Todo assignment

.gitignore

@@ -7,3 +7,18 @@ node_modules
 # Rust build artifacts
 /target
 **/target
+artifacts/
+cache/
+typechain-types/
+
+# Logs
+*.log
+
+# OS files
+.DS_Store
+Thumbs.db
+
+# IDE
+.idea/
+*.swp
+*.swo

assignments/9-Escrow V1/.gitignore

@@ -0,0 +1,33 @@
+# Dependencies
+/node_modules
+/lib
+# Build outputs
+/dist
+/bundle
+/artifacts
+/cache
+/coverage
+/types
+/typechain
+/typechain-types
+
+# Hardhat Ignition deployment output (keep ignition/modules tracked)
+/ignition/deployments
+
+# Local environment/secrets
+.env
+.env.*
+!.env.example
+
+# Logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+
+# OS/editor files
+.DS_Store
+Thumbs.db
+.vscode/*
+!.vscode/extensions.json

assignments/9-Escrow V1/README.md

@@ -0,0 +1,57 @@
+# Sample Hardhat 3 Beta Project (`mocha` and `ethers`)
+
+This project showcases a Hardhat 3 Beta project using `mocha` for tests and the `ethers` library for Ethereum interactions.
+
+To learn more about the Hardhat 3 Beta, please visit the [Getting Started guide](https://hardhat.org/docs/getting-started#getting-started-with-hardhat-3). To share your feedback, join our [Hardhat 3 Beta](https://hardhat.org/hardhat3-beta-telegram-group) Telegram group or [open an issue](https://github.com/NomicFoundation/hardhat/issues/new) in our GitHub issue tracker.
+
+## Project Overview
+
+This example project includes:
+
+- A simple Hardhat configuration file.
+- Foundry-compatible Solidity unit tests.
+- TypeScript integration tests using `mocha` and ethers.js
+- Examples demonstrating how to connect to different types of networks, including locally simulating OP mainnet.
+
+## Usage
+
+### Running Tests
+
+To run all the tests in the project, execute the following command:
+
+```shell
+npx hardhat test
+```
+
+You can also selectively run the Solidity or `mocha` tests:
+
+```shell
+npx hardhat test solidity
+npx hardhat test mocha
+```
+
+### Make a deployment to Sepolia
+
+This project includes an example Ignition module to deploy the contract. You can deploy this module to a locally simulated chain or to Sepolia.
+
+To run the deployment to a local chain:
+
+```shell
+npx hardhat ignition deploy ignition/modules/Counter.ts
+```
+
+To run the deployment to Sepolia, you need an account with funds to send the transaction. The provided Hardhat configuration includes a Configuration Variable called `SEPOLIA_PRIVATE_KEY`, which you can use to set the private key of the account you want to use.
+
+You can set the `SEPOLIA_PRIVATE_KEY` variable using the `hardhat-keystore` plugin or by setting it as an environment variable.
+
+To set the `SEPOLIA_PRIVATE_KEY` config variable using `hardhat-keystore`:
+
+```shell
+npx hardhat keystore set SEPOLIA_PRIVATE_KEY
+```
+
+After setting the variable, you can run the deployment with the Sepolia network:
+
+```shell
+npx hardhat ignition deploy --network sepolia ignition/modules/Counter.ts
+```

assignments/9-Escrow V1/contracts/Escrow-V1.sol

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+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.28;
+
+contract Escrow {
+    address public buyer;
+    address public seller;
+    address public escrowAgent;
+    bool public deliveryConfirmed;
+
+    enum EscrowState { AWAITING_PAYMENT, AWAITING_DELIVERY, COMPLETE }
+    EscrowState public state;
+
+    constructor(address _buyer, address _seller) {
+        require(_buyer != address(0) && _seller != address(0), "Invalid address");
+        require(_buyer != _seller, "Buyer and seller must differ");
+        buyer = _buyer; seller = _seller; escrowAgent = msg.sender;
+        state = EscrowState.AWAITING_PAYMENT;
+    }
+
+    modifier onlyBuyer() { require(msg.sender == buyer, "Only buyer"); _; }
+    modifier onlyEscrow() { require(msg.sender == escrowAgent, "Only escrow agent"); _; }
+    modifier inState(EscrowState s) { require(state == s, "Invalid state"); _; }
+
+    function deposit() external payable onlyBuyer inState(EscrowState.AWAITING_PAYMENT) {
+        require(msg.value > 0, "Must deposit ETH");
+        state = EscrowState.AWAITING_DELIVERY;
+    }
+
+    // Important fix: buyer confirms delivery, not seller.
+    function confirmDelivery() external onlyBuyer inState(EscrowState.AWAITING_DELIVERY) {
+        deliveryConfirmed = true;
+    }
+
+    // Important fix: funds can only be released after delivery is confirmed.
+    function releaseFunds() external onlyEscrow inState(EscrowState.AWAITING_DELIVERY) {
+        require(deliveryConfirmed, "Delivery not confirmed");
+        uint256 amount = address(this).balance;
+        require(amount > 0, "No funds");
+        state = EscrowState.COMPLETE;
+        (bool ok, ) = payable(seller).call{value: amount}("");
+        require(ok, "Release failed");
+    }
+
+    function refundBuyer() external onlyEscrow inState(EscrowState.AWAITING_DELIVERY) {
+        uint256 amount = address(this).balance;
+        require(amount > 0, "No funds");
+        state = EscrowState.COMPLETE;
+        (bool ok, ) = payable(buyer).call{value: amount}("");
+        require(ok, "Refund failed");
+    }
+
+    function getEscrowBalance() external view returns (uint256) { return address(this).balance; }
+}

assignments/9-Escrow V1/hardhat.config.ts

@@ -0,0 +1,38 @@
+import hardhatToolboxMochaEthersPlugin from "@nomicfoundation/hardhat-toolbox-mocha-ethers";
+import { configVariable, defineConfig } from "hardhat/config";
+
+export default defineConfig({
+  plugins: [hardhatToolboxMochaEthersPlugin],
+  solidity: {
+    profiles: {
+      default: {
+        version: "0.8.28",
+      },
+      production: {
+        version: "0.8.28",
+        settings: {
+          optimizer: {
+            enabled: true,
+            runs: 200,
+          },
+        },
+      },
+    },
+  },
+  networks: {
+    hardhatMainnet: {
+      type: "edr-simulated",
+      chainType: "l1",
+    },
+    hardhatOp: {
+      type: "edr-simulated",
+      chainType: "op",
+    },
+    sepolia: {
+      type: "http",
+      chainType: "l1",
+      url: configVariable("SEPOLIA_RPC_URL"),
+      accounts: [configVariable("SEPOLIA_PRIVATE_KEY")],
+    },
+  },
+});

assignments/9-Escrow V1/ignition/modules/Counter.ts

@@ -0,0 +1,9 @@
+import { buildModule } from "@nomicfoundation/hardhat-ignition/modules";
+
+export default buildModule("CounterModule", (m) => {
+  const counter = m.contract("Counter");
+
+  m.call(counter, "incBy", [5n]);
+
+  return { counter };
+});

assignments/9-Escrow V1/package.json

@@ -0,0 +1,28 @@
+{
+  "name": "9-escrow-v1",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "devDependencies": {
+    "@nomicfoundation/hardhat-ethers": "^4.0.5",
+    "@nomicfoundation/hardhat-ignition": "^3.0.8",
+    "@nomicfoundation/hardhat-toolbox-mocha-ethers": "^3.0.3",
+    "@types/chai": "^5.2.3",
+    "@types/chai-as-promised": "^8.0.2",
+    "@types/mocha": "^10.0.10",
+    "@types/node": "^22.19.13",
+    "chai": "^6.2.2",
+    "ethers": "^6.16.0",
+    "forge-std": "github:foundry-rs/forge-std#v1.9.4",
+    "hardhat": "^3.1.10",
+    "mocha": "^11.7.5",
+    "typescript": "~5.8.0"
+  },
+  "type": "module"
+}

assignments/9-Escrow V1/scripts/send-op-tx.ts

@@ -0,0 +1,22 @@
+import { network } from "hardhat";
+
+const { ethers } = await network.connect({
+  network: "hardhatOp",
+  chainType: "op",
+});
+
+console.log("Sending transaction using the OP chain type");
+
+const [sender] = await ethers.getSigners();
+
+console.log("Sending 1 wei from", sender.address, "to itself");
+
+console.log("Sending L2 transaction");
+const tx = await sender.sendTransaction({
+  to: sender.address,
+  value: 1n,
+});
+
+await tx.wait();
+
+console.log("Transaction sent successfully");

assignments/9-Escrow V1/test/Escrow-V1.ts

@@ -0,0 +1,39 @@
+import { expect } from "chai";
+import { network } from "hardhat";
+
+const { ethers } = await network.connect();
+
+describe("Escrow", function () {
+  const one = ethers.parseEther("1");
+  const setup = async () => {
+    const [agent, buyer, seller, other] = await ethers.getSigners();
+    const e = await ethers.deployContract("Escrow", [buyer.address, seller.address]);
+    return { e, agent, buyer, seller, other };
+  };
+
+  it("buyer deposits, confirms delivery, escrow releases to seller", async function () {
+    const { e, buyer, seller } = await setup();
+    await e.connect(buyer).deposit({ value: one });
+    await e.connect(buyer).confirmDelivery();
+    await e.releaseFunds();
+    expect(await ethers.provider.getBalance(await e.getAddress())).to.equal(0n);
+    expect(await e.state()).to.equal(2n);
+  });
+
+  it("enforces roles and requires delivery confirmation before release", async function () {
+    const { e, buyer, other } = await setup();
+    await expect(e.connect(other).deposit({ value: one })).to.be.revertedWith("Only buyer");
+    await e.connect(buyer).deposit({ value: one });
+    await expect(e.releaseFunds()).to.be.revertedWith("Delivery not confirmed");
+    await expect(e.connect(other).confirmDelivery()).to.be.revertedWith("Only buyer");
+  });
+
+  it("escrow can refund buyer in delivery stage", async function () {
+    const { e, buyer, other } = await setup();
+    await e.connect(buyer).deposit({ value: one });
+    await e.refundBuyer();
+    expect(await ethers.provider.getBalance(await e.getAddress())).to.equal(0n);
+    await expect(e.refundBuyer()).to.be.revertedWith("Invalid state");
+    await expect(e.connect(other).releaseFunds()).to.be.revertedWith("Only escrow agent");
+  });
+});

assignments/9-Escrow V1/tsconfig.json

@@ -0,0 +1,13 @@
+/* Based on https://github.com/tsconfig/bases/blob/501da2bcd640cf95c95805783e1012b992338f28/bases/node22.json */
+{
+  "compilerOptions": {
+    "lib": ["es2023"],
+    "module": "node16",
+    "target": "es2022",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "moduleResolution": "node16",
+    "outDir": "dist"
+  }
+}

assignments/Assignment/8-todo-contract/.gitignore

@@ -0,0 +1,33 @@
+# Dependencies
+/node_modules
+/lib
+# Build outputs
+/dist
+/bundle
+/artifacts
+/cache
+/coverage
+/types
+/typechain
+/typechain-types
+
+# Hardhat Ignition deployment output (keep ignition/modules tracked)
+/ignition/deployments
+
+# Local environment/secrets
+.env
+.env.*
+!.env.example
+
+# Logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+
+# OS/editor files
+.DS_Store
+Thumbs.db
+.vscode/*
+!.vscode/extensions.json