H"""
    <li class="border p-4" data-show={starts_with?("'#{@item}'")}>
      {@item}
    </li>
    """
  end

  @impl StarView
  def handle_event("search", %{"query" => query} = signals, conn) do
    conn
    |> signal(:results, get_items(query))
    |> maybe_patch_list(signals)
  end

  def handle_event("reset", signals, conn) do
    conn
    |> signal(:query, "")
    |> signal(:results, @items)
    |> maybe_patch_list(signals)
  end

  defp get_items(""), do: @items

  defp get_items(query) do
    search_query = String.trim(String.downcase(query))
    Enum.filter(@items, &String.contains?(&1 |> String.downcase(), search_query))
  end

  # We use this to make the response as light as possible
  # Compared to LiveView which does this automatically with change tracking
  defp maybe_patch_list(%{assigns: %{results: x}} = conn, %{"results" => x}), do: conn
  defp maybe_patch_list(conn, _signals), do: patch_element(conn, &item_list/1)

  # JS helpers - for optimistic updates
  defp starts_with?(item) do
    "#{item}.trim().toLowerCase().startsWith($query.trim().toLowerCase())"
  end

  defp query_results(condition) do
    "$results.filter(x => #{starts_with?("x")}).length #{condition}"
  end
end