package at.gv.egiz.eaaf.core.impl.json;

import java.io.IOException;
import java.io.StringWriter;
import java.util.Collection;

import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.fasterxml.jackson.databind.node.TextNode;
import com.fasterxml.jackson.databind.ser.std.StdSerializer;


/**
 * Custom Jackson Serializer to support generic types and serialize them as
 * escaped Strings.
 * 
 * <p>
 * Code was an example from stack-overflow.
 * </p>
 * 
 * @author tlenz
 *
 */
public class EscapedJsonSerializer extends StdSerializer<Object> {
  private static final long serialVersionUID = 7334472154148003249L;

  public EscapedJsonSerializer() {
    super((Class<Object>) null);
  }

  @Override
  public void serialize(Object value, JsonGenerator gen, SerializerProvider provider) throws IOException {
    StringWriter str = new StringWriter();
    JsonGenerator tempGen = new JsonFactory().setCodec(gen.getCodec()).createGenerator(str);
    if (value instanceof Collection || value.getClass().isArray()) {
      tempGen.writeStartArray();
      if (value instanceof Collection) {
        for (Object it : (Collection) value) {
          writeTree(gen, it, tempGen);
        }
      } else if (value.getClass().isArray()) {
        for (Object it : (Object[]) value) {
          writeTree(gen, it, tempGen);
        }
      }
      tempGen.writeEndArray();
    } else {
      provider.defaultSerializeValue(value, tempGen);
    }
    tempGen.flush();
    gen.writeString(str.toString());
  }

  @Override
  public void serializeWithType(Object value, JsonGenerator gen, SerializerProvider serializers,
      TypeSerializer typeSer) throws IOException {
    StringWriter str = new StringWriter();
    JsonGenerator tempGen = new JsonFactory().setCodec(gen.getCodec()).createGenerator(str);
    writeTree(gen, value, tempGen);
    tempGen.flush();
    gen.writeString(str.toString());
  }

  private void writeTree(JsonGenerator gen, Object it, JsonGenerator tempGen) throws IOException {
    ObjectNode tree = ((ObjectMapper) gen.getCodec()).valueToTree(it);
    tree.set("@class", new TextNode(it.getClass().getName()));
    tempGen.writeTree(tree);
  }
}