/**
 *    Copyright (C) 2013 10gen Inc.
 *
 *    This program is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    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 Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the GNU Affero General Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */

/** Unit tests for BSONElementHasher. */

#include "mongo/db/hasher.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/json.h"
#include "mongo/bson/bsontypes.h"

#include "mongo/unittest/unittest.h"

namespace mongo {
namespace {

    // Helper methods
    long long hashIt( const BSONObj& object, int seed ) {
        return BSONElementHasher::hash64( object.firstElement(), seed );
    }
    long long hashIt( const BSONObj& object ) {
        int seed = 0;
        return hashIt( object, seed );
    }

    // Test different oids hash to different things
    TEST( BSONElementHasher, DifferentOidsAreDifferentHashes ) {
        int seed = 0;

        long long int oidHash = BSONElementHasher::hash64(
                BSONObjBuilder().genOID().obj().firstElement() , seed );
        long long int oidHash2 = BSONElementHasher::hash64(
                BSONObjBuilder().genOID().obj().firstElement() , seed );
        long long int oidHash3 = BSONElementHasher::hash64(
                BSONObjBuilder().genOID().obj().firstElement() , seed );

        ASSERT_NOT_EQUALS( oidHash , oidHash2 );
        ASSERT_NOT_EQUALS( oidHash , oidHash3 );
        ASSERT_NOT_EQUALS( oidHash3 , oidHash2 );
    }

    // Test 32-bit ints, 64-bit ints, doubles hash to same thing
    TEST( BSONElementHasher, ConsistentHashOfIntLongAndDouble ) {
        int i = 3;
        BSONObj p1 = BSON("a" << i);
        long long int intHash = hashIt( p1 );

        long long int ilong = 3;
        BSONObj p2 = BSON("a" << ilong);
        long long int longHash = hashIt( p2 );

        double d = 3.1;
        BSONObj p3 = BSON("a" << d);
        long long int doubleHash = hashIt( p3 );

        ASSERT_EQUALS( intHash, longHash );
        ASSERT_EQUALS( doubleHash, longHash );
    }

    // Test different ints don't hash to same thing
    TEST( BSONElementHasher, DifferentIntHashesDiffer ) {
        ASSERT_NOT_EQUALS(
                hashIt( BSON("a" << 3) ) ,
                hashIt( BSON("a" << 4) )
        );
    }

    // Test seed makes a difference
    TEST( BSONElementHasher, SeedMatters ) {
        ASSERT_NOT_EQUALS(
                hashIt( BSON("a" << 4), 0 ) ,
                hashIt( BSON("a" << 4), 1 )
        );
    }

    // Test strings hash to different things
    TEST( BSONElementHasher, IntAndStringHashesDiffer ) {
        ASSERT_NOT_EQUALS(
                hashIt( BSON("a" << 3) ) ,
                hashIt( BSON("a" << "3") )
        );
    }

    // Test regexps and strings hash to different things
    TEST( BSONElementHasher, RegexAndStringHashesDiffer ) {
        BSONObjBuilder builder;

        ASSERT_NOT_EQUALS(
                hashIt( BSON("a" << "3") ) ,
                hashIt( builder.appendRegex("a","3").obj() )
        );
    }

    // Test arrays and subobject hash to different things
    TEST( BSONElementHasher, ArrayAndSubobjectHashesDiffer ) {
        ASSERT_NOT_EQUALS(
                hashIt( fromjson("{a : {'0' : 0 , '1' : 1}}") ) ,
                hashIt( fromjson("{a : [0,1]}") )
        );
    }

    // Testing sub-document grouping
    TEST( BSONElementHasher, SubDocumentGroupingHashesDiffer ) {
        ASSERT_NOT_EQUALS(
                hashIt( fromjson("{x : {a : {}, b : 1}}") ) ,
                hashIt( fromjson("{x : {a : {b : 1}}}") )
        );
    }

    // Testing codeWscope scope squashing
    TEST( BSONElementHasher, CodeWithScopeSquashesScopeIntsAndDoubles ) {
        int seed = 0;

        BSONObjBuilder b1;
        b1.appendCodeWScope("a","print('this is some stupid code')", BSON("a" << 3));
        BSONObj p10 = b1.obj();

        BSONObjBuilder b2;
        b2.appendCodeWScope("a","print('this is some stupid code')", BSON("a" << 3.1));

        BSONObjBuilder b3;
        b3.appendCodeWScope("a","print('this is \nsome stupider code')", BSON("a" << 3));
        ASSERT_EQUALS(
                BSONElementHasher::hash64( p10.firstElement() , seed ) ,
                BSONElementHasher::hash64( b2.obj().firstElement() , seed )
        );
        ASSERT_NOT_EQUALS(
                BSONElementHasher::hash64( p10.firstElement() , seed ) ,
                BSONElementHasher::hash64( b3.obj().firstElement() , seed )
        );
    }

    // Test some recursive squashing
    TEST( BSONElementHasher, RecursiveSquashingIntsAndDoubles ) {
        ASSERT_EQUALS(
                hashIt( fromjson("{x : {a : 3 ,   b : [ 3.1, {c : 3  }]}}") ) ,
                hashIt( fromjson("{x : {a : 3.1 , b : [ 3,   {c : 3.0}]}}") )
        );
    }

    // Test minkey and maxkey don't hash to same thing
    TEST( BSONElementHasher, MinKeyMaxKeyHashesDiffer ) {
        ASSERT_NOT_EQUALS(
                hashIt( BSON("a" << MAXKEY) ) ,
                hashIt( BSON("a" << MINKEY) )
        );
    }

    // Test squashing very large doubles and very small doubles
    TEST( BSONElementHasher, VeryLargeAndSmallDoubles ) {
        long long maxInt = std::numeric_limits<long long>::max();
        double smallerDouble = maxInt/2;
        double biggerDouble = ( (double)maxInt )*( (double)maxInt );
        ASSERT_NOT_EQUALS(
                hashIt( BSON("a" << maxInt ) ) ,
                hashIt( BSON("a" << smallerDouble ) )
        );
        ASSERT_EQUALS(
                hashIt( BSON("a" << maxInt ) ) ,
                hashIt( BSON("a" << biggerDouble ) )
        );

        long long minInt = std::numeric_limits<long long>::min();
        double negativeDouble = -( (double)maxInt )*( (double)maxInt );
        ASSERT_EQUALS(
                hashIt( BSON("a" << minInt ) ) ,
                hashIt( BSON("a" << negativeDouble ) )
        );
    }

    // Remaining tests are hard-coded checks to ensure the hash function is
    // consistent across platforms and server versions
    //
    // All of the values in the remaining tests have been determined experimentally.
    TEST( BSONElementHasher, HashIntOrLongOrDouble ) {
        BSONObj o = BSON( "check" << 42 );
        ASSERT_EQUALS( hashIt( o ), -944302157085130861LL );
        o = BSON( "check" << 42.123 );
        ASSERT_EQUALS( hashIt( o ), -944302157085130861LL );
        o = BSON( "check" << (long long) 42 );
        ASSERT_EQUALS( hashIt( o ), -944302157085130861LL );

        o = BSON( "check" << 0 );
        ASSERT_EQUALS( hashIt( o ), 4854801880128277513LL );
        o = BSON( "check" << 0.456 );
        ASSERT_EQUALS( hashIt( o ), 4854801880128277513LL );
        o = BSON( "check" << (long long) 0 );
        ASSERT_EQUALS( hashIt( o ), 4854801880128277513LL );
        // NAN is treated as zero.
        o = BSON( "check" << std::numeric_limits<double>::signaling_NaN() );
        ASSERT_EQUALS( hashIt( o ), 4854801880128277513LL );
        o = BSON( "check" << std::numeric_limits<double>::quiet_NaN() );
        ASSERT_EQUALS( hashIt( o ), 4854801880128277513LL );

        o = BSON( "check" << 1 );
        ASSERT_EQUALS( hashIt( o ), 5902408780260971510LL );
        o = BSON( "check" << 1.987 );
        ASSERT_EQUALS( hashIt( o ), 5902408780260971510LL );
        o = BSON( "check" << (long long) 1 );
        ASSERT_EQUALS( hashIt( o ), 5902408780260971510LL );

        o = BSON( "check" << -1 );
        ASSERT_EQUALS( hashIt( o ), 1140205862565771219LL );
        o = BSON( "check" << -1.789 );
        ASSERT_EQUALS( hashIt( o ), 1140205862565771219LL );
        o = BSON( "check" << (long long) -1 );
        ASSERT_EQUALS( hashIt( o ), 1140205862565771219LL );

        o = BSON( "check" << std::numeric_limits<int>::min() );
        ASSERT_EQUALS( hashIt( o ), 6165898260261354870LL );
        o = BSON( "check" << (double) std::numeric_limits<int>::min() );
        ASSERT_EQUALS( hashIt( o ), 6165898260261354870LL );
        o = BSON( "check" << (long long) std::numeric_limits<int>::min() );
        ASSERT_EQUALS( hashIt( o ), 6165898260261354870LL );

        o = BSON( "check" << std::numeric_limits<int>::max() );
        ASSERT_EQUALS( hashIt( o ), 1143184177162245883LL );
        o = BSON( "check" << (double) std::numeric_limits<int>::max() );
        ASSERT_EQUALS( hashIt( o ), 1143184177162245883LL );
        o = BSON( "check" << (long long) std::numeric_limits<int>::max() );
        ASSERT_EQUALS( hashIt( o ), 1143184177162245883LL );

        // Large/small double values.
        ASSERT( std::numeric_limits<long long>::max() < std::numeric_limits<double>::max() );
        o = BSON( "check" << std::numeric_limits<double>::max() );
        ASSERT_EQUALS( hashIt( o ), 921523596458303250LL );
        o = BSON( "check" << std::numeric_limits<long long>::max() ); // 9223372036854775807
        ASSERT_EQUALS( hashIt( o ), 921523596458303250LL );

        // Have to create our own small double.
        // std::numeric_limits<double>::lowest() - Not available until C++11
        // std::numeric_limits<double>::min() - Closest positive value to zero, not most negative.
        double smallDouble = - std::numeric_limits<double>::max();
        ASSERT( smallDouble < static_cast<double>( std::numeric_limits<long long>::min() ) );
        o = BSON( "check" << smallDouble );
        ASSERT_EQUALS( hashIt( o ), 4532067210535695462LL );
        o = BSON( "check" << std::numeric_limits<long long>::min() ); // -9223372036854775808
        ASSERT_EQUALS( hashIt( o ), 4532067210535695462LL );
    }

    TEST( BSONElementHasher, HashMinKey ) {
        BSONObj o = BSON( "check" << MINKEY );
        ASSERT_EQUALS( hashIt( o ), 7961148599568647290LL );
    }

    TEST( BSONElementHasher, HashMaxKey ) {
        BSONObj o = BSON( "check" << MAXKEY );
        ASSERT_EQUALS( hashIt( o ), 5504842513779440750LL );
    }

    TEST( BSONElementHasher, HashUndefined ) {
        BSONObj o = BSON( "check" << BSONUndefined );
        ASSERT_EQUALS( hashIt( o ), 40158834000849533LL );
    }

    TEST( BSONElementHasher, HashNull ) {
        BSONObj o = BSON( "check" << BSONNULL );
        ASSERT_EQUALS( hashIt( o ), 2338878944348059895LL );
    }

    TEST( BSONElementHasher, HashString ) {
        BSONObj o = BSON( "check" << "abc" );
        ASSERT_EQUALS( hashIt( o ), 8478485326885698097LL );
        o = BSON( "check" << BSONSymbol( "abc" ) );
        ASSERT_EQUALS( hashIt( o ), 8478485326885698097LL );

        o = BSON( "check" << "" );
        ASSERT_EQUALS( hashIt( o ), 2049396243249673340LL );
        o = BSON( "check" << BSONSymbol( "" ) );
        ASSERT_EQUALS( hashIt( o ), 2049396243249673340LL );
    }

    TEST( BSONElementHasher, HashObject ) {
        BSONObj o = BSON( "check" << BSON( "a" << "abc" << "b" << 123LL ) );
        ASSERT_EQUALS( hashIt( o ), 4771603801758380216LL );

        o = BSON( "check" << BSONObj() );
        ASSERT_EQUALS( hashIt( o ), 7980500913326740417LL );
    }

    TEST( BSONElementHasher, HashArray ) {
        BSONObj o = BSON( "check" << BSON_ARRAY( "bar" << "baz" << "qux" ) );
        ASSERT_EQUALS( hashIt( o ), -2938911267422831539LL );

        o = BSON( "check" << BSONArray() );
        ASSERT_EQUALS( hashIt( o ), 8849948234993459283LL );
    }

    TEST( BSONElementHasher, HashBinary ) {
        uint8_t bytes[] = { 0, 1, 2, 3, 4, 6 };
        BSONObj o = BSON( "check" << BSONBinData( bytes, 6, BinDataGeneral ) );
        ASSERT_EQUALS( hashIt( o ), 7252465090394235301LL );

        o = BSON( "check" << BSONBinData( bytes, 6, bdtCustom ) );
        ASSERT_EQUALS( hashIt( o ), 5736670452907618262LL );

        uint8_t uuidBytes[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
        o = BSON( "check" << BSONBinData( uuidBytes, 16, newUUID ) );
        ASSERT_EQUALS( hashIt( o ), 6084661258071355978LL );
    }

    TEST( BSONElementHasher, HashObjectId ) {
        BSONObj o = BSON( "check" << OID( "010203040506070809101112" ) );
        ASSERT_EQUALS( hashIt( o ), -5588663249627035708LL );

        o = BSON( "check" << OID( "000000000000000000000000" ) );
        ASSERT_EQUALS( hashIt( o ), -4293118519463489418LL );
    }

    TEST( BSONElementHasher, HashBoolean ) {
        BSONObj o = BSON( "check" << true );
        ASSERT_EQUALS( hashIt( o ), 6405873908747105701LL );

        o = BSON( "check" << false );
        ASSERT_EQUALS( hashIt( o ), 6289544573401934092LL );
    }

    TEST( BSONElementHasher, HashTimeStamp ) {
        BSONObjBuilder builder1;
        BSONObjBuilder builder2;

        BSONObj o = BSON( "check" << Date_t( 0x5566778811223344LL ) );
        ASSERT_EQUALS( hashIt( o ), 4476222765095560467LL );
        o = builder1.appendTimestamp( "check", 0x55667788LL * 1000LL, 0x11223344LL ).obj();
        ASSERT_EQUALS( hashIt( o ), 4476222765095560467LL );

        o = BSON( "check" << Date_t( 0 ) );
        ASSERT_EQUALS( hashIt( o ), -1178696894582842035LL );
        o = builder2.appendTimestamp( "check", 0 ).obj();
        ASSERT_EQUALS( hashIt( o ), -1178696894582842035LL );
    }

    TEST( BSONElementHasher, HashRegEx ) {
        BSONObj o = BSON( "check" << BSONRegEx( "mongodb" ) );
        ASSERT_EQUALS( hashIt( o ), -7275792090268217043LL );

        o = BSON( "check" << BSONRegEx( ".*", "i" ) );
        ASSERT_EQUALS( hashIt( o ), 7095855029187981886LL );
    }

    TEST( BSONElementHasher, HashDBRef ) {
        BSONObj o = BSON( "check" << BSONDBRef( "c", OID( "010203040506070809101112" ) ) );
        ASSERT_EQUALS( hashIt( o ), 940175826736461384LL );

        o = BSON( "check" << BSONDBRef( "db.c", OID( "010203040506070809101112" ) ) );
        ASSERT_EQUALS( hashIt( o ), 2426768198104018194LL );
    }

    TEST( BSONElementHasher, HashCode ) {
        BSONObj o = BSON( "check" << BSONCode( "func f() { return 1; }" ) );
        ASSERT_EQUALS( hashIt( o ), 6861638109178014270LL );
    }

    TEST( BSONElementHasher, HashCodeWScope ) {
        BSONObj o = BSON( "check" <<
                          BSONCodeWScope( "func f() { return 1; }", BSON( "c" << true ) ) );
        ASSERT_EQUALS( hashIt( o ), 501342939894575968LL );
    }

} // namespace
} // namespace mongo