package io.gitlab.jfronny.googlechat.api;

import io.gitlab.jfronny.googlechat.GoogleChat;
import org.apache.commons.lang3.StringEscapeUtils;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class GoogleService {
    private static final Pattern TRANSLATION_RESULT = Pattern.compile("class=\"result-container\">([^<]*)</div>", Pattern.MULTILINE);

    public static String translate(String textToTranslate, Language translateFrom, Language translateTo) {
        if (textToTranslate == null)
            return null;
        String pageSource = "";
        try {
            pageSource = getPageSource(textToTranslate, translateFrom.value, translateTo.value);
            Matcher matcher = TRANSLATION_RESULT.matcher(pageSource);
            if (matcher.find()) {
                String match = matcher.group(1);
                if (match != null && !match.isEmpty()) {
                    return StringEscapeUtils.unescapeHtml4(match);
                }
            }
            GoogleChat.LOGGER.error("Could not translate \"" + textToTranslate + "\": result page couldn't be parsed");
            return null;
        } catch (Exception e) {
            try {
                Path p = Files.createTempFile("translater-pagedump-", ".html").toAbsolutePath();
                Files.writeString(p, pageSource);
                GoogleChat.LOGGER.error("Could not translate string, see dumped page at " + p, e);
            } catch (IOException ioe) {
                GoogleChat.LOGGER.error("Could not translate string and the page could not be dumped", ioe);
            }
            return null;
        }
    }

    private static String getPageSource(String textToTranslate, String translateFrom, String translateTo)
            throws Exception {
        if (textToTranslate == null)
            return null;
        String pageUrl = String.format("https://translate.google.com/m?hl=en&sl=%s&tl=%s&ie=UTF-8&prev=_m&q=%s",
                translateFrom, translateTo, URLEncoder.encode(textToTranslate.trim(), StandardCharsets.UTF_8));
        URL url = new URL(pageUrl);
        HttpURLConnection connection = null;
        BufferedReader bufferedReader = null;
        StringBuilder pageSource = new StringBuilder();
        try {
            connection = (HttpURLConnection) url.openConnection();
            connection.setConnectTimeout(5000);
            connection.setRequestProperty("User-Agent",
                    "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.95 Safari/537.11");
            bufferedReader = new BufferedReader(new InputStreamReader(connection.getInputStream(), StandardCharsets.UTF_8));
            String line;
            while ((line = bufferedReader.readLine()) != null) {
                pageSource.append(line).append('\n');
            }
            return pageSource.toString();
        } catch (Exception e) {
            GoogleChat.LOGGER.error("Could not load translation from google", e);
            return null;
        } finally {
            if (connection != null)
                connection.disconnect();
            if (bufferedReader != null)
                bufferedReader.close();
        }
    }
}