#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#define MIN_DIGIT '0'
#define MAX_DIGIT '9'
#define MOBILE_LEGNTH 10
#define HOME_LENGTH 9
#define MOBILE_DIGIT '5'
#define HOME_DIGIT '4'
#define COUNTRY_START_DIGIT '0'
#define MALLOC_MAX_DIGITS 11
char** add_number(char* phonebook[], int* phonebook_len);
int get_exists(char* phonebook[], char* phone_num, int* phonebook_len);
int valid(char* phone_num);
char** get_bigger_phonebook(char* old_phonebook[], int* phonebook_len);



void delete_phonebook(char* phonebook[], int* phonebook_len) {
    char res = 0;
    printf("Are you sure you want to delete the phonebook [Y/N]: ");
    scanf(" %c", &res);
    if ((res != 'Y') && (res != 'y'))
        return;
    for (int i = 0; i < (*phonebook_len) + 1 - 1; i++)
        //if (valid(phonebook[i])) // check if phone number is valid to be free'd.
            free(phonebook[i]);
    printf("The phonebook has been successfully cleared.\n");
}

void delete_number(char* phonebook[], int *phonebook_len) {
    char new_phone_num[11];
    scanf("%s", new_phone_num); // will scan string to new_phone_num.
    int exists_indx = get_exists(phonebook, new_phone_num, phonebook_len); // will go to get_exists to get existing phone number index.
    if (exists_indx != -1) {
        phonebook[exists_indx] = NULL;
        printf("The number has been successfully removed from the phone book.\n");
    }
    else
        printf("The number does not exist in the phone book.\n");
}

int get_exists(char* phonebook[], char* phone_num, int* phonebook_len) {
    for (int i = 0; i < (*phonebook_len); i++)
        if (!(strcmp(phonebook[i], phone_num)))//if the same then return index in phonebook.
            return i;
    return -1;
}

int valid(char* phone_num) {
    if (phone_num[0] != COUNTRY_START_DIGIT) // phone number must start at 0
        return 0;
    int phone_len = (phone_num[1] == MOBILE_DIGIT) ? MOBILE_LEGNTH : HOME_LENGTH; // if 05 then mobile, else its home.
    for (int i = 0; i < phone_len; i++)
        if (!((MIN_DIGIT <= phone_num[i]) && (phone_num[i] <= MAX_DIGIT))) // if temp[i] is not in range.
            return 0;
    return 1;
}

int check_number(char* phonebook[], int* phonebook_len, char* phone_num) {
    if (phone_num[0] != COUNTRY_START_DIGIT)
        return -1;
    int phone_len = (phone_num[1] == MOBILE_DIGIT) ? MOBILE_LEGNTH : HOME_LENGTH;
    for (int i = 0; i < phone_len; i++)
        if (!((MIN_DIGIT <= phone_num[i]) && (phone_num[i] <= MAX_DIGIT))) // if temp[i] is not in range.
            return -1;
    for (int i = 0; i < (*phonebook_len); i++)
        if (!(strcmp(phonebook[i], phone_num)))
            return 1;
    return 0;
}

void printError(int error) {
    if (error == 1)
        printf("The number already exists\n");
    else
        if (error == -1)
            printf("The number is invalid\n");
}

char** add_number(char* phonebook[], int* phonebook_len) {
    printf("Please enter a number: ");
    char new_phone_num[11];
    scanf("%s", new_phone_num);
    int res = check_number(phonebook, phonebook_len, new_phone_num);
    if (res) {
        printError(res);
        return NULL;
    }
    char** bigger_phonebook = get_bigger_phonebook(phonebook, phonebook_len);
    strcpy(bigger_phonebook[*phonebook_len - 1], new_phone_num);
    return bigger_phonebook;
}

char** get_bigger_phonebook(char* old_phonebook[], int* phonebook_len) {
    (*phonebook_len)++;
    char** new_phonebook = (char**)malloc((*phonebook_len) * sizeof(char*));

    for (int i = 0; i < (*phonebook_len) - 1; i++) {
        new_phonebook[i] = (char**)malloc(MALLOC_MAX_DIGITS*sizeof(char*));
        strcpy(new_phonebook[i], old_phonebook[i]);
        free(old_phonebook[i]);
    }
    new_phonebook[(*phonebook_len) - 1] = (char**)malloc(MALLOC_MAX_DIGITS * sizeof(char*));

    return new_phonebook;
}


void main() {
    int user_choice = 0;
    int phonebook_len = 0;
    int* p_len = &phonebook_len;
    char** phonebook = 0;
    char** flag = 0;
    printf("Weolcome to the Phone Book!\n");
    while (1) {
        printf("1. Add number\n2. Remove number\n3. Statistics\n4. Clear\nPlease select an action: ");
        scanf("%d", &user_choice);
        switch (user_choice) {
        case 1:
            flag = add_number(phonebook, p_len);
            if (flag)
                phonebook = flag;
            break;
        case 2:
            delete_number(phonebook, p_len);
            break;
        case 3:
            break;
        case 4:
            delete_phonebook(phonebook, p_len);
            break;
        default:
            if (user_choice == 'q' || user_choice == 'Q')
                break;
            else;
            }
    }
}