defmodule Flop.Phoenix do
  @moduledoc """
  Components for Phoenix and Flop.

  ## Introduction

  Please refer to the [Readme](README.md) for an introduction.

  ## Customization

  `Flop.Phoenix` sets some default classes and aria attributes.

      <nav aria-label="pagination" class="pagination is-centered" role="navigation">
        <span class="pagination-previous" disabled="disabled">Previous</span>
        <a class="pagination-next" href="/pets?page=2&amp;page_size=10">Next</a>
        <ul class="pagination-list">
          <li><span class="pagination-ellipsis">&hellip;</span></li>
          <li>
            <a aria-current="page"
               aria-label="Go to page 1"
               class="pagination-link is-current"
               href="/pets?page=1&amp;page_size=10">1</a>
          </li>
          <li>
            <a aria-label="Go to page 2"
               class="pagination-link"
               href="/pets?page=2&amp;page_size=10">2</a>
          </li>
          <li>
            <a aria-label="Go to page 3"
               class="pagination-link"
               href="/pets?page=3&amp;page_size=2">3</a>
          </li>
          <li><span class="pagination-ellipsis">&hellip;</span></li>
        </ul>
      </nav>

  If you want to customize the pagination or table markup, you probably want
  to do that once for all templates, so that your templates aren't cluttered
  with options.

  To do that, create a new file `live/flop_components.ex` (or
  `views/flop_helpers.ex`, or `views/component_helpers.ex`).

      defmodule MyAppWeb.FlopComponents do
        use Phoenix.Component

        def pagination(assigns) do
          ~H\"""
          <Flop.Phoenix.pagination
            meta={@meta},
            path_helper={@path_helper},
            path_helper_args{@path_helper_args},
            opts={pagination_opts(@opts)}
          />
          \"""
        end

        defp pagination_opts(opts) do
          default_opts = [
            ellipsis_attrs: [class: "ellipsis"],
            ellipsis_content: "‥",
            next_link_attrs: [class: "next"],
            next_link_content: next_icon(),
            page_links: {:ellipsis, 7},
            pagination_link_aria_label: &"\#{&1}ページ目へ",
            pagination_link_attrs: [class: "page-link"],
            pagination_list_attrs: [class: "page-links"],
            previous_link_attrs: [class: "prev"],
            previous_link_content: previous_icon(),
            wrapper_attrs: [class: "paginator"]
          ]

          Keyword.merge(default_opts, opts)
        end

        defp next_icon do
          tag :i, class: "fas fa-chevron-right"
        end

        defp previous_icon do
          tag :i, class: "fas fa-chevron-left"
        end
      end

  You can do this similarly for `Flop.Phoenix.table/1`

  To make the functions available in all templates, import the module in
  `my_app_web.ex`.

      defp view_helpers do
        quote do
          # ...

          import MyAppWeb.FlopComponents

          # ...
        end
      end

  ## Hiding default parameters

  Default values for page size and ordering are omitted from the query
  parameters. If you pass the `:for` option, the Flop.Phoenix function will
  pick up the default values from the schema module deriving `Flop.Schema`.

  ## LiveView

  The functions in this module can be used in both `.eex` and `.heex` templates.

  Links are generated with `Phoenix.LiveView.Helpers.live_patch/2`. This will
  lead to `<a>` tags with `data-phx-link` and `data-phx-link-state` attributes,
  which will be ignored outside of LiveViews and LiveComponents.

  When used in LiveView templates, you will need to handle the new params in the
  `handle_params/3` callback of your LiveView module.

  ## Event Based Pagination and Sorting

  To make `Flop.Phoenix` use event based pagination and sorting, you need to set
  the `:event` option on the pagination and table generators. This will
  generate an `<a>` tag with `phx-click` and `phx-value` attributes set.

  You can set a different target by setting the `:target` option. The value
  will be used in the `phx-target` attribute.

      <Flop.Phoenix.pagination
        meta={@meta},
        path_helper={&Routes.pet_path/4},
        path_helper_args{[@conn, :index, @owner]},
        opts={[for: MyApp.Pet, event: "paginate-pets", target: @myself]}
      />

  You will need to handle the event in the `handle_event/3` callback of your
  LiveView module. The event name will be the one you set with the `:event`
  option.

      def handle_event("paginate-pets", %{"page" => page}, socket) do
        flop = Flop.set_page(socket.assigns.meta.flop, page)

        with {:ok, {pets, meta}} <- Pets.list_pets(params) do
          {:noreply, assign(socket, pets: pets, meta: meta)}
        end
      end

      def handle_event("order_pets", %{"order" => order}, socket) do
        flop = Flop.push_order(socket.assigns.meta.flop, order)

        with {:ok, {pets, meta}} <- Pets.list_pets(flop) do
          {:noreply, assign(socket, pets: pets, meta: meta)}
        end
      end
  """

  use Phoenix.Component
  use Phoenix.HTML

  import Phoenix.LiveView.Helpers

  alias Flop.Meta
  alias Flop.Phoenix.Pagination
  alias Flop.Phoenix.Table

  @typedoc """
  Defines the available options for `Flop.Phoenix.pagination/1`.

  - `:current_link_attrs` - The attributes for the link to the current page.
    Default: `#{inspect(Pagination.default_opts()[:current_link_attrs])}`.
  - `:ellipsis_attrs` - The attributes for the `<span>` that wraps the
    ellipsis.
    Default: `#{inspect(Pagination.default_opts()[:ellipsis_attrs])}`.
  - `:ellipsis_content` - The content for the ellipsis element.
    Default: `#{inspect(Pagination.default_opts()[:ellipsis_content])}`.
  - `:for` - The schema module deriving `Flop.Schema`. If set, `Flop.Phoenix`
    will remove default parameters from the query parameters.
    Default: `#{inspect(Pagination.default_opts()[:for])}`.
  - `:next_link_attrs` - The attributes for the link to the next page.
    Default: `#{inspect(Pagination.default_opts()[:next_link_attrs])}`.
  - `:next_link_content` - The content for the link to the next page.
    Default: `#{inspect(Pagination.default_opts()[:next_link_content])}`.
  - `:page_links` - Specifies how many page links should be rendered.
    Default: `#{inspect(Pagination.default_opts()[:page_links])}`.
    - `:all` - Renders all page links.
    - `{:ellipsis, n}` - Renders `n` page links. Renders ellipsis elements if
      there are more pages than displayed.
    - `:hide` - Does not render any page links.
  - `:pagination_link_aria_label` - 1-arity function that takes a page number
    and returns an aria label for the corresponding page link.
    Default: `&"Go to page \#{&1}"`.
  - `:pagination_link_attrs` - The attributes for the pagination links.
    Default: `#{inspect(Pagination.default_opts()[:pagination_link_attrs])}`.
  - `:pagination_list_attrs` - The attributes for the pagination list.
    Default: `#{inspect(Pagination.default_opts()[:pagination_list_attrs])}`.
  - `:previous_link_attrs` - The attributes for the link to the previous page.
    Default: `#{inspect(Pagination.default_opts()[:previous_link_attrs])}`.
  - `:previous_link_content` - The content for the link to the previous page.
    Default: `#{inspect(Pagination.default_opts()[:previous_link_content])}`.
  - `:wrappers_attrs` - The attributes for the `<nav>` element that wraps the
    pagination links.
    Default: `#{inspect(Pagination.default_opts()[:wrappers_attrs])}`.
  """
  @type pagination_option ::
          {:current_link_attrs, keyword}
          | {:ellipsis_attrs, keyword}
          | {:ellipsis_content, Phoenix.HTML.safe() | binary}
          | {:for, module}
          | {:next_link_attrs, keyword}
          | {:next_link_content, Phoenix.HTML.safe() | binary}
          | {:page_links, :all | :hide | {:ellipsis, pos_integer}}
          | {:pagination_link_aria_label, (pos_integer -> binary)}
          | {:pagination_link_attrs, keyword}
          | {:pagination_list_attrs, keyword}
          | {:previous_link_attrs, keyword}
          | {:previous_link_content, Phoenix.HTML.safe() | binary}
          | {:wrapper_attrs, keyword}

  @typedoc """
  Defines the available options for `Flop.Phoenix.table/1`.

  - `:container` - Wraps the table in a `<div>` if `true`.
    Default: `#{inspect(Table.default_opts()[:container])}`.
  - `:container_attrs` - The attributes for the table container.
    Default: `#{inspect(Table.default_opts()[:container_attrs])}`.
  - `:event`: If set, `Flop.Phoenix` will render links with a `phx-click`
    attribute. Default: `#{inspect(Table.default_opts()[:event])}`.
  - `:for` - The schema module deriving `Flop.Schema`. If set, header links are
    only added for fields that are defined as sortable.
    Default: `#{inspect(Table.default_opts()[:for])}`.
  - `:no_results_content` - Any content that should be rendered if there are no
    results. Default: `#{inspect(Table.default_opts()[:no_results_content])}`.
  - `:table_attrs` - The attributes for the `<table>` element.
    Default: `#{inspect(Table.default_opts()[:table_attrs])}`.
  - `:th_wrapper_attrs` - The attributes for the `<span>` element that wraps the
    header link and the order direction symbol.
    Default: `#{inspect(Table.default_opts()[:th_wrapper_attrs])}`.
  - `:symbol_asc` - The symbol that is used to indicate that the column is
    sorted in ascending order.
    Default: `#{inspect(Table.default_opts()[:symbol_asc])}`.
  - `:symbol_attrs` - The attributes for the `<span>` element that wraps the
    order direction indicator in the header columns.
    Default: `#{inspect(Table.default_opts()[:symbol_attrs])}`.
  - `:symbol_desc` - The symbol that is used to indicate that the column is
    sorted in ascending order.
    Default: `#{inspect(Table.default_opts()[:symbol_desc])}`.
  - `:target`: Sets the `phx-target` attribute for the header links.
    Default: `#{inspect(Table.default_opts()[:target])}`.
  - `:tbody_td_attrs`: Attributes to added to each `<td>` tag within the
    `<tbody>`. Default: `#{inspect(Table.default_opts()[:tbody_td_attrs])}`.
  - `:tbody_tr_attrs`: Attributes to added to each `<tr>` tag within the
    `<tbody>`. Default: `#{inspect(Table.default_opts()[:tbody_tr_attrs])}`.
  - `:thead_th_attrs`: Attributes to added to each `<th>` tag within the
    `<thead>`. Default: `#{inspect(Table.default_opts()[:thead_th_attrs])}`.
  - `:thead_tr_attrs`: Attributes to added to each `<tr>` tag within the
    `<thead>`. Default: `#{inspect(Table.default_opts()[:thead_tr_attrs])}`.
  """
  @type table_option ::
          {:container, boolean}
          | {:container_attrs, keyword}
          | {:event, binary | atom}
          | {:for, module}
          | {:no_results_content, Phoenix.HTML.safe() | binary}
          | {:symbol_asc, Phoenix.HTML.safe() | binary}
          | {:symbol_attrs, keyword}
          | {:symbol_desc, Phoenix.HTML.safe() | binary}
          | {:table_attrs, keyword}
          | {:target, binary | atom}
          | {:tbody_td_attrs, keyword}
          | {:tbody_tr_attrs, keyword}
          | {:th_wrapper_attrs, keyword}
          | {:thead_th_attrs, keyword}
          | {:thead_tr_attrs, keyword}

  @doc """
  Generates a pagination element.

  - `meta`: The meta information of the query as returned by the `Flop` query
    functions.
  - `path_helper`: The path helper function that builds a path to the current
    page, e.g. `&Routes.pet_path/3`.
  - `path_helper_args`: The arguments to be passed to the route helper
    function, e.g. `[@conn, :index]`. The page number and page size will be
    added as query parameters.
  - `opts`: Options to customize the pagination. See
    `t:Flop.Phoenix.pagination_option/0`. Note that the options passed to the
    function are deep merged into the default options.

  ## Page link options

  By default, page links for all pages are shown. You can limit the number of
  page links or disable them altogether by passing the `:page_links` option.

  - `:all`: Show all page links (default).
  - `:hide`: Don't show any page links. Only the previous/next links will be
    shown.
  - `{:ellipsis, x}`: Limits the number of page links. The first and last page
    are always displayed. The `x` refers to the number of additional page links
    to show.

  ## Pagination link aria label

  For the page links, there is the `:pagination_link_aria_label` option to set
  the aria label. Since the page number is usually part of the aria label, you
  need to pass a function that takes the page number as an integer and returns
  the label as a string. The default is `&"Goto page \#{&1}"`.

  ## Previous/next links

  By default, the previous and next links contain the texts `Previous` and
  `Next`. To change this, you can pass the `:previous_link_content` and
  `:next_link_content` options.

  See the module documentation and [Readme](README.md) for examples.
  """
  @doc section: :generators
  @spec pagination(map) :: Phoenix.LiveView.Rendered.t()
  def pagination(assigns) do
    assigns = assign(assigns, :opts, Pagination.init_opts(assigns.opts))

    ~H"""
    <%= if @meta.total_pages > 1 do %>
      <Pagination.render
        meta={@meta}
        opts={@opts}
        page_link_helper={Pagination.build_page_link_helper(
          @meta,
          @path_helper,
          @path_helper_args,
          @opts
        )}
      />
    <% end %>
    """
  end

  @doc """
  Generates a table with sortable columns.

  The argument is a map with the following keys:

  - `headers`: A list of header columns. Can be a list of strings (or markup),
    or a list of `{value, field_name}` tuples.
  - `items`: The list of items to be displayed in rows. This is the result list
    returned by the query.
  - `meta`: The `Flop.Meta` struct returned by the query function.
  - `path_helper`: The Phoenix path or url helper that leads to the current
    page.
  - `path_helper_args`: The argument list for the path helper. For example, if
    you would call `Routes.pet_path(@conn, :index)` to generate the path for the
    current page, this would be `[@conn, :index]`.
  - `opts`: Keyword list with additional options (see
    `t:Flop.Phoenix.table_option/0`). This list will also be passed as the
    second argument to the row function. Note that the options passed to the
    function are deep merged into the default options.
  - `row_func`: A function that takes one item of the `items` list and the
    `opts` and returns the column values for that item's row.

  ## Table headers

  Table headers need to be passed as a list. It is recommended to define a
  function in the `View`, `LiveView` or `LiveComponent` module that returns the
  table headers:

      def table_headers do
        ["ID", {"Name", :name}, {"Age", :age}, ""]
      end

  This defines four header columns: One for the ID, which is not sortable, and
  columns for the name and the age, which are both sortable, and a fourth
  column without a header value. The last column will hold the links to the
  detail pages. The name and age column headers will be linked, so that they the
  order on the `:name` and `:age` field, respectively.

  ## Table rows

  You need to define a function that takes a single item from the list and the
  opts passed to the component. The function needs to return a list with one
  item for each column.

      def table_row(%Pet{id: id, name: name, age: age}, opts) do
        socket = Keyword.fetch!(opts, :socket)
        [id, name, age, link("show", to: Routes.pet_path(socket, :show, id))]
      end

  See the module documentation and [Readme](README.md) for examples.
  """
  @doc since: "0.6.0"
  @doc section: :generators
  @spec table(map) :: Phoenix.LiveView.Rendered.t()
  def table(assigns) do
    assigns = assign(assigns, :opts, Table.init_opts(assigns.opts))

    ~H"""
    <%= if @items == [] do %>
      <%= @opts[:no_results_content] %>
    <% else %>
      <%= if @opts[:container] do %>
        <div {@opts[:container_attrs]}>
          <Table.render
            headers={@headers}
            items={@items}
            meta={@meta}
            opts={@opts}
            path_helper={@path_helper}
            path_helper_args={@path_helper_args}
            row_func={@row_func}
          />
        </div>
      <% else %>
        <Table.render
          headers={@headers}
          items={@items}
          meta={@meta}
          opts={@opts}
          path_helper={@path_helper}
          path_helper_args={@path_helper_args}
          row_func={@row_func}
        />
      <% end %>
    <% end %>
    """
  end

  @doc """
  Converts a Flop struct into a keyword list that can be used as a query with
  Phoenix route helper functions.

  Default limits and default order parameters set via the application
  environment are omitted. You can pass the `:for` option to pick up the
  default options from a schema module deriving `Flop.Schema`. You can also
  pass `default_limit` and `default_order` as options directly. The function
  uses `Flop.get_option/2` internally to retrieve the default options.

  ## Examples

      iex> to_query(%Flop{})
      []

      iex> f = %Flop{order_by: [:name, :age], order_directions: [:desc, :asc]}
      iex> to_query(f)
      [order_directions: [:desc, :asc], order_by: [:name, :age]]
      iex> f |> to_query |> Plug.Conn.Query.encode()
      "order_directions[]=desc&order_directions[]=asc&order_by[]=name&order_by[]=age"

      iex> f = %Flop{page: 5, page_size: 20}
      iex> to_query(f)
      [page_size: 20, page: 5]

      iex> f = %Flop{first: 20, after: "g3QAAAABZAAEbmFtZW0AAAAFQXBwbGU="}
      iex> to_query(f)
      [first: 20, after: "g3QAAAABZAAEbmFtZW0AAAAFQXBwbGU="]

      iex> f = %Flop{
      ...>   filters: [
      ...>     %Flop.Filter{field: :name, op: :=~, value: "Mag"},
      ...>     %Flop.Filter{field: :age, op: :>, value: 25}
      ...>   ]
      ...> }
      iex> to_query(f)
      [
        filters: %{
          0 => %{field: :name, op: :=~, value: "Mag"},
          1 => %{field: :age, op: :>, value: 25}
        }
      ]
      iex> f |> to_query() |> Plug.Conn.Query.encode()
      "filters[0][field]=name&filters[0][op]=%3D~&filters[0][value]=Mag&filters[1][field]=age&filters[1][op]=%3E&filters[1][value]=25"

      iex> f = %Flop{page: 5, page_size: 20}
      iex> to_query(f, default_limit: 20)
      [page: 5]
  """
  @doc since: "0.6.0"
  @doc section: :miscellaneous
  @spec to_query(Flop.t()) :: keyword
  def to_query(%Flop{filters: filters} = flop, opts \\ []) do
    filter_map =
      filters
      |> Stream.with_index()
      |> Enum.into(%{}, fn {filter, index} ->
        {index, Map.from_struct(filter)}
      end)

    keys = [
      :after,
      :before,
      :first,
      :last,
      :offset,
      :page
    ]

    default_limit = Flop.get_option(:default_limit, opts)
    default_order = Flop.get_option(:default_order, opts)

    keys
    |> Enum.reduce([], &maybe_add_param(&2, &1, Map.get(flop, &1)))
    |> maybe_add_param(:page_size, flop.page_size, default_limit)
    |> maybe_add_param(:limit, flop.limit, default_limit)
    |> maybe_add_order_params(flop, default_order)
    |> maybe_add_param(:filters, filter_map)
  end

  defp maybe_add_param(params, key, value, default \\ nil)
  defp maybe_add_param(params, _, nil, _), do: params
  defp maybe_add_param(params, _, [], _), do: params
  defp maybe_add_param(params, _, map, _) when map == %{}, do: params
  defp maybe_add_param(params, :page, 1, _), do: params
  defp maybe_add_param(params, :offset, 0, _), do: params
  defp maybe_add_param(params, _, val, val), do: params
  defp maybe_add_param(params, key, val, _), do: Keyword.put(params, key, val)

  defp maybe_add_order_params(
         params,
         %Flop{order_by: order_by, order_directions: order_directions},
         %{order_by: order_by, order_directions: order_directions}
       ),
       do: params

  defp maybe_add_order_params(
         params,
         %Flop{order_by: order_by, order_directions: order_directions},
         _
       ) do
    params
    |> maybe_add_param(:order_by, order_by)
    |> maybe_add_param(:order_directions, order_directions)
  end

  @doc """
  Takes a Phoenix path helper function and a list of path helper arguments and
  builds a path that includes query parameters for the given `Flop` struct.

  Default values for `limit`, `page_size`, `order_by` and `order_directions` are
  omit from the query parameters. To pick up the default parameters from a
  schema module deriving `Flop.Schema`, you need to pass the `:for` option.

  ## Examples

      iex> pet_path = fn _conn, :index, query ->
      ...>   "/pets?" <> Plug.Conn.Query.encode(query)
      ...> end
      iex> flop = %Flop{page: 2, page_size: 10}
      iex> build_path(pet_path, [%Plug.Conn{}, :index], flop)
      "/pets?page_size=10&page=2"

  We're defining fake path helpers for the scope of the doctests. In a real
  Phoenix application, you would pass something like `&Routes.pet_path/3` as the
  first argument.

  You can also pass a `Flop.Meta` struct or a keyword list as the third
  argument.

      iex> pet_path = fn _conn, :index, query ->
      ...>   "/pets?" <> Plug.Conn.Query.encode(query)
      ...> end
      iex> flop = %Flop{page: 2, page_size: 10}
      iex> meta = %Flop.Meta{flop: flop}
      iex> build_path(pet_path, [%Plug.Conn{}, :index], meta)
      "/pets?page_size=10&page=2"
      iex> query_params = to_query(flop)
      iex> build_path(pet_path, [%Plug.Conn{}, :index], query_params)
      "/pets?page_size=10&page=2"

  If the path helper takes additional path parameters, just add them to the
  second argument.

      iex> user_pet_path = fn _conn, :index, id, query ->
      ...>   "/users/\#{id}/pets?" <> Plug.Conn.Query.encode(query)
      ...> end
      iex> flop = %Flop{page: 2, page_size: 10}
      iex> build_path(user_pet_path, [%Plug.Conn{}, :index, 123], flop)
      "/users/123/pets?page_size=10&page=2"

  If the last path helper argument is a query parameter list, the Flop
  parameters are merged into it.

      iex> pet_url = fn _conn, :index, query ->
      ...>   "https://pets.flop/pets?" <> Plug.Conn.Query.encode(query)
      ...> end
      iex> flop = %Flop{order_by: :name, order_directions: [:desc]}
      iex> build_path(pet_url, [%Plug.Conn{}, :index, [user_id: 123]], flop)
      "https://pets.flop/pets?user_id=123&order_directions[]=desc&order_by=name"
      iex> build_path(
      ...>   pet_url,
      ...>   [%Plug.Conn{}, :index, [category: "small", user_id: 123]],
      ...>   flop
      ...> )
      "https://pets.flop/pets?category=small&user_id=123&order_directions[]=desc&order_by=name"
  """
  @doc since: "0.6.0"
  @doc section: :miscellaneous
  @spec build_path(function, [any], Meta.t() | Flop.t() | keyword, keyword) ::
          String.t()
  def build_path(path_helper, args, meta_or_flop_or_params, opts \\ [])

  def build_path(path_helper, args, %Meta{flop: flop}, opts),
    do: build_path(path_helper, args, flop, opts)

  def build_path(path_helper, args, %Flop{} = flop, opts) do
    build_path(path_helper, args, Flop.Phoenix.to_query(flop, opts))
  end

  def build_path(path_helper, args, flop_params, _opts)
      when is_function(path_helper) and
             is_list(args) and
             is_list(flop_params) do
    final_args =
      case Enum.reverse(args) do
        [last_arg | rest] when is_list(last_arg) ->
          query_arg = Keyword.merge(last_arg, flop_params)
          Enum.reverse([query_arg | rest])

        _ ->
          args ++ [flop_params]
      end

    apply(path_helper, final_args)
  end
end