#include "phone_number.h"

#include <algorithm>
#include <cctype>

using namespace std;

static const size_t number_size     = 10;
static const size_t area_code_size  = 3;
static const size_t exchange_size   = 3;

static const char invalid_number[] = "0000000000";


phone_number::phone_number(const string &str)
{
    number_.resize(str.size());
    string::iterator iter = copy_if(str.cbegin(), str.cend(),
            number_.begin(), static_cast<int (*)(int)>(isdigit));
    number_.resize(distance(number_.begin(), iter));

    if (number_.size() == number_size + 1 && number_.front() == '1') {

        number_.erase(number_.begin());
    }
    else if (number_.size() != number_size) {

        number_ = invalid_number;
    }
}

string phone_number::number() const
{
    return number_;
}

string phone_number::area_code() const
{
    return number_.substr(0, area_code_size);
}

phone_number::operator string() const
{
    return string("(") + area_code() + ") "
        + number_.substr(area_code_size, exchange_size)
        + '-'
        + number_.substr(area_code_size + exchange_size);
}