// Copyright (C) 2016 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.gerrit.server.events;

import static com.google.common.base.Preconditions.checkArgument;

import com.google.common.base.Supplier;
import com.google.common.base.Suppliers;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonParseException;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

public class SupplierDeserializer implements JsonDeserializer<Supplier<?>> {

  @Override
  public Supplier<?> deserialize(JsonElement json, Type typeOfT,
      JsonDeserializationContext context) throws JsonParseException {
    checkArgument(typeOfT instanceof ParameterizedType);
    ParameterizedType parameterizedType = (ParameterizedType) typeOfT;
    if (parameterizedType.getActualTypeArguments().length != 1) {
      throw new JsonParseException(
          "Expected one parameter type in Supplier interface.");
    }
    Type supplierOf = parameterizedType.getActualTypeArguments()[0];
    return Suppliers.ofInstance(context.deserialize(json, supplierOf));
  }
}

Add custom JSON deserializer for Supplier
Add custom JSON deserializer for Supplier

This deserializer is useful for plugins to deserialize Events wrapped in
the Supplier interface.

Deserialization using EventDeserializer was broken by change 73527 [1].

[1] https://gerrit-review.googlesource.com/73527

Change-Id: Ia681fafe25054fca6ce98f9a5c93592697c162fa
Signed-off-by: Dariusz Luksza <d9c42035ad9447bda4101be2f02a7db3fa874023@luksza.org>
