#include <iostream>
#include <cassert>
#include <vector>
#include <chrono>
#include <leveldb/db.h>

using namespace std::chrono;

// 定义字段
struct Field {
    std::string first;
    std::string second;
};

// 解析数据值
std::vector<std::pair<std::string, std::string>> ParseValue(const std::string& value) {
    std::vector<std::pair<std::string, std::string>> fields;
    size_t start = 0;
    size_t end = value.find("|");
    
    while (end != std::string::npos) {
        std::string field = value.substr(start, end - start);
        size_t separator = field.find(":");
        
        if (separator != std::string::npos) {
            fields.push_back({field.substr(0, separator), field.substr(separator + 1)});
        }
        
        start = end + 1;
        end = value.find("|", start);
    }
    
    return fields;
}

// 查询函数：根据字段查找所有包含该字段的 Key
std::vector<std::string> FindKeysByField(leveldb::DB* db, const Field& field) {
    std::vector<std::string> keys;
    leveldb::Iterator* it = db->NewIterator(leveldb::ReadOptions());

    for (it->SeekToFirst(); it->Valid(); it->Next()) {
        std::string key = it->key().ToString();
        std::string value = it->value().ToString();

        std::vector<std::pair<std::string, std::string>> fields = ParseValue(value);

        // 查找是否有匹配的字段
        for (const auto& f : fields) {
            if (f.first == field.first && f.second == field.second) {
                keys.push_back(key);
                break;
            }
        }
    }

    delete it;
    return keys;
}

// 生成数据并插入数据库
void GenerateAndInsertData(leveldb::DB* db, int num_entries) {
    leveldb::WriteOptions write_options;
    leveldb::Status status;

    for (int i = 1; i <= num_entries; ++i) {
        std::string key = "k_" + std::to_string(i);
        std::string name = "Customer#" + std::to_string(i);
        std::string address = "Address_" + std::to_string(i);
        std::string phone = "25-989-741-" + std::to_string(1000 + i);

        std::string value = "name:" + name + "|address:" + address + "|phone:" + phone;

        status = db->Put(write_options, key, value);
        assert(status.ok() && "Failed to insert data");
    }
}

// 基准测试：二级索引性能提升
void BenchmarkFieldQueryWithIndex(leveldb::DB* db) {
    // 测试前，查询无索引的字段性能
    auto start = high_resolution_clock::now();
    Field field = {"name", "Customer#10000"};
    std::vector<std::string> keys_without_index = FindKeysByField(db, field);
    auto end = high_resolution_clock::now();
    auto duration = duration_cast<microseconds>(end - start);
    std::cout << "Time without index: " << duration.count() << " microseconds" << std::endl;

    // 创建二级索引
    // 在此添加创建索引的代码（可以使用 DBImpl::CreateIndexOnField 函数）
    start = high_resolution_clock::now();
    leveldb::Status status = db->CreateIndexOnField("name");
    end = high_resolution_clock::now();
    duration = duration_cast<microseconds>(end - start);
    std::cout << "Time to create index: " << duration.count() << std::endl;

    // 测试后，查询有索引的字段性能
    start = high_resolution_clock::now();
    std::vector<std::string> keys_with_index = db->QueryByIndex("name:Customer#10000");  // 使用二级索引查询
    end = high_resolution_clock::now();
    duration = duration_cast<microseconds>(end - start);
    std::cout << "Time with index: " << duration.count() << " microseconds" << std::endl;

    // 输出查询结果
    std::cout << "Found " << keys_with_index.size() << " keys with index." << std::endl;
    assert(!keys_with_index.empty() && "Query by index returned no results");

    std::cout << "Query by index results for name=Customer#10000: ";
    for (const auto& result : keys_with_index) {
        std::cout << result << ", ";
    }
}

// 基准测试：记录插入时的性能影响
void BenchmarkWritePerformance(leveldb::DB* db, int num_entries) {
    leveldb::WriteOptions write_options;
    auto start = high_resolution_clock::now();
    
    GenerateAndInsertData(db, num_entries);  // 执行批量插入
    
    auto end = high_resolution_clock::now();
    auto duration = duration_cast<microseconds>(end - start);
    std::cout << "Insertion time for " << num_entries << " entries: " << duration.count() << " microseconds" << std::endl;
}

// 基准测试：记录删除二级索引的开销
void BenchmarkDeleteIndex(leveldb::DB* db, const std::string& field_name) {
    auto start = high_resolution_clock::now();
    
    // 删除二级索引
    leveldb::Status status = db->DeleteIndex(field_name);
    assert(status.ok() && "Failed to delete index");

    auto end = high_resolution_clock::now();
    auto duration = duration_cast<microseconds>(end - start);
    std::cout << "Time to delete index on field '" << field_name << "': " << duration.count() << " microseconds" << std::endl;
}

// 获取数据库大小（用来估算二级索引的空间占用）
void GetDatabaseSize(leveldb::DB* db) {
    std::string property;
    
    // 使用 bool 返回值检查是否成功获取属性
    bool success = db->GetProperty("leveldb.stats", &property);
    if (!success) {
        std::cerr << "Failed to get db stats" << std::endl;
        return;
    }

    std::cout << "Database stats: " << std::endl;
    std::cout << property << std::endl;
}

int main() {
    leveldb::Options options;
    options.create_if_missing = true;

    // 打开数据库
    leveldb::DB* db = nullptr;
    leveldb::Status status = leveldb::DB::Open(options, "./testdb", &db);
    assert(status.ok() && "Failed to open database");

    // 测试写入性能
    BenchmarkWritePerformance(db, 100001);  // 插入 100001 条数据

    // 测试二级索引对查询性能的提升
    BenchmarkFieldQueryWithIndex(db);

    // 获取数据库大小
    GetDatabaseSize(db);

    // 测试删除二级索引的开销
    BenchmarkDeleteIndex(db, "name");

    // 关闭数据库
    delete db;

    std::cout << "Benchmark tests completed." << std::endl;

    return 0;
}