// Copyright 2012 Google Inc. All Rights Reserved.

package com.google.collide.server.documents;

import static com.google.collide.dto.DocOpComponent.Type.DELETE;
import static com.google.collide.dto.DocOpComponent.Type.INSERT;
import static com.google.collide.dto.DocOpComponent.Type.RETAIN;
import static com.google.collide.dto.DocOpComponent.Type.RETAIN_LINE;

import com.google.collide.dto.DocOpComponent;
import com.google.collide.dto.DocOpComponent.Delete;
import com.google.collide.dto.DocOpComponent.Insert;
import com.google.collide.dto.DocOpComponent.Retain;
import com.google.collide.dto.DocOpComponent.RetainLine;
import com.google.collide.dto.server.DtoServerImpls.DocOpComponentImpl;
import com.google.collide.dto.server.ServerDocOpFactory;
import com.google.gson.Gson;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;

import java.lang.reflect.Type;

/*
 * TODO(jasonparekh): consider creating custom deserializers for subclasses as a
 * feature in our DTO generator, or at minimum constants for the JSON property
 * keys.
 */

/**
 * Custom {@link Gson} deserializer for {@link DocOpComponent} subclasses.
 *
 * @author jasonparekh@google.com (Jason Parekh)
 */
public class DocOpComponentDeserializer
    implements
      JsonDeserializer<DocOpComponentImpl>,
      JsonSerializer<DocOpComponentImpl> {

  @Override
  public DocOpComponentImpl deserialize(JsonElement json, Type typeOfT,
      JsonDeserializationContext context) throws JsonParseException {

    JsonObject componentJo = json.getAsJsonObject();

    switch (componentJo.get("type").getAsInt()) {
      case DELETE:
        return (DocOpComponentImpl) ServerDocOpFactory.INSTANCE.createDelete(componentJo
            .get("text")
            .getAsString());

      case INSERT:
        return (DocOpComponentImpl) ServerDocOpFactory.INSTANCE.createInsert(componentJo
            .get("text")
            .getAsString());

      case RETAIN:
        return (DocOpComponentImpl) ServerDocOpFactory.INSTANCE.createRetain(
            componentJo.get("count").getAsInt(),
            componentJo.get("hasTrailingNewline").getAsBoolean());

      case RETAIN_LINE:
        return (DocOpComponentImpl) ServerDocOpFactory.INSTANCE.createRetainLine(componentJo.get(
            "lineCount").getAsInt());

      default:
        throw new IllegalArgumentException("Could not deserialize DocOpComponent: "
            + componentJo);
    }
  }

  @Override
  public JsonElement serialize(DocOpComponentImpl component, Type typeOfSrc,
      JsonSerializationContext context) {

    JsonObject componentJo = new JsonObject();
    componentJo.addProperty("type", component.getType());

    switch (component.getType()) {
      case DELETE:
        componentJo.addProperty("text", ((Delete) component).getText());
        break;

      case INSERT:
        componentJo.addProperty("text", ((Insert) component).getText());
        break;

      case RETAIN:
        componentJo.addProperty("count", ((Retain) component).getCount());
        componentJo.addProperty("hasTrailingNewline", ((Retain) component).hasTrailingNewline());
        break;

      case RETAIN_LINE:
        componentJo.addProperty("lineCount", ((RetainLine) component).getLineCount());
        break;

      default:
        throw new IllegalArgumentException("Could not serialize DocOpComponent: " + component);
    }

    return componentJo;
  }
}