#include "beer_song.h"

#include <cassert>
#include <cctype>

namespace beer {

using namespace std;

namespace {

string count_bottles(int count)
{
    if (0 == count)
        return "no more bottles";

    if (1 == count)
        return "1 bottle";

    return to_string(count) + " bottles";
};

void capitalize_first(string &str)
{
    assert(!str.empty());
    str.front() = toupper(str.front());
};

}

string verse(int index)
{
    string result = count_bottles(index)
        + " of beer on the wall, "
        + count_bottles(index)
        + " of beer.\n"
        + (index ? string("Take ")
                    + (index == 1 ? "it" : "one")
                    + " down and pass it around, "
                 : string("Go to the store and buy some more, "))
        + count_bottles(index ? index - 1 : 99)
        + " of beer on the wall.\n";

    capitalize_first(result);

    return result;
}

string sing(int from_index, int to_index)
{
    string result;

    assert(from_index >= to_index);

    for (int i = from_index; i >= to_index; --i) {

        result += (i == from_index ? "" : "\n");
        result += verse(i);
    }

    return result;
}

}