daisy_ui_components

defmodule DaisyUIComponents.Pagination do
  @moduledoc """
  Button Group component

  https://daisyui.com/components/pagination/


  """

  use DaisyUIComponents, :component

  import DaisyUIComponents.Button
  import DaisyUIComponents.Join

  @doc """
  Renders a button group.

  ## Examples

      <.pagination page={1} page_size={10} total_entries={100} />
  """
  attr :page, :integer, default: 1
  attr :page_size, :integer, default: 10
  attr :total_entries, :integer, default: 100
  attr :button_class, :string, default: nil
  attr :size, :string, values: sizes()
  attr :target, :string, default: nil
  attr :page_click_event, :string, default: "page_click"

  attr :on_page_click, Phoenix.LiveView.JS,
    default: nil,
    doc: "JS event to trigger when a page button is clicked, if not using `page_click_event`"

  attr :rest, :global

  def pagination(assigns) do
    assigns =
      assign_new(assigns, :size, fn -> nil end)

    ~H"""
    <.join :if={@total_entries > 0} {@rest}>
      <%= for block <- calculate_display_btn(@page, @page_size, @total_entries) do %>
        <.button
          class={["join-item", @button_class]}
          size={@size}
          phx-click={(@on_page_click && @on_page_click) || JS.push(@page_click_event)}
          phx-value-page={block}
          phx-target={@target}
          active={block == @page}
          disabled={block == "..."}
        >
          {block}
        </.button>
      <% end %>
    </.join>
    """
  end

  @max_display_block 7
  @doc """

  Returns a list of display buttons for pagination based on the current page, page size, and total entries.

  ## Parameters

  - page - the current page number.
  - page_size - the number of entries per page.
  - total_entries - the total number of entries available.

  ## Description
  Calculates which page numbers to display as buttons in a pagination control.

  """
  def calculate_display_btn(page, page_size, total_entries) do
    {max_blocks, _remain} =
      Float.ceil(total_entries / page_size) |> to_string() |> Integer.parse()

    cond do
      max_blocks <= @max_display_block ->
        Enum.map(1..max_blocks, & &1)

      page <= 4 ->
        Enum.map(1..5, & &1) ++ ["...", max_blocks]

      max_blocks - page <= 3 ->
        start_max_block_4 = max_blocks - 4
        [1, "..."] ++ Enum.map(start_max_block_4..max_blocks, & &1)

      true ->
        [1, "...", page - 1, page, page + 1, "...", max_blocks]
    end
  end
end