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Devcon5 Day2 hands-on
# Devcon 5 Auction
# Masked Reveal Auction
#Every user has a bid amount, hash (bidamount,pass), sent masked amount
struct Data:
bidval: wei_value
hashval: bytes32
sentval: wei_value
hasBid: bool
hasRevealed: bool
winner: bool
refunded: bool
# map each address with the above information
# *************** State Variables ******************
addToData: public(map(address, Data))
owner: public(address)
minBid: public(wei_value)
minWin: public(wei_value)
countOfTickets: public(int128)
bidOpenTime: public(timestamp)
bidCloseTime: public(timestamp)
revealOpenTime: public(timestamp)
revealCloseTime: public(timestamp)
# **************************************************
# specify the minimum bid amount at the starting of the contract
def __init__(_minBid: wei_value, revealTime: timedelta):
self.owner = msg.sender
self.minBid = _minBid
self.bidOpenTime = block.timestamp
self.bidCloseTime = self.bidOpenTime + revealTime
# calculate hash of -> bid amount + password
def calculateHash(_bidval: wei_value, passw: bytes[10]) -> bytes32:
return keccak256(concat(convert(_bidval,bytes32), passw))
# bid using the obatained hash
# conditions - check if bid placed during the bidding phase
# check if bid is greater than minimum bid amount
# allow only one bid per person
def bid(hash: bytes32):
assert block.timestamp >= self.bidOpenTime and block.timestamp <= self.bidCloseTime
assert msg.value >= self.minBid, "The masked amount is lower."
assert self.addToData[msg.sender].hasBid == False, "Only one bid."
self.addToData[msg.sender] = Data({bidval: 0, hashval: hash, sentval: msg.value, hasBid: True,
hasRevealed: False, winner: False, refunded: False})
# let the owner set the win amount, let the reveal phase open
def selectWinningBidAmount(_amount: wei_value, revealTime: timedelta):
assert msg.sender == self.owner, "No access."
self.minWin = _amount
self.revealOpenTime = block.timestamp
self.revealCloseTime = self.revealOpenTime + revealTime
# reveal the bid by checking with the stored hash and computing hash from the inputs
# check if the masked amount was actually greater than the bid amount
# check if we are in the reveal period
# if bid value is favorable make the person a winner
def reveal(_bidval: wei_value, passw: bytes[10]):
assert keccak256(concat(convert(_bidval, bytes32), passw)) == self.addToData[msg.sender].hashval, "Wrong Bid amount provided."
assert self.addToData[msg.sender].sentval >= _bidval, "Wrong Nice Try!"
self.addToData[msg.sender].hasRevealed = True
self.addToData[msg.sender].bidval = _bidval
if self.countOfTickets <= 50:
assert self.addToData[msg.sender].winner == False
self.addToData[msg.sender].winner = True
self.countOfTickets += 1
# if you want to able to select winners your self.
# def selectWinners(winners: address[50]):
# for i in range(50):
# self.addToData[winners[i]].winner = True
# let bidders withdraw, check if has revealed or if refund has not been done already
def withdraw():
assert self.addToData[msg.sender].hasRevealed == True, "Reveal First to ..."
assert self.addToData[msg.sender].refunded == False, "Already Refunded."
if self.addToData[msg.sender].winner == True:
send(msg.sender, self.addToData[msg.sender].sentval - self.addToData[msg.sender].bidval)
self.addToData[msg.sender].refunded = True
send(msg.sender, self.addToData[msg.sender].sentval)
# find out the contract balance '
def checkBalance() -> wei_value:
return self.balance
# let the owner withdraw the contract balance
def withdrawAll():
assert msg.sender == self.owner, "Deny!"
send(self.owner, self.balance)
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