// test.hpp
#include <eosiolib/eosio.hpp>
#include <eosiolib/asset.hpp>

#define EOS_SYMBOL symbol("EOS", 4)

CONTRACT test : public eosio::contract
{
  test(name receiver, name code, datastream<const char *> ds) 
  : contract(receiver, code, ds), games(receiver, receiver.value) {}

  public:
    struct init
    {
        init(){};
        eosio::name name;
        EOSLIB_SERIALIZE(init, (name))
    };

    ACTION init(eosio::name name);
    void transfer(
        eosio::name from,
        eosio::name to,
        eosio::asset quantity,
        std::string memo
    );
};

// test.cpp
#include "./test.hpp"

using namespace eosio;
using namespace std;

void test::init(name name)
{
    require_auth(_self);
}

void test::transfer(name from, name to, asset quantity, string memo)
{
    if (from == _self)
    {
        // we're sending money, do nothing additional
        return;
    }

    eosio_assert(to == _self, "contract is not involved in this transfer");
    eosio_assert(quantity.symbol.is_valid(), "invalid quantity");
    eosio_assert(quantity.amount > 0, "only positive quantity allowed");
    eosio_assert(quantity.symbol == EOS_SYMBOL, "only EOS tokens allowed");
}

extern "C" void apply(uint64_t receiver, uint64_t code, uint64_t action)
{
    if (code == "eosio.token"_n.value && action == "transfer"_n.value)
    {
        eosio::execute_action(
            eosio::name(receiver), eosio::name(code), &test::transfer
        );
    }
    else if (code == receiver)
    {
        switch (action)
        {
            EOSIO_DISPATCH_HELPER(test, (init))
        }
    }
}