//It's database library
//Use the function "set_filesize" to set a default size of the data file
//Use the function "set_path" to set path for saving data files
#ifndef DATABASE_LIBRARY_H
#define DATABASE_LIBRARY_H
#include <iostream>
#include <fstream>
#include <string>
#include <cassert>
#include <cstring>
using namespace std;
string filename = "data0";
string path;
int num = 0;
int default_filesize = 8388608;

void set_path(const string &saving_path) {
    path = saving_path;
}

void set_filesize(int custom_size) {
    default_filesize = custom_size;
}

bool is_datafile_full(const string &current_filename) {
    ifstream file(current_filename.c_str(), ifstream::in | ifstream::binary);
    int current_filesize = file.tellg();
    file.close();
    if (default_filesize <= current_filesize) {
        return true;
    }
    return false;
}

void store(int id, void* data) {
    if (path.empty()) {
        throw std::runtime_error("path is invalid");
    }
    if (is_datafile_full(filename)) {
        num++;
        string num_str = to_string(num);
        filename = "data" + num_str;
    }
    ofstream datafile;
    datafile.open(path + filename + ".txt");
    datafile << id << " " << data << endl;
    datafile.close();
}

string load(int id) {
    string line;
    ifstream datafile;
    datafile.open(path + filename + ".txt");
    while (getline(datafile, line)) {
        size_t pos = line.find(' ');
        string user_id = line.substr(0, line.find(' '));
        if (user_id == to_string(id)) {
            datafile.close();
            string user_data = line.substr(pos + 1);
            return user_data;
        }
    }
}