#include <stdio.h>
#include <stdlib.h>
#include <string.h>

//Создание узла
typedef struct Stud {
    char *first_name, *last_name;
    int day, month, year;
    double av_grade;
    struct Stud *next;
} Stud;

//Добавление узла
void push(Stud **head, char *first_name, char *last_name, int day, int month, int year, double av_grade) {
    Stud *tmp = (Stud*) malloc(sizeof(Stud));
    tmp -> first_name = (char*) malloc(strlen(first_name));
    strcpy(tmp -> first_name, first_name);
    tmp -> last_name = (char*) malloc(strlen(last_name));
    strcpy(tmp -> last_name, last_name);
    tmp -> day = day;
    tmp -> month = month;
    tmp -> year = year;
    tmp -> av_grade = av_grade;
    tmp -> next = *head;
    *head = tmp;
}

//УДаление узла head
void pop(Stud **head) {
    Stud* prev = NULL;
    if (head == NULL){
        printf("Node Error\n");
        exit(1);
    }
    prev = *head;
    *head = (*head) -> next;
    free(prev);
}

//Указатель на э-т списка
Stud* getNth(Stud* head, int n) {
    int counter = 0;
    while (counter < n && head) {
        head = head -> next;
        counter++;
    }
    return head;
}

//УДаление э-та
void deleteNth(Stud **head, int n) {
    if (n == 0)
        return pop(head);
    else {
        Stud *prev = getNth(*head, n - 1);
        Stud *elm = prev -> next;
        prev -> next = elm -> next;
        free(elm);
    }
}

//УДаление списка
void deleteList(Stud **head) {
    Stud* prev = NULL;
    while ((*head)->next) {
        prev = (*head);
        (*head) = (*head)->next;
        free(prev);
    }
    prev = (*head);
    (*head) = (*head)->next;
    free(prev);
}

//Запись в файл
void write_to_file(Stud *head, FILE *target) {
    int flag = 0;
    while (head != NULL) {
        if (flag == 0) {
            fprintf(target, "%s", head->first_name);
            flag = 1;
        }
        else
            fprintf(target, "\n%s", head -> first_name);
        fprintf(target, "%s", head -> last_name);
        fprintf(target, "%d\n", head -> day);
        fprintf(target, "%d\n", head -> month);
        fprintf(target, "%d\n", head -> year);
        fprintf(target, "%lf", head -> av_grade);
        head = head -> next;
    }
}

//Вывод списка
void printList(Stud *head) {
    while (head) {
        printf("First name: %s", head -> first_name);
        printf("Last name: %s", head -> last_name);
        printf("Date of Birth: %d %d %d\n", head -> day, head -> month, head -> year);
        printf("Av_grade: %lf\n\n", head -> av_grade);
        head = head -> next;
    }
    printf("\n");
}

int main() {

    Stud *head = NULL;
    Stud *prev = NULL;
    char  first_name[50], last_name[50], name_file[100], buf[10];
    int year, month, day, flag = 0, flag_list = 0;
    double av_grade;

    FILE *source;

    printf("Entering an action number:\n");
    printf("1. Reading base from file;\n");
    printf("2. Writing a database to a file;\n");
    printf("3. Display base;\n");
    printf("4. Add base from keyboard;\n");
    printf("5. Add database from file;\n");
    printf("6. Delete information by last name\n");
    printf("7. Search for students in the database\n");
    printf("8. Finish work\n\n");

    while(1) {
        int act;

        scanf("%d", &act);

        switch (act) {
            case 1: {
                if (flag_list == 1) {
                    deleteList(&head);
                }
                else
                    flag_list = 1;
                printf("Enter file name:\n");
                scanf("%s", name_file);

                if ((source = fopen(name_file, "r")) == NULL)
                    printf("File error!");

                while (fgets(first_name, 64, source) != NULL) {
                    fgets(last_name, 64, source);
                    fgets(buf, 10, source);
                    day = atoi(buf);
                    fgets(buf, 10, source);
                    month = atoi(buf);
                    fgets(buf, 10, source);
                    year = atoi(buf);
                    fgets(buf, 10, source);
                    av_grade = atof(buf);

                    push(&head, first_name, last_name, day, month, year, av_grade);

                }
                fclose(source);
                break;
            }
            case 2: {
                printf("New file name:\n");
                scanf("%s", name_file);
                FILE *target;
                target = fopen(name_file, "w");
                write_to_file(head, target);
                fclose(target);
                break;
            }

            case 3: {
                printList(head);
                break;
            }
            case 4: {
                printf("First name, surname:\n");
                scanf("%s %s", first_name, last_name);
                sprintf(first_name, "%s%s", first_name, "\n\0");
                sprintf(last_name, "%s%s", last_name, "\n\0");
                printf("Enter date of birth (DD MM YYYY):\n");
                scanf("%d %d %d", &day, &month, &year);
                printf("Grade point average:\n");
                scanf("%lf", &av_grade);

                push(&head, first_name, last_name, year, month, day, av_grade);

                break;
            }
            case 5: {
                printf("Base Plot File:\n");
                scanf("%s", name_file);
                source = fopen(name_file, "r");

                while (fgets(first_name, 50, source) != NULL) {
                    fgets(last_name, 50, source);
                    fgets(buf, 10, source);
                    year = atoi(buf);
                    fgets(buf, 10, source);
                    month = atoi(buf);
                    fgets(buf, 10, source);
                    day = atoi(buf);
                    fgets(buf, 10, source);
                    av_grade = atof(buf);

                    push(&head, first_name, last_name, year, month, day, av_grade);
                }
                fclose(source);
                break;
            }

            case 6: {
                int n = 0;
                prev = head;
                printf("Enter last name:\n");
                scanf("%s", last_name);
                sprintf(last_name, "%s%s", last_name, "\n\0");
                while (prev != NULL) {
                    if (!strcmp(last_name, prev -> last_name)) {
                        deleteNth(&head, n);
                        prev = head;
                        n = 0;
                        flag = 1;
                    }
                    if (flag == 0) {
                        prev = prev -> next;
                        n++;
                    }
                    else
                        flag = 0;
                }
                break;
            }

            case 7: {
                printf("First name:\n");
                scanf("%s", first_name);
                printf("Surname\n");
                scanf("%s", last_name);
                sprintf(first_name, "%s%s", first_name, "\n\0");
                sprintf(last_name, "%s%s", last_name, "\n\0");
                prev = head;
                while (prev != NULL) {
                    if (!strcmp(first_name, prev -> first_name) && !strcmp(last_name, prev -> last_name)) {
                        printf("Last name: %s", prev -> first_name);
                        printf("First name: %s", prev -> last_name);
                        printf("Date of Birth: %d %d %d\n", prev -> day, prev -> month, prev -> year);
                        printf("Av_grade: %lf\n\n", prev -> av_grade);
                    }
                    prev = prev->next;
                }
                break;
            }

            case 8:
                return 0;

        }
    }
}