Important Notes to Know Before Interacting with the contract :

• Need a evm wallet like metamask to interact with the protocol, and setup a custom network,
• since deployment from local environment was not working , the contract was deployed through BlockDag ide and then integrated using the frontend with the contract address and the abi of the contract
• so no script file was created to deploy with foundry or forge script
• Due to Time constraint , test were omitted
• source code directory : /src/BdagTokenEngine.sol

BlockDag Network Details

• chain id : 1043
• rpc-url : https://rpc.primordial.bdagscan.com
• explorer-url : https://primordial.bdagscan.com/
• faucet-url : https://primordial.bdagscan.com/faucet
• symbol : BDAG

This Info can be used to create a custom Network inside metamask;

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BdagTokenEngine

Overview

BdagTokenEngine is a Solidity smart contract designed to manage minting and burning of BDAG tokens while maintaining a 1:1 peg with the BlockDag USD value. It uses native BDAG tokens as collateral to back newly minted BDAG tokens. The contract is intended to be owned and controlled by a LendingPool contract with exclusive rights to mint and burn BDAG.

This contract inherits from OpenZeppelin's ReentrancyGuard for protection against reentrancy attacks and the ERC20 standard for token functionality.

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Features

• Collateral Deposit & Minting
  Users deposit native BDAG tokens as collateral and mint new BDAG tokens proportionally.

• Collateral Redemption
  Users can redeem their collateral by burning BDAG tokens and withdrawing the locked collateral.

• Health Factor Enforcement
  Ensures users maintain a minimum collateralization ratio (health factor) to avoid under-collateralization and potential liquidation.

• Reentrancy Protection
  Protects critical functions like minting, burning, and redeeming collateral from reentrancy attacks.

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Contract Details

Constants

• PRECISION: Decimal precision for calculations (1e18).
• LIQUIDATION_THRESHOLD: 50% threshold for liquidation.
• LIQUIDATION_PRECISION: Precision factor for liquidation (100).
• MIN_HEALTH_FACTOR: Minimum required health factor (1).
• BDAG_PRICE: Fixed price of $1 per BDAG token (for peg enforcement).

Key Mappings

• s_collateralBalances: Tracks user's deposited collateral balances.
• s_bdagMinted: Tracks the amount of BDAG minted per user.
• s_users: List of users who have interacted with the protocol.

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Important Functions

depositCollateralAndMintBdag

• Allows users to deposit collateral and mint BDAG tokens in one call.
• Requires the sent ETH amount (msg.value) to match or exceed collateral * PRECISION.
• Updates user's collateral balance and mints BDAG tokens accordingly.
• The function take input in uint256 so no need to convert it to 18 decimals , the backend handles it automatically.

redeemCollateral

• Allows users to redeem their collateral by withdrawing Ether.
• Checks that the user has enough collateral deposited.
• Sends Ether back to the user and updates collateral balances.
• Checks if user's health factor remains valid after redemption.

mintBdag

• Users mint BDAG tokens against their deposited collateral.
• Enforces that user has sufficient collateral to mint requested amount.
• Mints tokens and updates the user’s collateral balance.

burnBdag

• Users burn BDAG tokens to reduce their debt.
• Updates collateral balance accordingly.
• Checks health factor after burning tokens.

revertIfHealthFactorIsBroken

• Checks if the user's health factor is above the minimum threshold.
• Reverts if user would be undercollateralized.

getUserInfo

• Returns collateral value in USD, minted BDAG amount, and current health factor for a given user.

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Events

• collateralDeposited(address user, uint256 amount): Emitted when collateral is deposited.
• collateralRedeemed(address user, uint256 amount): Emitted when collateral is redeemed.

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Usage Notes

• Collateral amounts and minted BDAG are calculated using fixed-point arithmetic with 18 decimals (PRECISION).
• The health factor enforces a minimum collateralization ratio to keep the system solvent.
• The contract follows security best practices including reentrancy guards on critical functions.
• Designed to be owned and controlled by a LendingPool contract with exclusive rights to mint and burn.

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Requirements

• Solidity version 0.8.20 or above.
• OpenZeppelin Contracts for ReentrancyGuard and ERC20.

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License

MIT License

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Author

James Lego

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