feat: pay & repay

contracts/Bank.sol

@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >=0.4.22 <0.9.0;
+import "@openzeppelin/contracts/utils/Counters.sol";
+import "./SoulboundToken.sol";
+
+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.");
+        _;
+    }
+
+	modifier onlyClient {
+		require(sbt_number[msg.sender] != 0);
+		_;
+	}
+
+	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.");
+		require(target == number, "This is not your SBT number.");
+		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

@@ -17,9 +17,10 @@ contract SoulboundToken is ERC721, Ownable {
 
     mapping(address => bool) private isReliableBank;
     mapping(address => Certificate[]) private certificates;
+    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") {}
@@ -28,6 +29,7 @@ contract SoulboundToken is ERC721, Ownable {
         _tokenIds.increment();
         uint256 newItemId = _tokenIds.current();
         _mint(player, newItemId);
+        address_to_number[player] = newItemId;
 
         return newItemId;
     }
@@ -88,8 +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 {
+    function logRepaying(address client, uint id, uint amount) public onlyBank {
-        emit Repay(client, msg.sender, id, amount, finish);
+        emit Repay(client, msg.sender, id, amount);
     }
 
     function logWarning(address client) public onlyBank {
@@ -103,4 +105,8 @@ contract SoulboundToken is ERC721, Ownable {
     function listCertificate(address client) public view onlyBank returns (Certificate[] memory){
         return certificates[client];
     }
+
+    function getAccountNumber(address client) public view onlyBank returns (uint) {
+        return address_to_number[client];
+    }
 }

migrations/1685866933_migrate_credit_system.js

@@ -1,6 +1,11 @@
-var MyNFT = artifacts.require("SoulboundToken");
+var SBT = artifacts.require("SoulboundToken");
+var Bank = artifacts.require("Bank");
 
 module.exports = function(_deployer) {
 	// Use deployer to state migration tasks.
-	_deployer.deploy(MyNFT, );
+	_deployer.deploy(SBT).then((SBT_instance) => {
+		return _deployer.deploy(Bank, SBT_instance.address).then((Bank_instance) => {
+			return SBT_instance.addReliableBank(Bank_instance.address);
+		});
+	});
 };