第1节 世界杯竞猜（solidity）
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概述
通过学习，初步了解以太坊开发的基础工具链，通过一个案例（世界杯精彩）实战，使大家掌握基本的solidity开发，完成语法学习。
点击查看效果
点击获取代码
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学习目标
Metamask：助记词、私钥、地址、gas费相关
Remix：部署、交互、abi、bytecode
Etherscan：交易分析、verify合约
基础solidity语法：基础类型、如何转账、可见性、手续费、Event
业务需求
参赛球队一经设定不可改变，整个活动结束后无法投票；
全⺠均可参与，无权限控制；
每次投票为1ether，且只能选择一支球队；
每个人可以投注多次；
仅管理员公布最终结果，完成奖金分配，开奖后逻辑：
winner共享整个奖金池（一部分是自己的本金，一部分是利润）；
winner需自行领取奖金（因为有手续费）；
下一期自行开始
最初状态
开始投票
开奖后
需求分析
状态变量(真正上链）：管理员、记录所有玩家、统计每个球队参与者、记录获奖者信息、第几期、参赛球队
核心方法：投票、开奖、领奖
辅助方法：获取奖金池金额、管理员地址、当前期数、参与人数、所有玩家、参赛球队
知识点
1 ether = 10^18wei,
1 gwei = 10^9 wei
1 ether = 10^9 gwei
tx：
1. from：交易发起人， 合约中是：msg.sender
2. to：交互合约地址，传给合约的数据：msg.data
3. value：传递的金额，msg.value
"storage", "memory"
Storage: 引用传值，修改会同步修改原变量
memory：值传递，完全独立的拷贝
代码
goerli地址：0xD0f85823D7e118BB7fa4D460A25851fCf99f7Fa9
https://goerli.etherscan.io/address/0xD0f85823D7e118BB7fa4D460A25851fCf99f7Fa9
// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.9.0;
import "hardhat/console.sol";
contract WorldCup {
// 1. 状态变量：管理员、所有玩家、获奖者地址、第几期、参赛球队
// 2. 核心方法：下注、开奖、
// 3. 辅助方法：获取奖金池金额、管理员地址、当前期数、参与人数、所有玩家、参赛球队
address public admin;
uint8 public currRound;
// string[] public countries; // ["GERMANY", "FRANCH", "CHINA", "BRIZAL", "KOREA"]
string[] public countries = ["GERMANY", "FRANCH", "CHINA", "BRIZAL", "KOREA"];
mapping (uint8 => mapping (address => Player)) players;
mapping (uint8 => mapping (Country => address[])) public countryToPlayers;
mapping (address => uint256) public winnerVaults;
uint256 public immutable deadline;
uint256 public lockedAmts;
enum Country {
GERMANY,
FRANCH,
CHINA,
BRAZIL,
KOREA
}
event Play(uint8 _currRound, address _player, Country _country);
event Finialize(uint8 _currRound, uint256 _country);
event ClaimReward(address _claimer, uint256 _amt);
modifier onlyAdmin {
require(msg.sender == admin, "not authorized!");
_;
}
struct Player {
bool isSet;
mapping (Country => uint256) counts;
}
// constructor(string[] memory _countries, uint256 _deadline) {
constructor(uint256 _deadline) {
admin = msg.sender;
require(_deadline > block.timestamp, "WorldCupLottery: invalid deadline!");
deadline = _deadline;
}
function play(Country _selected) payable external {
// 参数校验
require(msg.value == 1 gwei, "invalid funds provided!");
require(block.timestamp < deadline, "it's all over!");
// 更新countryToPlayers
countryToPlayers[currRound][_selected].push(msg.sender);
// 更新players
Player storage player = players[currRound][msg.sender];
// player.isSet = false;
player.counts[_selected] += 1;
emit Play(currRound, msg.sender, _selected);
}
// 写另外一个合约，模拟oracle，讲解合约间调用
function finialize(Country _country) onlyAdmin external {
// 找到winners
address[] memory winners = countryToPlayers[currRound][_country];
uint256 distributeAmt;
// 分配奖励金额
uint currAvalBalance = getVaultBalance() - lockedAmts;
console.log("currAvalBalance:", currAvalBalance, "winners count:", winners.length);
for (uint i = 0; i< winners.length; i++) {
address currWinner = winners[i];
// 获取每个地址应该得到的份额
Player storage winner = players[currRound][currWinner];
if (winner.isSet) {
console.log("this winner has been set already, will be skipped!");
continue;
}
winner.isSet = true;
uint currCounts = winner.counts[_country];
// （本期总奖励 / 总参与人数）* 当前地址持有份额
uint amt = (currAvalBalance / countryToPlayers[currRound][_country].length) * currCounts;
winnerVaults[currWinner] += amt;
distributeAmt += amt;
lockedAmts += amt;
console.log("winner:", currWinner, "currCounts:", currCounts);
console.log("reward amt curr:", amt, "total:", winnerVaults[currWinner]);
}
uint giftAmt = currAvalBalance - distributeAmt;
if (giftAmt > 0) {
winnerVaults[admin] += giftAmt;
}
emit Finialize(currRound++, uint256(_country));
}
function claimReward() external {
uint256 rewards = winnerVaults[msg.sender];
require(rewards > 0, "nothing to claim!");
winnerVaults[msg.sender] = 0;
lockedAmts -= rewards;
(bool succeed,) = msg.sender.call{value: rewards}("");
require(succeed, "claim reward failed!");
console.log("rewards:", rewards);
emit ClaimReward(msg.sender, rewards);
}
////////////////////////////////////////////// getter functions ////////////////////////////////////////////////
function getVaultBalance() public view returns(uint256 bal){
bal = address(this).balance;
}
function getCountryPlayters(uint8 _round, Country _country) external view returns (uint256) {
return countryToPlayers[_round][_country].length;
}
function getPlayerInfo(uint8 _round, address _player, Country _country) external view returns (uint256 _counts) {
return players[_round][_player].counts[_country];
}
}
下次预告
使用工程化来管理合约
自动编译、部署、verify、单元测试、fork主网
资源链接
详细知识点：https://github.com/dukedaily/solidity-expert
快速添目标网络：https://chainlist.org/
水龙头领取Goerli主币：https://goerlifaucet.com/
一键领取多个水龙头，需要Twitter登录：https://faucet.paradigm.xyz/
详细知识点托管在github：https://github.com/dukedaily/solidity-expert
加V入群：dukeweb3，公众号：阿杜在新加坡，一起抱团拥抱web3，下期见！
关于作者：国内第一批区块链布道者；2017年开始专注于区块链教育(btc, eth, fabric)，目前base新加坡，专注海外defi,dex,元宇宙等业务方向。