using System;
using System.Net;

namespace NetCalc
{
    /// <summary>
    /// Summary description for IPTool.
    /// </summary>
    public class IPTool
    {
        // first (0x00) only for fill - so array starts with bit 1
        static byte[] bit = { 0x00, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, (byte)0x80 };

        protected string ip = null;
        protected byte[] ipBytes = null;
        //protected byte a,b,c,d;
        protected int networkPrefix; // z.b. 24 for /24
        protected bool firstSubNetBit = false;

        public IPTool(string ip)
        {
            this.setIp(ip);
        }

        public static byte getBit(int bit)
        {
            byte r = 0;
            if (bit >= 1 && bit <= 8)
                r = IPTool.bit[bit];

            return r;
        }

        public static byte setBit(byte b, int bit)
        {
            if (bit >= 1 && bit <= 8)
                return (byte)(b | IPTool.bit[bit]);
            else return 0;
        }

        public static bool isBitSet(byte b, int bit)
        {
            bool r = false;
            if (bit >= 1 && bit <= 8)
                r = ((b & IPTool.bit[bit]) != 0);

            return r;
        }


        /*
		 * return true if domainName is an IP
		 */
        static public bool isIP(String domainName)
        {
            //if (domainName.matches("[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}"))
            if (domainName.Equals("[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}"))
                return true;
            else return false;
        }

        /*
		 * Converts (unsigned)byte to int
		 */
        public static int byte2int(byte b)
        {
            int i = b;
            if (b < 0) i = b & 0x7f + 128;

            return i;
        }

        // return first byte of IP
        public byte get1Byte()
        {
            return this.ipBytes[0];
        }

        //	return second byte of IP
        public byte get2Byte()
        {
            return this.ipBytes[1];
        }

        //	return third byte of IP
        public byte get3Byte()
        {
            return this.ipBytes[2];
        }

        //	return fourth byte of IP
        public byte get4Byte()
        {
            return this.ipBytes[3];
        }

        //	return array with all bytes of IP
        public byte[] getBytes()
        {
            //return InetAddress.getByName(this.ip).getAddress();
            //return Dns.GetHostByName(this.ip).AddressList;
            return IPAddress.Parse(this.ip).GetAddressBytes();
        }

        public String getIp()
        {
            return this.ip;
        }

        public void setIp(String ip)
        {
            this.ip = ip;
            this.ipBytes = getBytes();
            this.setPrefix2NetworkClassPrefix();
        }

        public void setPrefix2NetworkClassPrefix()
        {
            this.setNetworkPrefix(this.getNetworkClassPrefix());
        }

        public int getNetworkClassPrefix()
        {
            // set network-prefix with Class-Type
            int netClass = getNetworkClass();
            switch (netClass)
            {
                case 0: return 8;   // Class A
                case 1: return 16;  // Class B									
                case 2: return 24;  // Class C
                                    //default: setNetworkPrefix(-1);	// other Classes have no default Prefix										
            }
            return -1;
        }

        /*
		* return -1 if out of range (0-255) or other error
		*/
        private int convertIPByte(String ipByte)
        {
            //int res = Integer.valueOf(ipByte).intValue();
            int res = Int32.Parse(ipByte);
            if (res < 0 || res > 255)
            {
                res = -1;
                this.ip = null;
            }
            return res;
        }

        /**
		 * @return
		 */
        public int getNetworkPrefix()
        {
            return this.networkPrefix;
        }

        /**
		 * @param prefix
		 */
        public void setNetworkPrefix(int prefix)
        {
            this.networkPrefix = prefix;
        }

        public String getNetworkClassName()
        {
            switch (this.getNetworkClass())
            {
                case 0: return "Class A";
                case 1: return "Class B";
                case 2: return "Class C";
                case 3: return "Class D/Multicast";
                case 4: return "Class E/not used";
                default: return "error";
            }
        }

        /*
		 * 0=Class A
		 * 1=Class B
		 * 2=Class C
		 * 3=Class D
		 * 4=Class E
		 * -1=error
		 */
        public int getNetworkClass()
        {
            // Test Class A: first bit=0
            if (!IPTool.isBitSet(this.get1Byte(), 8)) return 0;
            // Test Class B: first 2bit=10
            else if (!IPTool.isBitSet(this.get1Byte(), 7)) return 1;
            //	Test Class C: first 3bit=110
            else if (!IPTool.isBitSet(this.get1Byte(), 6)) return 2;
            //	Test Class D: first 4bit=1110
            else if (!IPTool.isBitSet(this.get1Byte(), 5)) return 3;
            //	Test Class E: first 4bit=1111 ( = all other)
            //		else if (!IPTool.isBitSet(this.get1Byte(),8)) return 4;
            else return 4;


            /*		
					// Test Class A: first bit=0
					if ((this.get1Byte() | (byte)0x7f) == (byte)0x7f) return 0;
					//	Test Class B: first 2bit=10
					if ((this.get1Byte() | 0xbf) == 0xbf) return 1;
					//	Test Class C: first 3bit=110
					if ((this.get1Byte() | 0xdf) == 0xdf) return 2;
					//	Test Class D: first 4bit=1110
					if ((this.get1Byte() | 0xef) == 0xef) return 3;
					//	Test Class E: first 4bit=1111
					if ((this.get1Byte() & 0xf0) == 0xf0) return 4;		
					return -1;
			*/

        }

        public String getNetworkMask()
        {
            return getNetworkMaskByPrefix(this.networkPrefix);
        }

        public String getNetworkMaskByPrefix(int prefix)
        {
            switch (prefix)
            {
                case 8: return "255.0.0.0";
                case 9: return "255.128.0.0";
                case 10: return "255.192.0.0";
                case 11: return "255.224.0.0";
                case 12: return "255.240.0.0";
                case 13: return "255.248.0.0";
                case 14: return "255.252.0.0";
                case 15: return "255.254.0.0";
                case 16: return "255.255.0.0";
                case 17: return "255.255.128.0";
                case 18: return "255.255.192.0";
                case 19: return "255.255.224.0";
                case 20: return "255.255.240.0";
                case 21: return "255.255.248.0";
                case 22: return "255.255.252.0";
                case 23: return "255.255.254.0";
                case 24: return "255.255.255.0";
                case 25: return "255.255.255.128";
                case 26: return "255.255.255.192";
                case 27: return "255.255.255.224";
                case 28: return "255.255.255.240";
                case 29: return "255.255.255.248";
                case 30: return "255.255.255.252";
                default: return "";
            }
        }

        public int getMaxNetworkHosts()
        {
            // 2^(32-networkprefix)
            // -2 ... because .0 and .255
            return ((int)Math.Pow(2, (32 - this.networkPrefix))) - 2;
        }

        public int getMaxSubNets()
        {
            // Bits from Subnet = prefix-class_prefix

            int count = (int)Math.Pow(2, this.networkPrefix - this.getNetworkClassPrefix());

            //	-2 because 1 bit for routing
            if (!this.isFirstSubNetBit() || this.getNetworkClassPrefix() == this.networkPrefix)
                count -= 2;

            if (count < 0) count = 0;
            return count;
        }

        public long getNetworkLong()
        {
            long mask = (long)Math.Pow(2, this.networkPrefix) - 1;
            mask = mask << (32 - this.networkPrefix);

            return (mask & ip2Long());
        }

        public String getNetwork()
        {
            return long2String(getNetworkLong());
        }

        public long getBroadCastLong()
        {
            long netMask = (long)Math.Pow(2, this.networkPrefix) - 1;
            netMask = netMask << (32 - this.networkPrefix);
            long hostMask = (long)Math.Pow(2, 32 - this.networkPrefix) - 1;

            return (netMask = (ip2Long() & netMask) | hostMask);
        }

        public String getBroadCast()
        {
            return long2String(getBroadCastLong());
        }


        public String[] getNetworkIPRange()
        {
            String[] result = new String[2];
            //String from, to;
            /**
			 * Start
			 * +1 because first = network
			 */
            result[0] = long2String(getNetworkLong() + 1);
            /**
			 * End
			 * -1 because last = broadcast
			 */
            result[1] = long2String(getBroadCastLong() - 1);
            return result;
        }

        public long ip2Long()
        {
            return ((long)(IPTool.byte2int(this.get1Byte()) * 256 +
                IPTool.byte2int(this.get2Byte())) * 256 +
                IPTool.byte2int(this.get3Byte())) * 256 +
                IPTool.byte2int(this.get4Byte());
        }

        public String long2String(long ip)
        {
            long a = (long)(ip & 0xff000000) >> 24;
            long b = (long)(ip & 0x00ff0000) >> 16;
            long c = (long)(ip & 0x0000ff00) >> 8;
            long d = (long)(ip & 0xff);

            return a + "." + b + "." + c + "." + d;
        }

        public bool isFirstSubNetBit()
        {
            return firstSubNetBit;
        }

        public void setFirstSubNetBit(bool b)
        {
            firstSubNetBit = b;
        }

        public static IPTool getNextIP(String ip)
        {
            IPTool nextIp = new IPTool(ip);
            nextIp.setIp(nextIp.long2String(nextIp.ip2Long() + (long)1));

            return nextIp;

        }

        public IPTool getNextSubNet(long numberOfHosts)
        {
            IPTool ip = IPTool.getNextIP(this.getBroadCast());
            ip.setIp(this.long2String(ip.ip2Long() + (long)1));
            ip.setFirstSubNetBit(this.isFirstSubNetBit());

            int lastPrefix = ip.getNetworkClassPrefix();

            int prefix = 30;
            do
            {
                if (prefix < ip.getNetworkClassPrefix())
                    return null; // no subnet found
                ip.setNetworkPrefix(prefix);
                prefix--;
                // ignore subnetbit?
                if (!ip.isFirstSubNetBit() && prefix == lastPrefix + 1) prefix--;

            }
            while (ip.getMaxNetworkHosts() < numberOfHosts);

            return ip;
        }
    }
}