#include "evalexpr.h"

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

#define BUFFER_SIZE 10

char *get_input(void)
{
    size_t r;
    char buf[BUFFER_SIZE];
    size_t size = 0;
    char *expr = malloc(size * sizeof(char) + 1);
    if (expr == NULL)
        return NULL;
    expr[0] = '\0';
    do
    {
        r = fread(buf, sizeof(char), BUFFER_SIZE - 1, stdin);
        if (r != 0)
        {
            buf[r] = '\0';
            size += r;
            char *tmp = realloc(expr, size * sizeof(char) + 1);
            if (tmp == NULL)
            {
                free(expr);
                return NULL;
            }
            expr = tmp;
            strcat(expr, buf);
        }
    } while (r != 0);
    if (size == 0)
    {
        free(expr);
        return NULL;
    }
    if (expr[size - 1] == '\n')
        expr[size - 1] = '\0';
    return expr;
}

void cleanup(char *expr, char *rpn)
{
    free(expr);
    free(rpn);
}

int main(int argc, char **argv)
{
    if ((argc == 2 && strcmp(argv[1], "-rpn") != 0) || (argc > 2))
        return 4;
    char *expr = get_input();
    if (expr == NULL)
        return 4;
    if (argc == 1)
    {
        char *rpn;
        int e = shunting_yard(expr, &rpn);
        if (e != 0)
            return e;
        // call shunting yard
        int retval;
        e = evalrpn(rpn, &retval);
        if (e != 0)
        {
            cleanup(expr, rpn);
            return e;
        }
        // FREE RPN
        printf("%d\n", retval);
        cleanup(expr, rpn);
        // return
        return 0;
    }

    if (argc == 2 && strcmp(argv[1], "-rpn") == 0)
    {
        // call rpn eval
        int retval;
        int e = evalrpn(expr, &retval);
        printf("%d\n", retval);
        // return
        free(expr);
        if (e != 0)
            return e;
        return 0;
    }

    return 4;
}