#include <iostream>
#include <string>
#include <fstream>
#include <windows.h>
#include <vector>
#include <math.h>

struct referat {
    char topic[25];
    char author[20];
    int str;
    char date[10];
};

using namespace std;

void printTask() {
    cout << "База данных о рефератах с возможностью редактирования" << endl;
}

bool checkPath(string path) {
    ifstream file(path);
    if (file.is_open()) {
        cout << path << " найден" << endl;
        return true;
    }
    else {
        cout << path << " не найден" << endl;
        return false;
    }
}

string getPathToFile() {
    string path;
    bool isNotValid = false;
    do {
        cout << "Введите абсолютный путь к файлу с данными" << endl;
        cin >> path;
    } while (!checkPath(path));
    return path;
}

int getCount() {
    ifstream file("Data.txt");
    file.open("Data.txt");
    file.clear();
    referat a;
    int i = 0;
    while (!file.eof())
    {
        file >> a.topic >> a.author >> a.str >> a.date;
        i++;
    }
    return i;
}

vector <referat> getDataFromFile() {
    vector <referat> a;
    ifstream file("Data.txt");
    file.open("Data.txt");
    file.clear();
    int n = getCount();
    referat input;
    for (int i = 0; i < n; i++) {
        file >> input.topic >> input.author >> input.str >> input.date;
        a.push_back(input);
    }
    file.close();
    return a;
}

void printData(vector <referat> arr) {
    cout << "Данные: " << endl << endl;
    cout << "Номер " << "Тема                    " << "Автор              " << "Кол-во страниц      " << "Дата      " << endl << endl;
    for (int i = 0; i < arr.size(); i++) {
        cout << i + 1;
        string s = to_string(i + 1);
        for (int i = s.size(); i < 6; i++)
            cout << " ";
        cout << arr[i].topic;
        s = arr[i].topic;
        for (int i = s.size(); i < 24; i++)
            cout << " ";
        cout << arr[i].author;
        s = arr[i].author;
        for (int i = s.size(); i < 19; i++)
            cout << " ";
        cout << arr[i].str;
        auto ss = to_string(arr[i].str);
        for (int i = ss.size(); i < 20; i++)
            cout << " ";
        cout << arr[i].date;
        s = arr[i].date;
        cout << endl;
    }
    cout << endl;
}

short chooseAct() {
    cout << "Выберите действие: " << endl << endl;
    cout << "1 - Добавить реферат" << endl;
    cout << "2 - Удалить реферат" << endl;
    cout << "3 - Редактировать реферат" << endl;
    cout << "4 - показать сведения о рефератах, написанных в текущем году с количеством страниц не более 20 в порядке дат написания. "
         << endl;
    short act;
    do {
        cin >> act;
        if (act != 1 && act != 2 && act != 3 && act != 4)
            cout << "Введите 1, 2, 3 или 4" << endl;
    } while (act != 2 && act != 1 && act != 3 && act != 4);
    return act;
}

referat newReferat() {
    referat a;
    cout << "Введите тему реферата:" << endl;
    cin >> a.topic;
    OemToCharA(a.topic, a.topic);
    cout << "Введите автора реферата:" << endl;
    cin >> a.author;
    OemToCharA(a.author, a.author);
    cout << "Введите кол-во страниц реферата:" << endl;
    cin >> a.str;
    cout << "Введите дату написания реферата:" << endl;
    cin >> a.date;
    OemToCharA(a.date, a.date);
    return a;
}

void addData() {
    referat a = newReferat();
    ofstream file;
    file.open("Data.txt", ios::app);
    file << endl;
    file << a.topic << " " << a.author << " " << a.str << " " << a.date;
    file.close();
}

int chooseIndex() {
    cout << "Введите номер реферата: ";
    int n;
    cin >> n;
    return n;
}

void deleteData() {
    int deleteIndex = chooseIndex();
    ifstream file("Data.txt");
    ofstream newFile("NewData.txt");
    int id = 0;
    while (!file.eof()) {
        id++;
        string data, s;
        for (int i = 0; i < 4; i++) {
            file >> s;
            if (i != 3)
                data += s + " ";
            else
                data += s;
        }
        if (id != deleteIndex) {
            newFile << data;
            if (!file.eof() && data != "")
                newFile << endl;
        }
    }
    file.close();
    newFile.close();
    remove("Data.txt");
    rename("NewData.txt", "Data.txt");
}

void changeData() {
    int changeIndex = chooseIndex();
    referat a = newReferat();
    ifstream file("Data.txt");
    ofstream newFile("NewData.txt");
    int id = 0;
    while (!file.eof()) {
        id++;
        string data, s;
        for (int i = 0; i < 4; i++) {
            file >> s;
            if (i != 3)
                data += s + " ";
            else
                data += s;
        }
        if (id != changeIndex)
            newFile << data;
        else
            newFile << a.topic << " " << a.author << " " << a.str << " " << a.date;
            if (!file.eof() && data != "")
                newFile << endl;
    }
    file.close();
    newFile.close();
    remove("Data.txt");
    rename("NewData.txt", "Data.txt");
}

vector <referat> findRef(vector <referat> arr) {
    vector <referat> a;
    for (int i = 0; i < arr.size(); i++) {
        string s = arr[i].date;
        short k = 2;
        while (k > 0) {
            if (s[0] == '.')
                k--;
            s.erase(0, 1);
        }
        if (s == "2021")
            a.push_back(arr[i]);
    }
    return a;
}

vector <referat> throwOutRef(vector <referat> arr) {
    vector <referat> b;
    for (int i = 0; i < arr.size(); i++)
        if (arr[i].str <= 20)
            b.push_back(arr[i]);
    return b;
}

vector <int> getDay(vector<referat> arr) {
    vector <referat> b;
    vector <int> day;
    for (int i = 0; i < arr.size(); i++) {
        b.push_back(arr[i]);
        string s = arr[i].date;
        short k = 1;
        string sDay = "";
        string sMonth = "";
        while (k > 0) {
            if (s[0] == '.')
                k--;
            else
                sDay = sDay + s[0];
            s.erase(0, 1);
        }
        day.push_back(stoi(sDay));
    }
    return day;
}

vector <int> getMonth(vector<referat> arr) {
    vector <referat> b;
    vector <int> month;
    for (int i = 0; i < arr.size(); i++) {
        b.push_back(arr[i]);
        string s = arr[i].date;
        short k = 2;
        string sDay = "";
        string sMonth = "";
        while (k > 0) {
            if (s[0] == '.')
                k--;
            else
                if (k == 2)
                    sDay = sDay + s[0];
                else
                    sMonth = sMonth + s[0];
            s.erase(0, 1);
        }
        month.push_back(stoi(sMonth));
    }
    return month;
}

vector <referat> sortByMonth(vector <referat> arr) {
    vector <int> month = getMonth(arr);
    for (int i = 0; i < arr.size() - 1; i++)
        for (int j = i; j < arr.size() - i; j++)
            if (month[i] > month[j]) {
                swap(arr[i], arr[j]);
                swap(month[i], month[j]);
            }
    return arr;
}

vector <referat> sortByDay(vector <referat> arr) {
    vector <int> day = getDay(arr);
    vector <int> month = getMonth(arr);
    int l = 0;
    int r = 0;
    while (l <= arr.size()) {
        while (month[l] == month[r] && r < arr.size() - 1)
            r++;
        if (r == arr.size() - 1)
            if (month[l] == month[r])
                r++;
        for (int i = l; i < r; i++)
            for (int j = i; j < r - i; j++)
                if (day[i] > day[j]) {
                    swap(arr[i], arr[j]);
                    swap(day[i], day[j]);
                }
        r++;
        l = r;
    }
    return arr;
}

void printRef(vector <referat> arr) {
    cout << endl;
    for (int i = 0; i < arr.size(); i++) {
        cout << i + 1;
        string s = to_string(i + 1);
        for (int i = s.size(); i < 6; i++)
            cout << " ";
        cout << arr[i].topic;
        s = arr[i].topic;
        for (int i = s.size(); i < 24; i++)
            cout << " ";
        cout << arr[i].author;
        s = arr[i].author;
        for (int i = s.size(); i < 19; i++)
            cout << " ";
        cout << arr[i].str;
        auto ss = to_string(arr[i].str);
        for (int i = ss.size(); i < 20; i++)
            cout << " ";
        cout << arr[i].date;
        s = arr[i].date;
        cout << endl;
    }
    cout << endl;
}

void start() {
    printTask();
    while (1 == 1) {
        vector <referat> arr = getDataFromFile();
        printData(arr);
        short act = chooseAct();
        if (act == 1)
            addData();
        if (act == 2)
            deleteData();
        if (act == 3)
            changeData();
        if (act == 4) {
            vector <referat> a = findRef(arr);
            a = throwOutRef(a);
            a = sortByMonth(a);
            a = sortByDay(a);
            printRef(a);
        }
    }
}

int main()
{
    setlocale(LC_ALL, "Russian");
    start();
}