package com.example.demo.demos.web.nginx;

import java.util.ArrayList;
import java.util.List;

public class WeightedRoundRobin {

    private static List<Server> servers = new ArrayList<>(); // 存储服务器的列表
    private static int currentIndex = -1; // 当前服务器的索引
    private static int currentWeight = 0; // 当前处理的权重
    private static int maxWeight = 0; // 所有服务器中的最大权重
    private static int gcd; // 所有服务器权重的最大公约数

    public static void main(String[] args) {
        // 初始化服务器及其权重
        servers.add(new Server("服务器1", 4));
        servers.add(new Server("服务器2", 2));
        servers.add(new Server("服务器3", 2));

        // 计算所有服务器权重的最大公约数
        gcd = calculateGCD();

        // 找到具有最大权重的服务器
        maxWeight = getMaxWeight();

        // 执行权重轮询算法
        for (int i = 0; i < 10; i++) {
            Server selectedServer = selectServer();
            System.out.println("请求 " + i + " 由 " + selectedServer.getName() + " 处理");
        }
    }

    private static Server selectServer() {
        while (true) {
            currentIndex = (currentIndex + 1) % servers.size(); // 循环选择下一个服务器
            if (currentIndex == 0) {
                currentWeight = currentWeight - gcd; // 减少当前权重
                if (currentWeight <= 0) {
                    currentWeight = maxWeight; // 将当前权重重置为最大权重
                }
            }
            if (servers.get(currentIndex).getWeight() >= currentWeight) {
                return servers.get(currentIndex); // 返回选择的服务器
            }
        }
    }

    private static int calculateGCD() {
        int result = servers.get(0).getWeight();
        for (int i = 1; i < servers.size(); i++) {
            result = gcd(result, servers.get(i).getWeight()); // 计算所有服务器权重的最大公约数
        }
        return result;
    }

    private static int gcd(int a, int b) {
        return b == 0 ? a : gcd(b, a % b); // 使用欧几里德算法计算最大公约数
    }

    private static int getMaxWeight() {
        int max = 0;
        for (Server server : servers) {
            if (server.getWeight() > max) {
                max = server.getWeight(); // 找到所有服务器中的最大权重
            }
        }
        return max;
    }

    static class Server {
        private String name;
        private int weight;

        public Server(String name, int weight) {
            this.name = name;
            this.weight = weight; // 初始化服务器的名称和权重
        }

        public String getName() {
            return name;
        }

        public int getWeight() {
            return weight;
        }
    }
}

运行结果如下：