guide.txt

# guide.txt

This Solidity project is a smart contract called "SlabTokenStorage." The contract aims to provide a storage service for a given ERC20 token. Users can deposit their tokens into the storage contract, and the deposited amount will be assigned to a specific "slab" based on capacity. Each slab has a predefined capacity, and the deposited tokens will be assigned to the first available slab that can accommodate the deposit.

The contract has the following components:

1. State variables:
   - `token`: An instance of the IERC20 interface to interact with the ERC20 token.
   - `slabs`: An array representing the slab capacities.
   - `slabCapacities`: An array representing the available capacities in each slab.
   - `depositSlab`: A mapping to store the slab index associated with each depositor's address.

2. Events:
   - `Deposit`: Emitted when a user deposits tokens into the contract.
   - `Withdraw`: Emitted when a user withdraws their tokens from the contract.

3. Errors:
   - `SlabTokenStorage__ERR_AMOUNT_ZERO`: Thrown when the deposit amount is zero.
   - `SlabTokenStorage__ERR_NO_SLAB_AVAILABLE`: Thrown when no slab can accommodate the deposit amount.
   - `SlabTokenStorage__ERR_NO_DEPOSIT_FOUND`: Thrown when the user tries to withdraw without having made a deposit.

4. Constructor:
   - Initializes the contract with the token address.

5. Functions:
   - `deposit`: Allows users to deposit their tokens into the contract and assign them to a slab.
   - `withdraw`: Allows users to withdraw their tokens from the contract.
   - `getSlabOfDepositor`: Returns the slab index associated with a depositor's address.
   - `_getAvailableSlabIndex`: Internal function to find the index of the first available slab that can accommodate the deposit amount.



Low-level Representation:

1. State variables:
   - token (address)
   - slabs (uint256[5])
   - slabCapacities (uint256[5])
   - depositSlab (mapping: address => uint256)

2. Events:
   - Deposit (indexed: user, amount, slab)
   - Withdraw (indexed: user, amount, slab)

3. Errors:
   - ERR_AMOUNT_ZERO
   - ERR_NO_SLAB_AVAILABLE
   - ERR_NO_DEPOSIT_FOUND

4. Constructor:
   - Input: _tokenAddress (address)
   - Initializes: token

5. Functions:
   - deposit:
     - Input: _amount (uint256)
     - Checks: amount > 0, available slab found
     - Effects: Updates depositSlab, slabCapacities, token balance, emits Deposit event
   - withdraw:
     - Checks: deposit exists
     - Effects: Updates slabCapacities, depositSlab, token balance, emits Withdraw event
   - getSlabOfDepositor:
     - Input: _depositor (address)
     - Output: slabIndex (uint256)
   - _getAvailableSlabIndex:
     - Input: _amount (uint256)
     - Output: slabIndex (int256)