PancakeSwap Lottery fork

Introduction

• Front-end repository
• Lottery contract
• Remix
• Unix Timestamp generator
• Ethereum Unit Converter
• Random Byte Generator

We will use Goerli test network.

tx - short name for transaction

Table of contents

• Deploy with Remix
  • Remix editor
  • Lottery contract code
  • Contract preparation
  • Contract Compilation
  • Deploy contract
  • Save Lottery contract address
• Frontend
  • Cloning PancakeSwap Lottery
  • Home page customization
  • Setting up a contract
  • Blockchain setup
  • Setting up a token
  • Launch of the project
• Lottery Rounds control
  • Round life cycle
  • Connection to a contract
  • Active round number
  • Start of a new round
  • Closing the round
  • Winning combination calculation

Deploy with Remix

1. Remix editor

   Go to Remix editor and create there file: Lottery.sol

2. Lottery contract code

   Copy Pancakeswap Lottery contract code from the Bscscan: https://bscscan.com/address/0x5aF6D33DE2ccEC94efb1bDF8f92Bd58085432d2c#contracts And paste it into the new Lottery.sol file:

3. Contract preparation

   Set up basic lottery rules
   MAX_TREASURY_FEE - Your commission
maxPriceTicketInCake - Maximum ticket price
minPriceTicketInCake - Minimum ticket price
MIN_DISCOUNT_DIVISOR - Minimum discount if the user buys many tickets at once
MIN_LENGTH_LOTTERY - Minimum round duration
MAX_LENGTH_LOTTERY - Maximum round duration


   Set the address where the commission will be transferred and who will be able to manage the lottery by adding this code to the constructor
   injectorAddress = msg.sender;
operatorAddress = msg.sender;
treasuryAddress = msg.sender;


   msg.sender; - Returns the address of the account from which the lottery contract will be deployed

   

   Add this code to the contract constructor. currentLotteryId++;
_lotteries[currentLotteryId] = Lottery({
    status: Status.Claimable,
    startTime: block.timestamp,
    endTime: block.timestamp,
    priceTicketInCake: 0,
    discountDivisor: 0,
    rewardsBreakdown: [uint256(250),uint256(375),uint256(625),uint256(1250),uint256(2500),uint256(5000)],
    treasuryFee: 2000,
    cakePerBracket: [uint256(0), uint256(0), uint256(0), uint256(0), uint256(0), uint256(0)],
    countWinnersPerBracket: [uint256(0), uint256(0), uint256(0), uint256(0), uint256(0), uint256(0)],
    firstTicketId: currentTicketId,
    firstTicketIdNextLottery: currentTicketId,
    amountCollectedInCake: pendingInjectionNextLottery,
    finalNumber: 1000000
});
Comment out this line in the methodcloseLottery
   Add the bytes32 _seed parameter to the drawFinalNumberAndMakeLotteryClaimable function of the IPancakeSwapLottery interface
   Add the bytes32 _seed parameter to the drawFinalNumberAndMakeLotteryClaimable function
   Comment out the line
   require(_lotteryId == randomGenerator.viewLatestLotteryId(), "Numbers not drawn");
   in the drawFinalNumberAndMakeLotteryClaimable method
   Replace the random number generator in the drawFinalNumberAndMakeLotteryClaimable method
   to this code
   uint256 randomness = uint(keccak256(abi.encodePacked(
    block.timestamp,
    _seed,
    _lotteryId,
    _lotteries[_lotteryId].firstTicketId,
    _lotteries[_lotteryId].firstTicketIdNextLottery,
    _lotteries[_lotteryId].amountCollectedInCake,
    block.coinbase,
    block.difficulty,
    block.gaslimit,
    tx.gasprice
)));
uint32 finalNumber = uint32(1000000 + (randomness % 1000000));

   

4. Contract Compilation

   Go to "Solidity Compiler" tab. Change compiler version with 0.8.18 if it's different. Enable optimization option to 99999 and click button "Compile":

5. Deploy contract

   Go to "Deploy & run transaction" tab. Select Injected Web3 in the ENVIRONMENT drop-down. It will use your external wallet. We will use Metamask wallet. If you didn't login in the wallet then login it now, reload page, come back and compile lottery contract one more time. And again chose Injected Web3 option. Chose Goerli network in the Metamask. Select PancakeSwapLottery in the CONTRACT drop-down (probably it's already made by default).
   
   Set an address of your ERC20 token in the _CAKETOKENADDRESS field.
   Set 0x0000000000000000000000000000000000000000 in the _RANDOMGENERATORADDRESS field
   Now you can see something like this in the deploy tab:
   
   So now click on "transact" button and confirm a modal window from external wallet with transaction fee:

6. Save Lottery contract address

   After transaction has been mined you can see all details in the Remix terminal: Copy a transaction hash and go to Goerli etherscan. Paste this hash in the search field and go to a new contract page. Copy his address and save it somewhere.

Now we have this data:


PancakeSwapLottery:

0xad661a60bd10caf905a177ac36cefdab43744a8a

Frontend

Main changes in this interface template:

• Removed all (or almost all) info about pancakeswap
• Installing Our Lottery Contract
• Set lottery page as default
• Changed source styles just a little.

1. Cloning PancakeSwap Lottery

   Create a new directory: Lottery. Copy front-endcode in this directory then install dependencies
   yarn
   After installing the dependencies, you will see the following

2. Home page customization

   Let's make the lottery the main page
   Open file\apps\web\src\pages\_app.tsx
   Add an import
   import Lottery from "./lottery"
   Add a lottery call <Lottery {...pageProps} /> and comment out the code below as shown in the image

3. Setting up a contract

   Open the file \apps\web\src\utils\addressHelpers.ts and add the following code
   return '0xad661a60bd10caf905a177ac36cefdab43744a8a'

   Enter the address of your lottery contract that you created earlier

   

4. Blockchain setup

   Set up the blockchain that will run the lottery
   Open \apps\web\src\config\constants\supportChains.ts
   And enter your network ID
   Open file \apps\web\src\hooks\useProviderOrSigner.ts
   And enter your network ID
   Open \apps\web\src\utils\contractHelpers.ts
   And enter your network ID
   Open file \apps\web\src\state\lottery\helpers.ts And specify your network ID in all calls to multicallv2 Open \apps\web\src\state\lottery\fetchUnclaimedUserRewards.ts And specify your network ID in all calls to multicallv2

5. Setting up a token

   Open \apps\web\src\utils\contractHelpers.ts
   Specify your network ID and the address of your token Open \apps\web\src\config\constants\tokenLists\pancake-default.tokenlist.json
   Add information about your token as shown in the example
   {
  "name": "WEENUS",
  "symbol": "WEENUS",
  "address": "0xbb4CdB9CBd36B01bD1cBaEBF2De08d9173bc095c",
  "chainId": 5,
  "decimals": 18,
  "logoURI": "https://pancakeswap.finance/images/lottery/star-small.png"
} Open file \apps\web\src\views\Lottery\components\BuyTicketsModal\BuyTicketsModal.tsx
   And find the line const { balance: userCake, fetchStatus } = useTokenBalance(bscTokens.cake.address) Replace bscTokens.cake.address with the address of your token
   Replace all references to "CAKE" with to the character of your token.
   To do this, just edit the files in the folder \apps\web\src\views\Lottery\
   Be careful. Replace only strings

6. Launch of the project

   To start the project, run the command in the root directory yarn dev If done correctly, the lottery will be available at http://localhost:3000/

These were the minimum actions needed for the lottery to work and to collect the commission.

Lottery Rounds control

1. Round life cycle

   In the lottery rounds have the following states

   • Open - The round is active. Users can buy tickets
   • Close - The round is closed. Waiting for the calculation of winnings
   • Pending - Waiting for results. Users cannot buy tickets
   • Claimable - Winning this round is calculated. Users can find out the result and get a reward
   
   Life cycle:
   Open > Close > Pending > Claimable
   To manage the lifecycle of rounds in a contract, the appropriate methods are

2. Connection with a contract

   To manage the rounds, you need to interact with the contract. To do this, you need to connect to the contract. For interaction with the contract will use Remix
   Go to Remix editor and select contract file Lottery.sol

   Compile the contract by compile instructions

   Go to "Deploy & run transaction" tab. Select Injected Web3 in the ENVIRONMENT drop-down. It will use your external wallet. We will use Metamask wallet. If you didn't login in the wallet then login it now, reload page, come back and compile lottery contract one more time. And again chose Injected Web3 option. Chose Goerli network in the Metamask. Select PancakeSwapLottery in the CONTRACT drop-down (probably it's already made by default).
   Enter your contract address and click "At Address" After that, the contract control panel will appear at the bottom. Click on it to display the control panel.

3. Active round number

   Most contract methods use the current round number. To find out it, execute the "currentLotteryId" method After pressing the button, the current lottery round will be shown

4. Start of a new round

   To start a new round, use the startLottery
   method Method parameters:
   

   • _endTime - The time the round will end. Value in UnixTimestamp
   • _priceTicketInCake - Price of a ticket in the current round. Meaning in Wei
   • _discountDivisor - Discount when buying several tickets at once in one transaction.
     Calculation formula _discountDivisor = needValue% * 100.
     Example: 0.5% = 0.5 * 100 = 50, 2% = 2 * 100 = 200
   • _rewardsBreakdown - Win percentage for each matched combination of balls
     An array of six numbers. The sum of the numbers must be equal to 10000
     Calculation formula V = needValue% * 100
     Example:
     Desired win distribution percentage: [0%, 7%, 13%, 20%, 25%, 30%]
     Method call data: [0, 700, 1300, 2000, 2500, 3500]
   • _treasuryFee - Your commission in the current round
     Calculation formula V = needValue% * 100
   Specify the desired parameters and click "transact" to start a new round.

5. Closing the round

   When the time of the round is over, it must be closed. To close, use the "closeLottery" method Method parameters:
   

   • _lotteryId - Number of the round to be closed
   
   Specify current round number and click "transact" to close the round

6. Winning combination calculation

   The final step in the life cycle of a round is the calculation of the winning numbers. To do this, use the drawFinalNumberAndMakeLotteryClaimable method Method parameters:
   

   • _lotteryId - Round number
   • _seed - Random set of bytes of length 32.
     Example: Let's create 32 random numbers through the service Random.org The service will generate 32 random numbers HEX string of these numbers will be
     0xf708a0a28a75973d69ea1d04065f62d57c135def2d750beb0ed39ae55a262cf9
   • _autoInjection - TRUE | FALSE, if set to TRUE, the balance of not won tokens will be automatically transferred to a new round
   
   To calculate the winning numbers, specify the parameters and click "transact" to calculate the winnings After that, the round is over. You can now start a new round