package ca.uhn.hl7v2.hoh.encoder;
   
   import static ca.uhn.hl7v2.hoh.util.StringUtils.*;
   
   import java.io.ByteArrayOutputStream;
   import java.io.IOException;
   import java.io.OutputStream;
   import java.io.OutputStreamWriter;
   import java.text.DateFormat;
  import java.text.SimpleDateFormat;
  import java.util.Date;
  import java.util.LinkedHashMap;
  import java.util.Map;
  import java.util.zip.GZIPOutputStream;
  
  import ca.uhn.hl7v2.hoh.api.EncodeException;
  import ca.uhn.hl7v2.hoh.api.ISendable;
  import ca.uhn.hl7v2.hoh.sign.SignatureFailureException;
  import ca.uhn.hl7v2.hoh.util.GZipUtils;
  import ca.uhn.hl7v2.hoh.util.HTTPUtils;
  
  /**
   * Base class that creates HL7 over HTTP requests. This class is intended to be
   * single use, so please create a new instance for each message.
   */
  public abstract class AbstractHl7OverHttpEncoder extends AbstractHl7OverHttp {
  
  	private static final org.slf4j.Logger ourLog = org.slf4j.LoggerFactory.getLogger(AbstractHl7OverHttpEncoder.class);
  	private static final DateFormat ourRfc1123DateFormat;
  
  	static {
  		ourRfc1123DateFormat = new SimpleDateFormat("EEE, dd MMM yy HH:mm:ss z");
  	}
  
  	private String myActionLine;
  	private boolean myGzipData;
  	private ISendable<?> mySendable;
  
  	/**
  	 * Constructor
  	 */
  	public AbstractHl7OverHttpEncoder() {
  		super();
  	}
  
  	/**
  	 * @throws EncodeException
  	 * 
  	 */
  	public void encode() throws EncodeException {
  		ourLog.trace("Entering encode()");
  		verifyNotUsed();
  
  		if (isBlank(getMessage()) && mySendable == null) {
  			throw new IllegalStateException("Either Message or Sendable must be set");
  		}
  		if (getMessage() != null) {
  			byte[] bytes = getMessage().getBytes(getCharset());
  			if (myGzipData) {
  				try {
  					bytes = GZipUtils.compress(bytes);
  				} catch (IOException e) {
  					throw new EncodeException("Failed to apply GZip coding", e);
  				}
  			}
  			setData(bytes);
  		} else {
  			ByteArrayOutputStream bos = new ByteArrayOutputStream();
  			OutputStream os;
  			if (myGzipData) {
  				try {
  					os = new GZIPOutputStream(bos);
  				} catch (IOException e) {
  					throw new EncodeException("Failed to create GZip encoder", e);
  				}
  			} else {
  				os = bos;
  			}
  
  			OutputStreamWriter w = new OutputStreamWriter(os, getCharset());
  			try {
  				mySendable.writeMessage(w);
  			} catch (IOException e) {
  				throw new EncodeException("Failed to convert message to sendable bytes");
  			}
  			setData(bos.toByteArray());
  		}
  
  		setActionLineAppropriately();
  
  		setHeaders(new LinkedHashMap<>());
  
  		StringBuilder ctBuilder = new StringBuilder();
  		if (mySendable != null) {
  			ctBuilder.append(mySendable.getEncodingStyle().getContentType());
  		} else {
  			ctBuilder.append(EncodingStyle.detect(getMessage()).getContentType());
  		}
  		ctBuilder.append("; charset=");
 		ctBuilder.append(getCharset().name());
 		getHeaders().put("Content-Type", ctBuilder.toString());
 
 		getHeaders().put("Content-Length", Integer.toString(getData().length));
 
 		addSpecificHeaders();
 
 		synchronized (ourRfc1123DateFormat) {
 			getHeaders().put("Date", ourRfc1123DateFormat.format(new Date()));
 		}
 
 		if (getSigner() != null) {
 			try {
 				getHeaders().put(HTTP_HEADER_HL7_SIGNATURE, getSigner().sign(getData()));
 			} catch (SignatureFailureException e) {
 				throw new EncodeException(e);
 			}
 		}
 
 		ourLog.trace("Exiting encode()");
 	}
 
 	public void encodeToOutputStream(OutputStream theOutputStream) throws IOException, EncodeException {
 		encode();
 
 		ourLog.debug("Writing HTTP action: {}", getActionLine());
 
 		OutputStreamWriter w = new OutputStreamWriter(theOutputStream, HTTPUtils.DEFAULT_CHARSET);
 		w.write(getActionLine());
 		w.write("\r\n");
 
 		for (Map.Entry<String, String> next : getHeaders().entrySet()) {
 			ourLog.debug("Writing HTTP header- {}: {}", next.getKey(), next.getValue());
 
 			w.write(next.getKey());
 			w.write(": ");
 			w.write(next.getValue());
 			w.write("\r\n");
 		}
 
 		w.write("\r\n");
 		w.flush();
 
 		ourLog.debug("Writing {} bytes of actual data", getData().length);
 		theOutputStream.write(getData());
 
 	}
 
 	/**
 	 * @return the actionLine
 	 */
 	public String getActionLine() {
 		return myActionLine;
 	}
 
 	/**
 	 * @param theActionLine
 	 *            the actionLine to set
 	 */
 	public void setActionLine(String theActionLine) {
 		myActionLine = theActionLine;
 	}
 
 	/**
 	 * Provide the message to send with a {@link ISendable} instance. Either
 	 * this method OR {@link #setMessage(String)} must be called, but not both.
 	 */
 	public void setDataProvider(ISendable<?> theSendable) {
 		if (getMessage() != null) {
 			throw new IllegalStateException("Message already provided");
 		}
 		mySendable = theSendable;
 	}
 
 	/**
 	 * Provide the message to send with a String. Either this method OR
 	 * {@link #setDataProvider(ISendable)} must be called, but not both.
 	 */
 	@Override
 	public void setMessage(String theData) {
 		if (mySendable != null) {
 			throw new IllegalStateException("Data provider already provided");
 		}
 		super.setMessage(theData);
 	}
 
 	protected abstract void addSpecificHeaders();
 
 	protected abstract void setActionLineAppropriately();
 
 	boolean isGzipData() {
 		return myGzipData;
 	}
 
 	/**
 	 * Should the encoded data be GZipped? Note that this doesn't set any
 	 * headers indicating this fact, so it's up to callers of this method to
 	 * take care of that.
 	 */
 	void setGzipData(boolean theGzipData) {
 		myGzipData = theGzipData;
 	}
 
 }