//Amon Guinan
//Some sections use techniques that were either inspired by or taken from other sources.
#include <stdio.h>
#include <string.h>
#include <cs50.h>

//Function converts letters (eg.hex, etc...) to ints
int deHex(char letter)
{
    if (letter>='0' && letter<='9')
    {
        return ((int)letter-'0');
    }
    else
    {
        return ((int)letter-'A'+10);
    }
}


int toBase10(char *input, int base)// Convert value from target base to base 10.
{
    int num = 0;
    int input_length = strlen(input);
    int power = 1;

    for (int counter = input_length - 1; counter >= 0; counter--)
    {
        if (deHex(input[counter]) >= base)
        {
            printf("toBase10 Failure: Invalid Input.");
            //exit(1);
        }

        num += deHex(input[counter]) * power;
        power = power * base;
    }

    return num;
}

//Reverse of deHex function, converts ints to letters
char hex(int value)
{
    if (value>=0 && value<=9)
    {
        return (char)(value+'0');
    }
    else
    {
        return ((char)(value-10+'A'));
    }
}

// Reverses a string. Required when converting from decimal to other bases.
void reverse(char *input_string)
{
    int string_length = strlen(input_string);
    int counter;
    char temp;
    for (counter = 0; counter < (string_length/2); counter++)
    {
        temp = input_string[counter];
        input_string[counter] = input_string[string_length-counter-1];
        temp = input_string[string_length-counter-1];
    }
}

char* fromDeci(char string_output[], int base, int input)
//Converts number from base 10 to other base. Char array declared in main due to implementation issues.
{
    int string_index = 0;
    while (input > 0)
    {
        string_output[string_index] = hex(input % base);
        input /= base;
        string_index++;
    }
    string_output[string_index] = '\0';
    reverse(string_output);

    return string_output;
}

int main(void)
{
    string input_string = get_string("Input value>");
    int start_base = get_int("Input initial base>");
    int end_base = get_int("Input target base>");
    char output_string[100];
    printf("Value %s in base %d is"
           " %s.\n", input_string, end_base, fromDeci(output_string,end_base,toBase10(input_string, start_base)));

    return 0;
}