SmartLease: NFT-Based House Leasing System

Internal development guide for the TTM4195 project.

1. Core Functionality

• System: A blockchain-based leasing system using a self-executing smart contract.
• Asset: Properties are represented as ERC-721 NFTs with on-chain metadata (location, size, value, condition).
• Actors: Landlord (mints NFTs) and Tenant (leases NFTs).
• Mechanics:
  • Dynamic rent calculation via a view function.
  • Fair exchange ensured by a 3-month rent deposit and dual confirmation.
  • Landlord protection through deposit seizure on tenant default.
  • End-of-lease options including termination and extension.

2. Implementation Checklist

• 1. NFT Modeling: Implement ERC-721 with Property struct and mintProperty function.
• 2. Dynamic Pricing: Implement the computeMonthlyRent view function.
• 3. Fair Exchange: Implement applyAndDeposit and confirmLease functions, including NFT escrow.
• 4. Default Protection: Implement claimDefault function.
• 5. End-of-Lease: Implement payRent, terminateLease, and extendLease functions.

3. Project Structure and File Roles

.
├── contracts/
│   └── SmartLease.sol      # Main contract (NFT + Leasing logic)
├── scripts/
│   ├── deploy.ts           # Simple script that initiates the deployment
│   ├── ethers-lib.ts       # Reusable helper with the core deployment 
│   └── scenario.ts         # Simulates E2E user flow for the demo
├── tests/
│   └── SmartLease_test.sol # Automated tests for contract functions
├── pdf/                    # Assignment documents
└── ...                     # Other config and supporting files

Key File Explanations:

• contracts/SmartLease.sol: The single source of truth for all on-chain logic.
• scripts/deploy.ts: The main script to run for deployment. It's kept simple and calls the helper library.
• scripts/ethers-lib.ts: A helper library containing the reusable deploy function. This separates the complex deployment logic from the simple act of running the deployment.
• scripts/scenario.ts: The script to run for the final presentation. It will execute a full user story.
• tests/smartlease.test.js: Contains all unit tests. Essential for verifying contract correctness.

4. Remix IDE Web Workflow

This project is designed to be developed, tested, and demonstrated entirely within the Remix IDE web interface.

A. Setup

1. Clone the project into a Remix workspace using the "Clone" feature on the homepage with the GitHub URL.
2. Work inside that workspace.

B. Development Cycle

1. Code: Edit contracts/SmartLease.sol.
2. Compile:
   • Go to the Solidity Compiler tab.
   • Select the correct compiler version (e.g., 0.8.26).
   • Compile SmartLease.sol.
3. Test:
   • Go to the Solidity Unit Testing tab.
   • Select the tests/ directory.
   • Click "Run" to execute the tests in SmartLease_test.sol.

C. Deployment and Demo

1. Deploy to a Testnet:
   • In the Deploy & Run Transactions tab, select an environment (e.g., "Injected Provider - MetaMask") connected to a testnet like Sepolia.
   • Deploy the SmartLease contract.
   • Copy the deployed contract address.
2. Run Demo Scenario:
   • Alternatively, for a quick demo, run the scripts. Navigate to the File Explorer.
   • Right-click scripts/deploy.ts -> Run.
   • Update scripts/scenario.ts with the new address if needed.
   • Right-click scripts/scenario.ts -> Run to show the full simulation in the terminal.