package com.hkm.urbansdk.gson;

import com.google.gson.Gson;
import com.google.gson.TypeAdapter;
import com.google.gson.TypeAdapterFactory;
import com.google.gson.reflect.TypeToken;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonToken;
import com.google.gson.stream.JsonWriter;

import java.io.IOException;

/**
 * Created by hesk on 2/17/15.
 */
public class NullStringToEmptyAdapterFactory<T> implements TypeAdapterFactory {
    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
        Class<T> rawType = (Class<T>) type.getRawType();
        if (!rawType.equals(String.class)) {
            return null;
        }
        return (TypeAdapter<T>) new StringAdapter();
    }

    public class StringAdapter extends TypeAdapter<String> {
        public String read(JsonReader reader) throws IOException {
            if (reader.peek() == JsonToken.NULL) {
                reader.nextNull();
                return "";
            }
            return reader.nextString();
        }

        public void write(JsonWriter writer, String value) throws IOException {
            if (value == null) {
                writer.nullValue();
                return;
            }
            writer.value(value);
        }
    }
}
