# -*- coding: utf-8 -*-
#
# This file is part of the python-chess library.
# Copyright (C) 2012-2017 Niklas Fiekas <niklas.fiekas@backscattering.de>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.

import chess
import struct
import os
import mmap
import random

try:
    import backport_collections as collections
except ImportError:
    import collections

ENTRY_STRUCT = struct.Struct(">QHHI")


POLYGLOT_RANDOM_ARRAY = [
    0x9D39247E33776D41, 0x2AF7398005AAA5C7, 0x44DB015014623547, 0x9C15F73E62A76AE2,
    0x75834465489C0C89, 0x3290AC3A203001BF, 0x0FBBAD1F61042279, 0xE83A908FF2FB60CA,
    0x0D7E765D58755C10, 0x1A083822CEAFE02D, 0x9605D5F0E25EC3B0, 0xD021FF5CD13A2ED5,
    0x40BDF15D4A672E32, 0x011355146FD56395, 0x5DB4832046F3D9E5, 0x239F8B2D7FF719CC,
    0x05D1A1AE85B49AA1, 0x679F848F6E8FC971, 0x7449BBFF801FED0B, 0x7D11CDB1C3B7ADF0,
    0x82C7709E781EB7CC, 0xF3218F1C9510786C, 0x331478F3AF51BBE6, 0x4BB38DE5E7219443,
    0xAA649C6EBCFD50FC, 0x8DBD98A352AFD40B, 0x87D2074B81D79217, 0x19F3C751D3E92AE1,
    0xB4AB30F062B19ABF, 0x7B0500AC42047AC4, 0xC9452CA81A09D85D, 0x24AA6C514DA27500,
    0x4C9F34427501B447, 0x14A68FD73C910841, 0xA71B9B83461CBD93, 0x03488B95B0F1850F,
    0x637B2B34FF93C040, 0x09D1BC9A3DD90A94, 0x3575668334A1DD3B, 0x735E2B97A4C45A23,
    0x18727070F1BD400B, 0x1FCBACD259BF02E7, 0xD310A7C2CE9B6555, 0xBF983FE0FE5D8244,
    0x9F74D14F7454A824, 0x51EBDC4AB9BA3035, 0x5C82C505DB9AB0FA, 0xFCF7FE8A3430B241,
    0x3253A729B9BA3DDE, 0x8C74C368081B3075, 0xB9BC6C87167C33E7, 0x7EF48F2B83024E20,
    0x11D505D4C351BD7F, 0x6568FCA92C76A243, 0x4DE0B0F40F32A7B8, 0x96D693460CC37E5D,
    0x42E240CB63689F2F, 0x6D2BDCDAE2919661, 0x42880B0236E4D951, 0x5F0F4A5898171BB6,
    0x39F890F579F92F88, 0x93C5B5F47356388B, 0x63DC359D8D231B78, 0xEC16CA8AEA98AD76,
    0x5355F900C2A82DC7, 0x07FB9F855A997142, 0x5093417AA8A7ED5E, 0x7BCBC38DA25A7F3C,
    0x19FC8A768CF4B6D4, 0x637A7780DECFC0D9, 0x8249A47AEE0E41F7, 0x79AD695501E7D1E8,
    0x14ACBAF4777D5776, 0xF145B6BECCDEA195, 0xDABF2AC8201752FC, 0x24C3C94DF9C8D3F6,
    0xBB6E2924F03912EA, 0x0CE26C0B95C980D9, 0xA49CD132BFBF7CC4, 0xE99D662AF4243939,
    0x27E6AD7891165C3F, 0x8535F040B9744FF1, 0x54B3F4FA5F40D873, 0x72B12C32127FED2B,
    0xEE954D3C7B411F47, 0x9A85AC909A24EAA1, 0x70AC4CD9F04F21F5, 0xF9B89D3E99A075C2,
    0x87B3E2B2B5C907B1, 0xA366E5B8C54F48B8, 0xAE4A9346CC3F7CF2, 0x1920C04D47267BBD,
    0x87BF02C6B49E2AE9, 0x092237AC237F3859, 0xFF07F64EF8ED14D0, 0x8DE8DCA9F03CC54E,
    0x9C1633264DB49C89, 0xB3F22C3D0B0B38ED, 0x390E5FB44D01144B, 0x5BFEA5B4712768E9,
    0x1E1032911FA78984, 0x9A74ACB964E78CB3, 0x4F80F7A035DAFB04, 0x6304D09A0B3738C4,
    0x2171E64683023A08, 0x5B9B63EB9CEFF80C, 0x506AACF489889342, 0x1881AFC9A3A701D6,
    0x6503080440750644, 0xDFD395339CDBF4A7, 0xEF927DBCF00C20F2, 0x7B32F7D1E03680EC,
    0xB9FD7620E7316243, 0x05A7E8A57DB91B77, 0xB5889C6E15630A75, 0x4A750A09CE9573F7,
    0xCF464CEC899A2F8A, 0xF538639CE705B824, 0x3C79A0FF5580EF7F, 0xEDE6C87F8477609D,
    0x799E81F05BC93F31, 0x86536B8CF3428A8C, 0x97D7374C60087B73, 0xA246637CFF328532,
    0x043FCAE60CC0EBA0, 0x920E449535DD359E, 0x70EB093B15B290CC, 0x73A1921916591CBD,
    0x56436C9FE1A1AA8D, 0xEFAC4B70633B8F81, 0xBB215798D45DF7AF, 0x45F20042F24F1768,
    0x930F80F4E8EB7462, 0xFF6712FFCFD75EA1, 0xAE623FD67468AA70, 0xDD2C5BC84BC8D8FC,
    0x7EED120D54CF2DD9, 0x22FE545401165F1C, 0xC91800E98FB99929, 0x808BD68E6AC10365,
    0xDEC468145B7605F6, 0x1BEDE3A3AEF53302, 0x43539603D6C55602, 0xAA969B5C691CCB7A,
    0xA87832D392EFEE56, 0x65942C7B3C7E11AE, 0xDED2D633CAD004F6, 0x21F08570F420E565,
    0xB415938D7DA94E3C, 0x91B859E59ECB6350, 0x10CFF333E0ED804A, 0x28AED140BE0BB7DD,
    0xC5CC1D89724FA456, 0x5648F680F11A2741, 0x2D255069F0B7DAB3, 0x9BC5A38EF729ABD4,
    0xEF2F054308F6A2BC, 0xAF2042F5CC5C2858, 0x480412BAB7F5BE2A, 0xAEF3AF4A563DFE43,
    0x19AFE59AE451497F, 0x52593803DFF1E840, 0xF4F076E65F2CE6F0, 0x11379625747D5AF3,
    0xBCE5D2248682C115, 0x9DA4243DE836994F, 0x066F70B33FE09017, 0x4DC4DE189B671A1C,
    0x51039AB7712457C3, 0xC07A3F80C31FB4B4, 0xB46EE9C5E64A6E7C, 0xB3819A42ABE61C87,
    0x21A007933A522A20, 0x2DF16F761598AA4F, 0x763C4A1371B368FD, 0xF793C46702E086A0,
    0xD7288E012AEB8D31, 0xDE336A2A4BC1C44B, 0x0BF692B38D079F23, 0x2C604A7A177326B3,
    0x4850E73E03EB6064, 0xCFC447F1E53C8E1B, 0xB05CA3F564268D99, 0x9AE182C8BC9474E8,
    0xA4FC4BD4FC5558CA, 0xE755178D58FC4E76, 0x69B97DB1A4C03DFE, 0xF9B5B7C4ACC67C96,
    0xFC6A82D64B8655FB, 0x9C684CB6C4D24417, 0x8EC97D2917456ED0, 0x6703DF9D2924E97E,
    0xC547F57E42A7444E, 0x78E37644E7CAD29E, 0xFE9A44E9362F05FA, 0x08BD35CC38336615,
    0x9315E5EB3A129ACE, 0x94061B871E04DF75, 0xDF1D9F9D784BA010, 0x3BBA57B68871B59D,
    0xD2B7ADEEDED1F73F, 0xF7A255D83BC373F8, 0xD7F4F2448C0CEB81, 0xD95BE88CD210FFA7,
    0x336F52F8FF4728E7, 0xA74049DAC312AC71, 0xA2F61BB6E437FDB5, 0x4F2A5CB07F6A35B3,
    0x87D380BDA5BF7859, 0x16B9F7E06C453A21, 0x7BA2484C8A0FD54E, 0xF3A678CAD9A2E38C,
    0x39B0BF7DDE437BA2, 0xFCAF55C1BF8A4424, 0x18FCF680573FA594, 0x4C0563B89F495AC3,
    0x40E087931A00930D, 0x8CFFA9412EB642C1, 0x68CA39053261169F, 0x7A1EE967D27579E2,
    0x9D1D60E5076F5B6F, 0x3810E399B6F65BA2, 0x32095B6D4AB5F9B1, 0x35CAB62109DD038A,
    0xA90B24499FCFAFB1, 0x77A225A07CC2C6BD, 0x513E5E634C70E331, 0x4361C0CA3F692F12,
    0xD941ACA44B20A45B, 0x528F7C8602C5807B, 0x52AB92BEB9613989, 0x9D1DFA2EFC557F73,
    0x722FF175F572C348, 0x1D1260A51107FE97, 0x7A249A57EC0C9BA2, 0x04208FE9E8F7F2D6,
    0x5A110C6058B920A0, 0x0CD9A497658A5698, 0x56FD23C8F9715A4C, 0x284C847B9D887AAE,
    0x04FEABFBBDB619CB, 0x742E1E651C60BA83, 0x9A9632E65904AD3C, 0x881B82A13B51B9E2,
    0x506E6744CD974924, 0xB0183DB56FFC6A79, 0x0ED9B915C66ED37E, 0x5E11E86D5873D484,
    0xF678647E3519AC6E, 0x1B85D488D0F20CC5, 0xDAB9FE6525D89021, 0x0D151D86ADB73615,
    0xA865A54EDCC0F019, 0x93C42566AEF98FFB, 0x99E7AFEABE000731, 0x48CBFF086DDF285A,
    0x7F9B6AF1EBF78BAF, 0x58627E1A149BBA21, 0x2CD16E2ABD791E33, 0xD363EFF5F0977996,
    0x0CE2A38C344A6EED, 0x1A804AADB9CFA741, 0x907F30421D78C5DE, 0x501F65EDB3034D07,
    0x37624AE5A48FA6E9, 0x957BAF61700CFF4E, 0x3A6C27934E31188A, 0xD49503536ABCA345,
    0x088E049589C432E0, 0xF943AEE7FEBF21B8, 0x6C3B8E3E336139D3, 0x364F6FFA464EE52E,
    0xD60F6DCEDC314222, 0x56963B0DCA418FC0, 0x16F50EDF91E513AF, 0xEF1955914B609F93,
    0x565601C0364E3228, 0xECB53939887E8175, 0xBAC7A9A18531294B, 0xB344C470397BBA52,
    0x65D34954DAF3CEBD, 0xB4B81B3FA97511E2, 0xB422061193D6F6A7, 0x071582401C38434D,
    0x7A13F18BBEDC4FF5, 0xBC4097B116C524D2, 0x59B97885E2F2EA28, 0x99170A5DC3115544,
    0x6F423357E7C6A9F9, 0x325928EE6E6F8794, 0xD0E4366228B03343, 0x565C31F7DE89EA27,
    0x30F5611484119414, 0xD873DB391292ED4F, 0x7BD94E1D8E17DEBC, 0xC7D9F16864A76E94,
    0x947AE053EE56E63C, 0xC8C93882F9475F5F, 0x3A9BF55BA91F81CA, 0xD9A11FBB3D9808E4,
    0x0FD22063EDC29FCA, 0xB3F256D8ACA0B0B9, 0xB03031A8B4516E84, 0x35DD37D5871448AF,
    0xE9F6082B05542E4E, 0xEBFAFA33D7254B59, 0x9255ABB50D532280, 0xB9AB4CE57F2D34F3,
    0x693501D628297551, 0xC62C58F97DD949BF, 0xCD454F8F19C5126A, 0xBBE83F4ECC2BDECB,
    0xDC842B7E2819E230, 0xBA89142E007503B8, 0xA3BC941D0A5061CB, 0xE9F6760E32CD8021,
    0x09C7E552BC76492F, 0x852F54934DA55CC9, 0x8107FCCF064FCF56, 0x098954D51FFF6580,
    0x23B70EDB1955C4BF, 0xC330DE426430F69D, 0x4715ED43E8A45C0A, 0xA8D7E4DAB780A08D,
    0x0572B974F03CE0BB, 0xB57D2E985E1419C7, 0xE8D9ECBE2CF3D73F, 0x2FE4B17170E59750,
    0x11317BA87905E790, 0x7FBF21EC8A1F45EC, 0x1725CABFCB045B00, 0x964E915CD5E2B207,
    0x3E2B8BCBF016D66D, 0xBE7444E39328A0AC, 0xF85B2B4FBCDE44B7, 0x49353FEA39BA63B1,
    0x1DD01AAFCD53486A, 0x1FCA8A92FD719F85, 0xFC7C95D827357AFA, 0x18A6A990C8B35EBD,
    0xCCCB7005C6B9C28D, 0x3BDBB92C43B17F26, 0xAA70B5B4F89695A2, 0xE94C39A54A98307F,
    0xB7A0B174CFF6F36E, 0xD4DBA84729AF48AD, 0x2E18BC1AD9704A68, 0x2DE0966DAF2F8B1C,
    0xB9C11D5B1E43A07E, 0x64972D68DEE33360, 0x94628D38D0C20584, 0xDBC0D2B6AB90A559,
    0xD2733C4335C6A72F, 0x7E75D99D94A70F4D, 0x6CED1983376FA72B, 0x97FCAACBF030BC24,
    0x7B77497B32503B12, 0x8547EDDFB81CCB94, 0x79999CDFF70902CB, 0xCFFE1939438E9B24,
    0x829626E3892D95D7, 0x92FAE24291F2B3F1, 0x63E22C147B9C3403, 0xC678B6D860284A1C,
    0x5873888850659AE7, 0x0981DCD296A8736D, 0x9F65789A6509A440, 0x9FF38FED72E9052F,
    0xE479EE5B9930578C, 0xE7F28ECD2D49EECD, 0x56C074A581EA17FE, 0x5544F7D774B14AEF,
    0x7B3F0195FC6F290F, 0x12153635B2C0CF57, 0x7F5126DBBA5E0CA7, 0x7A76956C3EAFB413,
    0x3D5774A11D31AB39, 0x8A1B083821F40CB4, 0x7B4A38E32537DF62, 0x950113646D1D6E03,
    0x4DA8979A0041E8A9, 0x3BC36E078F7515D7, 0x5D0A12F27AD310D1, 0x7F9D1A2E1EBE1327,
    0xDA3A361B1C5157B1, 0xDCDD7D20903D0C25, 0x36833336D068F707, 0xCE68341F79893389,
    0xAB9090168DD05F34, 0x43954B3252DC25E5, 0xB438C2B67F98E5E9, 0x10DCD78E3851A492,
    0xDBC27AB5447822BF, 0x9B3CDB65F82CA382, 0xB67B7896167B4C84, 0xBFCED1B0048EAC50,
    0xA9119B60369FFEBD, 0x1FFF7AC80904BF45, 0xAC12FB171817EEE7, 0xAF08DA9177DDA93D,
    0x1B0CAB936E65C744, 0xB559EB1D04E5E932, 0xC37B45B3F8D6F2BA, 0xC3A9DC228CAAC9E9,
    0xF3B8B6675A6507FF, 0x9FC477DE4ED681DA, 0x67378D8ECCEF96CB, 0x6DD856D94D259236,
    0xA319CE15B0B4DB31, 0x073973751F12DD5E, 0x8A8E849EB32781A5, 0xE1925C71285279F5,
    0x74C04BF1790C0EFE, 0x4DDA48153C94938A, 0x9D266D6A1CC0542C, 0x7440FB816508C4FE,
    0x13328503DF48229F, 0xD6BF7BAEE43CAC40, 0x4838D65F6EF6748F, 0x1E152328F3318DEA,
    0x8F8419A348F296BF, 0x72C8834A5957B511, 0xD7A023A73260B45C, 0x94EBC8ABCFB56DAE,
    0x9FC10D0F989993E0, 0xDE68A2355B93CAE6, 0xA44CFE79AE538BBE, 0x9D1D84FCCE371425,
    0x51D2B1AB2DDFB636, 0x2FD7E4B9E72CD38C, 0x65CA5B96B7552210, 0xDD69A0D8AB3B546D,
    0x604D51B25FBF70E2, 0x73AA8A564FB7AC9E, 0x1A8C1E992B941148, 0xAAC40A2703D9BEA0,
    0x764DBEAE7FA4F3A6, 0x1E99B96E70A9BE8B, 0x2C5E9DEB57EF4743, 0x3A938FEE32D29981,
    0x26E6DB8FFDF5ADFE, 0x469356C504EC9F9D, 0xC8763C5B08D1908C, 0x3F6C6AF859D80055,
    0x7F7CC39420A3A545, 0x9BFB227EBDF4C5CE, 0x89039D79D6FC5C5C, 0x8FE88B57305E2AB6,
    0xA09E8C8C35AB96DE, 0xFA7E393983325753, 0xD6B6D0ECC617C699, 0xDFEA21EA9E7557E3,
    0xB67C1FA481680AF8, 0xCA1E3785A9E724E5, 0x1CFC8BED0D681639, 0xD18D8549D140CAEA,
    0x4ED0FE7E9DC91335, 0xE4DBF0634473F5D2, 0x1761F93A44D5AEFE, 0x53898E4C3910DA55,
    0x734DE8181F6EC39A, 0x2680B122BAA28D97, 0x298AF231C85BAFAB, 0x7983EED3740847D5,
    0x66C1A2A1A60CD889, 0x9E17E49642A3E4C1, 0xEDB454E7BADC0805, 0x50B704CAB602C329,
    0x4CC317FB9CDDD023, 0x66B4835D9EAFEA22, 0x219B97E26FFC81BD, 0x261E4E4C0A333A9D,
    0x1FE2CCA76517DB90, 0xD7504DFA8816EDBB, 0xB9571FA04DC089C8, 0x1DDC0325259B27DE,
    0xCF3F4688801EB9AA, 0xF4F5D05C10CAB243, 0x38B6525C21A42B0E, 0x36F60E2BA4FA6800,
    0xEB3593803173E0CE, 0x9C4CD6257C5A3603, 0xAF0C317D32ADAA8A, 0x258E5A80C7204C4B,
    0x8B889D624D44885D, 0xF4D14597E660F855, 0xD4347F66EC8941C3, 0xE699ED85B0DFB40D,
    0x2472F6207C2D0484, 0xC2A1E7B5B459AEB5, 0xAB4F6451CC1D45EC, 0x63767572AE3D6174,
    0xA59E0BD101731A28, 0x116D0016CB948F09, 0x2CF9C8CA052F6E9F, 0x0B090A7560A968E3,
    0xABEEDDB2DDE06FF1, 0x58EFC10B06A2068D, 0xC6E57A78FBD986E0, 0x2EAB8CA63CE802D7,
    0x14A195640116F336, 0x7C0828DD624EC390, 0xD74BBE77E6116AC7, 0x804456AF10F5FB53,
    0xEBE9EA2ADF4321C7, 0x03219A39EE587A30, 0x49787FEF17AF9924, 0xA1E9300CD8520548,
    0x5B45E522E4B1B4EF, 0xB49C3B3995091A36, 0xD4490AD526F14431, 0x12A8F216AF9418C2,
    0x001F837CC7350524, 0x1877B51E57A764D5, 0xA2853B80F17F58EE, 0x993E1DE72D36D310,
    0xB3598080CE64A656, 0x252F59CF0D9F04BB, 0xD23C8E176D113600, 0x1BDA0492E7E4586E,
    0x21E0BD5016C619BF, 0x3B097ADAF088F94E, 0x8D14DEDB30BE846E, 0xF95CFFA23AF5F6F4,
    0x3871700761B3F743, 0xCA672B91E9E4FA16, 0x64C8E531BFF53B55, 0x241260ED4AD1E87D,
    0x106C09B972D2E822, 0x7FBA195410E5CA30, 0x7884D9BC6CB569D8, 0x0647DFEDCD894A29,
    0x63573FF03E224774, 0x4FC8E9560F91B123, 0x1DB956E450175779, 0xB8D91274B9E9D4FB,
    0xA2EBEE47E2FBFCE1, 0xD9F1F30CCD97FB09, 0xEFED53D75FD64E6B, 0x2E6D02C36017F67F,
    0xA9AA4D20DB084E9B, 0xB64BE8D8B25396C1, 0x70CB6AF7C2D5BCF0, 0x98F076A4F7A2322E,
    0xBF84470805E69B5F, 0x94C3251F06F90CF3, 0x3E003E616A6591E9, 0xB925A6CD0421AFF3,
    0x61BDD1307C66E300, 0xBF8D5108E27E0D48, 0x240AB57A8B888B20, 0xFC87614BAF287E07,
    0xEF02CDD06FFDB432, 0xA1082C0466DF6C0A, 0x8215E577001332C8, 0xD39BB9C3A48DB6CF,
    0x2738259634305C14, 0x61CF4F94C97DF93D, 0x1B6BACA2AE4E125B, 0x758F450C88572E0B,
    0x959F587D507A8359, 0xB063E962E045F54D, 0x60E8ED72C0DFF5D1, 0x7B64978555326F9F,
    0xFD080D236DA814BA, 0x8C90FD9B083F4558, 0x106F72FE81E2C590, 0x7976033A39F7D952,
    0xA4EC0132764CA04B, 0x733EA705FAE4FA77, 0xB4D8F77BC3E56167, 0x9E21F4F903B33FD9,
    0x9D765E419FB69F6D, 0xD30C088BA61EA5EF, 0x5D94337FBFAF7F5B, 0x1A4E4822EB4D7A59,
    0x6FFE73E81B637FB3, 0xDDF957BC36D8B9CA, 0x64D0E29EEA8838B3, 0x08DD9BDFD96B9F63,
    0x087E79E5A57D1D13, 0xE328E230E3E2B3FB, 0x1C2559E30F0946BE, 0x720BF5F26F4D2EAA,
    0xB0774D261CC609DB, 0x443F64EC5A371195, 0x4112CF68649A260E, 0xD813F2FAB7F5C5CA,
    0x660D3257380841EE, 0x59AC2C7873F910A3, 0xE846963877671A17, 0x93B633ABFA3469F8,
    0xC0C0F5A60EF4CDCF, 0xCAF21ECD4377B28C, 0x57277707199B8175, 0x506C11B9D90E8B1D,
    0xD83CC2687A19255F, 0x4A29C6465A314CD1, 0xED2DF21216235097, 0xB5635C95FF7296E2,
    0x22AF003AB672E811, 0x52E762596BF68235, 0x9AEBA33AC6ECC6B0, 0x944F6DE09134DFB6,
    0x6C47BEC883A7DE39, 0x6AD047C430A12104, 0xA5B1CFDBA0AB4067, 0x7C45D833AFF07862,
    0x5092EF950A16DA0B, 0x9338E69C052B8E7B, 0x455A4B4CFE30E3F5, 0x6B02E63195AD0CF8,
    0x6B17B224BAD6BF27, 0xD1E0CCD25BB9C169, 0xDE0C89A556B9AE70, 0x50065E535A213CF6,
    0x9C1169FA2777B874, 0x78EDEFD694AF1EED, 0x6DC93D9526A50E68, 0xEE97F453F06791ED,
    0x32AB0EDB696703D3, 0x3A6853C7E70757A7, 0x31865CED6120F37D, 0x67FEF95D92607890,
    0x1F2B1D1F15F6DC9C, 0xB69E38A8965C6B65, 0xAA9119FF184CCCF4, 0xF43C732873F24C13,
    0xFB4A3D794A9A80D2, 0x3550C2321FD6109C, 0x371F77E76BB8417E, 0x6BFA9AAE5EC05779,
    0xCD04F3FF001A4778, 0xE3273522064480CA, 0x9F91508BFFCFC14A, 0x049A7F41061A9E60,
    0xFCB6BE43A9F2FE9B, 0x08DE8A1C7797DA9B, 0x8F9887E6078735A1, 0xB5B4071DBFC73A66,
    0x230E343DFBA08D33, 0x43ED7F5A0FAE657D, 0x3A88A0FBBCB05C63, 0x21874B8B4D2DBC4F,
    0x1BDEA12E35F6A8C9, 0x53C065C6C8E63528, 0xE34A1D250E7A8D6B, 0xD6B04D3B7651DD7E,
    0x5E90277E7CB39E2D, 0x2C046F22062DC67D, 0xB10BB459132D0A26, 0x3FA9DDFB67E2F199,
    0x0E09B88E1914F7AF, 0x10E8B35AF3EEAB37, 0x9EEDECA8E272B933, 0xD4C718BC4AE8AE5F,
    0x81536D601170FC20, 0x91B534F885818A06, 0xEC8177F83F900978, 0x190E714FADA5156E,
    0xB592BF39B0364963, 0x89C350C893AE7DC1, 0xAC042E70F8B383F2, 0xB49B52E587A1EE60,
    0xFB152FE3FF26DA89, 0x3E666E6F69AE2C15, 0x3B544EBE544C19F9, 0xE805A1E290CF2456,
    0x24B33C9D7ED25117, 0xE74733427B72F0C1, 0x0A804D18B7097475, 0x57E3306D881EDB4F,
    0x4AE7D6A36EB5DBCB, 0x2D8D5432157064C8, 0xD1E649DE1E7F268B, 0x8A328A1CEDFE552C,
    0x07A3AEC79624C7DA, 0x84547DDC3E203C94, 0x990A98FD5071D263, 0x1A4FF12616EEFC89,
    0xF6F7FD1431714200, 0x30C05B1BA332F41C, 0x8D2636B81555A786, 0x46C9FEB55D120902,
    0xCCEC0A73B49C9921, 0x4E9D2827355FC492, 0x19EBB029435DCB0F, 0x4659D2B743848A2C,
    0x963EF2C96B33BE31, 0x74F85198B05A2E7D, 0x5A0F544DD2B1FB18, 0x03727073C2E134B1,
    0xC7F6AA2DE59AEA61, 0x352787BAA0D7C22F, 0x9853EAB63B5E0B35, 0xABBDCDD7ED5C0860,
    0xCF05DAF5AC8D77B0, 0x49CAD48CEBF4A71E, 0x7A4C10EC2158C4A6, 0xD9E92AA246BF719E,
    0x13AE978D09FE5557, 0x730499AF921549FF, 0x4E4B705B92903BA4, 0xFF577222C14F0A3A,
    0x55B6344CF97AAFAE, 0xB862225B055B6960, 0xCAC09AFBDDD2CDB4, 0xDAF8E9829FE96B5F,
    0xB5FDFC5D3132C498, 0x310CB380DB6F7503, 0xE87FBB46217A360E, 0x2102AE466EBB1148,
    0xF8549E1A3AA5E00D, 0x07A69AFDCC42261A, 0xC4C118BFE78FEAAE, 0xF9F4892ED96BD438,
    0x1AF3DBE25D8F45DA, 0xF5B4B0B0D2DEEEB4, 0x962ACEEFA82E1C84, 0x046E3ECAAF453CE9,
    0xF05D129681949A4C, 0x964781CE734B3C84, 0x9C2ED44081CE5FBD, 0x522E23F3925E319E,
    0x177E00F9FC32F791, 0x2BC60A63A6F3B3F2, 0x222BBFAE61725606, 0x486289DDCC3D6780,
    0x7DC7785B8EFDFC80, 0x8AF38731C02BA980, 0x1FAB64EA29A2DDF7, 0xE4D9429322CD065A,
    0x9DA058C67844F20C, 0x24C0E332B70019B0, 0x233003B5A6CFE6AD, 0xD586BD01C5C217F6,
    0x5E5637885F29BC2B, 0x7EBA726D8C94094B, 0x0A56A5F0BFE39272, 0xD79476A84EE20D06,
    0x9E4C1269BAA4BF37, 0x17EFEE45B0DEE640, 0x1D95B0A5FCF90BC6, 0x93CBE0B699C2585D,
    0x65FA4F227A2B6D79, 0xD5F9E858292504D5, 0xC2B5A03F71471A6F, 0x59300222B4561E00,
    0xCE2F8642CA0712DC, 0x7CA9723FBB2E8988, 0x2785338347F2BA08, 0xC61BB3A141E50E8C,
    0x150F361DAB9DEC26, 0x9F6A419D382595F4, 0x64A53DC924FE7AC9, 0x142DE49FFF7A7C3D,
    0x0C335248857FA9E7, 0x0A9C32D5EAE45305, 0xE6C42178C4BBB92E, 0x71F1CE2490D20B07,
    0xF1BCC3D275AFE51A, 0xE728E8C83C334074, 0x96FBF83A12884624, 0x81A1549FD6573DA5,
    0x5FA7867CAF35E149, 0x56986E2EF3ED091B, 0x917F1DD5F8886C61, 0xD20D8C88C8FFE65F,
    0x31D71DCE64B2C310, 0xF165B587DF898190, 0xA57E6339DD2CF3A0, 0x1EF6E6DBB1961EC9,
    0x70CC73D90BC26E24, 0xE21A6B35DF0C3AD7, 0x003A93D8B2806962, 0x1C99DED33CB890A1,
    0xCF3145DE0ADD4289, 0xD0E4427A5514FB72, 0x77C621CC9FB3A483, 0x67A34DAC4356550B,
    0xF8D626AAAF278509
]


class ZobristHasher(object):
    def __init__(self, array):
        assert len(array) >= 781
        self.array = array

    def hash_board(self, board):
        zobrist_hash = 0

        for pivot, squares in enumerate(board.occupied_co):
            for square in chess.scan_reversed(squares):
                piece_index = (board.piece_type_at(square) - 1) * 2 + pivot
                zobrist_hash ^= self.array[64 * piece_index + square]

        return zobrist_hash

    def hash_castling(self, board):
        zobrist_hash = 0

        # Hash in the castling flags.
        if board.has_kingside_castling_rights(chess.WHITE):
            zobrist_hash ^= self.array[768]
        if board.has_queenside_castling_rights(chess.WHITE):
            zobrist_hash ^= self.array[768 + 1]
        if board.has_kingside_castling_rights(chess.BLACK):
            zobrist_hash ^= self.array[768 + 2]
        if board.has_queenside_castling_rights(chess.BLACK):
            zobrist_hash ^= self.array[768 + 3]

        return zobrist_hash

    def hash_ep_square(self, board):
        # Hash in the en passant file.
        if board.ep_square:
            # But only if there's actually a pawn ready to capture it. Legality
            # of the potential capture is irrelevant.
            if board.turn == chess.WHITE:
                ep_mask = chess.shift_down(chess.BB_SQUARES[board.ep_square])
            else:
                ep_mask = chess.shift_up(chess.BB_SQUARES[board.ep_square])
            ep_mask = chess.shift_left(ep_mask) | chess.shift_right(ep_mask)

            if ep_mask & board.pawns & board.occupied_co[board.turn]:
                return self.array[772 + chess.square_file(board.ep_square)]
        return 0

    def hash_turn(self, board):
        # Hash in the turn.
        return self.array[780] if board.turn == chess.WHITE else 0

    def __call__(self, board):
        return (self.hash_board(board) ^ self.hash_castling(board) ^
                self.hash_ep_square(board) ^ self.hash_turn(board))


def zobrist_hash(board, _hasher=ZobristHasher(POLYGLOT_RANDOM_ARRAY)):
    """
    Calculates the Polyglot Zobrist hash of the position.

    A Zobrist hash is an XOR of pseudo-random values picked from
    an array. Which values are picked is decided by features of the
    position, such as piece positions, castling rights and en passant
    squares.
    """
    return _hasher(board)


class Entry(collections.namedtuple("Entry", "key raw_move weight learn")):
    """An entry from a Polyglot opening book."""

    __slots__ = ()

    def move(self, chess960=False):
        """Gets the move (as a :class:`~chess.Move` object)."""
        # Extract source and target square.
        to_square = self.raw_move & 0x3f
        from_square = (self.raw_move >> 6) & 0x3f

        # Extract the promotion type.
        promotion_part = (self.raw_move >> 12) & 0x7
        promotion = promotion_part + 1 if promotion_part else None

        # Convert castling moves.
        if not chess960 and not promotion:
            if from_square == chess.E1:
                if to_square == chess.H1:
                    return chess.Move(chess.E1, chess.G1)
                elif to_square == chess.A1:
                    return chess.Move(chess.E1, chess.C1)
            elif from_square == chess.E8:
                if to_square == chess.H8:
                    return chess.Move(chess.E8, chess.G8)
                elif to_square == chess.A8:
                    return chess.Move(chess.E8, chess.C8)

        if promotion and from_square == to_square:
            return chess.Move(from_square, to_square, drop=promotion)
        else:
            return chess.Move(from_square, to_square, promotion)


class MemoryMappedReader(object):
    """Maps a Polyglot opening book to memory."""

    def __init__(self, filename):
        self.fd = os.open(filename, os.O_RDONLY | os.O_BINARY if hasattr(os, "O_BINARY") else os.O_RDONLY)

        try:
            self.mmap = mmap.mmap(self.fd, 0, access=mmap.ACCESS_READ)
        except (ValueError, mmap.error):
            # Can not memory map empty opening books.
            self.mmap = None

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        return self.close()

    def __len__(self):
        if self.mmap is None:
            return 0
        else:
            return self.mmap.size() // ENTRY_STRUCT.size

    def __getitem__(self, key):
        if self.mmap is None:
            raise IndexError()

        if key < 0:
            key = len(self) + key

        try:
            key, raw_move, weight, learn = ENTRY_STRUCT.unpack_from(self.mmap, key * ENTRY_STRUCT.size)
        except struct.error:
            raise IndexError()

        return Entry(key, raw_move, weight, learn)

    def __iter__(self):
        i = 0
        size = len(self)
        while i < size:
            yield self[i]
            i += 1

    def bisect_key_left(self, key):
        lo = 0
        hi = len(self)

        while lo < hi:
            mid = (lo + hi) // 2
            mid_key, _, _, _ = ENTRY_STRUCT.unpack_from(self.mmap, mid * ENTRY_STRUCT.size)
            if mid_key < key:
                lo = mid + 1
            else:
                hi = mid

        return lo

    def __contains__(self, entry):
        return any(current == entry for current in self.find_all(entry.key, entry.weight))

    def find_all(self, board, minimum_weight=1, exclude_moves=()):
        """Seeks a specific position and yields corresponding entries."""
        try:
            key = int(board)
            board = None
        except (TypeError, ValueError):
            key = zobrist_hash(board)

        i = self.bisect_key_left(key)
        size = len(self)

        while i < size:
            entry = self[i]
            i += 1

            if entry.key != key:
                break

            if entry.weight < minimum_weight:
                continue

            if board:
                move = entry.move(chess960=board.chess960)
            elif exclude_moves:
                move = entry.move()

            if exclude_moves and move in exclude_moves:
                continue

            if board and not board.is_legal(move):
                continue

            yield entry

    def find(self, board, minimum_weight=1, exclude_moves=()):
        """
        Finds the main entry for the given position or Zobrist hash.

        The main entry is the first entry with the highest weight.

        By default entries with weight ``0`` are excluded. This is a common way
        to delete entries from an opening book without compacting it. Pass
        *minimum_weight* ``0`` to select all entries.

        :raises: :exc:`IndexError` if no entries are found.
        """
        try:
            return max(self.find_all(board, minimum_weight, exclude_moves), key=lambda entry: entry.weight)
        except ValueError:
            raise IndexError()

    def choice(self, board, minimum_weight=1, exclude_moves=(), random=random):
        """
        Uniformly selects a random entry for the given position.

        :raises: :exc:`IndexError` if no entries are found.
        """
        chosen_entry = None

        for i, entry in enumerate(self.find_all(board, minimum_weight, exclude_moves)):
            if chosen_entry is None or random.randint(0, i) == i:
                chosen_entry = entry

        if chosen_entry is None:
            raise IndexError()

        return chosen_entry

    def weighted_choice(self, board, exclude_moves=(), random=random):
        """
        Selects a random entry for the given position, distributed by the
        weights of the entries.

        :raises: :exc:`IndexError` if no entries are found.
        """
        total_weights = sum(entry.weight for entry in self.find_all(board, exclude_moves=exclude_moves))
        if not total_weights:
            raise IndexError()

        choice = random.randint(0, total_weights - 1)

        current_sum = 0
        for entry in self.find_all(board, exclude_moves=exclude_moves):
            current_sum += entry.weight
            if current_sum > choice:
                return entry

        assert False

    def close(self):
        """Closes the reader."""
        if self.mmap is not None:
            self.mmap.close()

        try:
            os.close(self.fd)
        except OSError:
            pass


def open_reader(path):
    """
    Creates a reader for the file at the given path.

    The following example opens a book to find all entries for the start
    position:

    >>> import chess
    >>> import chess.polyglot
    >>>
    >>> board = chess.Board()
    >>>
    >>> with chess.polyglot.open_reader("data/polyglot/performance.bin") as reader:
    ...    for entry in reader.find_all(board):
    ...        print(entry.move(), entry.weight, entry.learn)
    e2e4 1 0
    d2d4 1 0
    c2c4 1 0
    """
    return MemoryMappedReader(path)
