package ca.ucalgary.services.util;

import java.io.*;
import java.net.*;
 
/**
 * <code>MultiPartFormOutputStream</code> is used to write 
 * "multipart/form-data" to a <code>java.net.URLConnection</code> for 
 * POSTing.  This is primarily for file uploading to HTTP servers.  
 *
 * Code taken from Useful Code of the Day:
 *
 * http://forums.sun.com/thread.jspa?threadID=451245&forumID=31
 * 
 * @since  JDK1.3
 */
public class MultiPartFormOutputStream {
	/**
	 * The line end characters.  
	 */
	private static final String NEWLINE = "\r\n";
 
	/**
	 * The boundary prefix.  
	 */
	private static final String PREFIX = "--";
 
	/**
	 * The output stream to write to.  
	 */
	private DataOutputStream out = null;
 
	/**
	 * The multipart boundary string.  
	 */
	private String boundary = null;
 
	/**
	 * Creates a new <code>MultiPartFormOutputStream</code> object using 
	 * the specified output stream and boundary.  The boundary is required 
	 * to be created before using this method, as described in the 
	 * description for the <code>getContentType(String)</code> method.  
	 * The boundary is only checked for <code>null</code> or empty string, 
	 * but it is recommended to be at least 6 characters.  (Or use the 
	 * static createBoundary() method to create one.)
	 * 
	 * @param  os        the output stream
	 * @param  boundary  the boundary
	 * @see  #createBoundary()
	 * @see  #getContentType(String)
	 */
	public MultiPartFormOutputStream(OutputStream os, String boundary) {
		if(os == null) {
			throw new IllegalArgumentException("Output stream is required.");
		}
		if(boundary == null || boundary.length() == 0) {
			throw new IllegalArgumentException("Boundary stream is required.");
		}
		this.out = new DataOutputStream(os);
		this.boundary = boundary;
	}
 
	/**
	 * Writes an boolean field value.  
	 * 
	 * @param  name   the field name (required)
	 * @param  value  the field value
	 * @throws  java.io.IOException  on input/output errors
	 */
	public void writeField(String name, boolean value) 
			throws java.io.IOException {
		writeField(name, new Boolean(value).toString());
	}
 
	/**
	 * Writes an double field value.  
	 * 
	 * @param  name   the field name (required)
	 * @param  value  the field value
	 * @throws  java.io.IOException  on input/output errors
	 */
	public void writeField(String name, double value) 
			throws java.io.IOException {
		writeField(name, Double.toString(value));
	}
 
	/**
	 * Writes an float field value.  
	 * 
	 * @param  name   the field name (required)
	 * @param  value  the field value
	 * @throws  java.io.IOException  on input/output errors
	 */
	public void writeField(String name, float value) 
			throws java.io.IOException {
		writeField(name, Float.toString(value));
	}
 
	/**
	 * Writes an long field value.  
	 * 
	 * @param  name   the field name (required)
	 * @param  value  the field value
	 * @throws  java.io.IOException  on input/output errors
	 */
	public void writeField(String name, long value) 
			throws java.io.IOException {
		writeField(name, Long.toString(value));
	}
 
	/**
	 * Writes an int field value.  
	 * 
	 * @param  name   the field name (required)
	 * @param  value  the field value
	 * @throws  java.io.IOException  on input/output errors
	 */
	public void writeField(String name, int value) 
			throws java.io.IOException {
		writeField(name, Integer.toString(value));
	}
 
	/**
	 * Writes an short field value.  
	 * 
	 * @param  name   the field name (required)
	 * @param  value  the field value
	 * @throws  java.io.IOException  on input/output errors
	 */
	public void writeField(String name, short value) 
			throws java.io.IOException {
		writeField(name, Short.toString(value));
	}
 
	/**
	 * Writes an char field value.  
	 * 
	 * @param  name   the field name (required)
	 * @param  value  the field value
	 * @throws  java.io.IOException  on input/output errors
	 */
	public void writeField(String name, char value) 
			throws java.io.IOException {
		writeField(name, new Character(value).toString());
	}
 
	/**
	 * Writes an string field value.  If the value is null, an empty string 
	 * is sent ("").  
	 * 
	 * @param  name   the field name (required)
	 * @param  value  the field value
	 * @throws  java.io.IOException  on input/output errors
	 */
	public void writeField(String name, String value) 
			throws java.io.IOException {
		if(name == null) {
			throw new IllegalArgumentException("Name cannot be null or empty.");
		}
		if(value == null) {
			value = "";
		}
		/*
		--boundary\r\n
		Content-Disposition: form-data; name="<fieldName>"\r\n
		\r\n
		<value>\r\n
		*/
		// write boundary
		out.writeBytes(PREFIX);
		out.writeBytes(boundary);
		out.writeBytes(NEWLINE);
		// write content header
		out.writeBytes("Content-Disposition: form-data; name=\"" + name + "\"");
		out.writeBytes(NEWLINE);
		out.writeBytes(NEWLINE);
		// write content
		out.writeBytes(value);
		out.writeBytes(NEWLINE);
		out.flush();
	}
 
	/**
	 * Writes a file's contents.  If the file is null, does not exists, or 
	 * is a directory, a <code>java.lang.IllegalArgumentException</code> 
	 * will be thrown.  
	 * 
	 * @param  name      the field name
	 * @param  mimeType  the file content type (optional, recommended)
	 * @param  file      the file (the file must exist)
	 * @throws  java.io.IOException  on input/output errors
	 */
	public void writeFile(String name, String mimeType, File file) 
			throws java.io.IOException {
		if(file == null) {
			throw new IllegalArgumentException("File cannot be null.");
		}
		if(!file.exists()) {
			throw new IllegalArgumentException("File does not exist.");
		}
		if(file.isDirectory()) {
			throw new IllegalArgumentException("File cannot be a directory.");
		}
		writeFile(name, mimeType, file.getCanonicalPath(), new FileInputStream(file));
	}
 
	/**
	 * Writes a input stream's contents.  If the input stream is null, a 
	 * <code>java.lang.IllegalArgumentException</code> will be thrown.  
	 * 
	 * @param  name      the field name
	 * @param  mimeType  the file content type (optional, recommended)
	 * @param  fileName  the file name (required)
	 * @param  is        the input stream
	 * @throws  java.io.IOException  on input/output errors
	 */
	public void writeFile(String name, String mimeType, 
			String fileName, InputStream is) 
			throws java.io.IOException {
		if(is == null) {
			throw new IllegalArgumentException("Input stream cannot be null.");
		}
		if(fileName == null || fileName.length() == 0) {
			throw new IllegalArgumentException("File name cannot be null or empty.");
		}
		/*
		--boundary\r\n
		Content-Disposition: form-data; name="<fieldName>"; filename="<filename>"\r\n
		Content-Type: <mime-type>\r\n
		\r\n
		<file-data>\r\n
		*/
		// write boundary
		out.writeBytes(PREFIX);
		out.writeBytes(boundary);
		out.writeBytes(NEWLINE);
		// write content header
		out.writeBytes("Content-Disposition: form-data; name=\"" + name + 
			"\"; filename=\"" + fileName + "\"");
		out.writeBytes(NEWLINE);
		if(mimeType != null) {
			out.writeBytes("Content-Type: " + mimeType);
			out.writeBytes(NEWLINE);
		}
		out.writeBytes(NEWLINE);
		// write content
		byte[] data = new byte[1024];
		int r = 0;
		while((r = is.read(data, 0, data.length)) != -1) {
			out.write(data, 0, r);
		}
		// close input stream, but ignore any possible exception for it
		try {
			is.close();
		} catch(Exception e) {}
		out.writeBytes(NEWLINE);
		out.flush();
	}
 
	/**
	 * Writes the given bytes.  The bytes are assumed to be the contents 
	 * of a file, and will be sent as such.  If the data is null, a 
	 * <code>java.lang.IllegalArgumentException</code> will be thrown.  
	 * 
	 * @param  name      the field name
	 * @param  mimeType  the file content type (optional, recommended)
	 * @param  fileName  the file name (required)
	 * @param  data      the file data
	 * @throws  java.io.IOException  on input/output errors
	 */
	public void writeFile(String name, String mimeType, 
			String fileName, byte[] data) 
			throws java.io.IOException {
		if(data == null) {
			throw new IllegalArgumentException("Data cannot be null.");
		}
		if(fileName == null || fileName.length() == 0) {
			throw new IllegalArgumentException("File name cannot be null or empty.");
		}
		/*
		--boundary\r\n
		Content-Disposition: form-data; name="<fieldName>"; filename="<filename>"\r\n
		Content-Type: <mime-type>\r\n
		\r\n
		<file-data>\r\n
		*/
		// write boundary
		out.writeBytes(PREFIX);
		out.writeBytes(boundary);
		out.writeBytes(NEWLINE);
		// write content header
		out.writeBytes("Content-Disposition: form-data; name=\"" + name + 
			"\"; filename=\"" + fileName + "\"");
		out.writeBytes(NEWLINE);
		if(mimeType != null) {
			out.writeBytes("Content-Type: " + mimeType);
			out.writeBytes(NEWLINE);
		}
		out.writeBytes(NEWLINE);
		// write content
		out.write(data, 0, data.length);
		out.writeBytes(NEWLINE);
		out.flush();
	}
 
	/**
	 * Flushes the stream.  Actually, this method does nothing, as the only 
	 * write methods are highly specialized and automatically flush.  
	 * 
	 * @throws  java.io.IOException  on input/output errors
	 */
	public void flush() throws java.io.IOException {
		// out.flush();
	}
 
	/**
	 * Closes the stream.  <br />
	 * <br />
	 * <b>NOTE:</b> This method <b>MUST</b> be called to finalize the 
	 * multipart stream.
	 * 
	 * @throws  java.io.IOException  on input/output errors
	 */
	public void close() throws java.io.IOException {
		// write final boundary
		out.writeBytes(PREFIX);
		out.writeBytes(boundary);
		out.writeBytes(PREFIX);
		out.writeBytes(NEWLINE);
		out.flush();
		out.close();
	}
 
	/**
	 * Gets the multipart boundary string being used by this stream.  
	 * 
	 * @return  the boundary
	 */
	public String getBoundary() {
		return this.boundary;
	}
 
	/**
	 * Creates a new <code>java.net.URLConnection</code> object from the 
	 * specified <code>java.net.URL</code>.  This is a convenience method 
	 * which will set the <code>doInput</code>, <code>doOutput</code>, 
	 * <code>useCaches</code> and <code>defaultUseCaches</code> fields to 
	 * the appropriate settings in the correct order.  
	 * 
	 * @return  a <code>java.net.URLConnection</code> object for the URL
	 * @throws  java.io.IOException  on input/output errors
	 */
	public static URLConnection createConnection(URL url) 
			throws java.io.IOException {
		URLConnection urlConn = url.openConnection();
		if(urlConn instanceof HttpURLConnection) {
			HttpURLConnection httpConn = (HttpURLConnection)urlConn;
			httpConn.setRequestMethod("POST");
		}
		urlConn.setDoInput(true);
		urlConn.setDoOutput(true);
		urlConn.setUseCaches(false);
		urlConn.setDefaultUseCaches(false);
		return urlConn;
	}
 
	/**
	 * Creates a multipart boundary string by concatenating 20 hyphens (-) 
	 * and the hexadecimal (base-16) representation of the current time in 
	 * milliseconds.  
	 * 
	 * @return  a multipart boundary string
	 * @see  #getContentType(String)
	 */
	public static String createBoundary() {
		return "--------------------" + 
			Long.toString(System.currentTimeMillis(), 16);
	}
 
	/**
	 * Gets the content type string suitable for the 
	 * <code>java.net.URLConnection</code> which includes the multipart 
	 * boundary string.  <br />
	 * <br />
	 * This method is static because, due to the nature of the 
	 * <code>java.net.URLConnection</code> class, once the output stream 
	 * for the connection is acquired, it's too late to set the content 
	 * type (or any other request parameter).  So one has to create a 
	 * multipart boundary string first before using this class, such as 
	 * with the <code>createBoundary()</code> method.  
	 * 
	 * @param  boundary  the boundary string
	 * @return  the content type string
	 * @see  #createBoundary()
	 */
	public static String getContentType(String boundary) {
		return "multipart/form-data; boundary=" + boundary;
	}
}