import java.io.*;
import java.net.*;
import java.util.*;

/**
 * A partial encapsulation of an HTTP message (i.e., request
 * or response)
 *
 * @author  Prof. David Bernstein, James Madison University
 * @version 0.2
 */
public abstract class HttpMessage
{
    protected byte[]         content;
    protected NameValueMap   headers;


    /**
     * Default Constructor
     */
    public HttpMessage()
    {
       content         = null;        
       headers         = NameValueMap.createNameValueMap();       
    }

    /**
     * Get the content of this HttpMessage
     *
     * @return   The content
     */
    public byte[] getContent()
    {
       return content;
    }

    /**
     * Returns the length, in bytes, of the content contained in the 
     * request and sent by way of the input stream
     *
     * @return  The length or -1 if the length is not known
     */
    public int getContentLength()
    {
       int        result;
       
       try
       {
          result = Integer.parseInt(getHeader("Content-Length"));
       }
       catch (Exception e)
       {
          result = -1;
       }

       return result;
    }

    /**
     * Returns the value of the specified header
     *
     * @param name   The name of the header
     * @return       The value of the header
     */
    public String getHeader(String name)
    {
	return headers.getValue(name);
    }

    /**
     * Returns the names of all headers
     *
     * @return       The names of all headers
     */
    public Iterator<String> getHeaderNames()
    {
	return headers.getNames();
    }

    /**
     * Read this HttpMessage (up to, but not including, the
     * content).
     *
     * Note: The content is not read so that the content may
     * be read in a specialized way (e.g., as formatted binary data)
     * or in case the content is large (and should be "streamed").
     *
     * @param in   The HttpInputStream to read from
     */
    public abstract void read(HttpInputStream in) throws 
                                                IndexOutOfBoundsException,
                                                IOException, 
                                                URISyntaxException;
    
    

    /**
     * Read the content of this HttpMessage.
     * Note: This method must only be called after read()
     * in the child classes.
     *
     * @param in   The HttpInputStream to read from
     */
    public void readContent(HttpInputStream in)
    {
       int          contentLength;
       
       contentLength = getContentLength();

       if (contentLength > 0)
       {
          content = new byte[contentLength];
          try
          {
             in.readFully(content);
          }
          catch (IOException ioe)
          {
             content = null;
             setContentLength(-1);             
          }
       }
    }

    /**
     * Set the content (i.e., payload) for this HttpMessage
     *
     * @param content   The payload/content
     */
    public void setContent(byte[] content)
    {
       this.content = content;
       setContentLength(content.length);
    }

    /**
     * Sets the content length
     * 
     * @param  contentLength    The contentLength
     */
    public void setContentLength(int contentLength)
    {
        setHeader("Content-Length", Integer.toString(contentLength));
    }

    /**
     * Sets the type of the content the server returns to the client
     *
     * @param type   The type
     */
    public void setContentType(String type)
    {
       setHeader("Content-Type", type);       
    }

    /**
     * Adds a field (with the given name and value) to the 
     * response header
     *
     * Note: This method must be called before getOutputStream()
     *
     * @param name   The name of the field
     * @param value  The value of the field
     */
    public void setHeader(String name, String value)
    {
	headers.put(name, value);
    }

    /**
     * Set the headers
     * 
     * @param   headers The headers
     */
    public void setHeaders(NameValueMap headers)
    {
	this.headers         = headers;
    }
}