/**
 * 微服务治理框架
 * 包含服务发现、负载均衡和熔断降级功能
 */
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;

public class MicroServiceGovernance {
    // 服务注册中心组件
    private final ServiceRegistry serviceRegistry;
    // 负载均衡器映射
    private final Map<String, LoadBalancer> loadBalancers;
    // 断路器映射
    private final Map<String, CircuitBreaker> circuitBreakers;
    // 故障服务列表
    private final Map<String, Boolean> faultyServices = new ConcurrentHashMap<>();
    // 服务调用统计
    private final Map<String, CallStats> callStats = new ConcurrentHashMap<>();
    // 单例实例
    private static volatile MicroServiceGovernance instance;
    
    private MicroServiceGovernance() {
        this.serviceRegistry = new ServiceRegistry();
        this.loadBalancers = new ConcurrentHashMap<>();
        this.circuitBreakers = new ConcurrentHashMap<>();
        System.out.println("微服务治理框架初始化完成");
    }
    
    // 获取单例实例
    public static MicroServiceGovernance getInstance() {
        if (instance == null) {
            synchronized (MicroServiceGovernance.class) {
                if (instance == null) {
                    instance = new MicroServiceGovernance();
                }
            }
        }
        return instance;
    }
    
    // 服务注册
    public void registerService(String serviceName, String host, int port) {
        serviceRegistry.register(serviceName, host, port);
        // 为新服务初始化负载均衡器
        getLoadBalancer(serviceName);
        // 为新服务初始化断路器
        getCircuitBreaker(serviceName);
    }
    
    // 服务注销
    public void deregisterService(String serviceName, String host, int port) {
        serviceRegistry.deregister(serviceName, host, port);
    }
    
    // 获取负载均衡器
    private LoadBalancer getLoadBalancer(String serviceName) {
        return loadBalancers.computeIfAbsent(serviceName, name -> {
            LoadBalancer balancer = new LoadBalancer(name);
            System.out.println("为服务 " + name + " 创建负载均衡器");
            return balancer;
        });
    }
    
    // 获取断路器
    private CircuitBreaker getCircuitBreaker(String serviceName) {
        return circuitBreakers.computeIfAbsent(serviceName, name -> {
            CircuitBreaker breaker = new CircuitBreaker(name, 5, 10000, 2);
            System.out.println("为服务 " + name + " 创建断路器");
            return breaker;
        });
    }
    
    // 调用服务（适配测试类的方法签名）
    public String callService(String serviceName, String method, String path) {
        // 创建一个简单的参数映射
        Map<String, String> params = new HashMap<>();
        params.put("path", path);
        params.put("timestamp", String.valueOf(System.currentTimeMillis()));
        
        return callServiceInternal(serviceName, method, params);
    }
    
    // 服务调用（集成了服务发现、负载均衡和熔断降级）
    public ServiceCallResult callService(String serviceName, String path, Map<String, String> params) {
        // 获取断路器
        CircuitBreaker circuitBreaker = getCircuitBreaker(serviceName);
        
        // 检查断路器状态
        if (!circuitBreaker.allowRequest()) {
            System.out.println("服务调用被断路器拒绝: " + serviceName + " (状态: " + circuitBreaker.getState() + ")");
            return new ServiceCallResult(false, "服务暂时不可用，请稍后再试", null);
        }
        
        try {
            // 获取服务实例列表
            List<ServiceRegistry.ServiceInstance> instances = serviceRegistry.discover(serviceName);
            if (instances.isEmpty()) {
                circuitBreaker.recordFailure();
                return new ServiceCallResult(false, "未找到可用的服务实例: " + serviceName, null);
            }
            
            // 负载均衡选择实例
            LoadBalancer loadBalancer = getLoadBalancer(serviceName);
            ServiceRegistry.ServiceInstance instance = loadBalancer.choose(instances);
            
            if (instance == null) {
                circuitBreaker.recordFailure();
                return new ServiceCallResult(false, "负载均衡失败，未选择到服务实例", null);
            }
            
            // 模拟服务调用
            System.out.println("调用服务: " + serviceName + " 实例: " + instance + " 路径: " + path);
            
            // 模拟随机失败（用于测试熔断）
            boolean success = simulateServiceCall(instance, serviceName);
            
            // 更新调用统计
            updateCallStats(serviceName, instance, success);
            
            if (success) {
                circuitBreaker.recordSuccess();
                Map<String, Object> response = new HashMap<>();
                response.put("instance", instance.toString());
                response.put("path", path);
                response.put("timestamp", System.currentTimeMillis());
                return new ServiceCallResult(true, "调用成功", response);
            } else {
                circuitBreaker.recordFailure();
                return new ServiceCallResult(false, "服务调用失败", null);
            }
        } catch (Exception e) {
            circuitBreaker.recordFailure();
            return new ServiceCallResult(false, "服务调用异常: " + e.getMessage(), null);
        }
    }
    
    // 内部调用服务方法
    public String callServiceInternal(String serviceName, String method, Map<String, String> params) {
        // 1. 通过服务注册中心发现服务
        List<ServiceRegistry.ServiceInstance> instances = serviceRegistry.discover(serviceName);
        if (instances.isEmpty()) {
            return "服务不可用: " + serviceName;
        }
        
        // 2. 通过负载均衡器选择实例
        LoadBalancer loadBalancer = getLoadBalancer(serviceName);
        ServiceRegistry.ServiceInstance instance = loadBalancer.choose(instances);
        if (instance == null) {
            return "无法选择服务实例: " + serviceName;
        }
        
        // 3. 通过断路器调用服务
        String key = serviceName + ":" + instance.getHost() + ":" + instance.getPort();
        CircuitBreaker circuitBreaker = circuitBreakers.computeIfAbsent(key, name -> new CircuitBreaker(name, 5, 10000, 2));
        
        if (!circuitBreaker.allowRequest()) {
            return "服务调用被断路器拒绝: " + serviceName;
        }
        
        try {
            // 模拟服务调用
            String result = simulateServiceCallInternal(instance, method, params);
            circuitBreaker.recordSuccess();
            
            // 更新调用统计
            updateCallStats(serviceName, instance, true);
            
            return result;
        } catch (Exception e) {
            circuitBreaker.recordFailure();
            
            // 更新调用统计
            updateCallStats(serviceName, instance, false);
            
            return "服务调用失败: " + e.getMessage();
        }
    }
    
    // 模拟服务调用（内部方法）
    private String simulateServiceCallInternal(ServiceRegistry.ServiceInstance instance, String method, Map<String, String> params) {
        // 检查故障服务列表
        String faultKey = instance.getHost() + ":" + instance.getPort();
        if (faultyServices.containsKey(faultKey) && faultyServices.get(faultKey)) {
            throw new RuntimeException("模拟服务故障: " + instance);
        }
        
        // 模拟处理延迟
        try {
            Thread.sleep(10 + (int)(Math.random() * 50));
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
        
        // 生成调用结果
        String path = params.getOrDefault("path", "");
        return method + " " + instance.getHost() + ":" + instance.getPort() + path + " - 调用成功";
    }
    
    // 模拟服务调用（随机失败以测试熔断）
    private boolean simulateServiceCall(ServiceRegistry.ServiceInstance instance, String serviceName) {
        // 检查故障服务列表
        String faultKey = instance.getHost() + ":" + instance.getPort();
        if (faultyServices.containsKey(faultKey) && faultyServices.get(faultKey)) {
            return false;
        }
        // 90%的成功率，用于测试
        return Math.random() < 0.9;
    }
    
    // 更新调用统计
    private void updateCallStats(String serviceName, ServiceRegistry.ServiceInstance instance, boolean success) {
        CallStats stats = callStats.computeIfAbsent(serviceName, k -> new CallStats());
        stats.recordCall(success);
        
        // 更新实例统计
        String instanceKey = instance.getHost() + ":" + instance.getPort();
        stats.instanceStats.computeIfAbsent(instanceKey, k -> new ServiceInstanceStats()).recordCall(success);
    }
    
    // 列出所有服务
    public List<String> listServices() {
        List<String> services = new ArrayList<>();
        // 从服务注册中心获取所有服务
        serviceRegistry.getAllServices().forEach(service -> {
            List<ServiceRegistry.ServiceInstance> instances = serviceRegistry.discover(service);
            for (ServiceRegistry.ServiceInstance instance : instances) {
                services.add(service + " - " + instance.getHost() + ":" + instance.getPort());
            }
        });
        return services;
    }
    
    // 模拟服务故障
    public void simulateServiceFailure(String serviceName, String host, int port, boolean isFaulty) {
        String key = host + ":" + port;
        faultyServices.put(key, isFaulty);
        System.out.println("服务故障状态更新: " + serviceName + "[" + host + ":" + port + "] = " + (isFaulty ? "故障" : "正常"));
    }
    
    // 打印治理统计信息
    public void printGovernanceStats() {
        System.out.println("===== 微服务治理统计 =====");
        
        // 打印服务调用统计
        callStats.forEach((service, stats) -> {
            System.out.println("\n服务: " + service);
            System.out.println("  总调用次数: " + stats.getTotalCalls());
            System.out.println("  成功调用: " + stats.getSuccessCalls());
            System.out.println("  失败调用: " + stats.getFailureCalls());
            System.out.println("  成功率: " + String.format("%.2f%%", 
                stats.getTotalCalls() > 0 ? (double) stats.getSuccessCalls() / stats.getTotalCalls() * 100 : 0));
            
            // 打印实例统计
            System.out.println("  实例统计:");
            stats.getInstanceStats().forEach((instance, instanceStats) -> {
                System.out.println("    " + instance + ": 调用 " + instanceStats.getTotalCalls() + " 次, 成功率 " + 
                    String.format("%.2f%%", instanceStats.getSuccessRate()));
            });
        });
        
        // 打印断路器状态
        System.out.println("\n断路器状态:");
        circuitBreakers.forEach((key, breaker) -> {
            System.out.println("  " + key + ": " + breaker.getState() + ", 失败计数: " + breaker.getFailureCount());
        });
        
        System.out.println("========================");
    }
    
    // 获取服务治理统计信息
    public Map<String, Object> getGovernanceStats() {
        Map<String, Object> stats = new HashMap<>();
        
        // 服务统计
        Map<String, Integer> serviceStats = new HashMap<>();
        for (String service : serviceRegistry.getAllServices()) {
            int instanceCount = serviceRegistry.discover(service).size();
            serviceStats.put(service, instanceCount);
        }
        stats.put("services", serviceStats);
        
        // 断路器统计
        Map<String, String> breakerStats = new HashMap<>();
        for (Map.Entry<String, CircuitBreaker> entry : circuitBreakers.entrySet()) {
            CircuitBreaker breaker = entry.getValue();
            breakerStats.put(entry.getKey(), breaker.getState() + " (失败: " + breaker.getFailureCount() + ")");
        }
        stats.put("circuitBreakers", breakerStats);
        
        // 添加调用统计
        stats.put("callStats", callStats);
        
        return stats;
    }
    
    // 服务调用统计
    private static class CallStats {
        private final AtomicInteger totalCalls = new AtomicInteger(0);
        private final AtomicInteger successCalls = new AtomicInteger(0);
        private final AtomicInteger failureCalls = new AtomicInteger(0);
        private final Map<String, ServiceInstanceStats> instanceStats = new ConcurrentHashMap<>();
        
        // Getters
        public int getTotalCalls() { return totalCalls.get(); }
        public int getSuccessCalls() { return successCalls.get(); }
        public int getFailureCalls() { return failureCalls.get(); }
        public Map<String, ServiceInstanceStats> getInstanceStats() { return instanceStats; }
        
        // 更新统计
        public void recordCall(boolean success) {
            totalCalls.incrementAndGet();
            if (success) {
                successCalls.incrementAndGet();
            } else {
                failureCalls.incrementAndGet();
            }
        }
    }
    
    // 服务实例调用统计
    private static class ServiceInstanceStats {
        private final AtomicInteger totalCalls = new AtomicInteger(0);
        private final AtomicInteger successCalls = new AtomicInteger(0);
        
        public void recordCall(boolean success) {
            totalCalls.incrementAndGet();
            if (success) {
                successCalls.incrementAndGet();
            }
        }
        
        public int getTotalCalls() { return totalCalls.get(); }
        public int getSuccessCalls() { return successCalls.get(); }
        public double getSuccessRate() {
            int total = getTotalCalls();
            return total > 0 ? (double) getSuccessCalls() / total * 100 : 0;
        }
    }
    
    // 服务注册中心内部类
    public static class ServiceRegistry {
        private final Map<String, List<ServiceInstance>> services = new ConcurrentHashMap<>();
        
        public void register(String serviceName, String host, int port) {
            services.computeIfAbsent(serviceName, k -> new ArrayList<>()).add(new ServiceInstance(host, port));
            System.out.println("服务注册: " + serviceName + " at " + host + ":" + port);
        }
        
        public void deregister(String serviceName, String host, int port) {
            List<ServiceInstance> instances = services.get(serviceName);
            if (instances != null) {
                instances.removeIf(instance -> instance.getHost().equals(host) && instance.getPort() == port);
                if (instances.isEmpty()) {
                    services.remove(serviceName);
                }
            }
        }
        
        public List<ServiceInstance> discover(String serviceName) {
            List<ServiceInstance> instances = services.get(serviceName);
            return instances != null ? new ArrayList<>(instances) : Collections.emptyList();
        }
        
        public Set<String> getAllServices() {
            return new HashSet<>(services.keySet());
        }
        
        public static class ServiceInstance {
            private final String host;
            private final int port;
            
            public ServiceInstance(String host, int port) {
                this.host = host;
                this.port = port;
            }
            
            public String getHost() { return host; }
            public int getPort() { return port; }
            
            @Override
            public String toString() { return host + ":" + port; }
        }
    }
    
    // 负载均衡器内部类
    public static class LoadBalancer {
        private final String name;
        private final AtomicInteger counter = new AtomicInteger(0);
        
        public LoadBalancer(String name) {
            this.name = name;
        }
        
        // 轮询负载均衡
        public ServiceRegistry.ServiceInstance choose(List<ServiceRegistry.ServiceInstance> instances) {
            if (instances == null || instances.isEmpty()) {
                return null;
            }
            
            // 轮询选择实例
            int index = Math.abs(counter.getAndIncrement() % instances.size());
            return instances.get(index);
        }
    }
    
    // 断路器内部类
    public static class CircuitBreaker {
        public enum State { CLOSED, OPEN, HALF_OPEN }
        
        private final String name;
        private final int failureThreshold;
        private final long resetTimeoutMs;
        private final int successThreshold;
        
        private volatile State state = State.CLOSED;
        private final AtomicInteger failureCount = new AtomicInteger(0);
        private final AtomicInteger successCount = new AtomicInteger(0);
        private volatile long lastFailureTime = 0;
        
        public CircuitBreaker(String name, int failureThreshold, long resetTimeoutMs, int successThreshold) {
            this.name = name;
            this.failureThreshold = failureThreshold;
            this.resetTimeoutMs = resetTimeoutMs;
            this.successThreshold = successThreshold;
        }
        
        public boolean allowRequest() {
            if (state == State.CLOSED) {
                return true;
            }
            if (state == State.OPEN) {
                if (System.currentTimeMillis() - lastFailureTime > resetTimeoutMs) {
                    state = State.HALF_OPEN;
                    System.out.println("断路器状态切换: " + name + " 从 OPEN 到 HALF_OPEN");
                    return true;
                }
                return false;
            }
            return state == State.HALF_OPEN;
        }
        
        public void recordSuccess() {
            if (state == State.CLOSED) {
                failureCount.set(0);
            } else if (state == State.HALF_OPEN) {
                if (successCount.incrementAndGet() >= successThreshold) {
                    reset();
                    System.out.println("断路器状态切换: " + name + " 从 HALF_OPEN 到 CLOSED");
                }
            }
        }
        
        public void recordFailure() {
            if (state == State.CLOSED) {
                if (failureCount.incrementAndGet() >= failureThreshold) {
                    state = State.OPEN;
                    lastFailureTime = System.currentTimeMillis();
                    System.out.println("断路器状态切换: " + name + " 从 CLOSED 到 OPEN");
                }
            } else if (state == State.HALF_OPEN) {
                state = State.OPEN;
                lastFailureTime = System.currentTimeMillis();
                successCount.set(0);
                System.out.println("断路器状态切换: " + name + " 从 HALF_OPEN 到 OPEN");
            }
        }
        
        private void reset() {
            state = State.CLOSED;
            failureCount.set(0);
            successCount.set(0);
        }
        
        public State getState() { return state; }
        public int getFailureCount() { return failureCount.get(); }
        public String getName() { return name; }
    }
    
    // 服务调用结果
    public static class ServiceCallResult {
        private final boolean success;
        private final String message;
        private final Map<String, Object> data;
        
        public ServiceCallResult(boolean success, String message, Map<String, Object> data) {
            this.success = success;
            this.message = message;
            this.data = data;
        }
        
        public boolean isSuccess() { return success; }
        public String getMessage() { return message; }
        public Map<String, Object> getData() { return data; }
    }
}