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/*
 * Copyright (C) 2014 Square, Inc.
 *
 * 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.squareup.moshi;

import com.jn.langx.annotation.Nullable;

import java.io.IOException;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.util.*;

/**
 * Converts collection types to JSON arrays containing their converted contents.
 */
abstract class CollectionJsonAdapter, T> extends JsonAdapter {
    public static final JsonAdapter.Factory FACTORY = new JsonAdapter.Factory() {
        @Override
        public @Nullable
        JsonAdapter create(
                Type type, Set annotations, Moshi moshi) {
            Class rawType = Types.getRawType(type);
            if (!annotations.isEmpty()) {
                return null;
            }
            if (rawType == List.class || rawType == Collection.class) {
                return newArrayListAdapter(type, moshi).nullSafe();
            } else if (rawType == Set.class) {
                return newLinkedHashSetAdapter(type, moshi).nullSafe();
            }
            return null;
        }
    };

    private final JsonAdapter elementAdapter;

    private CollectionJsonAdapter(JsonAdapter elementAdapter) {
        this.elementAdapter = elementAdapter;
    }

    static  JsonAdapter> newArrayListAdapter(Type type, Moshi moshi) {
        Type elementType = Types.collectionElementType(type, Collection.class);
        JsonAdapter elementAdapter = moshi.adapter(elementType);
        return new CollectionJsonAdapter, T>(elementAdapter) {
            @Override
            Collection newCollection() {
                return new ArrayList();
            }
        };
    }

    static  JsonAdapter> newLinkedHashSetAdapter(Type type, Moshi moshi) {
        Type elementType = Types.collectionElementType(type, Collection.class);
        JsonAdapter elementAdapter = moshi.adapter(elementType);
        return new CollectionJsonAdapter, T>(elementAdapter) {
            @Override
            Set newCollection() {
                return new LinkedHashSet();
            }
        };
    }

    abstract C newCollection();

    @Override
    public C fromJson(JsonReader reader) throws IOException {
        C result = newCollection();
        reader.beginArray();
        while (reader.hasNext()) {
            result.add(elementAdapter.fromJson(reader));
        }
        reader.endArray();
        return result;
    }

    @Override
    public void toJson(JsonWriter writer, C value) throws IOException {
        writer.beginArray();
        for (T element : value) {
            elementAdapter.toJson(writer, element);
        }
        writer.endArray();
    }

    @Override
    public String toString() {
        return elementAdapter + ".collection()";
    }
}