feat: pay & repay

contracts/Bank.sol

@@ -7,15 +7,26 @@ contract Bank {
     using Counters for Counters.Counter;
     Counters.Counter private id_counter;
 
+	struct Order {
+		bool isFinished;
+		uint amount;
+	}
+
 	SoulboundToken sbt;
 	address owner;
 	mapping(address => uint) arrears;
+	mapping(uint => Order) order_amount;
+	mapping(address => uint[]) client_orders;
+	mapping(address => uint) credits;
 	mapping(address => uint) sbt_number;
 
 	constructor(address SBT_addr) {
 		sbt = SoulboundToken(SBT_addr);
+		owner = msg.sender;
 	}
 
+	receive() external payable {}
+
     modifier onlyBank {
         require(msg.sender == owner, "Only the owner can access this function.");
         _;
@@ -26,6 +37,10 @@ contract Bank {
 		_;
 	}
 
+	function setCredit(address client, uint amount) public onlyBank {
+		credits[client] = amount;
+	}
+
 	function register(uint number) public {
 		uint target = sbt.getAccountNumber(msg.sender);
 		require(target != 0, "You don't have SBT.");
@@ -33,4 +48,38 @@ contract Bank {
 		sbt_number[msg.sender] = target;
 	}
 
+	function pay(address shop, uint amount) public onlyClient {
+		require(amount <= credits[msg.sender], "You don't have enough credit.");
+		id_counter.increment();
+		uint id = id_counter.current();
+		arrears[msg.sender] += amount;
+		order_amount[id] = Order(false, amount);
+		client_orders[msg.sender].push(id);
+		payable(shop).transfer(amount);
+		sbt.logBorrowing(msg.sender, id, amount);
+	}
+
+	function repay() public payable onlyClient returns (uint[] memory, uint) {
+		uint value = msg.value;
+		uint repay_amount = 0;
+		uint should_pay;
+		uint[] memory unfinished = new uint[](client_orders[msg.sender].length);
+		uint refund;
+		uint item_counter = 0;
+		for (uint i=0; i<client_orders[msg.sender].length; i++) {
+			should_pay = order_amount[client_orders[msg.sender][i]].amount;
+			if ((value - repay_amount) >= should_pay){
+				repay_amount += should_pay;
+				order_amount[client_orders[msg.sender][i]].isFinished = true;
+			} else {
+				unfinished[item_counter] = (client_orders[msg.sender][i]);
+				item_counter += 1;
+			}
+		}
+		refund = value - repay_amount;
+		if (refund != 0){
+			payable(msg.sender).transfer(refund);
+		}
+		return (unfinished, refund);
+	}
 }

contracts/SoulboundToken.sol

@@ -20,7 +20,7 @@ contract SoulboundToken is ERC721, Ownable {
     mapping(address => uint) private address_to_number;
 
     event Borrow(address client, address bank, uint id, uint amount);
-    event Repay(address client, address bank, uint id, uint amount, bool finish);
+    event Repay(address client, address bank, uint id, uint amount);
     event Warning(address client, address bank);
 
     constructor() ERC721("Credit System Soulbound Token", "CS_SBT") {}
@@ -90,8 +90,8 @@ contract SoulboundToken is ERC721, Ownable {
         emit Borrow(client, msg.sender, id, amount);
     }
 
-    function logRepaying(address client, uint id, uint amount, bool finish) public onlyBank {
-        emit Repay(client, msg.sender, id, amount, finish);
+    function logRepaying(address client, uint id, uint amount) public onlyBank {
+        emit Repay(client, msg.sender, id, amount);
     }
 
     function logWarning(address client) public onlyBank {

migrations/1685866933_migrate_credit_system.js

@@ -6,6 +6,6 @@ module.exports = function(_deployer) {
 	_deployer.deploy(SBT).then((SBT_instance) => {
 		return _deployer.deploy(Bank, SBT_instance.address).then((Bank_instance) => {
 			return SBT_instance.addReliableBank(Bank_instance.address);
-		})
-	})
+		});
+	});
 };