CrestDataProcessor.java

package net.troja.eve.crest;

/*
 * ========================================================================
 * Library for the Eve Online CREST API
 * ------------------------------------------------------------------------
 * Copyright (C) 2014 - 2015 Jens Oberender <j.obi@troja.net>
 * ------------------------------------------------------------------------
 * 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.
 * ========================================================================
 */

import java.io.IOException;

import net.troja.eve.crest.processors.CrestApiProcessor;
import net.troja.eve.crest.utils.JsonPaths;

import org.apache.commons.lang.StringUtils;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonToken;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

public class CrestDataProcessor {
    private static final Logger LOGGER = LogManager.getLogger(CrestHandler.class);

    private CrestAccessor accessor = new CrestAccessor();
    private final ObjectMapper mapper;

    public CrestDataProcessor() {
        mapper = new ObjectMapper();
        mapper.enable(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT);
        mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
    }

    public void setAccessor(final CrestAccessor accessor) {
        this.accessor = accessor;
    }

    public <T> T downloadAndProcessData(final CrestApiProcessor<T> processor) {
        T result = null;
        try {
            final String data = accessor.getData(processor.getPath());
            if (StringUtils.isNotBlank(data)) {
                final JsonNode node = mapper.readTree(data);
                result = processor.parseEntry(node);
            } else if (LOGGER.isWarnEnabled()) {
                LOGGER.warn("No data to parse for " + processor.getClass().getSimpleName());
            }
        } catch (final IOException e) {
            if (LOGGER.isErrorEnabled()) {
                LOGGER.error("Could not download data", e);
            }
        }
        return result;
    }

    public <T> CrestContainer<T> downloadAndProcessContainerData(final CrestApiProcessor<T> processor) {
        CrestContainer<T> container = null;
        try {
            String data = accessor.getData(processor.getPath());
            if (StringUtils.isNotBlank(data)) {
                container = new CrestContainer<T>();
                String next = processData(processor, container, data);
                while (next != null) {
                    data = accessor.getDataPage(next);
                    next = processData(processor, container, data);
                }
                container.setTimestamp(System.currentTimeMillis());
            } else if (LOGGER.isWarnEnabled()) {
                LOGGER.warn("No data to parse for " + processor.getClass().getSimpleName());
            }
        } catch (final IOException e) {
            if (LOGGER.isErrorEnabled()) {
                LOGGER.error("Could not download data", e);
            }
        }
        return container;
    }

    private <T> String processData(final CrestApiProcessor<T> processor, final CrestContainer<T> container, final String data) {
        String next = null;
        try {
            final JsonFactory parserFactory = new JsonFactory();
            final JsonParser jsonParser = parserFactory.createParser(data);
            jsonParser.nextToken();
            while (jsonParser.nextToken() != JsonToken.END_OBJECT) {
                final String fieldname = jsonParser.getCurrentName();
                jsonParser.nextToken();
                switch (fieldname) {
                    case "totalCount":
                        container.setTotalCount(jsonParser.getIntValue());
                        break;
                    case "pageCount":
                        container.setPageCount(jsonParser.getIntValue());
                        break;
                    case "items":
                        processItems(processor, container, jsonParser);
                        break;
                    case "next":
                        next = processNext(jsonParser);
                        break;
                    default:
                        break;
                }
            }
        } catch (final IOException e) {
            if (LOGGER.isWarnEnabled()) {
                LOGGER.warn("Problems while parsing json data: " + e.getMessage(), e);
            }
        }
        return next;
    }

    private <T> void processItems(final CrestApiProcessor<T> processor, final CrestContainer<T> container, final JsonParser jsonParser)
            throws IOException {
        if (jsonParser.isExpectedStartArrayToken()) {
            while (jsonParser.nextToken() != JsonToken.END_ARRAY) {
                container.addEntry(processor.parseEntry((JsonNode) mapper.readTree(jsonParser)));
            }
        }
    }

    private String processNext(final JsonParser jsonParser) throws IOException {
        String next = null;
        jsonParser.nextToken();
        if (JsonPaths.HREF.equals(jsonParser.getCurrentName())) {
            jsonParser.nextToken();
            next = jsonParser.getText();
            jsonParser.nextToken();
        }
        return next;
    }
}