Superfluid Constant Flow Toy Model

SuperfluidToken.js

let currentTime = parseInt(Date.now()/1000); // current unix time in seconds

class SuperfluidToken {

    accounts = {};
    cfaAgreements = {}

    _getAccount(owner) {
        let acc = this.accounts[owner];
        if (!acc) {
            this.accounts[owner] = acc = {
                settledBalance: 0,
                settledTime: currentTime,
                netFlowRate: 0,
            }
        }
        return acc;
    }

    balanceOf(owner) {
        const acc = this.accounts[owner];
        if (!acc) return 0;
        return acc.settledBalance + 
            (currentTime - acc.settledTime) * acc.netFlowRate;
    }

    mint(owner, amount) {
        const acc = this._getAccount(owner);
        acc.settledBalance += amount;
    }

    transfer(sender, receiver, amount) {
        const senderAcc = this._getAccount(sender);
        const receiverAcc = this._getAccount(receiver);
        if (this.balanceOf(sender) < amount) throw new Error("Not enough balance");
        senderAcc.settledBalance -= amount;
        receiverAcc.settledBalance += amount;
    }

    updateFlow(sender, receiver, flowRate) {
        const senderAcc = this._getAccount(sender);
        const receiverAcc = this._getAccount(receiver);
        const flowId = sender + ":" + receiver;
        const flow = this.cfaAgreements[flowId];
        if (flow) {
            flow.updatedAt = currentTime;
            flow.flowRate = flowRate;
        } else {
            this.cfaAgreements[flowId] = {
                createdAt: currentTime,
                updatedAt: currentTime,
                flowRate 
            }
        }
        [senderAcc, receiverAcc].map(acc => {
            acc.settledBalance += (currentTime - acc.settledTime) * acc.netFlowRate;
            acc.settledTime = currentTime;
        });
        senderAcc.netFlowRate -= flowRate;
        receiverAcc.netFlowRate += flowRate;
    }
}


// Tests

function printAccount(token, owner) {
    console.log(`${owner} balanceOf:${token.balanceOf(owner)}`);
}

const token = new SuperfluidToken();

console.log("# mint to bob $100");
printAccount(token, "bob");
token.mint("bob", 100);
printAccount(token, "bob");
console.log("# transfer $10 from bob to alice");
token.transfer("bob", "alice", 10);
printAccount(token, "bob");
printAccount(token, "alice");
console.log("# transfer $100.1 from bob should fail");
try { token.transfer("bob", "alice", 100.1) } catch (err) { console.log("Caught:", err.message); };
console.log("# create flow from bob to alice at $10/hour");
token.updateFlow("bob", "alice", 10/3600);
printAccount(token, "bob");
printAccount(token, "alice");
console.log("# advancing for 2 hours...");
currentTime += 3600 *2;
printAccount(token, "bob");
printAccount(token, "alice");
console.log("# create flow from alice to carol at $5/hour");
token.updateFlow("alice", "carol", 5/3600);
printAccount(token, "bob");
printAccount(token, "alice");
printAccount(token, "carol");
console.log("# advancing for 2 hours...");
currentTime += 3600 *2;
printAccount(token, "bob");
printAccount(token, "alice");
printAccount(token, "carol");