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

int validateExpression(char*);
double parseExpression(char*);
void removeAt(char*, int);

int main(int argc, char **argv) {

    char *exp;

    if(argc != 2) {
        printf("Error\nFormat : super_calculator \"...expression...\"\n");
        return 1;
    }

    exp = argv[1];

    if(!validateExpression(exp)) {
        printf("Expression not valid !\n");
    }

    double result = parseExpression(exp);

    printf("%f", result);
    return 0;
}

int validateExpression(char *exp) {
    unsigned int i, openBrackets = 0, closeBrackets = 0;
    for(i = 0; i < strlen(exp); i++) {
        exp[i] == '(' ? openBrackets++ : 1;
        exp[i] == ')' ? closeBrackets++ : 1;
    }
    return (openBrackets == closeBrackets) && i; // i contains actual length of exp
}

double parseExpression(char *exp) {
    unsigned int i, j, lastPos, openBrackets = 0, closeBrackets = 0;
    char *secondExp = NULL;
    for(i = 0; i < strlen(exp); i++) {
        if(exp[i] == '(') {
            // Let's find the corresponding ')' in exp
            openBrackets++;
            j = i + 1 ;
            while(openBrackets != closeBrackets) {
                exp[j] == '(' ? openBrackets++ : 1;
                exp[j] == ')' ? closeBrackets++ : 1;
                j++;
            }
            lastPos = j - 1;
            secondExp = (char*) malloc(lastPos - i + 1);
            memset(secondExp, '\0', lastPos - i + 1);
            memcpy(secondExp, exp + i + 1, lastPos - i - 1);
            printf("%s\n", secondExp);
        }
    }
    if(secondExp != NULL) free(secondExp);
    return 0;
}

void removeAt(char *str, int pos) {
    char *src, *dst;
    for (src = dst = str; *src != '\0'; src++) {
        *dst = *src;
        if (*dst != pos) dst++;
    }
    *dst = '\0';
}