package org.lionsoul.ip2region;

/**
 * util class 
 * 
 * @author chenxin<chenxin619315@gmail.com>
*/
public class Util 
{
    /**
     * write specfield bytes to a byte array start from offset
     * 
     * @param    b
     * @param    offset
     * @param    v
     * @param    bytes
    */
    public static void write( byte[] b, int offset, long v, int bytes)
    {
        for ( int i = 0; i < bytes; i++ ) {
            b[offset++] = (byte)((v >>> (8 * i)) & 0xFF);
        }
    }
    
    /**
     * write a int to a byte array
     * 
     * @param    b
     * @param    offet
     * @param    v
    */
    public static void writeIntLong( byte[] b, int offset, long v )
    {
        b[offset++] = (byte)((v >>  0) & 0xFF);
        b[offset++] = (byte)((v >>  8) & 0xFF);
        b[offset++] = (byte)((v >> 16) & 0xFF);
        b[offset  ] = (byte)((v >> 24) & 0xFF);
    }
    
    /**
     * get a int from a byte array start from the specifiled offset
     * 
     * @param    b
     * @param    offset
    */
    public static long getIntLong( byte[] b, int offset )
    {
        return (
            ((b[offset++] & 0x000000FFL)) |
            ((b[offset++] <<  8) & 0x0000FF00L) |
            ((b[offset++] << 16) & 0x00FF0000L) | 
            ((b[offset  ] << 24) & 0xFF000000L)
        );
    }
    
    /**
     * get a int from a byte array start from the specifield offset
     * 
     * @param    b
     * @param    offset
    */
    public static int getInt3( byte[] b, int offset )
    { 
        return (
            (b[offset++] & 0x000000FF) |
            (b[offset++] & 0x0000FF00) |
            (b[offset  ] & 0x00FF0000)
        );
    }
    
    public static int getInt2( byte[] b, int offset )
    {
        return (
            (b[offset++] & 0x000000FF) |
            (b[offset  ] & 0x0000FF00)
        );
    }
    
    public static int getInt1( byte[] b, int offset )
    {
        return (
            (b[offset] & 0x000000FF)
        );
    }
    
    /**
     * string ip to long ip
     * 
     * @param    ip
     * @return    long
    */
    public static long ip2long( String ip )
    {
        String[] p = ip.split("\\.");
        if ( p.length != 4 ) return 0;
        
        int p1 = ((Integer.valueOf(p[0]) << 24) & 0xFF000000);
        int p2 = ((Integer.valueOf(p[1]) << 16) & 0x00FF0000);
        int p3 = ((Integer.valueOf(p[2]) <<  8) & 0x0000FF00);
        int p4 = ((Integer.valueOf(p[3]) <<  0) & 0x000000FF);
        
        return ((p1 | p2 | p3 | p4) & 0xFFFFFFFFL);
    }
    
    /**
     * int to ip string 
     * 
     * @param    ip
     * @return    string
    */
    public static String long2ip( long ip )
    {
        StringBuilder sb = new StringBuilder();
        
        sb
        .append((ip >> 24) & 0xFF).append('.')
        .append((ip >> 16) & 0xFF).append('.')
        .append((ip >>  8) & 0xFF).append('.')
        .append((ip >>  0) & 0xFF);
        
        return sb.toString();
    }
    
    /**
     * check the validate of the specifeld ip address
     * 
     * @param    ip
     * @return    boolean
    */
    public static boolean isIpAddress( String ip )
    {
        String[] p = ip.split("\\.");
        if ( p.length != 4 ) return false;
        
        for ( String pp : p ) {
            if ( pp.length() > 3 ) return false;
            int val = Integer.valueOf(pp);
            if ( val > 255 ) return false;
        }
        
        return true;
    }
}