CoinFlipVyper.vy.py

struct Player: 
    id : uint256
    playerAddress : address
    wager : wei_value 
    
GameBegan : event({_firstPlayer : address, _amount : wei_value})

    
wager : public(wei_value)
winner : public(uint256)
players: public(map(uint256, Player))
tmp : public(timestamp)

@public
def generateRandomBit() -> bool:
    if((block.timestamp - self.tmp) % 2 == 0):
        return True
    else:
        return False

@public 
@payable
def beginGame():
    assert(msg.value > 0)
    self.players[1] = Player({id:1, playerAddress:msg.sender, wager:msg.value})
    self.wager = msg.value
    log.GameBegan(msg.sender, msg.value)

@public
@payable
def acceptChallenge():
    assert(
        msg.sender != self.players[1].playerAddress and 
        msg.value == self.wager
    )
    self.players[2] = Player({id:2, playerAddress:msg.sender, wager:msg.value})
    if(self.generateRandomBit()):
        self.winner = 1
        self.players[1].wager += self.wager
        self.players[2].wager -= self.wager
    else:
        self.winner =2 
        self.players[2].wager += self.wager
        self.players[1].wager -= self.wager

@public
def withdrawPrize() :
    assert(msg.sender == self.players[self.winner].playerAddress)
    prizeAmount : wei_value = self.players[self.winner].wager
    send(self.players[self.winner].playerAddress, prizeAmount)