// Modifications copyright (C) 2017, Baidu.com, Inc.
// Copyright 2017 The Apache Software Foundation

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

#include "exprs/hll_hash_function.h"

#include "exprs/expr.h"
#include "runtime/tuple_row.h"
#include "runtime/datetime_value.h"
#include "util/path_builder.h"
#include "runtime/string_value.hpp"
#include "exprs/aggregate_functions.h"
#include "exprs/cast_functions.h"
#include "olap/olap_common.h"
#include "olap/utils.h"

namespace palo {

using palo_udf::BigIntVal;
using palo_udf::StringVal;
 
void HllHashFunctions::init() {
}

StringVal HllHashFunctions::create_string_result(palo_udf::FunctionContext* ctx, 
                                                     const StringVal& val, const bool is_null) {
    std::string result;
    if (is_null) {
        // HLL_DATA_EMPTY
        result = "0";
    } else {
        // HLL_DATA_EXPLHLL_DATA_EXPLICIT
        uint64_t hash = HashUtil::murmur_hash64A(val.ptr, val.len, HashUtil::MURMUR_SEED);
        char buf[10];
        buf[0] = HLL_DATA_EXPLICIT;
        buf[1] = 1;
        *((uint64_t*)(buf + 2)) = hash;
        result = std::string(buf, 10);
    }
    return AnyValUtil::from_buffer_temp(ctx, result.c_str(), result.length());
}

StringVal HllHashFunctions::hll_hash(palo_udf::FunctionContext* ctx, 
                                     const StringVal& input) {
    return create_string_result(ctx, input, input.is_null);
}
    
StringVal HllHashFunctions::hll_cardinality(palo_udf::FunctionContext* ctx, 
                                            const StringVal& input) {
    if (input.is_null) {
        return StringVal::null();
    }
    StringVal dst;
    AggregateFunctions::hll_union_agg_init(ctx, &dst);
    AggregateFunctions::hll_union_agg_update(ctx, input, &dst);
    return AggregateFunctions::hll_union_agg_finalize(ctx, dst);
}
}