⚽️ Crypto Fantasy Premier League

Welcome to Crypto FPL, a light PvP Fantasy Premier League game that runs on the Ethereum blockchain. For the demo client, please see the client repo

🎮 The Game

Players can mint their own footballer cards and create head-to-head game with a squad selected from their collection. Game creators can determine the wager at stake, and players can join open matches and submit their squads. The winner will be determined at the end of each Premier League gameweek by the total points of the players in their selected squad. This winner wins the pot.

📜 The Rules

• Players can be in up to 3 active games at a time
• A submitted squad must consist of 1 Goalkeeper, 1 Defender, 1 Midfield, and 1 Forward
• Players can submit a team as many times as they want before the gameweek deadline. But they must ensure to take note of the latest submitted team and salt in order to successfully reveal their team.

📖 How to Play

1. Buy a card pack to mint yourself a roster 15 footballers. This pack will include 3 Goalkeepers, 4 Defenders, 4 Midfielders, and 4 Forwards. Once the transaction is complete, you will be able to see your newly minted team.
2. Create a game and deposit a wager for that game. Any player who joins your game will have to also deposit your stated wager.
3. Select a team from your roster. A valid team consists of 1 Goalkeeper, 1 Defender, 1 Midfield, and 1 Forward

• 💡 IMPORTANT 💡 You must take note of your salt and the players you selected. You will have to resubmit this when revealing your team in the second phase of the game (see avoiding_common_attacks for more details).

4. When the gameweek deadline has passed, you will be able to calculate your score, submit it and reveal your team. In order to reveal, reselect the same footballers you submitted and put in the salt you submitted your team with.
5. Once both players have revealed their scores, the winner will be able to withdraw their payout, which is both players' wager deposit for that game.

🛠 Technology

• Footballer cards (CryptoFPLCards) are ERC1155 tokens on Ethereum. Once you own them, they are truly yours
• Game logic is open-source and is an Ethereum smart contract written in Solidity
• Footballer data (names, position, team, gameweek scores) is based on the Fantasy Premier League API
• ReactJS, NodeJS, mySQL* powers the client and backend

CryptoFPL Footballer Cards as Multi-Fungible Tokens

• CryptoFPLCards inherits from the ERC1155 implementation by Horizon Games. The EIP discussion for the Multi-Fungible Token Standard can be found here

Admin Features and Provable API

• The CryptoFPL league admin (contract deployer) can toggle the deadlinePassed boolean storage variable by calling toggleDeadlinePassed. This method uses a Provable API query to obtain the current time (GMT+1) and sets deadlinePassed to true if the UNIX timestamp surpasses the deadline variable. At the time of writing, there isn't a bridge to link the Provable API to a private development blockchain, therefore this feature will only work when called on testnet. If you call this function whilst on a private blockchain you will get a VM Exception while processing transaction: revert error.
• The admin can also increment the gameweek by calling incrementGameweek and pass in the UNIX timestamp uint for the deadline of the new gameweek. This will set the deadline variable to the new deadline.

ℹ For demonstration purposes, data has been seeded in cryptofpl-server/data/. as a regular object. In real life this will be stored in a server. Gameweek scores were randomly generated up to gameweek 3 to allow people to play with this demo app. In reality, players wouldn't be able to calculate their total scores until the Premier League gameweek has concluded and footballer scores have been finalized.

👩🏻‍💻 Development

Prerequisites

• Node v10.5.0
• Solidity v0.5.0 (solc-js)
• Truffle v5.0.7 (core: 5.0.7)

Setup

• Clone the repo using git clone https://github.com/nichanank/crypto-fpl.git
• cd crypto-fpl and clone the client repo using git clone https://github.com/nichanank/crypto-fpl-client.git
• Have a local blockchain running on port 7545 (e.g. using Ganache)
• From the main project folder (crypto-fpl), deploy contracts with truffle migrate --reset
  • If you get an at Deployer._preFlightCheck error upon migration, delete the contracts folder at cryptofpl-client/src/contracts folder and try truffle migrate --reset again

To start the server:

• Navigate to the cryptofpl-server folder with cd cryptofpl-server
• Run npm install and then npm run server

To start the client:

• Navigate to the cryptofpl-client folder with cd cryptofpl-client
• Run npm install and then npm run start
• Open up your browser and the project should be up on localhost:3000

Contract interaction on a local blockchain

• Ensure your browser has a plugin (e.g. Metamask) that allows you to interact with the Ethereum blockchain
• Ensure you have a local blockchain running (e.g. on Ganache)
• Select Localhost:8545 or Custom RPC depending on which port your Ganache blockchain is running on
• Interact with the web interface

Contract interaction on Rinkeby Testnet

• Ensure your browser has a plugin (e.g. Metamask) that allows you to interact with the Ethereum blockchain
• Select Rinkeby Test Network and choose a Metamask account that has some testnet ether. You can obtain some Rinkeby testnet ether via this faucet
• Interact with the web interface

Contract interaction on Remix

In order to easily interact with the contract using Remix, you can use the truffle-flattener package to aggregate the contract code and its parent contracts into one file and paste the file into the Remix editor.

1. npm install -g truffle-flattener
2. From the directory with your ./contracts folder containing the Solidity files, do truffle-flattener ./contracts/CryptoFPLCore/CryptoFPL.sol >> CryptoFPL.txt
3. Create a new file on Remix and name it CryptoFPL.sol, paste the newly created contents of CryptoFPL.txt into this file and save. Repeat with the CryptoFPLCards contract:

• truffle-flattener ./contracts/CryptoFPLCore/CryptoFPLCards.sol >> CryptoFPLCards.txt
• Create another file on Remix and name it CryptoFPLCards.sol, paste contents of CryptoFPLCards.txt into here

4. Deploy the two contracts on Remix and you should be good to go If you have Ganache running, choose Web3 provider as your environment and connect to the port hosting the local blockchain (the default is http://localhost:8545). Otherwise you can select the provided Javascript VM

✅ Testing

• You can run the tests by running truffle test from the CryptoFPL directory
• If you get an at Deployer._preFlightCheck error upon migrate, delete the contracts folder atcryptofpl-client/src/contracts folder and try truffle test again

🚀 Future Goals & TODOs

• Host immutable footballer data for a given season on IPFS
• Add ENS capability to resolve human-readable names to Ethereum addresses
• Implement upgradable design or autodeprecation
• Add league admin features to the client web app