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


class Ip2Region(object):

    def __init__(self):
        self.__INDEX_BLOCK_LENGTH = 12
        self.__TOTAL_HEADER_LENGTH = 8192
        self.__f = None
        self.__headerSip = []
        self.__headerPtr = []
        self.__headerLen = 0
        self.__indexSPtr = 0
        self.__indexLPtr = 0
        self.__indexCount = 0
        self.__dbBinStr = ''
        dbfile = Path(__file__).parent.parent / 'config/ip2region.db'
        self.initDatabase(dbfile)

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

        if self.__dbBinStr == '':
            self.__dbBinStr = self.__f.read()  # read all the contents in file
            self.__indexSPtr = self.getLong(self.__dbBinStr, 0)
            self.__indexLPtr = self.getLong(self.__dbBinStr, 4)
            self.__indexCount = int((self.__indexLPtr - self.__indexSPtr) / self.__INDEX_BLOCK_LENGTH) + 1

        low, h, dataPtr = (0, self.__indexCount, 0)
        while low <= h:
            m = int((low + h) >> 1)
            p = self.__indexSPtr + m * self.__INDEX_BLOCK_LENGTH
            sip = self.getLong(self.__dbBinStr, p)

            if ip < sip:
                h = m - 1
            else:
                eip = self.getLong(self.__dbBinStr, p + 4)
                if ip > eip:
                    low = m + 1
                else:
                    dataPtr = self.getLong(self.__dbBinStr, p + 8)
                    break

        if dataPtr == 0:
            raise Exception("Data pointer not found")

        return self.returnData(dataPtr)

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

        if self.__indexCount == 0:
            self.__f.seek(0)
            superBlock = self.__f.read(8)
            self.__indexSPtr = self.getLong(superBlock, 0)
            self.__indexLPtr = self.getLong(superBlock, 4)
            self.__indexCount = int((self.__indexLPtr - self.__indexSPtr) / self.__INDEX_BLOCK_LENGTH) + 1

        low, h, dataPtr = (0, self.__indexCount, 0)
        while low <= h:
            m = int((low + h) >> 1)
            p = m * self.__INDEX_BLOCK_LENGTH

            self.__f.seek(self.__indexSPtr + p)
            buffer = self.__f.read(self.__INDEX_BLOCK_LENGTH)
            sip = self.getLong(buffer, 0)
            if ip < sip:
                h = m - 1
            else:
                eip = self.getLong(buffer, 4)
                if ip > eip:
                    low = m + 1
                else:
                    dataPtr = self.getLong(buffer, 8)
                    break

        if dataPtr == 0:
            raise Exception("Data pointer not found")

        return self.returnData(dataPtr)

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

        if len(self.__headerSip) < 1:
            headerLen = 0
            # pass the super block
            self.__f.seek(8)
            # read the header block
            b = self.__f.read(self.__TOTAL_HEADER_LENGTH)
            # parse the header block
            for i in range(0, len(b), 8):
                sip = self.getLong(b, i)
                ptr = self.getLong(b, i + 4)
                if ptr == 0:
                    break
                self.__headerSip.append(sip)
                self.__headerPtr.append(ptr)
                headerLen += 1
            self.__headerLen = headerLen

        low, h, sptr, eptr = (0, self.__headerLen, 0, 0)
        while low <= h:
            m = int((low + h) >> 1)

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

            if ip < self.__headerSip[m]:
                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
            else:
                if m == self.__headerLen - 1:
                    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
                low = m + 1

        if sptr == 0:
            raise Exception("Index pointer not found")

        indexLen = eptr - sptr
        self.__f.seek(sptr)
        index = self.__f.read(indexLen + self.__INDEX_BLOCK_LENGTH)

        low, h, dataPrt = (0, int(indexLen / self.__INDEX_BLOCK_LENGTH), 0)
        while low <= h:
            m = int((low + h) >> 1)
            offset = int(m * self.__INDEX_BLOCK_LENGTH)
            sip = self.getLong(index, offset)

            if ip < sip:
                h = m - 1
            else:
                eip = self.getLong(index, offset + 4)
                if ip > eip:
                    low = m + 1
                else:
                    dataPrt = self.getLong(index, offset + 8)
                    break

        if dataPrt == 0:
            raise Exception("Data pointer not found")

        return self.returnData(dataPrt)

    def initDatabase(self, dbfile):
        """
        " initialize the database for search
        " param: dbFile
        """
        try:
            self.__f = io.open(dbfile, "rb")
        except IOError as e:
            print("[Error]: %s" % e)
            sys.exit()

    def returnData(self, dataPtr):
        """
        " get ip data from db file by data start ptr
        " param: dsptr
        """
        dataLen = (dataPtr >> 24) & 0xFF
        dataPtr = dataPtr & 0x00FFFFFF

        self.__f.seek(dataPtr)
        data = self.__f.read(dataLen)

        return {
            "city_id": self.getLong(data, 0),
            "region": data[4:]
        }

    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):
        if self.__f is not None:
            self.__f.close()

        self.__dbBinStr = None
        self.__headerPtr = None
        self.__headerSip = None
