// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.

#include "util/coding.h"
#include "leveldb/db.h"
#include <iostream> 

#include<vector>

namespace leveldb {

void PutFixed32(std::string* dst, uint32_t value) {
  char buf[sizeof(value)];
  EncodeFixed32(buf, value);
  dst->append(buf, sizeof(buf));
}

void PutFixed64(std::string* dst, uint64_t value) {
  char buf[sizeof(value)];
  EncodeFixed64(buf, value);
  dst->append(buf, sizeof(buf));
}

char* EncodeVarint32(char* dst, uint32_t v) {
  // Operate on characters as unsigneds
  uint8_t* ptr = reinterpret_cast<uint8_t*>(dst);
  static const int B = 128;
  if (v < (1 << 7)) {
    *(ptr++) = v;
  } else if (v < (1 << 14)) {
    *(ptr++) = v | B;
    *(ptr++) = v >> 7;
  } else if (v < (1 << 21)) {
    *(ptr++) = v | B;
    *(ptr++) = (v >> 7) | B;
    *(ptr++) = v >> 14;
  } else if (v < (1 << 28)) {
    *(ptr++) = v | B;
    *(ptr++) = (v >> 7) | B;
    *(ptr++) = (v >> 14) | B;
    *(ptr++) = v >> 21;
  } else {
    *(ptr++) = v | B;
    *(ptr++) = (v >> 7) | B;
    *(ptr++) = (v >> 14) | B;
    *(ptr++) = (v >> 21) | B;
    *(ptr++) = v >> 28;
  }
  return reinterpret_cast<char*>(ptr);
}

void PutVarint32(std::string* dst, uint32_t v) {
  char buf[5];
  char* ptr = EncodeVarint32(buf, v);
  // printf("加入的长度%d\n", ptr - buf);
  dst->append(buf, ptr - buf);
  // printf("插入之后的长度为：%d", dst->length());
}

char* EncodeVarint64(char* dst, uint64_t v) {
  static const int B = 128;
  uint8_t* ptr = reinterpret_cast<uint8_t*>(dst);
  while (v >= B) {
    *(ptr++) = v | B;
    v >>= 7;
  }
  *(ptr++) = static_cast<uint8_t>(v);
  return reinterpret_cast<char*>(ptr);
}

void PutVarint64(std::string* dst, uint64_t v) {
  char buf[10];
  char* ptr = EncodeVarint64(buf, v);
  dst->append(buf, ptr - buf);
}

void PutLengthPrefixedSlice(std::string* dst, const Slice& value) {
  PutVarint32(dst, value.size());
  dst->append(value.data(), value.size());
}

int VarintLength(uint64_t v) {
  int len = 1;
  while (v >= 128) {
    v >>= 7;
    len++;
  }
  return len;
}

const char* GetVarint32PtrFallback(const char* p, const char* limit,
                                   uint32_t* value) {
  uint32_t result = 0;
  for (uint32_t shift = 0; shift <= 28 && p < limit; shift += 7) {
    uint32_t byte = *(reinterpret_cast<const uint8_t*>(p));
    p++;
    if (byte & 128) {
      // More bytes are present
      result |= ((byte & 127) << shift);
    } else {
      result |= (byte << shift);
      *value = result;
      return reinterpret_cast<const char*>(p);
    }
  }
  return nullptr;
}

bool GetVarint32(Slice* input, uint32_t* value) {
  const char* p = input->data();
  const char* limit = p + input->size();
  const char* q = GetVarint32Ptr(p, limit, value);
  if (q == nullptr) {
    return false;
  } else {
    *input = Slice(q, limit - q);
    return true;
  }
}

const char* GetVarint64Ptr(const char* p, const char* limit, uint64_t* value) {
  uint64_t result = 0;
  for (uint32_t shift = 0; shift <= 63 && p < limit; shift += 7) {
    uint64_t byte = *(reinterpret_cast<const uint8_t*>(p));
    p++;
    if (byte & 128) {
      // More bytes are present
      result |= ((byte & 127) << shift);
    } else {
      result |= (byte << shift);
      *value = result;
      return reinterpret_cast<const char*>(p);
    }
  }
  return nullptr;
}

bool GetVarint64(Slice* input, uint64_t* value) {
  const char* p = input->data();
  const char* limit = p + input->size();
  const char* q = GetVarint64Ptr(p, limit, value);
  if (q == nullptr) {
    return false;
  } else {
    *input = Slice(q, limit - q);
    return true;
  }
}

bool GetLengthPrefixedSlice(Slice* input, Slice* result) {
  uint32_t len;
  if (GetVarint32(input, &len) && input->size() >= len) {
    *result = Slice(input->data(), len);
    input->remove_prefix(len);
    return true;
  } else {
    return false;
  }
}
// 序列化为字符串
std::string SerializeValue(const FieldArray& fields) { 
  std::string serialized_value = ""; 
  uint32_t num = fields.size();
  // std::cout<< "加入的值中包含的字段数："<<num<<std::endl;
  PutVarint32(&serialized_value, num);  // 编码字段个数

  for (uint32_t i = 0; i < num; i++) {  // 依次编码字段名和字段值
    PutLengthPrefixedSlice(&serialized_value, fields[i].first);
    PutLengthPrefixedSlice(&serialized_value, fields[i].second);
  }

  return serialized_value;
}

// 反序列化为字段数组
FieldArray ParseValue(const std::string& value_str) {
  uint32_t num=0;
  FieldArray fields;
  Slice value_sl(value_str);  // 把字符串类型的值转为slice类型
  if (GetVarint32(&value_sl, &num)) {
 
    for (uint32_t i = 0; i < num; i++) 
    {
      Slice field_name, field_value;
      GetLengthPrefixedSlice(&value_sl, &field_name);
      GetLengthPrefixedSlice(&value_sl, &field_value);
      fields.push_back({field_name.ToString().substr(0, field_name.size()), field_value.ToString().substr(0, field_value.size())});
      // std::string str = field_name.data().substr(0, field_name.size());
      //std::cout << "字段名："<< strncpy(str1, field_name.data(),field_name.size())<< std::endl;
      // std::cout<<field_name.data()<<"__"<<field_value.data()<< std::endl;
    }
  }
  return fields;
}



}  // namespace leveldb