module Attributor
  # It is the abstract base class to hold an attribute, both a leaf and a container (hash/Array...)
  # TODO: should this be a mixin since it is an abstract class?
  module Type
    def self.included(klass)
      klass.extend(ClassMethods)
    end

    module ClassMethods
      # Does this type support the generation of subtypes?
      def constructable?
        false
      end

      # Allow a type to be marked as if it was anonymous (i.e. not referenceable by name)
      def anonymous_type(val = true)
        @_anonymous = val
      end

      def anonymous?
        if @_anonymous.nil?
          name.nil? # if nothing is set, consider it anonymous if the class does not have a name
        else
          @_anonymous
        end
      end

      # Generic decoding and coercion of the attribute.
      def load(value, context = Attributor::DEFAULT_ROOT_CONTEXT, **_options)
        return nil if value.nil?
        unless value.is_a?(native_type)
          raise Attributor::IncompatibleTypeError.new(context: context, value_type: value.class, type: self)
        end

        value
      end

      # Generic encoding of the attribute
      def dump(value, **_opts)
        value
      end

      # TODO: refactor this to take just the options instead of the full attribute?
      # TODO: delegate to subclass
      def validate(value, context = Attributor::DEFAULT_ROOT_CONTEXT, attribute) # rubocop:disable Style/OptionalArguments
        errors = []
        attribute.options.each do |option, opt_definition|
          case option
          when :max
            errors << "#{Attributor.humanize_context(context)} value (#{value}) is larger than the allowed max (#{opt_definition.inspect})" unless value <= opt_definition
          when :min
            errors << "#{Attributor.humanize_context(context)} value (#{value}) is smaller than the allowed min (#{opt_definition.inspect})" unless value >= opt_definition
          when :regexp
            errors << "#{Attributor.humanize_context(context)} value (#{value}) does not match regexp (#{opt_definition.inspect})" unless value =~ opt_definition
          end
        end
        errors
      end

      # Default, overridable valid_type? function
      def valid_type?(value)
        return value.is_a?(native_type) if respond_to?(:native_type)

        raise AttributorException, "#{self} must implement #valid_type? or #native_type"
      end

      # Default, overridable example function
      def example(_context = nil, options: {})
        raise AttributorException, "#{self} must implement #example"
      end

      # HELPER FUNCTIONS

      def check_option!(name, definition)
        case name
        when :min
          raise AttributorException, "Value for option :min does not implement '<='. Got: (#{definition.inspect})" unless definition.respond_to?(:<=)
        when :max
          raise AttributorException, "Value for option :max does not implement '>='. Got(#{definition.inspect})" unless definition.respond_to?(:>=)
        when :regexp
          # could go for a respoind_to? :=~ here, but that seems overly... cute... and not useful.
          raise AttributorException, "Value for option :regexp is not a Regexp object. Got (#{definition.inspect})" unless definition.is_a? ::Regexp
        else
          return :unknown
        end

        :ok
      end

      def generate_subcontext(context, subname)
        context + [subname]
      end

      def dsl_compiler
        DSLCompiler
      end

      # By default, non complex types will not have a DSL subdefinition this handles such case
      def compile_dsl(options, block)
        raise AttributorException, 'Basic structures cannot take extra block definitions' if block
        # Simply create a DSL compiler to store the options, and not to parse any DSL
        sub_definition = dsl_compiler.new(options)
        sub_definition
      end

      # Default describe for simple types...only their name (stripping the base attributor module)
      def describe(_root = false, example: nil)
        type_name = Attributor.type_name(self)
        hash = {
          name: type_name.gsub(Attributor::MODULE_PREFIX_REGEX, ''),
          family: family,
          id: id
        }
        hash[:anonymous] = @_anonymous unless @_anonymous.nil?
        hash[:example] = example if example
        hash
      end

      def id
        return nil if name.nil?
        name.gsub('::'.freeze, '-'.freeze)
      end

      def family
        'any'
      end
    end
  end
end