import java.io.InputStream;
import java.io.OutputStream;

import javax.servlet.http.HttpServletResponse;

import com.opensymphony.webwork.ServletActionContext;
import com.opensymphony.xwork.ActionInvocation;
import com.opensymphony.xwork.Result;

/**
 * Implements an XWork Result that takes an InputStream object available from a chained
 * Action and redirects it to the browser.
 * 
 * The following declaration must be added to the xwork.xml file after the <package> 
 * element:
 * 
 * <result-types>
 *    <result-type name="stream" class="StreamResult"/>
 * </result-types>
 * 
 * To use the stream result type add the following as part of the action declaration:
 * 
 * <result name="success" type="stream">
 *    <param name="contentType">image/jpeg</param>
 *    <param name="inputName">imageStream</param>
 *    <param name="bufferSize">1024</param>
 * </result>
 * 
 * contentType = the stream mime-type as sent to the web browser
 * inputName = the name of the InputStream property from the chained action (default = "inputStream")
 * bufferSize = the size of the buffer to copy from input to output (defaul = 1024)
 * 
 * @author mcrawford
 */
public class StreamResult implements Result {
	
	protected String contentType = "text/plain";
	
	protected String inputName = "inputStream";
	
	protected int bufferSize = 1024;
	
	/**
	 * @return Returns the bufferSize.
	 */
	public int getBufferSize() {
		return(bufferSize);
	}
	
	/**
	 * @param bufferSize The bufferSize to set.
	 */
	public void setBufferSize(int iBufferSize) {
		bufferSize = iBufferSize;
	}
	
	/**
	 * @return Returns the contentType.
	 */
	public String getContentType() {
		return(contentType);
	}
	
	/**
	 * @param contentType The contentType to set.
	 */
	public void setContentType(String sContentType) {
		contentType = sContentType;
	}
	
	/**
	 * @return Returns the inputName.
	 */
	public String getInputName() {
		return(inputName);
	}
	
	/**
	 * @param inputName The inputName to set.
	 */
	public void setInputName(String sInputName) {
		inputName = sInputName;
	}
	
	/**
	 * @see com.opensymphony.xwork.Result#execute(com.opensymphony.xwork.ActionInvocation)
	 */
	public void execute(ActionInvocation oInvocation) throws Exception {
		
		// Find the inputstream from the invocation variable stack
		InputStream oInput = (InputStream) oInvocation.getStack().findValue(inputName);
		
		// Find the Response in context
		HttpServletResponse oResponse = ServletActionContext.getResponse();
		
		// Set the content type
		oResponse.setContentType(contentType);
		
		// Get the outputstream
		OutputStream oOutput = oResponse.getOutputStream();
		
		// Copy input to output
		byte[] oBuff = new byte[bufferSize];
		int iSize= 0;
		while (-1 != (iSize = oInput.read(oBuff))) {
			oOutput.write(oBuff, 0, iSize);
		}
		
		// Flush
		oOutput.flush();
	}

}