crowdfund.vif

# Author: Haobin, 2018
# Crowdfund where people can contribute funds to the campaign
# If the funding reaches its goal, all the money will be sent to the benficiary
# Or else it will be refunded

funders: IFL({sender: address, value: wei_value}[int128], funders)
nextFunderIndex: IFL(int128, this)
beneficiary: IFL(address, beneficiary)
deadline: IFL(timestamp, this)
goal: IFL(wei_value, this)
refundIndex: IFL(int128, this)
timelimit: IFL(timedelta, this)


@public
@IFL_this
def __init__(_beneficiary: IFL(address, benficiary), _goal: IFL(wei_value, this), _timelimit: IFL(timedelta, this)):
    self.beneficiary = _beneficiary
    self.deadline = block.timestamp + _timelimit
    self.timelimit = _timelimit
    self.goal = _goal


@public
@payable
@IFL_this
def participate():
    assert block.timestamp < self.deadline
    nfi: int128 = self.nextFunderIndex # Its label can autoinferred
    self.funders[nfi] = endorse({sender: msg.sender, value: msg.value}, sender, funders)
    self.nextFunderIndex = nfi + 1


@public
@IFL_this
def finalize():
    assert block.timestamp >= self.deadline and self.balance >= self.goal
    selfdestruct(endorse(self.beneficiary, beneficiary, this))


@public
@IFL_this
def refund():
    assert block.timestamp >= self.deadline and self.balance < self.goal
    ind: int128 = self.refundIndex
    for i in range(ind, ind + 30):
        if i >= self.nextFunderIndex:
            self.refundIndex = self.nextFunderIndex
            return
        send(endorse(self.funders[i].sender, funders, this), endorse(self.funders[i].value, funders, this))
        self.funders[i] = None
    self.refundIndex = ind + 30