/*Rennex helped*/

#include <iostream>
#include <vector>
#include <cstring>
#include <string>
#include "stdio.h"  //strtok

using namespace std;

bool validateEmail(string);

int main(){
    string email;
    bool isValid;

    do{
        cout<< " Enter email (or q/Q to quit): ";
        getline(cin, email);
        isValid= validateEmail(email);

        if(isValid)
            cout<< "\n\t Valid Email\n";
        else
            cout<< "\n\tInvalid Email\n";
        
    } while (email != "q" && email != "Q");

    return 0;
}

bool validateEmail(string email){

    //check name exists (first character is alphanumeric)
    //check last character valid (alphanumeric)
    if(!isalnum(email.at(0)) || !isalnum(email.at(email.size()-1))){
        cout<<"\n\tINVALID NAME\n";
        return false;
    }

    //check if @ used multiple times
    int atPos= 0;

    for(int ctr= 0; ctr != email.size(); ++ctr){ 
        if(atPos != 0){
            cout<< "\n\t'@' used multiple times";
            return false;
        }
    }

    //split into sections
    vector<string> vData;

    char str[321];
    strcpy(str, email.c_str()); //convert to cstring

    char *pch;
    pch= strtok(str,"@.");    //first part until delimiter
    vData.push_back(pch);

    while(pch != NULL){         //each successive delimiter
        pch= strtok (NULL, "@.");
        if(pch == NULL) break;
        
        vData.push_back(pch);
    }

    if(vData.size() <3){    //make sure at least 3 parts exist (name, domain, tld)...but can have more than 3 EX: subdomains
        cout << "\n\tNot enough sections (name@domain.tld)";
        return false;
    }

    return true;
}