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/*
 * Copyright (c) 2008-2019 the original author or authors.
 *
 * 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 org.cometd.common;

import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.text.ParseException;
import java.util.List;

import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.cometd.bayeux.Message;

public abstract class JacksonJSONContext {
    private final ObjectMapper objectMapper = new ObjectMapper();
    private final JavaType rootArrayType;

    protected JacksonJSONContext() {
        rootArrayType = objectMapper.constructType(rootArrayClass());
    }

    public ObjectMapper getObjectMapper() {
        return objectMapper;
    }

    protected abstract Class rootArrayClass();

    public T[] parse(InputStream stream) throws ParseException {
        try {
            return getObjectMapper().readValue(stream, rootArrayType);
        } catch (IOException x) {
            throw (ParseException)new ParseException("", -1).initCause(x);
        }
    }

    public T[] parse(Reader reader) throws ParseException {
        try {
            return getObjectMapper().readValue(reader, rootArrayType);
        } catch (IOException x) {
            throw (ParseException)new ParseException("", -1).initCause(x);
        }
    }

    public T[] parse(String json) throws ParseException {
        try {
            return getObjectMapper().readValue(json, rootArrayType);
        } catch (IOException x) {
            throw (ParseException)new ParseException(json, -1).initCause(x);
        }
    }

    public String generate(T message) {
        try {
            return getObjectMapper().writeValueAsString(message);
        } catch (IOException x) {
            throw new RuntimeException(x);
        }
    }

    public String generate(List messages) {
        try {
            Message.Mutable[] mutables = new Message.Mutable[messages.size()];
            messages.toArray(mutables);
            return getObjectMapper().writeValueAsString(mutables);
        } catch (IOException x) {
            throw new RuntimeException(x);
        }
    }

    public JSONContext.Parser getParser() {
        return new ObjectMapperParser();
    }

    public JSONContext.Generator getGenerator() {
        return new ObjectMapperGenerator();
    }

    private class ObjectMapperParser implements JSONContext.Parser {
        @Override
        public  T parse(Reader reader, Class type) throws ParseException {
            try {
                return getObjectMapper().readValue(reader, type);
            } catch (IOException x) {
                throw (ParseException)new ParseException("", -1).initCause(x);
            }
        }
    }

    private class ObjectMapperGenerator implements JSONContext.Generator {
        @Override
        public String generate(Object object) {
            try {
                return getObjectMapper().writeValueAsString(object);
            } catch (IOException x) {
                throw new RuntimeException(x);
            }
        }
    }
}