defmodule Surface do
  @moduledoc """
  Surface is a component based library for **Phoenix LiveView**.

  Built on top of the new `Phoenix.LiveComponent` API, Surface provides
  a more declarative way to express and use components in Phoenix.

  Full documentation and live examples can be found at [surface-ui.org](https://surface-ui.org)

  This module defines the `~F` sigil that should be used to translate Surface
  code into Phoenix templates.

  In order to have `~F` available for any Phoenix view, add the following import to your web
  file in `lib/my_app_web.ex`:

      # lib/my_app_web.ex

      ...

      def view do
        quote do
          ...
          import Surface
        end
      end

  Additionally, use `Surface.init/1` in your mount function to initialize assigns used internally by surface:

      # A LiveView using surface templates

      defmodule PageLive do
        use Phoenix.LiveView
        import Surface

        def mount(_params, _session, socket) do
          socket = Surface.init(socket)
          ...
          {:ok, socket}
        end

        def render(assigns) do
          ~F"\""
          ...
          "\""
        end
      end

      # A LiveComponent using surface templates

      defmodule NavComponent do
        use Phoenix.LiveComponent
        import Surface

        def mount(socket) do
          socket = Surface.init(socket)
          ...
          {:ok, socket}
        end

        def render(assigns) do
          ~F"\""
          ...
          "\""
        end
      end

  ## Defining components

  To create a component you need to define a module and `use` one of the available component types:

    * `Surface.Component` - A stateless component.
    * `Surface.LiveComponent` - A live stateful component.
    * `Surface.LiveView` - A wrapper component around `Phoenix.LiveView`.
    * `Surface.MacroComponent` - A low-level component which is responsible for translating its own content at compile time.

  ## Example

      # A functional stateless component

      defmodule Button do
        use Surface.Component

        prop click, :event
        prop kind, :string, default: "is-info"

        def render(assigns) do
          ~F"\""
          <button class={"button", @kind} :on-click={@click}>
            <#slot/>
          </button>
          "\""
        end
      end

  You can visit the documentation of each type of component for further explanation and examples.
  """

  alias Phoenix.LiveView
  alias Surface.API
  alias Surface.Compiler.Helpers
  alias Surface.IOHelper
  alias Surface.TypeHandler

  @doc """
  Translates Surface code into Phoenix templates.
  """
  defmacro sigil_F({:<<>>, meta, [string]}, opts) do
    line_offset = if Keyword.has_key?(meta, :indentation), do: 1, else: 0
    line = __CALLER__.line + line_offset
    indentation = meta[:indentation] || 0
    column = meta[:column] || 1

    caller_is_surface_component =
      Module.open?(__CALLER__.module) &&
        Module.get_attribute(__CALLER__.module, :component_type) != nil

    string
    |> Surface.Compiler.compile(line, __CALLER__, __CALLER__.file,
      checks: [no_undefined_assigns: caller_is_surface_component],
      indentation: indentation,
      column: column
    )
    |> Surface.Compiler.to_live_struct(
      debug: Enum.member?(opts, ?d),
      file: __CALLER__.file,
      line: line
    )
  end

  @doc """
  Converts the given code into Surface's AST.

  The code must be passed with the `do` block using the `~F` sigil.

  Optional `line` and `file` metadata can be passed using `opts`.

  ## Example

      iex> [tag] =
      ...>   quote_surface do
      ...>     ~F"<div>content</div>"
      ...>   end
      ...>
      ...> tag.children
      [%Surface.AST.Literal{directives: [], value: "content"}]

  """
  defmacro quote_surface(opts \\ [], do: block) do
    {code, sigil_meta, string_meta} =
      case block do
        {:sigil_F, sigil_meta, [{:<<>>, string_meta, [code]}, _]} ->
          {code, sigil_meta, string_meta}

        _ ->
          message = "the code to be quoted must be wrapped in a `~F` sigil."
          IOHelper.compile_error(message, __CALLER__.file, __CALLER__.line)
      end

    delimiter = Keyword.fetch!(sigil_meta, :delimiter)
    line_offset = if delimiter == ~S("""), do: 1, else: 0
    default_line = Keyword.get(sigil_meta, :line) + line_offset

    line = Keyword.get(opts, :line, default_line)
    file = Keyword.get(opts, :file, __CALLER__.file)
    indentation = Keyword.get(string_meta, :indentation, 0)

    quote do
      Surface.Compiler.compile(unquote(code), unquote(line), __ENV__, unquote(file),
        checks: [no_undefined_assigns: false],
        indentation: unquote(indentation),
        column: 1,
        variables: binding()
      )
    end
  end

  @doc "Retrieve a component's config based on the `key`"
  def get_config(component, key) do
    config = get_components_config()
    config[component][key]
  end

  @doc "Retrieve the component's config based on the `key`"
  defmacro get_config(key) do
    component = __CALLER__.module

    quote do
      get_config(unquote(component), unquote(key))
    end
  end

  @doc "Retrieve all component's config"
  def get_components_config() do
    Application.get_env(:surface, :components, [])
  end

  @doc "Initialize surface state in the socket"
  def init(socket) do
    socket
    |> LiveView.assign_new(:__context__, fn -> %{} end)
  end

  @doc false
  def default_props(module) do
    props = if function_exported?(module, :__props__, 0), do: module.__props__(), else: []
    Enum.map(props, fn %{name: name, opts: opts} -> {name, opts[:default]} end)
  end

  @doc false
  def build_dynamic_assigns(context, static_props, dynamic_props, module, node_alias, ctx) do
    Code.ensure_loaded(module)

    static_props =
      for {name, value} <- static_props || [] do
        {clauses, opts, original} =
          case value do
            # Value is an expression
            {_clauses, _opts, _original} ->
              value

            # Value is a literal
            _ ->
              {[value], [], nil}
          end

        {name, TypeHandler.runtime_prop_value!(module, name, clauses, opts, inspect(module), original, ctx)}
      end

    build_assigns(context, static_props, dynamic_props, module, node_alias, ctx)
  end

  @doc false
  def build_assigns(context, static_props, dynamic_props, module, node_alias, ctx) do
    Code.ensure_loaded(module)

    static_prop_names = Keyword.keys(static_props)

    dynamic_props =
      for {name, value} <- dynamic_props || [], !Enum.member?(static_prop_names, name) do
        runtime_value = TypeHandler.runtime_prop_value!(module, name, [value], [], node_alias, nil, ctx)
        {name, runtime_value}
      end

    props =
      module
      |> default_props()
      |> Keyword.merge(dynamic_props)
      |> Keyword.merge(static_props)

    if module do
      Map.new([__context__: context] ++ props)
    else
      # Function components don't support contexts
      Map.new(props)
    end
  end

  @doc false
  def css_class(value) when is_list(value) do
    with {:ok, value} <- Surface.TypeHandler.CssClass.expr_to_value(value, [], _ctx = %{}),
         {:ok, string} <- Surface.TypeHandler.CssClass.value_to_html("class", value) do
      string
    else
      _ ->
        Surface.IOHelper.runtime_error(
          "invalid value. " <>
            "Expected a :css_class, got: #{inspect(value)}"
        )
    end
  end

  @doc false
  def event_to_opts(%{name: name, target: :live_view}, event_name) do
    [{event_name, name}]
  end

  def event_to_opts(%{name: name, target: target}, event_name) do
    [{event_name, name}, {:phx_target, target}]
  end

  def event_to_opts(%Phoenix.LiveView.JS{} = value, event_name) do
    [{event_name, value}]
  end

  def event_to_opts(nil, _event_name) do
    []
  end

  @doc false
  defmacro prop_to_attr_opts(prop_value, prop_name) do
    quote do
      prop_to_attr_opts(unquote(prop_value), unquote(prop_name), __ENV__)
    end
  end

  @doc false
  def prop_to_attr_opts(nil, _prop_name, _caller) do
    []
  end

  def prop_to_attr_opts(prop_value, prop_name, caller) do
    module = caller.module
    meta = %{caller: caller, line: caller.line, node_alias: module}
    {type, _opts} = Surface.TypeHandler.attribute_type_and_opts(module, prop_name, meta)
    Surface.TypeHandler.attr_to_opts!(type, prop_name, prop_value)
  end

  @doc """
  Tests if a slot has been filled in.

  Useful to avoid rendering unnecessary html tags that are used to wrap an optional slot
  in combination with `:if` directive.

  ## Examples

    ```
    <div :if={slot_assigned?(:header)}>
      <#slot name="header"/>
    </div>
    ```
  """
  defmacro slot_assigned?(slot) when is_atom(slot) do
    validate_undefined_slot(slot, __CALLER__)

    quote do
      !!var!(assigns)[unquote(slot)]
    end
  end

  # TODO: This is only for LV <= 0.17.5. Remove it when surface requires LV >= 0.17.6
  defmacro slot_assigned?(
             {{:., _, [Phoenix.LiveView.Engine, :fetch_assign!]}, _, [{:assigns, _, _}, slot_name]} = slot
           ) do
    validate_undefined_slot(slot_name, __CALLER__)

    quote do
      !!unquote(slot)
    end
  end

  defmacro slot_assigned?({{:., _, [{:assigns, _, _}, slot_name]}, _, _} = slot) do
    validate_undefined_slot(slot_name, __CALLER__)

    quote do
      !!unquote(slot)
    end
  end

  defp validate_undefined_slot(slot_name, caller) do
    defined_slots =
      API.get_slots(caller.module)
      |> Enum.map(& &1.name)
      |> Enum.uniq()

    if slot_name not in defined_slots do
      similar_slot_message =
        case Helpers.did_you_mean(slot_name, defined_slots) do
          {similar, score} when score > 0.8 ->
            "\n\n  Did you mean #{inspect(to_string(similar))}?"

          _ ->
            ""
        end

      existing_slots_message =
        if defined_slots == [] do
          ""
        else
          slots =
            defined_slots
            |> Enum.map(&to_string/1)
            |> Enum.sort()

          available = Helpers.list_to_string("slot:", "slots:", slots)
          "\n\n  Available #{available}"
        end

      message = """
      no slot "#{slot_name}" defined in the component '#{caller.module}'\
      #{similar_slot_message}\
      #{existing_slots_message}\
      """

      IOHelper.warn(message, caller)
    end
  end
end