Watch NFT-based CDP (Collateralized Debt Position)

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【Introduction of the Luxury Watch NFT-based CDP (Collateralized Debt Position)】

• This is a smart contract that allow a user to borrow the WatchSignals Token (WST) by depositing the own luxury watch (Watch NFT) as a collateral.

  • A user create a Watch NFT based on their own luxury watch and its luxury watch price.

    • Current luxury watch price is retrieved by the WatchSignals Luxury Watch Price Oracle via chainlink.

  • A user deposit a Watch NFT into the WatchCDP Pool.

  • By depositing a Watch NFT, a user can borrow the WatchSignals Token (WST) from the WatchCDP Pool.

    • A user can borrow WST until 60% of the watch price of the collateralized-watch NFT .
    • This depositing (collateral) and borrowing structure is simlar to MakerDAO's CDP (MCD).

  • When a user above repay, a user repay the WatchSignals Token (include principal + interest ) to the WatchCDP Pool.

    • Once a user finish to repay, a user can withdraw deposited-watch NFT from the WatchCDP Pool.

• The WatchSignals Token (WST) is ERC20 token that is original token of the WatchSignals.

• Use the WatchSignals Luxury Watch Price Oracle via chainlink for retrieving the watch price data. https://docs.chain.link/docs/watchsignals#config

 

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【Workflow】

• Diagram of workflow (※ The WatchCDP contract is also the WatchCDP Pool)

 

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【Versions】

• Version for following the Chainlink (v0.6) smart contract
  • Solidity (Solc): v0.6.12
  • Truffle: v5.1.60
  • web3.js: v1.2.9
  • openzeppelin-solidity: v3.2.0
  • ganache-cli: v6.9.1 (ganache-core: 2.10.2)

 

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【Setup】

③ Prepare for execution script

• 1: Get API-key from Infura
  https://infura.io/

• 2: Add .env to the root directory by referencing from .env.example You need to set 3 things below in your .env:
  • Mnemonic (MNEMONIC)
  • Infura key (INFURA_KEY)
  • Deployer address (DEPLOYER_ADDRESS)

② Install modules

• Install npm modules in the root directory

$ npm install

③ Compile & migrate contracts (on Kovan testnet)

$ npm run migrate:kovan

④ Scripts (for testing whole process) on Kovan

• 1: Process are that:
  • Creating a Watch NFT
  • Deposit a Watch NFT as a collateral into the WatchCDP Pool.
  • Borrow the WatchSignals Token (WST)

$ npm run script:WatchCDP-borrow

• 2: Process are that:
  • Repay the WatchSignals Token (include principal + interest ) to the WatchCDP Pool.
  • Withdraw the deposited-watch NFT from the WatchCDP Pool.

$ npm run script:WatchCDP-repay

(※ In case you want to execute again after scripts above is executed, you must migrate (Process③) again. Then you need to execute Step 1~2 above)

【Video demo】

• Video demo for executing scripts above (on Kovan testnet):
  https://youtu.be/W8of0SZCuAs

【Remarks】

• Arbitrum verison
  • In progress.

• The WatchCDP contract is also the WatchCDP Pool.

• Another Scripts (Each parts)

  • Script for calling oracle by using the WatchSignals Luxury Watch Price Oracle via chainlink $ npm run script:WatchSignalsLuxuryWatchPriceOracle

  • Script for creating the Watch NFT $ npm run script:WatchNFTFactory

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【References】

• WatchSignals Luxury Watch Price Oracle via chainlink

  • Article: https://watchsignals.com/watch-blog/luxury-watch-data-on-blockchain-chainlink.html
  • Doc: https://docs.chain.link/docs/watchsignals#config

• Chainlink

  • @chainlink/contracts (v0.1.6) => include solidity v0.6 based package https://www.npmjs.com/package/@chainlink/contracts

• Arbitrum

  • Public Testnet（Kovan => Arbitrum）: https://developer.offchainlabs.com/docs/public_testnet
  • How to deploy on Arbitrum by using Truffle: https://developer.offchainlabs.com/docs/contract_deployment

• Chainlink Virtual Hackathon Spring 2021 https://chainlink-2021.devpost.com/