defmodule LanternUI do
  @moduledoc """
  LanternUI — a dev-tool-native, open-source component system for Phoenix LiveView.

  Server-rendered HEEx/SVG components with thin JS hooks and no React or JS UI
  libraries. Built for embeddable developer tools (lantern, livecode, s3) first,
  and as a lightweight, drop-in replacement for Fluxon over time.

  ## Usage

  Import the whole component set the way you would Fluxon:

      use LanternUI

  or a subset:

      use LanternUI, only: [:charts]
      use LanternUI, except: [:charts]

  Then call components directly in HEEx (`<.area_chart .../>`, and — as they land —
  `<.button>`, `<.date_time_picker>`, …). The public API mirrors Fluxon's so a
  consumer can migrate by swapping `use Fluxon` for `use LanternUI`.

  ## Theming

  Components read every value from `--lantern-*` CSS variables, each chained to a
  host (Fluxon) token then a hard fallback, so they match a host design system
  automatically and still render standalone via the optional theme + tokens in
  `priv/static/lantern_ui.css` (light/dark + a `data-lantern-density="compact"`
  dev-tool mode). See the README for installation and JS hook setup.
  """

  # Registry of importable component groups → module. Grows as components land
  # (Phase 1: :button, :icon, :calendar, :date_picker, …). Keys are what
  # `use LanternUI, only:/except:` filters on.
  @components %{
    charts: LanternUI.Charts,
    button: LanternUI.Components.Button,
    icon: LanternUI.Components.Icon,
    form: LanternUI.Components.Form,
    calendar: LanternUI.Components.Calendar,
    datetime_field: LanternUI.Components.DatetimeField,
    date_picker: LanternUI.Components.DatePicker
  }

  @doc false
  def __components__, do: @components

  defmacro __using__(opts) do
    only = Keyword.get(opts, :only, [])
    except = Keyword.get(opts, :except, [])

    for {_key, module} <- LanternUI.__filter_components__(only, except) do
      quote do: import(unquote(module))
    end
  end

  @doc false
  def __filter_components__(only, except) do
    @components
    |> Enum.filter(fn {key, _module} ->
      cond do
        only != [] -> key in only
        except != [] -> key not in except
        true -> true
      end
    end)
  end
end