pragma solidity ^0.4.16;

contract BikeContract {
    address bikeOwner;
    Condition bikeCondition;
    address[] riders;
    Battery bikeBattery;

    struct Battery{
        uint capacity;
        uint chargeLevel;
    }

    enum Condition{
        in_use,
        broken,
        repaired,
        available
    }

    function changeStatus(Condition s) public returns (string) {
        if (bikeCondition == Condition.broken && (s == Condition.in_use || s == Condition.available)) {
            bikeBattery.chargeLevel -= 20;
            return "bike must be repaired first";
        } else {
            bikeCondition = s;
            bikeBattery.chargeLevel -= 20;
            return "color changed";
        }
    }

    constructor() public {
        bikeCondition = Condition.available;
        bikeBattery.chargeLevel = 100;
        riders.push(msg.sender);
        bikeOwner = msg.sender;
    }
}