#include "calculator.h"
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <math.h>
#include <string.h>

// Overenie, či je znak operátor
bool je_operator(char c) {
    return c == '+' || c == '-' || c == '*' || c == '/' || c == '^';
}

// Určenie priority operátorov
int priorita(char op) {
    switch (op) {
        case '+': case '-': return 1;
        case '*': case '/': return 2;
        case '^': return 3;
        default: return 0;
    }
}

// Matematické operácie
double scitaj(double a, double b) { return a + b; }
double odcitaj(double a, double b) { return a - b; }
double nasob(double a, double b) { return a * b; }
double del(double a, double b) { return a / b; }

double sinus(double x) { return sin(x); }
double cosinus(double x) { return cos(x); }
double odmocnin(double x) { return sqrt(x); }
double mocnina(double zaklad, double exponent) {
    return pow(zaklad, exponent);  // Funkcia 'pow' z matematickej knižnice
}
double logaritmus(double x) { return log(x); }

// Funkcia na konverziu infixového výrazu na postfixový (Shunting-yard algoritmus)
void infix_na_postfix(const char *infix, char *postfix) {
    char stack[100];
    int top = -1;
    int j = 0;

    for (int i = 0; infix[i] != '\0'; i++) {
        if (isdigit(infix[i]) || infix[i] == '.') {
            postfix[j++] = infix[i];
        } else if (je_operator(infix[i])) {
            postfix[j++] = ' ';
            while (top != -1 && priorita(stack[top]) >= priorita(infix[i])) {
                postfix[j++] = stack[top--];
                postfix[j++] = ' ';
            }
            stack[++top] = infix[i];
        } else if (infix[i] == '(') {
            stack[++top] = infix[i];
        } else if (infix[i] == ')') {
            while (top != -1 && stack[top] != '(') {
                postfix[j++] = ' ';
                postfix[j++] = stack[top--];
            }
            top--; // Odstrániť '(' zo zásobníka
        }
    }
    while (top != -1) {
        postfix[j++] = ' ';
        postfix[j++] = stack[top--];
    }
    postfix[j] = '\0';
}

// Vyhodnotenie postfixového výrazu
double vyhodnot_postfix(const char *postfix) {
    double stack[100];
    int top = -1;
    char *postfix_copy = malloc(strlen(postfix) + 1);
    strcpy(postfix_copy, postfix);
    char *token = strtok(postfix_copy, " ");

    while (token) {
        if (isdigit(token[0]) || (token[0] == '-' && isdigit(token[1]))) {
            stack[++top] = atof(token);
        } else if (je_operator(token[0]) && token[1] == '\0') {
            double b = stack[top--];
            double a = stack[top--];
            switch (token[0]) {
                case '+': stack[++top] = scitaj(a, b); break;
                case '-': stack[++top] = odcitaj(a, b); break;
                case '*': stack[++top] = nasob(a, b); break;
                case '/': stack[++top] = del(a, b); break;
                case '^': stack[++top] = mocnina(a, b); break;
            }
        }
        token = strtok(NULL, " ");
    }
    free(postfix_copy);
    return stack[top];
}