#include <stdio.h>
#include <learncs.h>
#include <ctype.h>

void exercise2(void);
void exercise3(void);
void exercise4(void);
int stringLength(char arr[]);
int countSpaces(char arr[]);
void removeVowels(char arr[]);


// main()
// Do not change this function at all.
int main(int argc, char * argv[])
{
    exercise2();
    exercise3();
    exercise4();
    printf("\n");
    return 0;
}


void exercise2(void)
{
    char    arr[17];
    int     magic = 42;

    printf("\n--------------------\n");
    printf("EXERCISE 2\n");
    printf("--------------------\n\n");

    // Print out the magic value
    printf("magic = %d\n", magic);

    // Prompt for string input
    printf("Enter a character string: ");

    // Retrieve up to 16 characters (plus the null terminator)
    getString(arr, 16+1);
    printf("The length of string [%s] is %d\n", arr, stringLength(arr));

    // Print out the magic value again
    printf("magic = %d\n", magic);

    /*
        Because we allocated only 16 + 1 element we go pass the stack creating a buffer overflow.
        This will erase the value for magic due to the overflow.

    */

}


void exercise3(void)
{
    int         spaces;
    char        string[] =
      "This is a test of the emergency broadcasting system. This is only a test.";

    printf("\n--------------------\n");
    printf("EXERCISE 3\n");
    printf("--------------------\n\n");

    // Count the number of spaces in the string.
    spaces = countSpaces(string);

    // The original countSpaces() function you are given simply returns -1.
    // If it still does that, it just means that you haven't yet implemented
    // the countSpaces() function according to the Exercise 2 instructions.
    if (spaces == -1)
    {
        printf("This exercise has not been completed yet.\n");
    }
    else
    {
        printf("The number of spaces in [%s] is %d\n", string, spaces);
    }
}


void exercise4(void)
{
    int         removed;
    char        string[] =
      "Hello world, how are you?";

    printf("\n--------------------\n");
    printf("EXERCISE 4\n");
    printf("--------------------\n\n");

    // Count the number of spaces in the string.
    removed = removeVowels(string);

    // The original removeVowels() function you are given simply returns -1.
    // If it still does that, it just means that you haven't yet implemented
    // the countSpaces() function according to the Exercise 2 instructions.
    if (removed == -1)
    {
        printf("This exercise has not been completed yet.\n");
    }
    else
    {
        printf("%d vowels were removed, yielding [%s]\n", removed, string);
    }
}


/**
 * Calculate the length of a character string
 *
 * @param arr
 *   The address of the first element of an array of characters containing
 *   the string.
 *
 * @return
 *   The number of characters in the string, not including the string's
 *   null terminator.
 */
int stringLength(char arr[])
{
    int     len;

    // Assume initially that the array is length 0.
    len = 0;

    // Look at each element of the array. If we find something other than
    // the null terminator, count this character by incrementing the length
    // variable.
    while (arr[len] != '\0')
    {
        // This character wasn't the null terminator, so increment the length
        ++len;
    }

    // Give 'em the calculated string length
    return len;
}


/**
 * Count the number of space characters in a string.
 *
 * @param arr
 *   The address of the first element of an array of characters containing
 *   the string.
 *
 * @return
 *   The number of space characters in the string.
 */
int countSpaces(char arr[])
{
    int i = 0, spaces = 0;

    while(arr[i] != '\0')
    {
        if(isspace(arr[i]))
        {
            spaces++;
        }
        i++;
    }
    return spaces;
}


/**
 * "Remove" each vowel from the provided character array, moving all
 * subsequent characters forward in the array to take up the space of the
 * removed vowel. Only the following characters are considered to be vowels:
 * 'a', 'e', 'i', 'o', and 'u'
 *
 * @param arr
 *   The address of the first element of an array of characters containing
 *   the string whose vowels are to be removed.
 *
 * @return
 *   The number of vowels removed from the provided string.
 */
int removeVowels(char arr[])
{
    int i = 0, vowels = 0;

    while(arr[i] != '\0')
    {
        if(arr[i] != 'a' && arr[i] != 'e' && arr[i] != 'i' && arr[i] != 'o' && arr[i] != 'u' )
        {
            arr[vowels] = arr[i]; //copy original to a temp array;
            vowels++; // move on to next element skip vowels
        }
        i++; //move to next element
    }
    //printf("i is %d, vowels is %d", i, vowels);
    return i - vowels; //original array subtract temp array to get how many vowel remove.
}