using Google.ProtocolBuffers.Descriptors;

namespace Google.ProtocolBuffers.ProtoGen {
  internal class MessageFieldGenerator : FieldGeneratorBase, IFieldSourceGenerator {

    internal MessageFieldGenerator(FieldDescriptor descriptor)
      : base(descriptor) {
    }

    public void GenerateMembers(TextGenerator writer) {
      writer.WriteLine("private bool has{0};", PropertyName);
      writer.WriteLine("private {0} {1}_ = {2};", TypeName, Name, DefaultValue);
      writer.WriteLine("public bool Has{0} {{", PropertyName);
      writer.WriteLine("  get {{ return has{0}; }}", PropertyName);
      writer.WriteLine("}");
      writer.WriteLine("public {0} {1} {{", TypeName, PropertyName);
      writer.WriteLine("  get {{ return {0}_; }}", Name);
      writer.WriteLine("}");
    }
    
    public void GenerateBuilderMembers(TextGenerator writer) {
      writer.WriteLine("public bool Has{0} {{", PropertyName);
      writer.WriteLine(" get {{ return result.Has{0}; }}", PropertyName);
      writer.WriteLine("}");
      writer.WriteLine("public {0} {1} {{", TypeName, PropertyName);
      writer.WriteLine("  get {{ return result.{0}; }}", PropertyName);
      writer.WriteLine("  set {{ Set{0}(value); }}", PropertyName);
      writer.WriteLine("}");
      writer.WriteLine("public Builder Set{0}({1} value) {{", PropertyName, TypeName);
      AddNullCheck(writer);
      writer.WriteLine("  result.has{0} = true;", PropertyName);
      writer.WriteLine("  result.{0}_ = value;", Name);
      writer.WriteLine("  return this;");
      writer.WriteLine("}");
      writer.WriteLine("public Builder Set{0}({1}.Builder builderForValue) {{", PropertyName, TypeName);
      AddNullCheck(writer, "builderForValue");
      writer.WriteLine("  result.has{0} = true;", PropertyName);
      writer.WriteLine("  result.{0}_ = builderForValue.Build();", Name);
      writer.WriteLine("  return this;");
      writer.WriteLine("}");
      writer.WriteLine("public Builder Merge{0}({1} value) {{", PropertyName, TypeName);
      AddNullCheck(writer);
      writer.WriteLine("  if (result.Has{0} &&", PropertyName);
      writer.WriteLine("      result.{0}_ != {1}) {{", Name, DefaultValue);
      writer.WriteLine("      result.{0}_ = {1}.CreateBuilder(result.{0}_).MergeFrom(value).BuildPartial();", Name, TypeName);
      writer.WriteLine("  } else {");
      writer.WriteLine("    result.{0}_ = value;", Name);
      writer.WriteLine("  }");
      writer.WriteLine("  result.has{0} = true;", PropertyName);
      writer.WriteLine("  return this;");
      writer.WriteLine("}");
      writer.WriteLine("public Builder Clear{0}() {{", PropertyName);
      writer.WriteLine("  result.has{0} = false;", PropertyName);
      writer.WriteLine("  result.{0}_ = {1};", Name, DefaultValue);
      writer.WriteLine("  return this;");
      writer.WriteLine("}");
    }

    public void GenerateMergingCode(TextGenerator writer) {
      writer.WriteLine("if (other.Has{0}) {{", PropertyName);
      writer.WriteLine("  Merge{0}(other.{0});", PropertyName);
      writer.WriteLine("}");
    }

    public void GenerateBuildingCode(TextGenerator writer) {
      // Nothing to do for singular fields
    }

    public void GenerateParsingCode(TextGenerator writer) {
      writer.WriteLine("{0}.Builder subBuilder = {0}.CreateBuilder();", TypeName);
      writer.WriteLine("if (Has{0}) {{", PropertyName);
      writer.WriteLine("  subBuilder.MergeFrom({0});", PropertyName);
      writer.WriteLine("}");
      if (Descriptor.FieldType == FieldType.Group) {
        writer.WriteLine("input.ReadGroup({0}, subBuilder, extensionRegistry);", Number);
      } else {
        writer.WriteLine("input.ReadMessage(subBuilder, extensionRegistry);");
      }
      writer.WriteLine("{0} = subBuilder.BuildPartial();", PropertyName);
    }

    public void GenerateSerializationCode(TextGenerator writer) {
      writer.WriteLine("if (Has{0}) {{", PropertyName);
      writer.WriteLine("  output.Write{0}({1}, {2});", MessageOrGroup, Number, PropertyName);
      writer.WriteLine("}");
    }

    public void GenerateSerializedSizeCode(TextGenerator writer) {
      writer.WriteLine("if (Has{0}) {{", PropertyName);
      writer.WriteLine("  size += pb::CodedOutputStream.Compute{0}Size({1}, {2});",
          MessageOrGroup, Number, PropertyName);
      writer.WriteLine("}");
    }
  }
}