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

#define MAX_GRADE 100
#define MIN_GRADE 0

void fillArr(int* arr, int len);
void fillGrade(int* arr, int index);
void printAvgGrade(int* arr, int len);
void changeGrade(int* arr, int len);
void printGrades(int* arr, int len);
void changeNumGrades(int* arr, int* len);
int validGrade(int grade);

enum options
{
    avarage = 1,
    gradeChange,
    changeAmountGrades,
    print,
    exitProgram
};

int main()
{
    int numGrades = 0;
    enum options choice = 0;
    int* arrGrades = 0;
    //getting input from user
    printf("Please enter the number of grades: ");
    scanf("%d", &numGrades);
    fillArr(arrGrades, numGrades);
    //executing choice
    do {
        printf("%d - Calculate avarage Grade\n", avarage);
        printf("%d - Change grade\n", gradeChange);
        printf("%d - Change number of grades\n", changeAmountGrades);
        printf("%d - Print Grades\n", print);
        printf("%d - Exit\n", exitProgram);
        printf("Choose an option: ");
        scanf("%d", &choice);
        switch (choice) {
            case avarage:
                printAvgGrade(arrGrades, numGrades);
                break;
            case gradeChange:
                changeGrade(arrGrades, numGrades);
                break;
            case changeAmountGrades:
                changeNumGrades(arrGrades, numGrades);
                break;
            case print:
                printGrades(arrGrades, numGrades);
                break;
            case exitProgram:
                break;
            default:
                printf("Invalid choice! only 1-5, try again...\n");
        }
    } while (choice != exitProgram);

    return 0;
}
/*
This function fill the array with a given len
input: a pointer to the array, its len
output: NONE
*/
void fillArr(int* arr, int len)
{
    int i = 0;
    arr = (int*)malloc(len * sizeof(int));
    if (arr == NULL)
    {
        printf("Malloc fail!\n");
        return 1;
    }
    for (i = 0; i < len; i++)
    {
        fillGrade(arr, i);
    }
}
/*
This funcion calc's and prints the avarage of grade
input: the arr, its len
outpu: NONE
*/
void printAvgGrade(int* arr, int len)
{
    int i = 0;
    int sum = 0;
    for (i = 0; i < len; i++)
    {
        sum += arr[i];//error here
    }
    printf("The avarage grade is %2f", (float)sum / len);
}
/*
This function changes a given grade in the array
input: The array, its lengh
output: NONE
*/
void changeGrade(int* arr, int len)
{
    int position = 0;
    printf("Which grade would you like to change?%d - %d: ", 1, len);
    do
    {
        scanf("%d", &position);
        (position < 1 && position > len) ? printf("Invalid position try again: ") : printf("\n");
    } while (position < 1 && position > len);
    fillGrade(arr, (position - 1));
}
/*
This function changes the amount of grade if it greater then the previous amount
input: the array, a pointer to its len
output: NONE
*/
void changeNumGrades(int* arr, int* len)
{
    int newLen = 0;
    int i = 0;
    printf("Please enter a new number of grades: ");
    scanf("%d", &newLen);
    if (newLen > *len)
    {
        for (i = *len; i < newLen; i++)
        {
            fillGrade(arr, i);
        }
        //changing the len of the arr to the new len
        *len = newLen;
    }
}
/*
This function prints the grades
input: the array and its len
output: NONE
*/
void printGrades(int* arr, int len)
{
    int i = 0;
    for (i = 0; i < len; i++)
    {
        printf("%d ", arr[i]);//error here
    }
}
/*
This function fills a grade of a given index
input: the index
output:NONE
*/
void fillGrade(int* arr, int index)
{
    printf("Enter Grade %d: ", index + 1);
    do
    {
        scanf("%d", &arr[index]);
        if (!validGrade(arr[index])) {
            printf("Invalid grade only 0-100 try again: ");
        }
    } while (!validGrade(arr[index]));
}
/*
This function check if a grade is valid
input: a number
output: 0 or 1
*/
int validGrade(int grade)
{
    return (grade >= MIN_GRADE && grade <= MAX_GRADE);
}