#include <iostream>
#include <iomanip>
#include <sstream>
#include "Polynomial.h"

std::string Polynomial::toString() const {
    std::string res = "";

    for (int i = degree(); i >= 0; --i) {
        double c = (*this)[i];
        if (fabs(c) <= POLYNOMIAL_EPS)
            continue;

        if (res.size() > 0) {
            // Sign of operation: either + or -
            if (c >= 0.) {
                res += " + ";
            } else {
                c = (-c);
                res += " - ";
            }
        }
        std::stringstream buffer;
        // buffer << std::fixed << std::setprecision(3);
        bool coeffPrinted = false;
        if (i == 0 || fabs(c - 1.) > POLYNOMIAL_EPS) {
            buffer << c;
            res += buffer.str();
            coeffPrinted = true;
        }
        if (i > 0) {
            if (coeffPrinted)
                res += "*";
            res += "x";
            if (i > 1) {
                res += "^";
                res += std::to_string(i);
            }
        }
    }
    return res;
}

std::istream& operator>>(std::istream& s, Polynomial& f) {
    int d = f.degree();
    double c;
    for (int i = d; i >= 0; --i) {
        if (!(s >> c))
            return s;
        f[i] = c;
    }
    f.trim();
    return s;
}