// 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.
// This file is copied from
// https://github.com/ClickHouse/ClickHouse/blob/master/base/base/StringRef.h
// and modified by Doris

#pragma once

#include <functional>
#include <ostream>
#include <string>
#include <string_view>
#include <vector>

#include "gutil/hash/city.h"
#include "gutil/hash/hash128to64.h"
#include "udf/udf.h"
#include "util/slice.h"
#include "vec/common/unaligned.h"
#include "vec/core/types.h"

#if defined(__SSE2__)
#include <emmintrin.h>
#endif

#if defined(__SSE4_2__)
#include <nmmintrin.h>
#include <smmintrin.h>
#endif

#if defined(__aarch64__)
#include <sse2neon.h>
#endif

#if defined(__SSE2__) || defined(__aarch64__)

/** Compare strings for equality.
  * The approach is controversial and does not win in all cases.
  * For more information, see hash_map_string_2.cpp
  */

inline bool compareSSE2(const char* p1, const char* p2) {
    return 0xFFFF ==
           _mm_movemask_epi8(_mm_cmpeq_epi8(_mm_loadu_si128(reinterpret_cast<const __m128i*>(p1)),
                                            _mm_loadu_si128(reinterpret_cast<const __m128i*>(p2))));
}

inline bool compareSSE2x4(const char* p1, const char* p2) {
    return 0xFFFF ==
           _mm_movemask_epi8(_mm_and_si128(
                   _mm_and_si128(
                           _mm_cmpeq_epi8(_mm_loadu_si128(reinterpret_cast<const __m128i*>(p1)),
                                          _mm_loadu_si128(reinterpret_cast<const __m128i*>(p2))),
                           _mm_cmpeq_epi8(
                                   _mm_loadu_si128(reinterpret_cast<const __m128i*>(p1) + 1),
                                   _mm_loadu_si128(reinterpret_cast<const __m128i*>(p2) + 1))),
                   _mm_and_si128(
                           _mm_cmpeq_epi8(
                                   _mm_loadu_si128(reinterpret_cast<const __m128i*>(p1) + 2),
                                   _mm_loadu_si128(reinterpret_cast<const __m128i*>(p2) + 2)),
                           _mm_cmpeq_epi8(
                                   _mm_loadu_si128(reinterpret_cast<const __m128i*>(p1) + 3),
                                   _mm_loadu_si128(reinterpret_cast<const __m128i*>(p2) + 3)))));
}

inline bool memequalSSE2Wide(const char* p1, const char* p2, size_t size) {
    /** The order of branches and the trick with overlapping comparisons
      * are the same as in memcpy implementation.
      * See the comments in
      * https://github.com/ClickHouse/ClickHouse/blob/master/base/glibc-compatibility/memcpy/memcpy.h
      */

    if (size <= 16) {
        if (size >= 8) {
            /// Chunks of [8,16] bytes.
            return unaligned_load<uint64_t>(p1) == unaligned_load<uint64_t>(p2) &&
                   unaligned_load<uint64_t>(p1 + size - 8) ==
                           unaligned_load<uint64_t>(p2 + size - 8);
        } else if (size >= 4) {
            /// Chunks of [4,7] bytes.
            return unaligned_load<uint32_t>(p1) == unaligned_load<uint32_t>(p2) &&
                   unaligned_load<uint32_t>(p1 + size - 4) ==
                           unaligned_load<uint32_t>(p2 + size - 4);
        } else if (size >= 2) {
            /// Chunks of [2,3] bytes.
            return unaligned_load<uint16_t>(p1) == unaligned_load<uint16_t>(p2) &&
                   unaligned_load<uint16_t>(p1 + size - 2) ==
                           unaligned_load<uint16_t>(p2 + size - 2);
        } else if (size >= 1) {
            /// A single byte.
            return *p1 == *p2;
        }
        return true;
    }

    while (size >= 64) {
        if (compareSSE2x4(p1, p2)) {
            p1 += 64;
            p2 += 64;
            size -= 64;
        } else
            return false;
    }

    switch (size / 16) {
    case 3:
        if (!compareSSE2(p1 + 32, p2 + 32)) return false;
        [[fallthrough]];
    case 2:
        if (!compareSSE2(p1 + 16, p2 + 16)) return false;
        [[fallthrough]];
    case 1:
        if (!compareSSE2(p1, p2)) return false;
    }

    return compareSSE2(p1 + size - 16, p2 + size - 16);
}

#endif

/// The thing to avoid creating strings to find substrings in the hash table.
struct StringRef {
    const char* data = nullptr;
    size_t size = 0;

    StringRef(const char* data_, size_t size_) : data(data_), size(size_) {}
    StringRef(const unsigned char* data_, size_t size_)
            : data(reinterpret_cast<const char*>(data_)), size(size_) {}
    StringRef(const std::string& s) : data(s.data()), size(s.size()) {}
    StringRef() = default;

    std::string to_string() const { return std::string(data, size); }
    std::string_view to_string_view() const { return std::string_view(data, size); }
    doris::Slice to_slice() const { return doris::Slice(data, size); }

    // this is just for show, eg. print data to error log, to avoid print large string.
    std::string to_prefix(size_t length) const { return std::string(data, std::min(length, size)); }

    explicit operator std::string() const { return to_string(); }

    StringRef substring(int start_pos, int new_len) const {
        return StringRef(data + start_pos, (new_len < 0) ? (size - start_pos) : new_len);
    }

    StringVal to_string_val() {
        return StringVal(reinterpret_cast<uint8_t*>(const_cast<char*>(data)), size);
    }

    static StringRef from_string_val(StringVal sv) {
        return StringRef(reinterpret_cast<char*>(sv.ptr), sv.len);
    }

    bool start_with(StringRef& search_string) const {
        DCHECK(size >= search_string.size);
        if (search_string.size == 0) return true;

#if defined(__SSE2__) || defined(__aarch64__)
        return memequalSSE2Wide(data, search_string.data, search_string.size);
#else
        return 0 == memcmp(data, search_string.data, search_string.size);
#endif
    }
    bool end_with(StringRef& search_string) const {
        DCHECK(size >= search_string.size);
        if (search_string.size == 0) return true;

#if defined(__SSE2__) || defined(__aarch64__)
        return memequalSSE2Wide(data + size - search_string.size, search_string.data,
                                search_string.size);
#else
        return 0 ==
               memcmp(data + size - search_string.size, search_string.data, search_string.size);
#endif
    }
};

using StringRefs = std::vector<StringRef>;

inline bool operator==(StringRef lhs, StringRef rhs) {
    if (lhs.size != rhs.size) return false;

    if (lhs.size == 0) return true;

#if defined(__SSE2__) || defined(__aarch64__)
    return memequalSSE2Wide(lhs.data, rhs.data, lhs.size);
#else
    return 0 == memcmp(lhs.data, rhs.data, lhs.size);
#endif
}

inline bool operator!=(StringRef lhs, StringRef rhs) {
    return !(lhs == rhs);
}

inline bool operator<(StringRef lhs, StringRef rhs) {
    int cmp = memcmp(lhs.data, rhs.data, std::min(lhs.size, rhs.size));
    return cmp < 0 || (cmp == 0 && lhs.size < rhs.size);
}

inline bool operator>(StringRef lhs, StringRef rhs) {
    int cmp = memcmp(lhs.data, rhs.data, std::min(lhs.size, rhs.size));
    return cmp > 0 || (cmp == 0 && lhs.size > rhs.size);
}

/** Hash functions.
  * You can use either CityHash64,
  *  or a function based on the crc32 statement,
  *  which is obviously less qualitative, but on real data sets,
  *  when used in a hash table, works much faster.
  * For more information, see hash_map_string_3.cpp
  */

struct StringRefHash64 {
    size_t operator()(StringRef x) const { return util_hash::CityHash64(x.data, x.size); }
};

#if defined(__SSE4_2__) || defined(__aarch64__)

/// Parts are taken from CityHash.

inline doris::vectorized::UInt64 hash_len16(doris::vectorized::UInt64 u,
                                            doris::vectorized::UInt64 v) {
    return Hash128to64(uint128(u, v));
}

inline doris::vectorized::UInt64 shift_mix(doris::vectorized::UInt64 val) {
    return val ^ (val >> 47);
}

inline doris::vectorized::UInt64 rotate_by_at_least1(doris::vectorized::UInt64 val, int shift) {
    return (val >> shift) | (val << (64 - shift));
}

inline size_t hash_less_than8(const char* data, size_t size) {
    static constexpr doris::vectorized::UInt64 k2 = 0x9ae16a3b2f90404fULL;
    static constexpr doris::vectorized::UInt64 k3 = 0xc949d7c7509e6557ULL;

    if (size >= 4) {
        doris::vectorized::UInt64 a = unaligned_load<uint32_t>(data);
        return hash_len16(size + (a << 3), unaligned_load<uint32_t>(data + size - 4));
    }

    if (size > 0) {
        uint8_t a = data[0];
        uint8_t b = data[size >> 1];
        uint8_t c = data[size - 1];
        uint32_t y = static_cast<uint32_t>(a) + (static_cast<uint32_t>(b) << 8);
        uint32_t z = size + (static_cast<uint32_t>(c) << 2);
        return shift_mix(y * k2 ^ z * k3) * k2;
    }

    return k2;
}

inline size_t hash_less_than16(const char* data, size_t size) {
    if (size > 8) {
        doris::vectorized::UInt64 a = unaligned_load<doris::vectorized::UInt64>(data);
        doris::vectorized::UInt64 b = unaligned_load<doris::vectorized::UInt64>(data + size - 8);
        return hash_len16(a, rotate_by_at_least1(b + size, size)) ^ b;
    }

    return hash_less_than8(data, size);
}

struct CRC32Hash {
    size_t operator()(StringRef x) const {
        const char* pos = x.data;
        size_t size = x.size;

        if (size == 0) return 0;

        if (size < 8) {
            return hash_less_than8(x.data, x.size);
        }

        const char* end = pos + size;
        size_t res = -1ULL;

        do {
            doris::vectorized::UInt64 word = unaligned_load<doris::vectorized::UInt64>(pos);
            res = _mm_crc32_u64(res, word);

            pos += 8;
        } while (pos + 8 < end);

        doris::vectorized::UInt64 word = unaligned_load<doris::vectorized::UInt64>(
                end - 8); /// I'm not sure if this is normal.
        res = _mm_crc32_u64(res, word);

        return res;
    }
};

struct StringRefHash : CRC32Hash {};

#else

struct CRC32Hash {
    size_t operator()(StringRef /* x */) const {
        throw std::logic_error {"Not implemented CRC32Hash without SSE"};
    }
};

struct StringRefHash : StringRefHash64 {};

#endif

namespace std {
template <>
struct hash<StringRef> : public StringRefHash {};
} // namespace std

namespace ZeroTraits {
inline bool check(const StringRef& x) {
    return 0 == x.size;
}
inline void set(StringRef& x) {
    x.size = 0;
}
} // namespace ZeroTraits

inline std::ostream& operator<<(std::ostream& os, const StringRef& str) {
    if (str.data) os.write(str.data, str.size);

    return os;
}