mvz/gir_ffi

# frozen_string_literal: true

GObject.load_class :Value

module GObject
  # Overrides for GValue, GObject's generic value container structure.
  class Value
    setup_instance_method! :init

    METHOD_MAP = {
      TYPE_INVALID => [:get_none, :set_none],
      # TYPE_NONE is skipped
      TYPE_INTERFACE => [:get_object, :set_instance_enhanced],
      TYPE_CHAR => [:get_schar, :set_schar],
      TYPE_UCHAR => [:get_uchar, :set_uchar],
      TYPE_BOOLEAN => [:get_boolean, :set_boolean],
      TYPE_INT => [:get_int, :set_int],
      TYPE_UINT => [:get_uint,           :set_uint],
      TYPE_LONG => [:get_long,           :set_long],
      TYPE_ULONG => [:get_ulong,          :set_ulong],
      TYPE_INT64 => [:get_int64,          :set_int64],
      TYPE_UINT64 => [:get_uint64, :set_uint64],
      TYPE_ENUM => [:get_enum_enhanced, :set_enum_enhanced],
      TYPE_FLAGS => [:get_flags_enhanced, :set_flags_enhanced],
      TYPE_FLOAT => [:get_float,          :set_float],
      TYPE_DOUBLE => [:get_double,         :set_double],
      TYPE_STRING => [:get_string,         :set_string],
      TYPE_POINTER => [:get_pointer, :set_pointer],
      TYPE_BOXED => [:get_boxed,          :set_boxed],
      TYPE_PARAM => [:get_param,          :set_param],
      TYPE_OBJECT => [:get_object, :set_instance_enhanced],
      TYPE_GTYPE => [:get_gtype, :set_gtype],
      TYPE_VARIANT => [:get_variant, :set_variant]
    }.freeze

    # TODO: Give more generic name
    def self.wrap_ruby_value(val)
      new.tap { |gv| gv.__send__ :set_ruby_value, val }
    end

    def self.from(val)
      case val
      when self
        val
      else
        wrap_ruby_value val
      end
    end

    def self.for_gtype(gtype)
      new.tap do |it|
        it.init gtype
      end
    end

    # TODO: Combine with wrap_ruby_value
    def self.wrap_instance(instance)
      new.tap do |it|
        it.init GObject.type_from_instance instance
        it.set_instance instance
      end
    end

    def self.copy_value_to_pointer(value, pointer, offset = 0)
      target = wrap(pointer + offset)
      target.init(value.current_gtype)
      Lib.g_value_copy value, target unless value.uninitialized?
    end

    CLASS_TO_GTYPE_MAP = {
      NilClass => TYPE_INVALID,
      TrueClass => TYPE_BOOLEAN,
      FalseClass => TYPE_BOOLEAN,
      Integer => TYPE_INT,
      String => TYPE_STRING
    }.freeze

    # Overrides for existing Value methods
    module Overrides
      def set_value(val)
        send set_method, val
      end

      alias_method :value=, :set_value

      def current_gtype
        struct[:g_type]
      end

      def current_fundamental_type
        GObject.type_fundamental current_gtype
      end

      def current_gtype_name
        GObject.type_name current_gtype
      end

      def get_value
        value = get_value_plain
        if current_fundamental_type == TYPE_BOXED
          wrap_boxed value
        else
          value
        end
      end

      def get_value_plain
        send get_method
      end

      def uninitialized?
        current_gtype == TYPE_INVALID
      end

      def init(type)
        Lib.g_value_init self, type unless [TYPE_NONE, TYPE_INVALID].include? type
        self
      end

      private

      def set_ruby_value(val)
        init_for_ruby_value val if uninitialized?
        set_value val
      end

      def init_for_ruby_value(val)
        return init val.class.gtype if val.class.respond_to? :gtype

        CLASS_TO_GTYPE_MAP.each do |klass, type|
          return init type if val.is_a? klass
        end
        raise "Can't handle #{val.class}"
      end

      def set_none(_val); end

      def get_none; end

      def set_instance_enhanced(val)
        check_type_compatibility val if val
        set_instance val
      end

      def set_enum_enhanced(val)
        val = current_gtype_class.to_native(val, nil)
        set_enum val
      end

      def get_enum_enhanced
        current_gtype_class.wrap(get_enum)
      end

      def set_flags_enhanced(val)
        val = current_gtype_class.to_native(val, nil)
        set_flags val
      end

      def get_flags_enhanced
        current_gtype_class.wrap(get_flags)
      end

      def current_gtype_class
        GirFFI::Builder.build_by_gtype(current_gtype)
      end

      def check_type_compatibility(val)
        if GObject::Value.type_compatible(GObject.type_from_instance(val), current_gtype)
          return
        end

        raise ArgumentError, "#{val.class} is incompatible with #{current_gtype_name}"
      end

      def wrap_boxed(boxed)
        case current_gtype
        when TYPE_STRV
          GLib::Strv.wrap boxed
        when TYPE_HASH_TABLE
          GLib::HashTable.wrap [:gpointer, :gpointer], boxed
        when TYPE_ARRAY
          GLib::Array.wrap nil, boxed
        else
          current_gtype_class.wrap(boxed) unless boxed.null?
        end
      end

      def get_method
        method_map_entry.first
      end

      def set_method
        method_map_entry.last
      end

      def method_map_entry
        METHOD_MAP[current_gtype] || METHOD_MAP[current_fundamental_type] ||
          raise("No method map entry for '#{current_gtype_name}'")
      end
    end

    prepend Overrides
  end
end