# frozen_string_literal: true

require 'ffi'
require_relative 'accessors'

module FFI
  # Helper to wrap structs with ugly names and attribute clashes with FFI::Struct (eg size)
  module StructWrapper
    # @!visibility private
    class ByReference < StructByReference
      def initialize(wrapper_class)
        super(wrapper_class.native_struct)
        @wrapper_class = wrapper_class
      end

      def to_native(value, ctx)
        return Pointer::NULL if value.nil?

        value = value.native if value.is_a?(StructWrapper)
        super(value, ctx)
      end

      def from_native(value, ctx)
        return nil if value.null?

        native = super(value, ctx)
        @wrapper_class.new(native)
      end
    end

    # Additional class methods for StructWrapper
    module ClassMethods
      # @!visibility private
      def from_native(value, _)
        new(value)
      end

      # @!visibility private
      def to_native(value, _)
        case value
        when native_type
          value
        when self
          value.native
        else
          new.fill(value).native
        end
      end

      # @!visibility private
      def native_struct(struct_class = nil)
        if struct_class
          native_type(struct_class.by_value)
          @struct_class = struct_class
        end
        @struct_class
      end

      # @return [Type] represents a pointer to the wrapped struct
      def by_ref
        @by_ref ||= ByReference.new(self)
      end

      # @return [Type] represents passing wrapped struct by value
      def by_value
        self
      end
    end

    class << self
      # @!visibility private
      def included(mod)
        mod.extend(DataConverter)
        mod.extend(ClassMethods)
        mod.include(Accessors)
      end
    end

    # @!parse extend ClassMethods
    # @!parse include Accessors

    # @!visibility private
    attr_reader :native

    # @!visibility private
    def initialize(native = self.class.native_struct.new)
      @native = native
    end

    # Get attribute
    def [](member_or_attr)
      @native[self.class.ffi_attr_readers.fetch(member_or_attr, member_or_attr)]
    end

    # Set attribute
    def []=(member_or_attr, val)
      @native[self.class.ffi_attr_writers.fetch(member_or_attr, member_or_attr)] = val
    end
  end
end