SS9X0zCD

1pragma solidity ^0.4.18;
2
3// written for Solidity version 0.4.18 and above that doesn't break functionality 
4contract Voting {
5
6    // an event that is called whenever a Candidate is added so the frontend could
7    // appropriately display the candidate with the right element id (it is used
8    // to vote for the candidate, since it is one of arguments for the function
9    //"vote")
10    event AddedCandidate(uint candidateID);
11    
12    // describes a Voter, which has an id and the ID of the candidate they voted for
13    address owner;
14    
15    function Voting() public {
16        owner=msg.sender; 
17    }
18    
19    modifier onlyOwner {
20        // describes a Candidate
21        require(msg.sender == owner);
22        _;
23    }
24    
25    struct Voter {
26        uint candidateIDVote; // this flag will help authorization of voter
27        bool isAuthorized;
28        bool hasVoted;  // this flag will help to keep track of 1 voter - 1 vote
29    }
30
31    // describes a Candidate
32    struct Candidate {
33        string name;
34        string party;
35        uint noOFVotes;
36        bool doesExist; // "bool doesExist" is to check if this Struct exists
37    }
38    
39    // This is so we can keep track of the candidates
40    
41    // These state variables are used keep track of the number of Candidates/Voters
42    // and used to as a way to index them
43    uint numCandidates; // declares a state variable - number Of Candidates
44    uint numVoters;
45    uint numOfVotes;
46    
47    // Think of these as a hash table, with the key as a uint and value of
48    // the struct Candidate/Voter. These mappings will be used in the majority
49    // of our transactions/calls
50    // These mappings will hold all the candidates and Voters respectively
51    mapping (uint => Candidate) candidates;
52    mapping (address => Voter) voters;
53
54    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
55    *
56    These functions perform transactions, editing the mappings *
57    * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
58    
59    function addCandidate(string name, string party) onlyOwner public {
60        // candidateID is the return variable
61        uint candidateID = numCandidates++;
62        // Create new Candidate Struct with name and saves it to storage.
63        candidates[candidateID] = Candidate(name,party,0,true);
64        AddedCandidate(candidateID);
65    }
66    
67    function vote(uint candidateID) public {
68        // checks if the struct exists for that candidate
69        require(!voters[msg.sender].hasVoted);// this statement is to check if this voter has not voted already 
70        require(voters[msg.sender].isAuthorized);// this statement is to check if this voter is authorized to vote
71        if (candidates[candidateID].doesExist == true) {
72            voters[msg.sender] = Voter(candidateID, true, true);
73            candidates[candidateID].noOFVotes++;
74            numOfVotes++;
75            numVoters++;
76        }
77    }
78    
79    /* * * * * * * * * * * * * * * * * * * * * * * * * *
80    *
81    Getter Functions, marked by the key word "view" *
82    * * * * * * * * * * * * * * * * * * * * * * * * * */
83    // finds the total amount of votes for a specific candidate by looping
84    //through voters
85    function totalVotes(uint candidateID) view public returns (uint) {
86        return candidates[candidateID].noOFVotes;
87    }
88    
89    function getNumOfCandidates() public view returns(uint) {
90        return numCandidates;
91    }
92    
93    function getNumOfVoters() public view returns(uint) {
94        return numVoters;
95    }
96    
97    // returns candidate information, including its ID, name, and party
98    function getCandidate(uint candidateID) public view returns(uint,string,string,uint)
99    {
100        return (candidateID,candidates[candidateID].name,candidates[candidateID].party,candidates[candidateID].noOFVotes);
101    } 
102    
103    function Authorize(address _Voter) onlyOwner public {
104        voters[_Voter].isAuthorized = true;
105    }
106    
107}