Casper-FFG.sol

pragma solidity ^0.5.0;

contract CasperFFG {

    // The minimum deposit required to become a validator
    uint constant MIN_DEPOSIT = 32 ether;

    // The duration of the deposit lock-in period in blocks
    uint constant WITHDRAWAL_DELAY = 86400;

    // The maximum number of validators
    uint constant MAX_VALIDATORS = 100;

    // The current validator set
    address[MAX_VALIDATORS] validators;

    // The current total deposit size
    uint totalDepositSize;

    // The current epoch number
    uint currentEpoch;

    // The current checkpoint block number
    uint currentCheckpoint;

    // The number of blocks per epoch
    uint blocksPerEpoch;

    // The number of blocks per checkpoint
    uint blocksPerCheckpoint;

    // The total number of blocks finalized
    uint totalFinalizedBlocks;

    // The threshold required for finalization
    uint finalizationThreshold;

    // The last finalized block number
    uint lastFinalizedBlock;

    // The validator struct
    struct Validator {
        uint deposit;
        uint withdrawalEpoch;
        bool isActive;
    }

    // The mapping of validator addresses to their respective validator struct
    mapping (address => Validator) validatorMap;

    // The deposit function for becoming a validator
    function deposit() public payable {
        require(msg.value >= MIN_DEPOSIT, "Deposit amount too low");
        require(totalDepositSize < MAX_VALIDATORS * MIN_DEPOSIT, "Maximum number of validators reached");
        require(validatorMap[msg.sender].deposit == 0, "Already a validator");

        // Create a new validator struct
        Validator memory validator;
        validator.deposit = msg.value;
        validator.withdrawalEpoch = currentEpoch + WITHDRAWAL_DELAY / blocksPerEpoch;
        validator.isActive = true;

        // Add the validator to the validator set
        validators[totalDepositSize / MIN_DEPOSIT] = msg.sender;

        // Add the deposit to the total deposit size
        totalDepositSize += msg.value;

        // Add the validator to the validator map
        validatorMap[msg.sender] = validator;
    }

    // The withdraw function for withdrawing as a validator
    function withdraw() public {
        Validator storage validator = validatorMap[msg.sender];

        require(validator.deposit > 0, "Not a validator");
        require(currentEpoch >= validator.withdrawalEpoch, "Withdrawal lock-in period not over");

        // Remove the validator from the validator set
        for (uint i = 0; i < validators.length; i++) {
            if (validators[i] == msg.sender) {
                validators[i] = validators[validators.length - 1];
                validators.length--;
                break;
            }
        }

        // Subtract the deposit from the total deposit size
        totalDepositSize -= validator.deposit;

        // Remove the validator from the validator map
        delete validatorMap[msg.sender];

        // Transfer the deposit back to the validator
        msg.sender.transfer(validator.deposit);
    }

    // The function for submitting a vote
    function vote(uint blockNumber) public {
        Validator storage validator = validatorMap[msg.sender];

        require(validator.isActive, "Inactive validator");
        require(blockNumber % blocksPerCheckpoint == 0, "Block number not a checkpoint");
        require(blockNumber > lastFinalizedBlock, "Block already finalized");

        //