Voting-system

pragma solidity ^0.4.24;

contract Ballot{
    
    address public chairperson;
    
    struct Voter{
        uint weight;
        bool voted;
        address delegate;
        uint vote;
    }
    
    struct Proposal{
        bytes32 name;
        uint votesCount;
    }
    
    mapping (address => Voter) public voters;
    
    Proposal[] public proposals;
    
    constructor (bytes32[] _proposalNames) public{
        chairperson = msg.sender;
        voters[chairperson].weight = 1;
        
        for (uint i = 0; i < _proposalNames.length; i++){
            proposals.push(Proposal({
                name:_proposalNames[i],
                votesCount: 0
            }));
        }
    }
    
    function giveRightToVote (address _voter) public{
        require(chairperson == msg.sender,"Only chairperson can give right to vote");
        require(!voters[_voter].voted, "Already voted.");
        require(voters[_voter].weight==0,"Weight issue.");
        voters[_voter].weight = 1;
    }
    
    function delegate (address _to) public{
        Voter storage sender = voters[msg.sender];
        require(!sender.voted,"Already voted.");
        require(_to != msg.sender,"Self-delegation not possible.");
        
        while (voters[_to].delegate != address(0)){
            _to = voters[_to].delegate;
            require(_to != msg.sender, "Self-delegation not possible - while loop");
        }
        
        sender.voted = true;
        sender.delegate = _to;
        Voter storage delegate_ = voters[_to];
        if (delegate_.voted){
            proposals[delegate_.vote].votesCount += sender.weight;
        }
        else{
            delegate_.weight += sender.weight;
        }
    }
    
    function vote (uint _proposal) public{
        Voter storage sender = voters[msg.sender];
        require(!sender.voted, "Already voted.");
        sender.voted = true;
        sender.vote = _proposal;
        
        proposals[_proposal].votesCount += sender.weight;
    }
    
    function winningProposal () public view returns (uint _winningProposal){
        uint winningVotesCount=0;
        for (uint i=0;i<proposals.length;i++){
            if (proposals[i].votesCount > winningVotesCount){
                winningVotesCount = proposals[i].votesCount;
                _winningProposal = i;
            }
        }
    }
    
    function winnerName() public view returns (bytes32 _winnerName){
        _winnerName = proposals[winningProposal()].name;
    }
    
    
}