package de.tudarmstadt.informatik.hostage.protocol;

import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;

import de.tudarmstadt.informatik.hostage.wrapper.ByteArray;


public class MySQL implements Protocol<ByteArray>{
	private enum STATE {
		NONE, CONNECTED, LOGIN_INFO, AUTHENTICATE, LOGGED_IN, CLOSED
	}
	
	private STATE state = STATE.NONE;
	
	private byte[] request;
	
	@Override
	public List<ByteArray> processMessage(ByteArray request) {
		List<ByteArray> response = new ArrayList<ByteArray>();
		if(request != null) {
			this.request = request.get();
		}
				
		switch(state) {
		case NONE:
			response.add(new ByteArray(greeting()));
			state = STATE.CONNECTED;
			break;
		case CONNECTED:
			response.add(new ByteArray(responseOK()));
			state = STATE.LOGIN_INFO;
			break;
		case LOGIN_INFO:
			if(this.request[4] == 0x01) {
				response = null;
				state = STATE.CLOSED;
			} else if(this.request[4] == 0x03) {
				response.add(new ByteArray(response()));
			} else {
				response.add(new ByteArray(responseError()));
			}
			break;
		case AUTHENTICATE:
			break;
		case LOGGED_IN:
			break;
		default:
			state = STATE.CLOSED;
			break;
		}
		
		return response;
	}
	
	@Override
	public TALK_FIRST whoTalksFirst() {
		return TALK_FIRST.SERVER;
	}

	@Override
	public String toString(){
		return "MySQL";		
	}
	
	@Override
	public int getPort() {
		return 3306;
	}
	
	@Override
	public boolean isClosed() {
		return state == STATE.CLOSED;
	}
	
	private byte[] wrapPckt(byte[] pckt) {
		byte[] buff = ByteBuffer.allocate(4).putInt(pckt.length).array();
		byte[] pcktLength = {buff[3], buff[2], buff[1]};
		byte[] pcktNumber = new byte[1];
		if(request != null) pcktNumber[0] = (byte) (request[3] + 1);
		else pcktNumber[0] = 0x00;
		
		byte[] response = concat(pcktLength, pcktNumber, pckt);
		return response;
	}
	
	private byte[] greeting() {
		byte[] protocol = {0x0a};
		String version = "5.5.31-0+wheezy1";
		byte[] versionFin = {0x00};
		byte[] thread = {0x2a, 0x00, 0x00, 0x00};
		byte[] salt = {0x44, 0x64, 0x49, 0x7e, 0x60, 0x48, 0x25, 0x7e, 0x00};
		byte[] capabilities = {(byte) 0xff, (byte) 0xf7};
		byte[] language = {0x08};
		byte[] status = {0x02, 0x00};
		byte[] unused = {0x0f, (byte) 0x80, 0x15, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
		byte[] salt2 = {0x6c, 0x26, 0x71, 0x2c, 0x25, 0x72, 0x31, 0x3d, 0x7d, 0x21, 0x26, 0x3b, 0x00};
		String payload = "mysql_native_password";
		byte[] fin = {0x00};
		
		byte[] response = concat(protocol, version.getBytes(),versionFin, thread, salt, capabilities, language, status, unused, salt2, payload.getBytes(), fin);
		
		return wrapPckt(response);
	}
	
	private byte[] responseOK() {
		byte[] affectedRows = {0x00, 0x00, 0x00};
		byte[] status = {0x02, 0x00};
		byte[] warnings = {0x00, 0x00};
		
		byte[] response = concat(affectedRows, status, warnings);
		return wrapPckt(response);
	}
	
	private byte[] response() {
		// 4 packets to respond
		byte[] pckt0 = {0x01, 0x00, 0x00, 0x01, 0x01};
		byte[] pckt1 = {0x27, 0x00, 0x00, 0x02, 0x03, 0x64, 0x65, 0x66, 0x00, 
				0x00, 0x00, 0x11, 0x40, 0x40, 0x76, 0x65, 0x72, 0x73, 0x69, 0x6f, 0x6e, 0x5f, 0x63, 0x6f, 0x6d, 0x6d,
				0x65, 0x6e, 0x74, 0x00, 0x0c, 0x21, 0x00, 0x18, 0x00, 0x00, 0x00, (byte) 0xfd, 0x00, 0x00, 0x1f, 0x00, 0x00};
		byte[] pckt2 = {0x05, 0x00, 0x00, 0x03, (byte) 0xfe, 0x00, 0x00, 0x02, 0x00};
		byte[] pckt3 = {0x09, 0x00, 0x00, 0x04, 0x08, 0x28, 0x44, 0x65, 0x62, 0x69, 0x61, 0x6e, 0x29};
		byte[] pckt4 = {0x05, 0x00, 0x00, 0x05, (byte) 0xfe, 0x00, 0x00, 0x02, 0x00};
			
		byte[] response = concat(pckt0, pckt1, pckt2, pckt3, pckt4);
		return response;	//no wrapPckt() needed, because packets already have length and number
	}
	
	private byte[] responseError() {
		byte[] fill1 = {(byte) 0xff};
		byte[] code = {0x17, 0x04};
		byte[] fill2 = {0x23};
		String state = "08S01";
		String msg = "Unknown command";
		
		byte[] response = concat(fill1, code, fill2, state.getBytes(), msg.getBytes());		
		return wrapPckt(response);
	}
	
	private byte[] concat(byte[]...bytes) {
		int newSize = 0;	
		for(byte[] b: bytes) newSize += b.length;		//get total new size
		byte[] dst = new byte[newSize];				//create new array with new size
		
		int currentPos = 0;				
		int newPos;	
		for(byte[] b:bytes) {									//for each elem b out of bytes
			newPos = b.length;									//get b.length and new position
			System.arraycopy(b, 0, dst, currentPos, newPos);	//copy b in dst from currentPos to newPos
			currentPos += newPos;								//increase currentPos to newPos + currentPos
		}
		return dst;
	}

	@Override
	public boolean isSecure() {
		return false;
	}

	@Override
	public Class<ByteArray> getType() {
		return ByteArray.class;
	}
}