// Validation functions for the course of OOP'2024
// (c) irmantas.radavicius@mif.vu.lt
// 2025-03-07 first draft

#include <iostream>
#include <fstream>
#include <sstream>
#include <cctype>
#include <vector>

using namespace std;

// gets valid input (single value per line) from cin
// msgInput: message to ask for data
// msgError: additional details after invalid input
// returns a value of type T
template <typename T>
T getValue(const string &msgInput, const string &msgError = ""){
    T x;                            // value to be returned
    while(1){                       // loops until input becomes valid
        cout << msgInput;
        cin >> x;                   // try to read value
        char c = cin.get();         // and one char after
        if(cin.fail() || (c != '\n'))
        {   // if reading failed or additional chars found
            cout << "Bad input! " << msgError << endl;
            cin.clear();            // clear error flags in cin
            cin.ignore(1024, '\n'); // clean input buffer
        } else {
            break;                  // input is valid
        }
    }
    return x;
}


// gets valid input (single value per line) from cin
// msgInput: message to ask for data
// msgError: additional details after invalid input
// returns a value of type T
template <typename T>
vector<T> getList(const string &msgInput, const string &msgError = ""){
    vector<T> v;                    // list to be returned
    while(1){                       // this loops until input becomes valid
        string line;
        cout << "Enter a list of numbers: ";
        getline(cin, line);         // read the whole line
        stringstream ss;            // now process it internally
        ss << line;
        int hasErrors = 0;          // is zero for valid input
        while(1){                   // process every value in the line
            T x;
            ss >> x;
            if(!ss.fail()){         // if the value is valid
                v.push_back(x);     // add it to the list
            } else {                // we failed
                if(!ss.eof())       // check the reason why
                    hasErrors = 1;  // garbage stopped us and not the end
                break;              // finish processing current line
            }
        }
        if(hasErrors == 0)
            break;                  // the line is valid
        else {                      // there was garbage
            cout << "Bad input!" << msgError << endl;
            v.clear();              // clear error flags in cin
        }
    }
    return v;
}

// prints the values in a single line
template <typename T>
void printList(vector<T> v){
    for(int i = 0; i < v.size(); i++)
        cout << v[i] << " ";
    cout << endl;
}

int main(){

    // compute the sum of two numbers - example on how to use getValue
    int x = getValue<int>("Enter first number: ", "Integer value required.");
    int y = getValue<int>("Enter second number: ", "Integer value required.");
    int z = x + y;
    cout << "The sum is " << z << endl << endl << endl;

    // compute the sum of all values in a list - example of how to use getList
    vector<int> values = getList<int>("Enter the list of integers: ");
    printList<int>(values);
    int sum = 0;
    for(int i = 0; i < values.size(); ++i){
        sum += values[i];
    }
    cout << "The sum is " << sum << endl;

    return 0;

}