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Lottery

Github Link: https://github.com/eatthepie/contracts-layer2/blob/main/src/Lottery.sol

This contract implements the core features of the Eat The Pie L2 lottery system.

Key Features​

  • 🎟️ Multiple ticket purchase support (up to 100 tickets per transaction)
  • 🔢 Three difficulty levels affecting number ranges (Easy, Medium, Hard)
  • 🎲 Secure random number generation using Witnet
  • 💰 Three-tiered prize system (Gold, Silver, Bronze)
  • 🏆 NFT minting for jackpot winners
  • 🔄 Automatic difficulty adjustment based on win patterns
  • 💸 Configurable token-based ticket pricing with scheduled changes
  • 🛡️ Comprehensive security measures with Permit2 integration
  • 💎 Prize pool management with excess handling
  • 🔍 Detailed game information tracking and querying
  • ⏮️ Emergency refund system

Contract Structure​

Inheritance​

  • Ownable: Provides basic authorization control functions
  • ReentrancyGuard: Prevents reentrant calls to functions

Dependencies​

  • IWitnetRandomness: Contract for secure randomness generation
  • NFTPrize: Contract for minting prize NFTs
  • IERC20: Interface for ERC20 token payments
  • IPermit2: Interface for gasless approvals

Constants​

  • BASIS_POINTS: 10000 (for percentage calculations)
  • GOLD_PERCENTAGE: 6000 (60% of prize pool)
  • SILVER_PLACE_PERCENTAGE: 2500 (25% of prize pool)
  • BRONZE_PLACE_PERCENTAGE: 1400 (14% of prize pool)
  • FEE_PERCENTAGE: 100 (1% of prize pool)
  • FEE_MAX_IN_TOKENS: 1,000,000 tokens
  • Difficulty-based number ranges:
    • Easy: 1-25 (main), 1-10 (etherball)
    • Medium: 1-50 (main), 1-10 (etherball)
    • Hard: 1-75 (main), 1-10 (etherball)
  • DRAW_MIN_TIME_PERIOD: 4 days

Key State Variables​

  • currentGameNumber: Current game identifier
  • ticketPrice: Price of a single ticket in tokens
  • lastDrawTime: Timestamp of the last draw
  • consecutiveJackpotGames: Counter for consecutive games with jackpot winners
  • consecutiveNonJackpotGames: Counter for consecutive games without jackpot winners
  • Prize pool and game state mappings
  • Winner tracking mappings for each prize tier

Core Functionality​

Ticket Purchase​

function buyTickets(
    uint256[4][] calldata tickets,
    IPermit2.PermitTransferFrom calldata permit,
    bytes calldata signature
) external nonReentrant
  • Allows purchase of up to 100 tickets in one transaction
  • Uses Permit2 for gasless token approvals
  • Each ticket requires 4 numbers (3 main numbers + 1 etherball)
  • Automatically tracks tickets for all prize tiers
  • Emits TicketPurchased and TicketsPurchased events

Drawing Process​

  1. Draw Initiation
function initiateDraw() external payable nonReentrant
  • Requires minimum time period (4 days)
  • Initiates Witnet randomness request
  • Starts the next game
  • Emits DrawInitiated event
  1. Random Value Setting
function setRandomAndWinningNumbers(uint256 gameNumber) external
  • Fetches randomness from Witnet
  • Sets winning numbers
  • Emits WinningNumbersSet event
  1. Payout Calculation
function calculatePayouts(uint256 gameNumber) external nonReentrant
  • Calculates prizes for each tier
  • Handles excess fee management
  • Transfers remaining prize pool to next game
  • Emits payout information

Prize Claiming​

function claimPrize(uint256 gameNumber) external nonReentrant
  • Allows winners to claim their prizes
  • Prevents double claiming
  • Emits PrizeClaimed event
function mintWinningNFT(uint256 gameNumber) external nonReentrant
  • Available only to gold tier winners
  • Mints unique NFT through NFTPrize contract
  • Emits NFTMinted event

Emergency Functions​

function stopGameAndEnableRefunds(uint256 targetGame) external onlyOwner
  • Allows owner to stop current or next game
  • Enables refund mechanism for players
function refundTickets(uint256 gameNumber) external nonReentrant
  • Allows players to refund tickets for stopped games
  • Updates prize pool accordingly
  • Emits TicketsRefunded event

Difficulty Management​

function changeDifficulty() external
  • Automatically adjusts difficulty based on win patterns
  • Requires 3 consecutive games for adjustment
  • Changes take effect on the next game
  • Emits DifficultyChanged event

Administrative Functions​

  • setTicketPrice: Schedules ticket price changes
  • setFeeRecipient: Updates fee recipient address

Query Functions​

function getCurrentGameInfo() external view returns (
    uint256 gameNumber,
    Difficulty difficulty,
    uint256 prizePool,
    uint256 drawTime,
    uint256 timeUntilDraw
)
function getBasicGameInfo(uint256 startGameId, uint256 endGameId)
    external view returns (GameBasicInfo[] memory)
function getDetailedGameInfo(uint256 gameId)
    external view returns (GameDetailedInfo memory)
function getUserGameWinnings(uint256 gameNumber, address user)
    external view returns (bool, bool, bool, uint256, bool)

Events​

  • TicketPurchased: Individual ticket purchase details
  • TicketsPurchased: Bulk ticket purchase information
  • DrawInitiated: Start of drawing process
  • RandomSet: Initial random value set
  • WinningNumbersSet: Final winning numbers
  • DifficultyChanged: Difficulty level updates
  • TicketPriceChangeScheduled: Future price changes
  • ExcessPrizePoolTransferred: Prize pool management
  • GamePrizePayoutInfo: Prize distribution details
  • FeeRecipientChanged: Fee recipient updates
  • PrizeClaimed: Winner prize claims
  • NFTMinted: NFT prize creation
  • GameStopped: Emergency game stoppage
  • GameRefundsEnabled: Refund availability
  • TicketsRefunded: Ticket refund processing