/**
 * @see <code>Server.java</code>
 * @version 1.0
 * 
 * The file is to build a Simple HTTP/1.0 Client with a Command Line Interface.
 *
 */

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


public class Client {

	// The port number in static final type . 
	private static final int  socketPort = 6789;
	
	// Default constructor.
	public Client() {}

	/**
	 * This method is used to send the client's request to the server.
	 * 
	 * @param <code>Socket</code>object and <code>String</code> message object.
	 * @return void.
	 * @exception <code>IOException</code>.
	 */
	public void sendMessage(Socket clientSocket, String message) {

		String clientRequest;
		System.out.println(message + " is listening to your request:\n");

		BufferedReader inFromClient = new BufferedReader(new InputStreamReader(System.in));
		
		// In "Try-Catch" block, we do the actual work to send the message out, 
		//		and when the IO erro countered, throw out "IOException". 
		try {

			DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream());
			clientRequest = inFromClient.readLine();
			outToServer.writeBytes(clientRequest + "\r\n\r\n");

		} catch (IOException ioe) {

			System.err.println("IO erro: ");
			ioe.printStackTrace();
		}
		 
	}

	/**
	 * The method header is used to get the header out from the server reply, and print it out to the console.
	 * 
	 * @param <code>InputStream</code>
	 * @return void
	 * @exception <code>IOException</code>
	 * 
     */ 
	public void header(InputStream inFromServer) {

		String header = "";
		int temp;
		boolean isHeader = false;
		
		try {
			temp = inFromServer.read();
			System.out.println(temp);
			header += (char) temp;
			
			// When the string is "\r\n\r\n", the header is over, and we get it.
			while (temp != -1 && !isHeader) {
				switch (temp) {
				case 13:
					temp = inFromServer.read();
					switch (temp) {
					case 10:
						header += (char) temp;
						if ((char) (temp = inFromServer.read()) == ('\r'))
							if ((char) (temp = inFromServer.read()) == ('\n'))
								isHeader = true;
						break;
					default:
						break;
					}
					break;
				default:
					break;
				}
				if (isHeader)
					break;
				temp = inFromServer.read();
				header += (char) temp;
			}

		} catch (IOException ioe) {

			System.err.println("IO erro: ");
			ioe.printStackTrace();
		}

			System.out.println("header:\n" + header + "\n");
	}

	/**
	 * This method is used to change the flow that come from server to the type of "byte".
	 * 
	 * @param <code>InputStream</code> object  and <code>Socket</code> object.
	 * @return <code>byte[]</code>
	 * @exception <code>EOFException</code> and <code>IOException</code>
	 */
	public byte[] serverReply(InputStream inFromServer, Socket clientSocket) {

		int fileLength=0;
		byte[] buffer = null;
		
		// Get the length of the flow that come from the server and it may cause the IOException.
		try {
			
			fileLength = inFromServer.available();
		} catch (IOException e) {
			
			System.err.println("IO erro when \"inFromServer.available()\" ");
			e.printStackTrace();
		}
		
		buffer = new byte[fileLength];
		DataInputStream receivedFile = null; 

		receivedFile = new DataInputStream(inFromServer);
			
		// Get every byte from the DataInputStream object to the buffer array.
		try {
			 
			 for (int i=0;i<buffer.length;i++){
					buffer[i] = receivedFile.readByte();
			 }
		} catch (EOFException eof) {
			
			eof.printStackTrace();
		}catch (IOException e2) {
			
			e2.printStackTrace();
		} 
	
		return buffer;
	}

	/**
	 * This method is used to save the infomation from server to the local file.
	 * 
	 * @param <code>BufferedReader</code> object and <code>byte[]</code> object.
	 * @return void.
	 * @exception <code>FileNotFoundException</code> and <code>IOException</code>.
	 */
	public void saveFile(BufferedReader inFromClient, byte[] buffer) {

		System.out.println("Input a file name to save the header:\n");
		
		// Write the infomation to the file whose name is inputed by the user.
		try {

			FileOutputStream fileout = new FileOutputStream(inFromClient.readLine());
			PrintStream ps = new PrintStream(fileout);
			ps.write(buffer);
			ps.close();

		} catch (FileNotFoundException fnfe) {

			System.err.println("The specified file is not exist!");
			fnfe.printStackTrace();

		} catch (IOException ioe) {

			System.err.println("IO erro: ");
			ioe.printStackTrace();
		}
	}

	
	public static void main(String[] args) throws Exception {

		// Creat a new Client object.
		Client client = new Client();
		Socket clientSocket = null;

		// Establish a socket connection.
		try {

			clientSocket = new Socket(args[0], socketPort);
		} catch (UnknownHostException unke) {

			System.err.println("The host is unknown!");
			unke.printStackTrace();
	
		} catch (IOException ioe) {

			System.err.println("IO erro: ");
			ioe.printStackTrace();
		} catch (SecurityException se) {

			System.err.println("A security manager exists and we cannot get throw it.");
			se.printStackTrace();
		}

		BufferedReader inFromClient = new BufferedReader(new InputStreamReader(
				System.in, "UTF-8"));

		InputStream inFromServer  = new BufferedInputStream(clientSocket.getInputStream());
		
		
		client.sendMessage(clientSocket, args[0]);						//Send message.
		client.header(inFromServer);									//Get header.
		byte[] buffer = client.serverReply(inFromServer, clientSocket); //Change the stream flow to the type of "byte"
		client.saveFile(inFromClient, buffer);							//Save file
		clientSocket.close();											//Close the connection.

	}

}