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Add Random Emoji on-chain NFT on OpenSea example (#3)
* Add Random Emoji on-chain NFT on OpenSea example * Update README.md * Migrate example to VRF v2 * Adjust Readme file * Remove numWords constructor parameter because the contract needs exactly four random values from VRF
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‎random-svg-nft/.env.example

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ETHERSCAN_API_KEY=<YOUR ETHERSCAN API>
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RINKEBY_URL=https://eth-rinkeby.alchemyapi.io/v2/<YOUR ALCHEMY KEY>
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PRIVATE_KEY=<YOUR PRIVATE KEY>
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SUBSCRIPTION_ID=<ID>

‎random-svg-nft/.eslintignore

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node_modules
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artifacts
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cache
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coverage

‎random-svg-nft/.eslintrc.js

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module.exports = {
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env: {
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browser: false,
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es2021: true,
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mocha: true,
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node: true,
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},
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plugins: ["@typescript-eslint"],
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extends: [
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"standard",
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"plugin:prettier/recommended",
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"plugin:node/recommended",
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],
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parser: "@typescript-eslint/parser",
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parserOptions: {
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ecmaVersion: 12,
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},
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rules: {
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"node/no-unsupported-features/es-syntax": [
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"error",
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{ ignores: ["modules"] },
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],
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},
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};

‎random-svg-nft/.gitignore

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node_modules
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.env
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coverage
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coverage.json
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typechain
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#Hardhat files
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cache
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artifacts
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yarn.lock
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package-lock.json

‎random-svg-nft/.npmignore

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hardhat.config.ts
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scripts
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test

‎random-svg-nft/.prettierignore

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node_modules
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artifacts
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cache
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coverage*
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gasReporterOutput.json

‎random-svg-nft/.solhint.json

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{
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"extends": "solhint:recommended",
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"rules": {
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"compiler-version": ["error", "^0.8.0"],
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"func-visibility": ["warn", { "ignoreConstructors": true }]
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}
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}

‎random-svg-nft/.solhintignore

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node_modules

‎random-svg-nft/README.md

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# Random Emoji NFT collection on OpenSea
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This demo project demonstrates how to create randomly generated on-chain Emoji NFTs using Chainlink VRF and how to host that collection on OpenSea on Rinkeby Testnet.
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## What we are building
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![demo](demo.png)
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## Getting started
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### Prerequisites
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Be sure to have installed the following
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- [Git](https://git-scm.com/book/en/v2/Getting-Started-Installing-Git)
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- [Node.js](https://nodejs.org/en/download/)
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- [Yarn](https://yarnpkg.com/getting-started/install)
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### Installation
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1. Get a RPC API Key from a node provider such as [Alchemy](https://www.alchemy.com/), [Infura](https://infura.io/), [Moralis](https://moralis.io/), or [QuickNode](https://www.quicknode.com/). This example uses the RINKEBY Ethereum test network.
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2. Clone the repo
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```
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git clone https://github.com/smartcontractkit/smart-contract-examples.git
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```
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3. Enter the direcory
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```
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cd smart-contract-examples/random-svg-nft
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```
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### Build and Deploy
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1. Install packages
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```shell
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yarn
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```
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2. Compile contracts
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```shell
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yarn compile
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```
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3. Run tests
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```shell
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yarn test
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```
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or
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```shell
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REPORT_GAS=true yarn test
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```
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4. Run test coverage
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```shell
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yarn coverage
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```
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5. Deploy contract to Rinkeby
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Go to [Chainlink VRF Subscription Managment Page](https://vrf.chain.link/), connect your wallet, create new subscription and fund it. Make sure to have at least 1 Rinkeby LINK in your wallet, you can obtain it from the [Chainlink Faucet](https://faucets.chain.link/arbitrum-rinkeby)
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Copy the `.env.example` file to a file named `.env`, and put your Private Key, RPC API Key, [Etherscan API Key](https://etherscan.io/apis), and Subscription ID like this
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```shell
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ETHERSCAN_API_KEY=<YOUR ETHERSCAN API>
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RINKEBY_URL=https://eth-rinkeby.alchemyapi.io/v2/<YOUR ALCHEMY KEY>
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PRIVATE_KEY=<YOUR PRIVATE KEY>
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SUBSCRIPTION_ID=<ID>
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```
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After that run the deployment script which will
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- deploy your smart contract to the Rinkeby
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- verify it on Etherscan
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```shell
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yarn deploy
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```
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Lastly, navigate back to the Chainlink VRF Subscription Managment Page and add the address of deployed smart contract as subscription consumer.
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If the verification process fails because the new contract hasn't been indexed yet on Etherscan, run the next command from your terminal
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```shell
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npx hardhat verify --network rinkeby <CONTRACT_ADDRESS> 0xd89b2bf150e3b9e13446986e571fb9cab24b13cea0a43ea20a6049a85cc807cc <SUBSCRIPTION_ID> 1000000 4 3
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```
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### Minting
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Call `mint()` function of your contract. Soon after the successful transaction, your NFT will be available on [OpenSea](https://testnets.opensea.io/)

‎random-svg-nft/contracts/EmojiNFT.sol

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//SPDX-License-Identifier: MIT
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pragma solidity ^0.8.7;
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import "@chainlink/contracts/src/v0.8/interfaces/VRFCoordinatorV2Interface.sol";
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import "@chainlink/contracts/src/v0.8/VRFConsumerBaseV2.sol";
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import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
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import "@openzeppelin/contracts/utils/Counters.sol";
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import "@openzeppelin/contracts/utils/Strings.sol";
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import "@openzeppelin/contracts/utils/Base64.sol";
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contract EmojiNFT is ERC721URIStorage, VRFConsumerBaseV2 {
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using Counters for Counters.Counter;
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Counters.Counter private tokenIds;
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string[] private emojis = [
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unicode"😁",
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unicode"😂",
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unicode"😍",
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unicode"😭",
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unicode"😴",
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unicode"😎",
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unicode"🤑",
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unicode"🥳",
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unicode"😱",
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unicode"🙄"
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];
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VRFCoordinatorV2Interface internal immutable vrfCoordinator;
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bytes32 internal immutable keyHash;
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uint64 internal immutable subscriptionId;
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uint32 internal immutable callbackGasLimit;
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uint32 internal immutable numWords;
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uint16 internal immutable requestConfirmations;
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mapping(uint256 => address) requestToSender;
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event RandomnessRequested(uint256 indexed requestId);
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constructor(
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address _vrfCoordinator,
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bytes32 _keyHash,
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uint64 _subscriptionId,
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uint32 _callbackGasLimit,
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uint16 _requestConfirmations
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) VRFConsumerBaseV2(_vrfCoordinator) ERC721("EmojiNFT", "EMOJI") {
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vrfCoordinator = VRFCoordinatorV2Interface(_vrfCoordinator);
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keyHash = _keyHash;
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subscriptionId = _subscriptionId;
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callbackGasLimit = _callbackGasLimit;
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numWords = 4;
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requestConfirmations = _requestConfirmations;
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}
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function mint() public returns (uint256 requestId) {
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requestId = vrfCoordinator.requestRandomWords(
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keyHash,
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subscriptionId,
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requestConfirmations,
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callbackGasLimit,
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numWords
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);
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requestToSender[requestId] = msg.sender;
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emit RandomnessRequested(requestId);
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}
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function pickRandomColor(uint256 firstRandomNumber, uint256 secondRandomNumber, uint256 thirdRandomNumber)
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internal
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pure
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returns (string memory)
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{
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uint256 r = firstRandomNumber % 256;
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uint256 g = secondRandomNumber % 256;
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uint256 b = thirdRandomNumber % 256;
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return
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string(
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abi.encodePacked(
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"rgb(",
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Strings.toString(r),
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", ",
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Strings.toString(g),
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", ",
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Strings.toString(b),
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");"
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)
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);
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}
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function createOnChainSvg(string memory emoji, string memory color) internal pure returns(string memory svg) {
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string memory baseSvg = "<svg xmlns='http://www.w3.org/2000/svg' preserveAspectRatio='xMinYMin meet' viewBox='0 0 350 350'><style>.base { font-size: 100px; }</style><rect width='100%' height='100%' style='fill:";
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string memory afterColorSvg = "' /><text x='50%' y='50%' class='base' dominant-baseline='middle' text-anchor='middle'>";
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svg = string(abi.encodePacked(baseSvg, color, afterColorSvg, emoji, "</text></svg>"));
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}
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function createTokenUri(string memory emoji, string memory svg) internal pure returns(string memory tokenUri) {
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string memory json = Base64.encode(
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bytes(
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string(
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abi.encodePacked(
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'{"name": "',
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emoji,
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'", "description": "Random Emoji NFT Collection Powered by Chainlink VRF", "image": "data:image/svg+xml;base64,',
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Base64.encode(bytes(svg)),
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'"}'
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)
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)
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)
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);
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tokenUri = string(
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abi.encodePacked("data:application/json;base64,", json)
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);
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}
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function fulfillRandomWords(uint256 requestId, uint256[] memory randomNumbers)
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internal
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override
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{
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uint256 tokenId = tokenIds.current();
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uint256 emojiIndex = (randomNumbers[0] % emojis.length) + 1;
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string memory emoji = emojis[emojiIndex];
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string memory color = pickRandomColor(randomNumbers[1], randomNumbers[2], randomNumbers[3]);
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string memory svg = createOnChainSvg(emoji, color);
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string memory tokenUri = createTokenUri(emoji, svg);
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_safeMint(requestToSender[requestId], tokenId);
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_setTokenURI(tokenId, tokenUri);
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tokenIds.increment();
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}
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}

‎random-svg-nft/contracts/test/LinkToken.sol

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// SPDX-License-Identifier: MIT
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pragma solidity ^0.4.24;
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import "@chainlink/contracts/src/v0.4/LinkToken.sol";

‎random-svg-nft/contracts/test/VRFCoordinatorV2Mock.sol

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//SPDX-License-Identifier: MIT
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pragma solidity ^0.8.0;
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import "@chainlink/contracts/src/v0.8/mocks/VRFCoordinatorV2Mock.sol";

‎random-svg-nft/demo.png

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‎random-svg-nft/hardhat.config.ts

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import * as dotenv from "dotenv";
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import { HardhatUserConfig } from "hardhat/config";
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import "@nomiclabs/hardhat-etherscan";
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import "@nomiclabs/hardhat-waffle";
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import "@typechain/hardhat";
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import "hardhat-gas-reporter";
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import "solidity-coverage";
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dotenv.config();
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const config: HardhatUserConfig = {
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solidity: {
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compilers: [
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{
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version: "0.8.7",
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},
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{
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version: "0.4.24",
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},
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],
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},
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networks: {
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rinkeby: {
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url: process.env.RINKEBY_URL || "",
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accounts:
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process.env.PRIVATE_KEY !== undefined ? [process.env.PRIVATE_KEY] : [],
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},
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},
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gasReporter: {
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enabled: process.env.REPORT_GAS !== undefined,
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currency: "USD",
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},
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etherscan: {
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apiKey: {
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rinkeby: process.env.ETHERSCAN_API_KEY,
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},
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},
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};
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export default config;

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