#-*- coding:utf-8 -*-
"""
" ip2region python seacher client module
"
" Autho: koma<komazhang@foxmail.com>
" Date : 2015-11-06
"""
import struct, io, socket, sys

class Ip2Region(object):
    __headerSip = []
    __headerPtr = []
    __f            = None

    def __init__(self, dbfile):
        self.initDatabase(dbfile)

    def binarySearch(self, ip):
        """
        " binary search method
        " param: ip
        """
        if not ip.isdigit(): ip = self.ip2long(ip)

        self.__f.seek(0)
        b = self.__f.read(8)
        startPtr = self.getLong(b, 0)
        endPtr   = self.getLong(b, 4)

        indexLen = endPtr - startPtr
        self.__f.seek(startPtr)
        b = self.__f.read(indexLen+12)

        l, h, mixPtr = (0, int(indexLen/12), 0)
        while l <= h:
            m   = int((l+h)/2)
            ptr = startPtr + m*12
            self.__f.seek(ptr)

            b     = self.__f.read(12)
            sip = self.getLong(b, 0)
            eip = self.getLong(b, 4)

            if ip > sip:
                if ip > eip:
                    l = m + 1
                else:
                    mixPtr = self.getLong(b, 8)
                    break;
            else:
                h = m - 1

        if mixPtr == 0: return "N2"

        dataPtr = mixPtr & 0x00FFFFFFL
        dataLen = (mixPtr >> 24) & 0xFF
        
        self.__f.seek(dataPtr)
        data = self.__f.read(dataLen)
        return {
            "city_id": self.getLong(data, 0),
            "region" : data[4:]
        }

    def btreeSearch(self, ip):
        """
        " b-tree search method
        " param: ip
        """
        if not ip.isdigit(): ip = self.ip2long(ip)

        headerLen          = len(self.__headerSip) - 1
        l, h, sptr, eptr = (0, headerLen, 0, 0)
        while l <= h:
            m = int((l+h)/2)

            if ip == self.__headerSip[m]:
                if m > 0:
                    sptr = self.__headerPtr[m-1]
                    eptr = self.__headerPtr[m]
                    break;
                else:
                    sptr = self.__headerPtr[m]
                    eptr = self.__headerPtr[m+1]
                    break;

            if ip > self.__headerSip[m]:
                if m == headerLen:
                    sptr = self.__headerPtr[m-1]
                    eptr = self.__headerPtr[m]
                    break;
                elif ip < self.__headerSip[m+1]:
                    sptr = self.__headerPtr[m]
                    eptr = self.__headerPtr[m+1]
                    break;

                l = m + 1
            else:
                if m == 0:
                    sptr = self.__headerPtr[m]
                    eptr = self.__headerPtr[m+1]
                    break;
                elif ip > self.__headerSip[m-1]:
                    sptr = self.__headerPtr[m-1]
                    eptr = self.__headerPtr[m]
                    break;

                h = m - 1

        if sptr == 0: return "N1"

        indexLen = eptr - sptr
        self.__f.seek(sptr)
        b = self.__f.read(indexLen + 12)
        
        l, h, mixPtr = (0, int(indexLen/12), 0)
        while l <= h:
            m = int((l+h)/2)
            offset = m * 12

            if ip > self.getLong(b, offset):
                if ip > self.getLong(b, offset+4):
                    l = m + 1
                else:
                    mixPtr = self.getLong(b, offset+8)
                    break;
            else:
                h = m - 1

        if mixPtr == 0: return "N2"

        dataPtr = mixPtr & 0x00FFFFFFL
        dataLen = (mixPtr >> 24) & 0xFF
        
        self.__f.seek(dataPtr)
        data = self.__f.read(dataLen)
        return {
            "city_id": self.getLong(data, 0),
            "region" : data[4:]
        }

    def initDatabase(self, dbfile):
        """
        " initialize the database for search
        " param: dbFile
        """
        try:
            self.__f = io.open(dbfile, "rb")
            #pass the super block
            self.__f.seek(8)
            #read the header block
            b = self.__f.read(4086)
            #parse the header block
            sip = None
            ptr = None
            for i in range(0, len(b)-1, 8):
                sip = self.getLong(b, i)
                ptr = self.getLong(b, i+4)
                if ptr == 0:
                    break
                self.__headerSip.append(sip)
                self.__headerPtr.append(ptr)

        except IOError, e:
            print "[Error]: ", e
            sys.exit()

    def ip2long(self, ip):
        _ip = socket.inet_aton(ip)
        return struct.unpack("!L", _ip)[0]

    def isip(self, ip):
        p = ip.split(".")

        if len(p) != 4           : return False
        for pp in p:
            if not pp.isdigit(): return False
            if len(pp) > 3       : return False
            if int(pp) > 255   : return False

        return True

    def getLong(self, b, offset):
        if len( b[offset:offset+4] ) == 4:
            return struct.unpack('I', b[offset:offset+4])[0]
        return 0

    def close(self):
        self.__headerSip = None
        self.__headerPtr = None
        self.__f.close()
        self.__f         = None