Introduction

How it works

OK, but how does it actually work?

These payouts will continue to increase with ticket sales.

The best way to understand how it works is to walk through the contract.

You can read the full contract here: FlowLottery Contract

For the special Christmas event, the organizers on the 25th of December will execute a special payout function (resolveWinner) 5 times - once for each prize.

As you can see, every time the resolveWinner() function executes, it picks a random prize winner in ascending order (from smallest, to largest). The 4 smallest prizes share roughly 30% of the pot, the rest goes to the jackpot winner.

// christmas special
pub fun resolveWinner() {
    let currentLotteryDetails: &LotteryDetails = self.borrowCurrentLotteryDetails()!
    assert(currentLotteryDetails.entries.length > 0, message: "No one has entered the lottery yet!")
    let numDone: Int = currentLotteryDetails.winners.length
    let percentAmounts: {Int: UFix64} = {
        0: 0.01,
        1: 0.02,
        2: 0.07,
        3: 0.20,
        4: 1.00
    }

    // get amount
    let amount: UFix64 = FlowLottery.pot.balance * percentAmounts[numDone]!
    let hitJackpot: Bool = numDone == 4

    // get the winner
    let randomWinnerIndex: UInt64 = FlowLottery.getRandom(min: 0, max: UInt64(currentLotteryDetails.entries.length) - 1)
    let winner: Address = currentLotteryDetails.entries[randomWinnerIndex]

    // remove rake
    // 2.5% total:
        // 0.5% is for the platform (development + marketing)
        // 2% rollover gets immediately deposited back into the pot for future drawings
    let winnings: @FungibleToken.Vault <- FlowLottery.pot.withdraw(amount: amount)
    let rollover: @FungibleToken.Vault <- winnings.withdraw(amount: amount * 0.02)
    let platformTax: @FungibleToken.Vault <- winnings.withdraw(amount: amount * 0.005)
    let platformVault: &FlowToken.Vault{FungibleToken.Receiver} = FlowLottery.account.getCapability(/public/flowTokenReceiver).borrow<&FlowToken.Vault{FungibleToken.Receiver}>()!
    platformVault.deposit(from: <- platformTax)

    // deposit winnings
    let winnerFlowVault: &FlowToken.Vault{FungibleToken.Receiver} = getAccount(winner).getCapability(/public/flowTokenReceiver)
                        .borrow<&FlowToken.Vault{FungibleToken.Receiver}>()
                        ?? panic("User does not have a Flow Token vault set up.")
    winnerFlowVault.deposit(from: <- winnings)

    // remove winner's ticket and add them as a winner
    currentLotteryDetails.addWinner(address: winner, amount: amount, removeAtIndex: randomWinnerIndex)

    // reset & automatically start a new lottery
    if hitJackpot {
        self.reset()
    }

    // deposit rollover
    FlowLottery.pot.deposit(from: <- rollover)

    emit LotteryWinner(winner: winner, amount: amount, winningNumber: randomWinnerIndex)
}
}

You can read the full contract here: FlowLottery Contract

How Funds are Stored