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Curve Gauge Single Staking Farm

Web3 applications often incentivize holding tokens through yield farming. A Single Staking Farm is a smart contract that allows a user to deposit a single token and accumulate rewards over time. These rewards are claimable through the same smart contract interface.

For example, a user can deposit their Curve liquidity pool tokens in a Gauge staking contract. Over time, the user will accumulate CRV tokens as an incentive for providing liquidity to Curve.

Using the SingleStakingFarmContractPositionHelper​

The SingleStakingFarmContractPositionHelper helper class can be used to build a list of ContractPosition objects for a farm contract position group. In this example, we'll look at Curve LP token staking.

Curve allows Curve LP token holders to stake their position to receive CRV and potentially other bonus reward tokens. Curve supports several different implementations of farm contracts, so for the purposes of this recipe, we'll specifically look at the nGauge implementation. This implementation is used for many newer Curve opportunities like the rETH / ETH pool.

First, let's generate a new contract position fetcher with yarn studio create-contract-position-fetcher curve. When prompted for a group, select Create New, then enter farm as the ID and Farms as the label. When prompted for a network, select ethereum.

Let's now open up our newly generator boilerplate in src/apps/curve/ethereum/curve.farm.contract-position-fetcher.ts:

import { Inject } from '@nestjs/common';

import { IAppToolkit, APP_TOOLKIT } from '~app-toolkit/app-toolkit.interface';
import { Register } from '~app-toolkit/decorators';
import { PositionFetcher } from '~position/position-fetcher.interface';
import { ContractPosition } from '~position/position.interface';
import { Network } from '~types/network.interface';

import { CurveContractFactory } from '../contracts';
import { CURVE_DEFINITION } from '../curve.definition';

const appId = CURVE_DEFINITION.id;
const groupId = CURVE_DEFINITION.groups.farm.id;
const network = Network.ETHEREUM_MAINNET;

@Register.ContractPositionFetcher({ appId, groupId, network })
export class EthereumCurveFarmContractPositionFetcher implements PositionFetcher<ContractPosition> {
  constructor(
    @Inject(APP_TOOLKIT) private readonly appToolkit: IAppToolkit,
    @Inject(CurveContractFactory) private readonly curveContractFactory: CurveContractFactory,
  ) {}

  async getPositions() {
    return [];
  }
}

Reference the helper class through the AppToolkit​

We'll use the SingleStakingFarmContractPositionHelper helper class registered in our AppToolkit to quickly build the farm contract positions. We'll call the getPositions method on this helper class, and pass in the generated Ethers contract interface for the nGauge contract.

@Register.ContractPositionFetcher({ appId, groupId, network })
export class EthereumCurveFarmContractPositionFetcher implements PositionFetcher<ContractPosition> {
  constructor(
    @Inject(APP_TOOLKIT) private readonly appToolkit: IAppToolkit,
    @Inject(CurveContractFactory) private readonly curveContractFactory: CurveContractFactory,
  ) {}

  async getPositions() {
    return this.appToolkit.helpers.singleStakingFarmContractPositionHelper.getContractPositions<CurveNGauge>({
      // ...
    });
  }
}

Add appId, groupId, and network parameters​

We'll specify our appId, groupId, and network identifiers. These should match the values specified in the @Register.ContractPositionFetcher decorator.

@Register.ContractPositionFetcher({ appId, groupId, network })
export class EthereumCurveFarmContractPositionFetcher implements PositionFetcher<ContractPosition> {
  constructor(
    @Inject(APP_TOOLKIT) private readonly appToolkit: IAppToolkit,
    @Inject(CurveContractFactory) private readonly curveContractFactory: CurveContractFactory,
  ) {}

  async getPositions() {
    return this.appToolkit.helpers.singleStakingFarmContractPositionHelper.getContractPositions<CurveNGauge>({
      appId: CURVE_DEFINITION.id,
      groupId: CURVE_DEFINITION.groups.farm.id,
      network: Network.ETHEREUM_MAINNET,
      // ...
    });
  }
}

Add dependencies parameter​

We'll use the dependencies parameter to specify which token groups are required as dependencies for building this set of farm contract positions. In the case of Curve, we deposit LP tokens into the Gauge staking contracts, so we'll reference the group in the dependencies array.

@Register.ContractPositionFetcher({ appId, groupId, network })
export class EthereumCurveFarmContractPositionFetcher implements PositionFetcher<ContractPosition> {
  async getPositions() {
    return this.appToolkit.helpers.singleStakingFarmContractPositionHelper.getContractPositions<CurveNGauge>({
      appId: CURVE_DEFINITION.id,
      groupId: CURVE_DEFINITION.groups.farm.id,
      network: Network.ETHEREUM_MAINNET,
      dependencies: [{ appId: CURVE_DEFINITION.id, groupIds: [CURVE_DEFINITION.groups.pool.id], network }],
      // ...
    });
  }
}

Add resolveFarmAddresses parameter​

We'll use the resolveFarmAddresses factory method to specify the addresses for the farm contracts. We could define these statically, but that static list would then need to be updated every time Curve adds a new farm contract.

Instead, we'll resolve the addresses from the Curve factory contract. Let's build a method to resolve the guage addresses.

NOTE: We build helper classes to encapsulate and reuse this logic in the implementation for Curve in Studio; the example displayed here is simplified.

@Register.ContractPositionFetcher({ appId, groupId, network })
export class EthereumCurveFarmContractPositionFetcher implements PositionFetcher<ContractPosition> {
  async getPositions() {
    return this.appToolkit.helpers.singleStakingFarmContractPositionHelper.getContractPositions<CurveNGauge>({
      appId: CURVE_DEFINITION.id,
      groupId: CURVE_DEFINITION.groups.farm.id,
      network: Network.ETHEREUM_MAINNET,
      dependencies: [{ appId: CURVE_DEFINITION.id, groupIds: [CURVE_DEFINITION.groups.pool.id], network }],
      resolveFarmAddresses: () => {
        const multicall = this.appToolkit.getMulticall(network);
        const factoryAddress = '0xb9fc157394af804a3578134a6585c0dc9cc990d4';
        const factoryContract = this.curveContractFactory.curveFactoryV2({ address: factoryAddress, network });

        const poolTokens = await this.appToolkit.getAppTokenPositions<CurvePoolTokenDataProps>({
          appId: CURVE_DEFINITION.id,
          groupIds: [CURVE_DEFINITION.groups.pool.id],
          network,
        });

        const maybeGaugeAddresses = await Promise.all(
          poolTokens.map(async poolToken => {
            const gaugeAddressRaw = await multicall.wrap(factoryContract).get_gauge(poolTokens.address);
            const gaugeAddress = gaugeAddressRaw.toLowerCase();
            return gaugeAddress;
          }),
        );

        return maybeGaugeAddresses.filter(v => v !== ZERO_ADDRESS);
      },
      // ...
    });
  }
}

Add resolveFarmContract parameter​

We'll use the resolveFarmContract method as a factory that returns an instance of the CurveNGauge contract for a given address and network.

@Register.ContractPositionFetcher({ appId, groupId, network })
export class EthereumCurveFarmContractPositionFetcher implements PositionFetcher<ContractPosition> {
  async getPositions() {
    return this.appToolkit.helpers.singleStakingFarmContractPositionHelper.getContractPositions<CurveNGauge>({
      appId: CURVE_DEFINITION.id,
      groupId: CURVE_DEFINITION.groups.farm.id,
      network: Network.ETHEREUM_MAINNET,
      dependencies: [{ appId: CURVE_DEFINITION.id, groupIds: [CURVE_DEFINITION.groups.pool.id], network }],
      resolveFarmAddresses: () => { /* ... */ },
      resolveFarmContract: ({ address, network }) => this.curveContractFactory.curveNGauge({ address, network }),
      // ....
    });
  }
}

Add resolveStakedTokenAddress parameter​

We'll use the resolveStakedTokenAddress method to resolve the address of the token that can be staked in this contract. In the case of the Curve nGauge contracts, we can simply call the lp_token method on the contract to get this value.

@Register.ContractPositionFetcher({ appId, groupId, network })
export class EthereumCurveFarmContractPositionFetcher implements PositionFetcher<ContractPosition> {
  async getPositions() {
    return this.appToolkit.helpers.singleStakingFarmContractPositionHelper.getContractPositions<CurveNGauge>({
      appId: CURVE_DEFINITION.id,
      groupId: CURVE_DEFINITION.groups.farm.id,
      network: Network.ETHEREUM_MAINNET,
      dependencies: [{ appId: CURVE_DEFINITION.id, groupIds: [CURVE_DEFINITION.groups.pool.id], network }],
      resolveFarmAddresses: () => { /* ... */ },
      resolveFarmContract: ({ address, network }) => this.curveContractFactory.curveNGauge({ address, network }),
      resolveStakedTokenAddress: ({ contract, multicall }) => multicall.wrap(contract).lp_token(),
      // ...
    });
  }
}

Add resolveRewardTokenAddresses parameter​

We'll use the resolveStakedTokenAddress method to resolve the address(es) of the tokens that can be claimed as rewards in this contract. In the case of the Curve nGauge contracts, we know that there is an emission of CRV tokens, and possibly a bonus reward token. This bonus reward token can be resolved by calling the reward_tokens method on the smart contract.

@Register.ContractPositionFetcher({ appId, groupId, network })
export class EthereumCurveFarmContractPositionFetcher implements PositionFetcher<ContractPosition> {
  async getPositions() {
    return this.appToolkit.helpers.singleStakingFarmContractPositionHelper.getContractPositions<CurveNGauge>({
      appId: CURVE_DEFINITION.id,
      groupId: CURVE_DEFINITION.groups.farm.id,
      network: Network.ETHEREUM_MAINNET,
      dependencies: [{ appId: CURVE_DEFINITION.id, groupIds: [CURVE_DEFINITION.groups.pool.id], network }],
      resolveFarmAddresses: () => { /* ... */ },
      resolveFarmContract: ({ address, network }) => this.curveContractFactory.curveNGauge({ address, network }),
      resolveStakedTokenAddress: ({ contract, multicall }) => multicall.wrap(contract).lp_token(),
      resolveRewardTokenAddresses: async ({ contract, multicall }) => {
        const CRV_TOKEN_ADDRESS = '0xd533a949740bb3306d119cc777fa900ba034cd52';
        const bonusRewardTokenAddress = await multicall.wrap(contract).reward_tokens(0);
        return [CRV_TOKEN_ADDRESS, bonusRewardTokenAddress].filter(v => v !== ZERO_ADDRESS);
      },
    });
  }
}

Add resolveTotalValueLocked parameter​

We'll use the resolveTotalValueLocked method to resolve the total amount of tokens locked in the contract. In the case of the nGauge contracts, this amount can be retrieved using the totalSupply() method on the smart contract. The helper class will use this value and the price of the staked token to determine the total value locked in USD.

@Register.ContractPositionFetcher({ appId, groupId, network })
export class EthereumCurveFarmContractPositionFetcher implements PositionFetcher<ContractPosition> {
  async getPositions() {
    return this.appToolkit.helpers.singleStakingFarmContractPositionHelper.getContractPositions<CurveNGauge>({
      appId: CURVE_DEFINITION.id,
      groupId: CURVE_DEFINITION.groups.farm.id,
      network: Network.ETHEREUM_MAINNET,
      dependencies: [{ appId: CURVE_DEFINITION.id, groupIds: [CURVE_DEFINITION.groups.pool.id], network }],
      resolveFarmAddresses: () => { /* ... */ },
      resolveFarmContract: ({ address, network }) => this.curveContractFactory.curveNGauge({ address, network }),
      resolveStakedTokenAddress: ({ contract, multicall }) => multicall.wrap(contract).lp_token(),
      resolveRewardTokenAddresses: ({ /* ... */ }) => { /* ... */ },
      resolveTotalValueLocked: ({ contract, multicall }) => multicall.wrap(contract).totalSupply(),
      // ...
    });
  }
}

Add resolveIsActive parameter​

We'll use the resolveIsActive method to resolve if the farm is active, that is, if the farm is still emitting rewards to users with staked tokens. In the case of Curve nGauge contracts, there's an inflation_rate that dictates the rate at which CRV token is emitted on this contract. If this is non-zero, we can consider the farm active.

@Register.ContractPositionFetcher({ appId, groupId, network })
export class EthereumCurveFarmContractPositionFetcher implements PositionFetcher<ContractPosition> {
  async getPositions() {
    return this.appToolkit.helpers.singleStakingFarmContractPositionHelper.getContractPositions<CurveNGauge>({
      appId: CURVE_DEFINITION.id,
      groupId: CURVE_DEFINITION.groups.farm.id,
      network: Network.ETHEREUM_MAINNET,
      dependencies: [{ appId: CURVE_DEFINITION.id, groupIds: [CURVE_DEFINITION.groups.pool.id], network }],
      resolveFarmAddresses: () => { /* ... */ },
      resolveFarmContract: ({ address, network }) => this.curveContractFactory.curveNGauge({ address, network }),
      resolveStakedTokenAddress: ({ contract, multicall }) => multicall.wrap(contract).lp_token(),
      resolveRewardTokenAddresses: ({ /* ... */ }) => { /* ... */ },
      resolveTotalValueLocked: ({ contract, multicall }) => multicall.wrap(contract).totalSupply(),
      resolveIsActive: async ({ contract, multicall }) => {
        const inflationRate = await multicall.wrap(contract).inflation_rate();
        return Number(inflationRate) > 0;
      },
      // ...
    });
  }
}

Add resolveRois parameter​

We'll use the resolveRois method to resolve the return on investment as a percentage of the total staked value. For the sake of simplicity, we'll only consider the ROI on the emitted CRV token. The gauge has a weight relative to the total working supply, so we'll use this as a fraction to determine the percentage of the emitted CRV token for this farm.

@Register.ContractPositionFetcher({ appId, groupId, network })
export class EthereumCurveFarmContractPositionFetcher implements PositionFetcher<ContractPosition> {
  async getPositions() {
    return this.appToolkit.helpers.singleStakingFarmContractPositionHelper.getContractPositions<CurveNGauge>({
      appId: CURVE_DEFINITION.id,
      groupId: CURVE_DEFINITION.groups.farm.id,
      network: Network.ETHEREUM_MAINNET,
      dependencies: [{ appId: CURVE_DEFINITION.id, groupIds: [CURVE_DEFINITION.groups.pool.id], network }],
      resolveFarmAddresses: () => { /* ... */ },
      resolveFarmContract: ({ address, network }) => this.curveContractFactory.curveNGauge({ address, network }),
      resolveStakedTokenAddress: ({ contract, multicall }) => multicall.wrap(contract).lp_token(),
      resolveRewardTokenAddresses: ({ /* ... */ }) => { /* ... */ },
      resolveTotalValueLocked: ({ contract, multicall }) => multicall.wrap(contract).totalSupply(),
      resolveIsActive: ({ /* ... */ }) => { /* ... */ },
      resolveRois: async ({ address, contract, multicall, rewardTokens, stakedToken, network }) => {
        const controllerContract = this.curveContractFactory.curveController({
          address: '0x2f50d538606fa9edd2b11e2446beb18c9d5846bb',
          network,
        });

        const [inflationRate, workingSupply, relativeWeight] = await Promise.all([
          multicall.wrap(gaugeContract).inflation_rate().then(v => Number(v) / 10 ** 18),
          multicall.wrap(gaugeContract).working_supply().then(v => Number(v) / 10 ** 18),
          multicall.wrap(controllerContract)['gauge_relative_weight(address)'](address).then(v => Number(v) / 10 ** 18),
        ]);

        const dailyROI =
          ((((inflationRate * relativeWeight * 86400) / workingSupply) * 0.4) / stakedToken.price) *
          rewardTokens[0].price;
        const weeklyROI =
          ((((inflationRate * relativeWeight * 604800) / workingSupply) * 0.4) / stakedToken.price) *
          rewardTokens[0].price;
        const yearlyROI =
          ((((inflationRate * relativeWeight * 31536000) / workingSupply) * 0.4) / stakedToken.price) *
          rewardTokens[0].price;

        return {
          dailyROI,
          weeklyROI,
          yearlyROI,
        };
      }
    });
  }
}

Simplify implementation using helpers​

Now that we know how things work, we'll just replace some of our implementations with helper classes that are available.

@Register.ContractPositionFetcher({ appId, groupId, network })
export class EthereumCurveFarmContractPositionFetcher implements PositionFetcher<ContractPosition> {
  constructor(
    @Inject(APP_TOOLKIT) private readonly appToolkit: IAppToolkit,
    @Inject(CurveContractFactory)
    private readonly curveContractFactory: CurveContractFactory,
    @Inject(CurveGaugeRoiStrategy)
    private readonly curveGaugeRoiStrategy: CurveGaugeRoiStrategy,
    @Inject(CurveGaugeIsActiveStrategy)
    private readonly curveGaugeIsActiveStrategy: CurveGaugeIsActiveStrategy,
    @Inject(CurveFactoryGaugeAddressHelper)
    private readonly curveFactoryGaugeAddressHelper: CurveFactoryGaugeAddressHelper,
  ) {}

  async getPositions() {
    return this.appToolkit.helpers.singleStakingFarmContractPositionHelper.getContractPositions<CurveNGauge>({
      network,
      appId,
      groupId,
      dependencies: [{ appId: CURVE_DEFINITION.id, groupIds: [CURVE_DEFINITION.groups.pool.id], network }],
      resolveFarmAddresses: async () => this.curveFactoryGaugeAddressHelper.getGaugeAddresses({
        factoryAddress: '0xb9fc157394af804a3578134a6585c0dc9cc990d4',
        network,
      }),
      resolveFarmContract: ({ address, network }) => this.curveContractFactory.curveNGauge({ address, network }),
      resolveStakedTokenAddress: ({ contract, multicall }) => multicall.wrap(contract).lp_token(),
      resolveRewardTokenAddresses: async ({ contract, multicall }) => {
        const bonusRewardTokenAddress = await multicall.wrap(contract).reward_tokens(0);
        return [CRV_TOKEN_ADDRESS, bonusRewardTokenAddress].filter(v => v !== ZERO_ADDRESS);
      },
      resolveTotalValueLocked: ({ contract, multicall }) => multicall.wrap(contract).totalSupply(),
      resolveIsActive: this.curveGaugeIsActiveStrategy.build({
        resolveInflationRate: ({ contract, multicall }) => multicall.wrap(contract).inflation_rate(),
      }),
      resolveRois: this.curveGaugeRoiStrategy.build<CurveNGauge, CurveController>({
        resolveControllerContract: ({ network }) =>
          this.curveContractFactory.curveController({
            address: '0x2f50d538606fa9edd2b11e2446beb18c9d5846bb',
            network,
          }),
        resolveInflationRate: ({ gaugeContract, multicall }) => multicall.wrap(gaugeContract).inflation_rate(),
        resolveWorkingSupply: ({ gaugeContract, multicall }) => multicall.wrap(gaugeContract).working_supply(),
        resolveRelativeWeight: ({ controllerContract, multicall, address }) =>
          multicall.wrap(controllerContract)['gauge_relative_weight(address)'](address),
      }),
    });
  }
}

We're done!