#include "food_chain.h"

namespace food_chain {

using namespace std;

#define VERSE_TABLE                                                        \
X(Fly,    "fly",    "")                                                     \
X(Spider, "spider", "It wriggled and jiggled and tickled inside her.\n")    \
X(Bird,   "bird",   "How absurd to swallow a bird!\n")                      \
X(Cat,    "cat",    "Imagine that, to swallow a cat!\n")                    \
X(Dog,    "dog",    "What a hog, to swallow a dog!\n")                      \
X(Goat,   "goat",   "Just opened her throat and swallowed a goat!\n")       \
X(Cow,    "cow",    "I don't know how she swallowed a cow!\n")              \
X(Horse,  "horse",  "She's dead, of course!\n")

#define X(a, b, c) a,
enum Verse {
    VERSE_TABLE
};
#undef X

#define X(a, b, c) b,
static const char *food_name[] = {
    VERSE_TABLE
};
#undef X

#define X(a, b, c) c,
static const char *verse_phrase[] = {
    VERSE_TABLE
};
#undef X


string verse(int index)
{
    string result;

    --index;

    result += string("I know an old lady who swallowed a ")
       + food_name[index]
       + ".\n"
       + verse_phrase[index];

    if (index != Verse::Horse) {

        for (int i = index; i > Verse::Fly; --i) {

            result += string("She swallowed the ")
               + food_name[i]
               + " to catch the "
               + food_name[i-1];

            if (i == Verse::Bird)
                result += string(" that wriggled and jiggled and "
                                 "tickled inside her");

            result += string(".\n");
        }

        result += "I don't know why she swallowed the fly. "
                  "Perhaps she'll die.\n";
    }

    return result;
}

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

    for (int i = from_index; i <= to_index; ++i)
        result += verse(i) + '\n';

    return result;
}

string sing()
{
    return verses(1, 8);
}

}