fund-function.scala

@Callable(i)
func fund(id: Int) = {
  	# receiving an attached payment; if there is no payment, an exception will be created
    let pmt = i.payments[0].extract()

  	# receiving campaign parameters
    let targetSum = getIntegerValue(this, keyTargetSum(id))
    let endTimestamp = getIntegerValue(this, keyEndTimestamp(id))
    let owner = getStringValue(this, keyOwner(id))

  	# receiving the number of collected tokens at this point
    let raised = getIntegerValue(this, keyRaised(id))

    # receiving the number of tokens the current user has already sent to the same campaign
	  # put 0 if none
    let alreadyFundedByUser = match getInteger(this, keyUserFunded(id, i.callerPublicKey.toBase58String())){
        case v: Int => v
        case _ => 0
    }

  	# making sure that all attached tokens are this team’s tokens
    if (pmt.assetId != thanksTokenId) then throw("You have to attach proper tokens with id: " + thanksTokenId.toBase58String()) else

  	# making sure the campaign initiator is not trying to provide tokens
    if (owner == i.callerPublicKey.toBase58String()) then throw("You cannot fund your own target") else

  	# making sure the campaign end time has not yet arrived
    if (endTimestamp > lastBlock.timestamp) then throw("This target is finished already") else

  	# making sure a user’s contribution after this transaction is below 33% 
    if (((alreadyFundedByUser + pmt.amount) > targetSum / 3 + 1)) then throw("You cannot fund more than 33% of the whole sum which is " + ((targetSum / 3 + 1) - alreadyFundedByUser).toString())
    else {
        [
          	# saving the new number of tokens received from the current calling account for this campaign
            IntegerEntry(keyUserFunded(id, i.callerPublicKey.toBase58String()), alreadyFundedByUser + pmt.amount),
          	# updating the number of tokens collected so far
            IntegerEntry(keyRaised(id), raised + pmt.amount)
        ]
    }
}