package cn.lili.modules;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.*;

public class Demo_1 {

    // 奖品类
  static   class Prize {
        private String name;        // 奖品名称
        private double probability; // 中奖概率(0-1之间)

        public Prize(String name, double probability) {
            this.name = name;
            this.probability = probability;
        }

        public String getName() {
            return name;
        }

        public double getProbability() {
            return probability;
        }
    }

    // 抽奖系统类
    public static class LotterySystem {
        private List<Prize> prizes;
        private List<Double> probabilityIntervals;
        private Random random;

        public  LotterySystem(List<Prize> prizes) {
            // 验证概率总和是否为1
            double totalProbability = 0;
            for (Prize prize : prizes) {
                totalProbability += prize.getProbability();
            }

            // 如果总和不是1，进行归一化处理
            if (Math.abs(totalProbability - 1.0) > 0.0001) {
                List<Prize> normalizedPrizes = new ArrayList<>();
                for (Prize prize : prizes) {
                    normalizedPrizes.add(new Prize(
                            prize.getName(),
                            prize.getProbability() / totalProbability
                    ));
                }
                this.prizes = normalizedPrizes;
            } else {
                this.prizes = prizes;
            }

            // 初始化概率区间
            initProbabilityIntervals();
            this.random = new Random();
        }

        // 初始化概率区间
        private void initProbabilityIntervals() {
            probabilityIntervals = new ArrayList<>();
            double current = 0;

            for (Prize prize : prizes) {
                current += prize.getProbability();
                probabilityIntervals.add(current);
            }
        }

        // 执行抽奖
        public String draw() {
            // 生成0-1之间的随机数
            double randomValue = random.nextDouble();

            // 查找随机数落在哪个区间
            for (int i = 0; i < probabilityIntervals.size(); i++) {
                if (randomValue < probabilityIntervals.get(i)) {
                    return prizes.get(i).getName();
                }
            }

            // 理论上不会走到这里
            return "未中奖";
        }

        // 测试抽奖系统
        public static void main(String[] args) {
            // 创建5个奖品，设置不同的中奖概率
            List<Prize> prizes = new ArrayList<>();
            prizes.add(new Prize("一等奖", 0.01));   // 1%概率
            prizes.add(new Prize("二等奖", 0.05));   // 5%概率
            prizes.add(new Prize("三等奖", 0.1));    // 10%概率
            prizes.add(new Prize("四等奖", 0.2));    // 20%概率
            prizes.add(new Prize("五等奖", 0.64));   // 64%概率

            // 创建抽奖系统
            LotterySystem lottery = new LotterySystem(prizes);

            // 测试10000次抽奖，查看概率分布
            Map<String, Integer> result = new HashMap<>();
            int totalDraws = 100000;

            for (int i = 0; i < totalDraws; i++) {
                String prizeName = lottery.draw();
                result.put(prizeName, result.getOrDefault(prizeName, 0) + 1);
            }

            // 输出结果
            System.out.println("抽奖" + totalDraws + "次的结果：");
            for (Map.Entry<String, Integer> entry : result.entrySet()) {
                double percentage = (entry.getValue() * 100.0) / totalDraws;
                System.out.printf("%s: %d次 (%.2f%%)\n",
                        entry.getKey(), entry.getValue(), percentage);
            }
        }
    }

}