Offer storage using Marketplace contract

contracts/Marketplace.sol

@@ -2,19 +2,19 @@
 pragma solidity ^0.8.0;
 
 import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
+import "./Collateral.sol";
 
-contract Marketplace {
-  IERC20 public immutable token;
+contract Marketplace is Collateral {
+  uint256 public immutable collateral;
   MarketplaceFunds private funds;
   mapping(bytes32 => Request) private requests;
+  mapping(bytes32 => Offer) private offers;
 
-  constructor(IERC20 _token) marketplaceInvariant {
-    token = _token;
-  }
-
-  function transferFrom(address sender, uint256 amount) private {
-    address receiver = address(this);
-    require(token.transferFrom(sender, receiver, amount), "Transfer failed");
+  constructor(IERC20 _token, uint256 _collateral)
+    Collateral(_token)
+    marketplaceInvariant
+  {
+    collateral = _collateral;
   }
 
   function requestStorage(Request calldata request)
@@ -31,6 +31,19 @@ contract Marketplace {
     emit StorageRequested(id, request);
   }
 
+  function offerStorage(Offer calldata offer) public marketplaceInvariant {
+    bytes32 id = keccak256(abi.encode(offer));
+    Request storage request = requests[offer.requestId];
+    require(balanceOf(msg.sender) >= collateral, "Insufficient collateral");
+    require(request.size != 0, "Unknown request");
+    require(offers[id].expiry == 0, "Offer already exists");
+    // solhint-disable-next-line not-rely-on-time
+    require(offer.expiry > block.timestamp, "Offer expired");
+    require(offer.price <= request.maxPrice, "Price too high");
+    offers[id] = offer;
+    emit StorageOffered(id, offer);
+  }
+
   struct Request {
     uint256 duration;
     uint256 size;
@@ -41,7 +54,14 @@ contract Marketplace {
     bytes32 nonce;
   }
 
+  struct Offer {
+    bytes32 requestId;
+    uint256 price;
+    uint256 expiry;
+  }
+
   event StorageRequested(bytes32 id, Request request);
+  event StorageOffered(bytes32 id, Offer offer);
 
   modifier marketplaceInvariant() {
     MarketplaceFunds memory oldFunds = funds;

test/Marketplace.test.js

@@ -1,10 +1,13 @@
 const { ethers } = require("hardhat")
 const { expect } = require("chai")
-const { exampleRequest } = require("./examples")
+const { exampleRequest, exampleOffer } = require("./examples")
+const { now, hours } = require("./time")
 const { keccak256, defaultAbiCoder } = ethers.utils
 
 describe("Marketplace", function () {
   const request = exampleRequest()
+  const offer = { ...exampleOffer(), requestId: requestId(request) }
+  const collateral = 100
 
   let marketplace
   let token
@@ -14,7 +17,7 @@ describe("Marketplace", function () {
     const TestToken = await ethers.getContractFactory("TestToken")
     token = await TestToken.deploy()
     const Marketplace = await ethers.getContractFactory("Marketplace")
-    marketplace = await Marketplace.deploy(token.address)
+    marketplace = await Marketplace.deploy(token.address, collateral)
     accounts = await ethers.getSigners()
     await token.mint(accounts[0].address, 1000)
   })
@@ -51,6 +54,60 @@ describe("Marketplace", function () {
       )
     })
   })
+
+  describe("offering storage", function () {
+    beforeEach(async function () {
+      await token.approve(marketplace.address, request.maxPrice)
+      await marketplace.requestStorage(request)
+      await token.approve(marketplace.address, collateral)
+      await marketplace.deposit(collateral)
+    })
+
+    it("emits event when storage is offered", async function () {
+      await expect(marketplace.offerStorage(offer))
+        .to.emit(marketplace, "StorageOffered")
+        .withArgs(offerId(offer), offerToArray(offer))
+    })
+
+    it("rejects offer for unknown request", async function () {
+      let unknown = exampleRequest()
+      let invalid = { ...offer, requestId: requestId(unknown) }
+      await expect(marketplace.offerStorage(invalid)).to.be.revertedWith(
+        "Unknown request"
+      )
+    })
+
+    it("rejects an expired offer", async function () {
+      let expired = { ...offer, expiry: now() - hours(1) }
+      await expect(marketplace.offerStorage(expired)).to.be.revertedWith(
+        "Offer expired"
+      )
+    })
+
+    it("rejects an offer that exceeds the maximum price", async function () {
+      let invalid = { ...offer, price: request.maxPrice + 1 }
+      await expect(marketplace.offerStorage(invalid)).to.be.revertedWith(
+        "Price too high"
+      )
+    })
+
+    it("rejects resubmission of offer", async function () {
+      await marketplace.offerStorage(offer)
+      await expect(marketplace.offerStorage(offer)).to.be.revertedWith(
+        "Offer already exists"
+      )
+    })
+
+    it("rejects offer with insufficient collateral", async function () {
+      let insufficient = collateral - 1
+      await marketplace.withdraw()
+      await token.approve(marketplace.address, insufficient)
+      await marketplace.deposit(insufficient)
+      await expect(marketplace.offerStorage(offer)).to.be.revertedWith(
+        "Insufficient collateral"
+      )
+    })
+  })
 })
 
 function requestId(request) {
@@ -70,6 +127,15 @@ function requestId(request) {
   )
 }
 
+function offerId(offer) {
+  return keccak256(
+    defaultAbiCoder.encode(
+      ["bytes32", "uint256", "uint256"],
+      offerToArray(offer)
+    )
+  )
+}
+
 function requestToArray(request) {
   return [
     request.duration,
@@ -81,3 +147,7 @@ function requestToArray(request) {
     request.nonce,
   ]
 }
+
+function offerToArray(offer) {
+  return [offer.requestId, offer.price, offer.expiry]
+}

test/examples.js

@@ -17,9 +17,14 @@ const exampleBid = () => ({
   bidExpiry: now() + hours(1),
 })
 
+const exampleOffer = () => ({
+  price: 42,
+  expiry: now() + hours(1),
+})
+
 const exampleLock = () => ({
   id: hexlify(randomBytes(32)),
   expiry: now() + hours(1),
 })
 
-module.exports = { exampleRequest, exampleBid, exampleLock }
+module.exports = { exampleRequest, exampleOffer, exampleBid, exampleLock }