# Counter Hooks Exercises In this exercise, you'll learn how to write a custom hooks contract. The starter code for this exercise is provided in [`foundry/src/exercises/CounterHook.sol`](https://github.com/Cyfrin/defi-uniswap-v4/blob/main/foundry/src/exercises/CounterHook.sol) Solution is in [`foundry/src/solutions/CounterHook.sol`](https://github.com/Cyfrin/defi-uniswap-v4/blob/main/foundry/src/solutions/CounterHook.sol) ## Task 1 - Configure hook permissions ```solidity function getHookPermissions() public pure returns (Hooks.Permissions memory) { return Hooks.Permissions({ beforeInitialize: false, afterInitialize: false, beforeAddLiquidity: false, afterAddLiquidity: false, beforeRemoveLiquidity: false, afterRemoveLiquidity: false, beforeSwap: false, afterSwap: false, beforeDonate: false, afterDonate: false, beforeSwapReturnDelta: false, afterSwapReturnDelta: false, afterAddLiquidityReturnDelta: false, afterRemoveLiquidityReturnDelta: false }); } ``` Set `beforeAddLiquidity`, `beforeRemoveLiquidity`, `beforeSwap` and `afterSwap` to `true`. ## Task 2 - Increment counts For each hook functions above, increment the state variable `counts`. `counts` is a nested mapping from `PoolId`, name of the function, to the number of times the function was called. For example the current count of `afterSwap` is ```solidity counts[key.toId()]["beforeSwap"] ``` ## Test 1. Find the value of `salt` needed to deploy the hooks contract at a valid address. ```shell forge test --match-path test/FindHookAddr.sol -vvv ``` 2. Export the salt printed to your terminal from executing the command in the previous step. ```shell export SALT=YOUR_SALT forge test --fork-url $FORK_URL --match-path test/CounterHook.test.sol -vvv ```