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exchange.cpp
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exchange.cpp
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/**
* simple decentralized exchange
* smart contract on eos
*
*/
#include "exchange.hpp"
#include <eosiolib/currency.hpp>
using namespace eosio;
void exchange::add_order(uint64_t scope, account_name maker, asset quantity, uint64_t price, account_name contract) {
order_index orders(_self, scope);
print("add order, maker: ", name{maker}, " quantity: ", quantity, " price: ", asset(price, settlement_token_symbol),
"\n");
if (quantity.amount > 0) {
orders.emplace(maker, [&](auto &r) {
r.id = orders.available_primary_key();
r.price = price;
r.quantity = quantity;
r.maker = maker;
r.contract = contract;
});
}
}
void exchange::cancelorder(account_name scope, uint64_t order_id) {
order_index orders(_self, scope);
const auto& order = orders.get( order_id, "no order object found" );
withdraw(order.contract, order.maker, order.quantity);
orders.erase( order );
}
void exchange::deposit(account_name contract, account_name user, asset quantity) {
print(name{user}, " deposit ", quantity, "\n");
if (quantity.amount == 0) {
print("amoutn equals to 0 abord\n");
return;
}
action(
permission_level{user, N(active)},
contract, N(transfer),
std::make_tuple(user, _self, quantity, std::string("deposit"))
).send();
}
void exchange::transfer(account_name contract, account_name from, account_name to, asset quantity) {
print(name{from}, " transfer ", quantity, " to ", name{to}, "\n");
action(
permission_level{from, N(active)},
contract, N(transfer),
std::make_tuple(from, to, quantity, std::string("transfer"))
).send();
}
void exchange::withdraw(account_name contract, account_name user, asset quantity) {
print(name{user}, " withdraw ", quantity, "\n");
if (quantity.amount <= 0) {
print("amoutn equals to 0 abord\n");
return;
}
// eosio_assert( quantity.amount > 0, "insufficient bid" );
action act(
permission_level{_self, N(active)},
contract, N(transfer),
std::make_tuple(_self, user, quantity, std::string("withdraw"))
);
act.send();
}
asset exchange::to_settlement_token(asset quantity, uint64_t price, bool floor) {
eosio_assert(quantity.amount >=0 , "insufficient amount");
//this is a simple logic, need to add more rules
uint64_t amt = quantity.amount * price;
int64_t p = (int64_t) quantity.symbol.precision();
int64_t p10 = 1;
while (p > 0) {
p10 *= 10;
--p;
}
// this arithmetician work for eos rule like eos.amount*10000
uint64_t res = amt / p10;
if (!floor && res * p10 != amt)
res++;
return asset(res, settlement_token_symbol);
}
asset exchange::asset_min(asset a, asset b) {
if (a > b) return b;
else return a;
}
//sell
void exchange::ask(account_name maker, asset quantity, uint64_t price, account_name ask_contract) {
//充值其他代币,卖
//deposit(exchange_token_contract, maker, quantity);
//查找所有的买单
order_index bid_orders(_self, N(bid));
//查找所有买价高于price的买方按照价格时间排序
auto bid_orders_by_price = bid_orders.get_index<N(byprice)>();
auto bid_it = bid_orders_by_price.end();
auto bid_end = bid_orders_by_price.lower_bound(price);
auto left = quantity;
asset maker_receive(0, settlement_token_symbol);
// require_auth(maker);
// require_recipient(maker);
while (left.amount > 0 && bid_it != bid_end) {
bid_it--;
print("bid order id: ", bid_it->id, " price: ", bid_it->price, "\n");
auto exchange_quantity = asset_min(bid_it->quantity, left);
auto settlement_token_quantity = to_settlement_token(exchange_quantity, price, true);
maker_receive += settlement_token_quantity;
//withdraw(exchange_token_contract, bid_it->maker, exchange_quantity);
transfer(ask_contract, maker, bid_it->maker, exchange_quantity);
left -= exchange_quantity;
if (bid_it->quantity == exchange_quantity) {
bid_it = bid_orders_by_price.erase(bid_it);
} else {
bid_orders_by_price.modify(bid_it, maker, [&](auto &r) {
r.quantity -= exchange_quantity;
});
}
}
deposit(ask_contract, maker, left);
add_order(N(ask), maker, left, price, ask_contract);
//just support xx/EOS trade now, maybe improve it to xx/xx
withdraw(settlement_token_contract, maker, maker_receive);
}
//buy
void exchange::bid(account_name maker, asset quantity, uint64_t price, asset bid_currency, account_name bid_contract) {
//查找卖单
order_index ask_orders(_self, N(ask));
//查找所有卖价低于price的卖方按照价格时间排序
auto ask_orders_by_price = ask_orders.get_index<N(byprice)>();
auto ask_it = ask_orders_by_price.begin();
auto ask_end = ask_orders_by_price.upper_bound(price);
auto left = quantity;
asset maker_receive(0, bid_currency.symbol);
// require_auth(maker);
// require_recipient(maker);
while (left.amount > 0 && ask_it != ask_end) {
print("ask order id: ", ask_it->id, " price: ", ask_it->price, "\n");
auto exchange_quantity = asset_min(ask_it->quantity, left);
auto settlement_token_quantity = to_settlement_token(exchange_quantity, ask_it->price, false);
maker_receive += exchange_quantity;
transfer(settlement_token_contract, maker, ask_it->maker, settlement_token_quantity);
left -= exchange_quantity;
if (ask_it->quantity == exchange_quantity) {
ask_orders_by_price.erase(ask_it);
}
else {
ask_orders_by_price.modify(ask_it, maker, [&](auto &r) {
r.quantity -= exchange_quantity;
});
}
ask_it++;
}
deposit(settlement_token_contract, maker, to_settlement_token(left, price, false));
add_order(N(bid), maker, left, price, settlement_token_contract);
withdraw(bid_contract, maker, maker_receive);
}
EOSIO_ABI(exchange, (bid)(ask)(cancelorder))