Discover Scenarios for Blockchains

[fyndalf]

• [x] Bicycle Scenario
• [x] MediXAIN
• [x] Grading
• [x] Fridge
• [x] Sommerfest Chips Meinel (opt.)
• [x] Others (opt.)

[simsieg]

Sommerfest Chips: Contracts: Student, Club, Owner

[t-lichtenstein]

pragma solidity ^0.4.0; contract EVAPCoin {

mapping(address => uint256) allUser;
mapping(address => string) roles;

address master;

function EVAPCoin() public {
    allUser[msg.sender] = 0;
    roles[msg.sender] = 'master';
    master = msg.sender;
}

function balanceOf(address _owner) private constant returns (uint256 balance){
    balance = allUser[_owner];
}

function myBalance() public constant returns (uint256 myBalance) {
    myBalance = allUser[msg.sender];
}

function generate(uint _value) public hasRole('master') returns (bool success) {
    allUser[msg.sender] = allUser[msg.sender] + _value;   
    success = true;
}

function registerAsStudent() public hasRole("") returns (bool success) {
    roles[msg.sender] = 'student';
}

function registerAsStore() public hasRole("") returns (bool success) {
    roles[msg.sender] = 'store';
}

function transfer(address _to, uint256 _value) public hasRole('student') returns (bool success){
    if(balanceOf(msg.sender) >= _value && _value > 0){
        Transfer(msg.sender, _to, _value);
        success = true;
        allUser[msg.sender] = allUser[msg.sender] - _value;
        allUser[_to] = allUser[_to] + _value;
    } else {
        success = false;
    }
}

function returnCoins() public hasRole('store') returns (bool success) {
    uint256 value = myBalance();
    if(value > 0) {
       Transfer(msg.sender, master, value);
       allUser[msg.sender] = 0;
       allUser[master] = allUser[master] + value;
      success = true;
    }
}

function stringCompare(string _a, string _b) private returns (bool equal) {
    equal = keccak256(_a) == keccak256(_b);
}

modifier hasRole (string role) {
    if (stringCompare(roles[msg.sender], role) || stringCompare(roles[msg.sender], "master")) {
        _;
    }
    else {
        throw;
    }
}

event Transfer(address indexed _from, address indexed _to, uint256 _value);

}