#define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <iostream>
#include <io.h>
#include <string.h>
using namespace std;
FILE *file;
FILE *txt;
struct book
{
    char name[40];
    char surname[20];
    int year;
    int pages;
};
void createfile();
void readfile();
void output();
void selectionsort();
void quicksort();
void linesearch(int);
void binsearch(int);
int menu();
int main()
{
    int x;//пусть пользователь вводит сколько страниц ему надо (условие 1575)
    while (true)
    {
        switch (menu())
        {
        case 1: createfile(); break;
        case 2: readfile(); break;
        case 3: output(); break;
        case 4: selectionsort(); break;
        case 5: quicksort(); break;
        case 6: cout << "Enter number of pages" << endl; cin >> x; linesearch(x); break;
        case 7: cout << "Enter number of pages" << endl; cin >> x; binsearch(x);  break;
        case 8: return 0;
        default: cout << "Incorrect choice!";
        }
        system("pause");
        system("cls");
    }
}

void createfile() {
    if ((file = fopen("binaryfile.dat", "ab")) == NULL)
        if ((file = fopen("binaryfile.dat", "wb")) == NULL)
        {
            cout << "creation error!"<<endl;
            return;
        }
    char act;
    do {
        book spisok;
        cout << "Enter bookname: " << endl;
        cin >> spisok.name;
        cout << "Enter author surname: " << endl;
        cin >> spisok.surname;
        cout << "Enter year of edition : " << endl;
        cin >> spisok.year;
        cout << "Enter number of pages " << endl;
        cin >> spisok.pages;
        cout << endl;
        fwrite(&spisok, sizeof(book), 1, file);
        cout << "Anything else? y/n ";
        cin >> act;
        cout << endl;
    } while (act == 'y');
    fclose(file);
}

void readfile() {
    if ((file = fopen("binaryfile.dat", "rb")) == NULL)
    {
        cout << "opening error!"<<endl;
        return;
    }
    book spisok;
    while (fread(&spisok, sizeof(book), 1, file))
    {
        cout << spisok.name << "  " << spisok.surname
            << "  " << spisok.year << "  " << spisok.pages <<endl;
    }
    fclose(file);
}

void output() {
    if ((file = fopen("binaryfile.dat", "rb")) == NULL)
    {
        cout << "opening error!"<<endl;
        return;
    }
    int n = _filelength(_fileno(file)) / sizeof(book);

    book *list = new book[n];
    fread(list, sizeof(book), n, file);
    fclose(file);
    book swap;
    for (int i = 0; i < n - 1; i++)
        for (int j = i + 1; j < n; j++)
            if (list[i].year <= 1990 && list[j].year <= 1990 && strcmp(list[i].name, list[j].name) == 1)
            {
                swap = list[i];
                list[i] = list[j];
                list[j] = swap;
            }

    if ((txt = fopen("fileout.txt", "w")) == NULL)
    {
        cout << "Error at creation!"<<endl;
        return;
    }
    for (int i = 0; i < n; i++)
        if (list[i].year <= 1990)
        {
            cout << list[i].name << endl;
            fprintf(txt, "%c ", list[i].name);
        }
    delete[] list;
    fclose(txt);
}

void selectionsort()
{
    if ((file = fopen("binaryfile.dat", "rb")) == NULL)
    {
        cout << "opening error!" << endl;
        return;
    }
    int n = _filelength(_fileno(file)) / sizeof(book);
    book *list = new book[n];
    fread(list, sizeof(book), n, file);
    fclose(file);
    book t;
    int imin, i, j;
    for (i = 0; i<n - 1; i++)
    {
     imin = i;
        for (j = i + 1; j<n; j++)
            if (list[imin].pages > list[j].pages) imin = j;
        if (imin != i)
        {
            t = list[imin];
            list[imin] = list[i];
            list[i] = t;
        }
    }
    if ((txt = fopen("fileout.txt", "w")) == NULL)
    {
        cout << "Error at creation!" << endl;
        return;
    }
    for (int i = 0; i < n; i++)
    //  if (list[i].year <= 1990)
        {
            cout << list[i].name <<"  "<<list[i].pages<< endl;
            fprintf(txt, "%c ", list[i].name);
            fprintf(txt, "%c ", list[i].pages);
        }
    delete[] list;
    fclose(txt);
}

void quicksort()
{
    if ((file = fopen("binaryfile.dat", "rb")) == NULL)
    {
        cout << "opening error!" << endl;
        return;
    }
    int n = _filelength(_fileno(file)) / sizeof(book);
    book *list = new book[n];
    fread(list, sizeof(book), n, file);
    fclose(file);
    struct {
        int l;
        int r;
    } stack[20];

    int i, j, left, right, s = 0;
    book t, x;
    stack[s].l = 0; stack[s].r = n - 1;

    while (s != -1)
    {
        left = stack[s].l; right = stack[s].r;
        s--;
        while (left < right)
        {
            i = left; j = right; x = list[(left + right) / 2];
            while (i <= j)
            {
                while (list[i].pages < x.pages) i++;
                while (list[j].pages > x.pages) j--;
                if (i <= j) {
                    t = list[i];
                    list[i] = list[j];
                    list[j] = t;
                    i++;  j--;
                }
            }

            if ((j - left) < (right - i)) // Выбор более короткой части
            {
                if (i < right) { s++;  stack[s].l = i;  stack[s].r = right; }
                right = j;
            }
            else {
                if (left < j) { s++;  stack[s].l = left;  stack[s].r = j; }
                left = i;
            }
        }
    }
    if ((txt = fopen("fileout.txt", "w")) == NULL)
    {
        cout << "Error at creation!" << endl;
        return;
    }
    for (int i = 0; i < n; i++)
        //  if (list[i].year <= 1990)
    {
        cout << list[i].name << "  " << list[i].pages << endl;
        fprintf(txt, "%c ", list[i].name);
        fprintf(txt, "%c ", list[i].pages);
    }
    delete[] list;
    fclose(txt);
}

void linesearch(int x)
{
    if ((file = fopen("binaryfile.dat", "rb")) == NULL)
    {
        cout << "opening error!" << endl;
        return;
    }
    int n = _filelength(_fileno(file)) / sizeof(book);
    book *list = new book[n];
    fread(list, sizeof(book), n, file);
    fclose(file);
    list[n + 1].pages = x;
    int i = 0;
    while (list[i].pages != x) i++;
    if (i == n + 1) cout << "Required book not found" << endl;
    else cout <<"Found! "<< list[i].name << "  " << list[i].pages << endl;
}

void binsearch(int x)
{
    if ((file = fopen("binaryfile.dat", "rb")) == NULL)
    {
        cout << "opening error!" << endl;
        return;
    }
    int n = _filelength(_fileno(file)) / sizeof(book);
    book *list = new book[n];
    fread(list, sizeof(book), n, file);
    fclose(file);
    int i = 0, j = n - 1, m;
    while (i < j)
    {
        m = (i + j) / 2;
        if (x > list[m].pages) i = m + 1; else j = m;
    }
    if (list[i].pages == x) cout << "Found! " << list[i].name << "  " << list[i].pages << endl;
    else cout << "Required book not found" << endl;
}

int menu() {
    int i;
    cout << "Choose action:"<<endl;
    cout << "1)Enter data to file" << endl;
    cout << "2)Read from file" << endl;
    cout << "3)Output" << endl;
    cout << "4)Sort pages with selectionsort"<<endl;
    cout << "5)Sort pages with QuickSort" << endl;
    cout << "6)Line searching the required book " << endl;
    cout << "7)Binary searching the required book" << endl;
    cout << "8)Exit" << endl;
    cin >> i;
    return i;
}