compile_time_subclasses.cr

require "json"

abstract class Plugin
  macro def self.find_by_name(name) : Plugin.class
    case name
      {% for subclass in Plugin.all_subclasses %}
        when {{subclass.name}}
          {{subclass.name.id}}
      {% end %}
    else
      raise "Uknown plugin: #{name}"
    end
  end
end

class PluginOne < Plugin
  json_mapping({one: String})
end

class PluginTwo < Plugin
  json_mapping({two: String})
end

class Plugins
  def self.new(pull : JSON::PullParser)
    plugins = [] of Plugin
    pull.read_object do |key|
      plugins << Plugin.find_by_name(key).new(pull)
    end
    plugins
  end
end

class Config
  json_mapping({plugins: Plugins})
end

json = %(
  {
    "plugins": {
      "PluginOne": {
        "one": "HOLA"
      },
      "PluginTwo": {
        "two": "CHAU"
      }
    }
  }
)

config = Config.from_json(json)
pp config