package org.oxerr.okcoin.rest.dto.valuereader;
   
   import java.io.IOException;
   import java.io.InputStream;
   import java.io.InputStreamReader;
   import java.nio.charset.Charset;
   
   import javax.annotation.Nonnull;
   import javax.annotation.Nullable;
  
  import org.apache.commons.io.IOUtils;
  import org.cyberneko.html.parsers.DOMParser;
  import org.oxerr.okcoin.rest.service.web.OKCoinClient;
  import org.oxerr.okcoin.rest.service.web.OKCoinClientException;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.w3c.dom.html.HTMLDocument;
  import org.xml.sax.InputSource;
  import org.xml.sax.SAXException;
  
  public abstract class HtmlPageReader<T> implements ValueReader<T> {
  
  	private static final Charset CHARSET = Charset.forName(OKCoinClient.ENCODING);
  
  	private final Logger log = LoggerFactory.getLogger(IndexHtmlPageReader.class);
  
  	/**
  	 * {@inheritDoc}
  	 */
  	@Override
  	public T read(InputStream inputStream,
  		@Nullable String mimeType, @Nullable Charset charset) throws IOException {
  		HTMLDocument document;
  		try {
  			document = toDocument(inputStream, charset != null ? charset: CHARSET);
  		} catch (SAXException e) {
  			throw new IOException(e);
  		}
  		return read(document);
  	}
  
  	protected abstract T read(HTMLDocument document) throws OKCoinClientException;
  
  	private HTMLDocument toDocument(InputStream inputStream, @Nonnull Charset charset)
  			throws IOException, SAXException {
  		final InputSource inputSource;
  		if (log.isTraceEnabled()) {
  			String html = IOUtils.toString(inputStream, charset);
  			log.trace("Parsing HTML:\n{}", html);
  			inputSource = new InputSource(new InputStreamReader(
  					IOUtils.toInputStream(html, charset), charset));
  		} else {
  			inputSource = new InputSource(new InputStreamReader(inputStream,
  					charset));
  		}
  		DOMParser parser = new DOMParser();
  		parser.parse(inputSource);
  		HTMLDocument document = (HTMLDocument) parser.getDocument();
  		return document;
  	}
  
  }