# `Strategy` Exercises `Strategy` is a contract that handles authorization and calls internal functions of `GmxHelper` to interact with GMX. You need to complete the implementation of the `Strategy.sol` contract. ## Task 1: Implement `totalValueInToken` ```solidity function totalValueInToken() external view returns (uint256) {} ``` This function will calculate the total value of `WETH` managed by this contract. Return the sum of `WETH` in this contract, collateral in GMX and profit and loss of the position managed by this contract. > Hint: > > - Call the internal function `getPositionWithPnlInToken` to get the amount of collateral plus the profit and loss of the current short position. ## Task 2: Implement `increase` ```solidity function increase(uint256 wethAmount) external payable auth returns (bytes32 orderKey) {} ``` This function will create a market increase order, adding `wethAmount` as collateral. > Hint: > > - Call an internal function in `GmxHelper` ## Task 3: Implement `decrease` ```solidity function decrease(uint256 wethAmount, address callbackContract) external payable auth returns (bytes32 orderKey) {} ``` This function will create a market decrease order. - When `callbackContract` is `address(0)`, create a market decrease order with the specified inputs. When this function is called from the `Vault`, `callbackContract` will not be `address(0)`. - Set `callbackGasLimit` to max callback gas limit by calling `getMaxCallbackGasLimit`. - Check `msg.value` is greater than the max callback gas limit. - Calculate `longTokenAmount` to withdraw from the current position. ``` long token amount = position collateral amount * wethAmount / position with pnl in token ``` Here `wethAmount` is the amount calculated by the `Vault` base on the profit and loss of this strategy. Amount of collateral to remove from the position is proportional to `wethAmount / position with pnl in token` - Create a market decrease order. > Hints: > > - Get position collateral amount by calling `getPositionCollateralAmount` > - Get position collateral amount with profit and loss by calling `getPositionWithPnlInToken` ## Task 4: Implement `cancel` ```solidity function cancel(bytes32 orderKey) external payable auth {} ``` This function will cancel an order. > Hint: > > - Call an internal function in `GmxHelper` ## Task 5: Implement `claim` ```solidity function claim() external {} ``` This function will claim funding fees. > Hint: > > - Call an internal function in `GmxHelper` ## Test ```shell forge test --fork-url $FORK_URL --fork-block-number $FORK_BLOCK_NUM --match-path test/app/Strategy.test.sol -vvv ```