/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.tika.language.translate;

import static java.nio.charset.StandardCharsets.UTF_8;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Properties;

import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

import org.apache.cxf.jaxrs.client.WebClient;
import org.apache.tika.exception.TikaException;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * An implementation of a REST client for the
 * <a href="https://developer.lingo24.com/premium-machine-translation-api">Premium MT API v1</a>.
 * You can sign up for an access plan online on the <a href="https://developer.lingo24.com/plans">Lingo24 Developer Portal</a>
 * and set your Application's User Key in the <code>translator.lingo24.properties</code> file.
 */
public class Lingo24Translator extends AbstractTranslator {

    private static final Logger LOG = LoggerFactory.getLogger(Lingo24Translator.class);

    private static final String LINGO24_TRANSLATE_URL_BASE = "https://api.lingo24.com/mt/v1/translate";

    private static final String DEFAULT_KEY = "dummy-key";

    private WebClient client;

    private String userKey;

    private boolean isAvailable;

    public Lingo24Translator() {
        this.client = WebClient.create(LINGO24_TRANSLATE_URL_BASE);
        this.isAvailable = true;
        Properties config = new Properties();
        try {
            config.load(Lingo24Translator.class
                    .getResourceAsStream(
                            "translator.lingo24.properties"));
            this.userKey = config.getProperty("translator.user-key");
            if (this.userKey.equals(DEFAULT_KEY))
                this.isAvailable = false;
        } catch (Exception e) {
            LOG.warn("Couldn't read config file", e);
            isAvailable = false;
        }
    }

    @Override
    public String translate(String text, String sourceLanguage,
                            String targetLanguage) throws TikaException, IOException {
        if (!this.isAvailable)
            return text;
        Response response = client.accept(MediaType.APPLICATION_JSON)
                .query("user_key", userKey).query("source", sourceLanguage)
                .query("target", targetLanguage).query("q", text).get();
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                (InputStream) response.getEntity(), UTF_8));
        String line = null;
        StringBuffer responseText = new StringBuffer();
        while ((line = reader.readLine()) != null) {
            responseText.append(line);
        }

        ObjectMapper mapper = new ObjectMapper();
        JsonNode jsonResp = mapper.readTree(responseText.toString());
        if (jsonResp.findValuesAsText("errors").isEmpty()) {
            return jsonResp.findValuesAsText("translation").get(0);
        } else {
            throw new TikaException(jsonResp.findValue("errors").get(0).asText());
        }
    }

    @Override
    public String translate(String text, String targetLanguage)
            throws TikaException, IOException {
        if (!this.isAvailable)
            return text;
        
        String sourceLanguage = detectLanguage(text).getLanguage();
        return translate(text, sourceLanguage, targetLanguage);
    }

    @Override
    public boolean isAvailable() {
        return this.isAvailable;
    }

}