# YearnMaticUSDCStakingStrategy

## Overview

The YearnMaticUSDCStakingStrategy contract is a strategy that supplies USDC into a Yearn V3 Vault and stakes the vault shares to earn additional WMATIC rewards. It manages reward claiming and conversion through Uniswap V3.

## Constants

```solidity
address public constant wpol = WPOL_POLYGON;                                      // WMATIC token address
IRouter public constant router = IRouter(UNISWAP_V3_ROUTER_POLYGON);             // Uniswap V3 router
IStakingRewardsMulti public constant yearnStakingRewards =                       // Yearn staking rewards
    IStakingRewardsMulti(0x602920E7e0a335137E02DF139CdF8D1381DAdBfD);
```

## State Variables

```solidity
uint256 public minSwapMatic;    // Minimum amount of WMATIC to swap
```

## Functions

### Initialization Functions

#### constructor

```solidity
constructor() initializer
```

Empty constructor marked as initializer.

#### initialize

```solidity
function initialize(
    IMaxApyVault _vault,
    address[] calldata _keepers,
    bytes32 _strategyName,
    address _strategist,
    IYVaultV3 _yVault
) public override initializer
```

Initializes the strategy with required components.

Parameters:

* `_vault`: MaxApy vault address
* `_keepers`: Array of keeper addresses
* `_strategyName`: Name of the strategy
* `_strategist`: Strategist address
* `_yVault`: Yearn V3 vault address

### Core Functions

#### liquidateExact

```solidity
function liquidateExact(uint256 amountNeeded) external override checkRoles(VAULT_ROLE) returns (uint256 loss)
```

Withdraws exact amount and re-stakes remaining shares.

Parameters:

* `amountNeeded`: Amount to withdraw

Returns:

* `loss`: Amount of realized loss

### Internal Core Functions

#### \_beforePrepareReturn

```solidity
function _beforePrepareReturn() internal override
```

Claims and processes staking rewards before preparing return.

#### \_adjustPosition

```solidity
function _adjustPosition(uint256, uint256 minOutputAfterInvestment) internal override
```

Adjusts strategy positions based on available capital.

Parameters:

* `minOutputAfterInvestment`: Minimum expected output

#### \_invest

```solidity
function _invest(uint256 amount, uint256 minOutputAfterInvestment) internal override returns (uint256 depositedAmount)
```

Invests assets and stakes received shares.

Parameters:

* `amount`: Amount to invest
* `minOutputAfterInvestment`: Minimum expected shares

Returns:

* `depositedAmount`: Amount of tokens received

#### \_divest

```solidity
function _divest(uint256 shares) internal override returns (uint256 withdrawn)
```

Withdraws assets from staking and vault.

Parameters:

* `shares`: Amount of shares to withdraw

Returns:

* `withdrawn`: Amount of assets received

#### \_liquidatePosition

```solidity
function _liquidatePosition(uint256 amountNeeded) internal override returns (uint256 liquidatedAmount, uint256 loss)
```

Liquidates position up to requested amount.

Parameters:

* `amountNeeded`: Amount to liquidate

Returns:

* `liquidatedAmount`: Amount actually liquidated
* `loss`: Amount of losses incurred

#### \_unwindRewards

```solidity
function _unwindRewards(IStakingRewardsMulti _yearnStakingRewards) internal
```

Claims WMATIC rewards and converts to USDC.

Parameters:

* `_yearnStakingRewards`: Staking rewards contract

### Internal View Functions

#### \_wpolBalance

```solidity
function _wpolBalance() internal view returns (uint256)
```

Returns strategy's WMATIC balance.

Returns:

* Current WMATIC balance

#### \_shareBalance

```solidity
function _shareBalance() internal view override returns (uint256 _balance)
```

Returns strategy's staked vault share balance.

Returns:

* Current staked share balance