package com.soa.monitoring;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import java.util.concurrent.ConcurrentHashMap;
import java.util.Map;

/**
 * 服务监控组件 - 负责监控服务的性能、可用性和错误率
 */
public class ServiceMonitor {
    private static final Logger logger = LogManager.getLogger(ServiceMonitor.class);
    private static ServiceMonitor instance;
    private final Map<String, ServiceMetrics> metricsMap = new ConcurrentHashMap<>();
    
    private ServiceMonitor() {}
    
    /**
     * 获取监控器单例
     */
    public static synchronized ServiceMonitor getInstance() {
        if (instance == null) {
            instance = new ServiceMonitor();
        }
        return instance;
    }
    
    /**
     * 记录服务调用开始
     */
    public long startMonitoring(String serviceName) {
        return System.currentTimeMillis();
    }
    
    /**
     * 记录服务调用结束
     */
    public void endMonitoring(String serviceName, long startTime, boolean success) {
        long executionTime = System.currentTimeMillis() - startTime;
        
        ServiceMetrics metrics = metricsMap.computeIfAbsent(serviceName, k -> new ServiceMetrics());
        metrics.recordCall(executionTime, success);
        
        logger.info("Service: {} - Execution time: {}ms, Status: {}", 
                serviceName, executionTime, success ? "SUCCESS" : "FAILED");
        
        // 检查性能阈值
        if (executionTime > 1000) { // 1秒阈值
            logger.warn("Service {} performance warning: execution time {}ms exceeds threshold", 
                    serviceName, executionTime);
        }
    }
    
    /**
     * 获取服务指标
     */
    public ServiceMetrics getServiceMetrics(String serviceName) {
        return metricsMap.get(serviceName);
    }
    
    /**
     * 打印所有服务的监控报告
     */
    public void printMonitoringReport() {
        logger.info("===== SERVICE MONITORING REPORT =====");
        for (Map.Entry<String, ServiceMetrics> entry : metricsMap.entrySet()) {
            String serviceName = entry.getKey();
            ServiceMetrics metrics = entry.getValue();
            logger.info("Service: {}", serviceName);
            logger.info("  Total calls: {}", metrics.getTotalCalls());
            logger.info("  Successful calls: {}", metrics.getSuccessfulCalls());
            logger.info("  Failed calls: {}", metrics.getFailedCalls());
            logger.info("  Avg response time: {}ms", metrics.getAvgResponseTime());
            logger.info("  Error rate: {}%", metrics.getErrorRate());
        }
        logger.info("===================================");
    }
    
    /**
     * 服务指标内部类
     */
    public static class ServiceMetrics {
        private long totalCalls = 0;
        private long successfulCalls = 0;
        private long failedCalls = 0;
        private long totalResponseTime = 0;
        
        public synchronized void recordCall(long executionTime, boolean success) {
            totalCalls++;
            totalResponseTime += executionTime;
            if (success) {
                successfulCalls++;
            } else {
                failedCalls++;
            }
        }
        
        public long getTotalCalls() { return totalCalls; }
        public long getSuccessfulCalls() { return successfulCalls; }
        public long getFailedCalls() { return failedCalls; }
        public double getAvgResponseTime() {
            return totalCalls > 0 ? (double) totalResponseTime / totalCalls : 0;
        }
        public double getErrorRate() {
            return totalCalls > 0 ? (double) failedCalls / totalCalls * 100 : 0;
        }
    }
}