package com.example.config;

import jakarta.annotation.PostConstruct;
import jakarta.annotation.PreDestroy;
import lombok.extern.slf4j.Slf4j;
import org.springframework.core.io.FileSystemResource;
import org.springframework.core.io.Resource;
import org.springframework.util.ResourceUtils;

import java.io.IOException;
import java.nio.file.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

@Slf4j
public class ConfigFileWatcher {
    // 監(jiān)聽(tīng)的配置文件路徑（默認(rèn)監(jiān)聽(tīng)classpath下的application.yaml）
    private final String configPath = "classpath:application.yaml";
    private WatchService watchService;
    private final ExecutorService executor = Executors.newSingleThreadExecutor();
    private final ConfigRefreshHandler refreshHandler;
    private long lastProcessTime;
    private final long EVENT_DEBOUNCE_TIME = 500; // 500毫秒防抖時(shí)間

    // 注入配置刷新處理器（后面實(shí)現(xiàn)）
    public ConfigFileWatcher(ConfigRefreshHandler refreshHandler) {
        this.refreshHandler = refreshHandler;
    }

    @PostConstruct
    public void init() throws IOException {
        // 獲取配置文件的實(shí)際路徑
        Resource resource = new FileSystemResource(ResourceUtils.getFile(configPath));
        Path configDir = resource.getFile().toPath().getParent(); // 監(jiān)聽(tīng)配置文件所在目錄
        String fileName = resource.getFilename(); // 配置文件名（如application.yaml）

        watchService = FileSystems.getDefault().newWatchService();
        // 注冊(cè)文件修改事件（ENTRY_MODIFY）
        configDir.register(watchService, StandardWatchEventKinds.ENTRY_MODIFY);

        // 啟動(dòng)線程監(jiān)聽(tīng)文件變化
        executor.submit(() -> {
            while (true) {
                try {
                    WatchKey key = watchService.take(); // 阻塞等待事件
                    // 防抖檢查：忽略短時(shí)間內(nèi)重復(fù)事件
                    if (System.currentTimeMillis() - lastProcessTime < EVENT_DEBOUNCE_TIME) {
                        continue;
                    }
                    for (WatchEvent<?> event : key.pollEvents()) {
                        WatchEvent.Kind<?> kind = event.kind();
                        if (kind == StandardWatchEventKinds.OVERFLOW) {
                            continue; // 事件溢出，忽略
                        }

                        // 檢查是否是目標(biāo)配置文件被修改
                        Path changedFile = (Path) event.context();
                        if (changedFile.getFileName().toString().equals(fileName)) {
                            log.info("檢測(cè)到配置文件修改：{}", fileName);
                            refreshHandler.refresh(); // 觸發(fā)配置刷新
                        }
                    }
                    boolean valid = key.reset(); // 重置監(jiān)聽(tīng)器
                    if (!valid) break; // 監(jiān)聽(tīng)器失效，退出循環(huán)
                } catch (InterruptedException e) {
                    Thread.currentThread().interrupt();
                    break;
                }
            }
        });
        log.info("配置文件監(jiān)聽(tīng)器啟動(dòng)成功，監(jiān)聽(tīng)路徑：{}", configDir);
    }

    @PreDestroy
    public void destroy() {
        executor.shutdownNow();
        try {
            watchService.close();
        } catch (IOException e) {
            log.error("關(guān)閉WatchService失敗", e);
        }
    }
}

import org.springframework.context.ApplicationEvent;
import java.util.Set;

/**
 * 自定義配置刷新事件
 */
public class ConfigRefreshedEvent extends ApplicationEvent {
    // 存儲(chǔ)變化的配置鍵（可選，方便業(yè)務(wù)判斷哪些配置變了）
    private final Set<String> changedKeys;

    public ConfigRefreshedEvent(Object source, Set<String> changedKeys) {
        super(source);
        this.changedKeys = changedKeys;
    }

    // 獲取變化的配置鍵
    public Set<String> getChangedKeys() {
        return changedKeys;
    }
}



import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.config.YamlPropertiesFactoryBean;
import org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.MapPropertySource;
import org.springframework.core.env.PropertySource;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
import org.springframework.stereotype.Component;

import java.io.IOException;
import java.util.*;

@Component
@Slf4j
public class ConfigRefreshHandler implements ApplicationContextAware {
    @Autowired
    private ConfigurableEnvironment environment;
    private ApplicationContext applicationContext;

    @Autowired
    private ConfigurationPropertiesBindingPostProcessor bindingPostProcessor; // 屬性綁定工具

    // 刷新配置的核心方法
    public void refresh() {
        try {
            // 1. 重新讀取配置文件內(nèi)容
            Properties properties = loadConfigFile();

            // 2. 更新Environment中的屬性
            Set<String> changeKeys = updateEnvironment(properties);

            // 3. 重新綁定所有@ConfigurationProperties Bean
            if (!changeKeys.isEmpty()) {
                rebindConfigurationProperties();
            }

            applicationContext.publishEvent( new ConfigRefreshedEvent(this,changeKeys));
            log.info("配置文件刷新完成");
        } catch (Exception e) {
            log.error("配置文件刷新失敗", e);
        }
    }

    // 讀取配置文件內(nèi)容（支持properties和yaml）
    private Properties loadConfigFile() throws IOException {
        // 使用Spring工具類讀取classpath下的配置文件
        Resource resource = new ClassPathResource("application.yaml");
        YamlPropertiesFactoryBean yamlFactory = new YamlPropertiesFactoryBean();
        yamlFactory.setResources(resource);

        // 獲取解析后的Properties對(duì)象
        Properties properties = yamlFactory.getObject();
        if (properties == null) {
            throw new IOException("Failed to load configuration file");
        }
        return properties;
    }

    // 更新Environment中的屬性，返回變化的配置鍵集合
    private Set<String> updateEnvironment(Properties properties) {
        String sourceName = "Config resource 'class path resource [application.yaml]' via location 'optional:classpath:/'";
        Set<String> changedKeys = new HashSet<>();
        PropertySource<?> appConfig = environment.getPropertySources().get(sourceName);

        if (appConfig instanceof MapPropertySource) {
            Map<String, Object> sourceMap = new HashMap<>(((MapPropertySource) appConfig).getSource());

            properties.forEach((k, v) -> {
                String key = k.toString();
                Object oldValue = sourceMap.get(key);
                if (!Objects.equals(oldValue, v)) {
                    changedKeys.add(key);
                }
                sourceMap.put(key, v);
            });

            environment.getPropertySources().replace(sourceName, new MapPropertySource(sourceName, sourceMap));
        }
        return changedKeys;
    }

    // 重新綁定所有@ConfigurationProperties Bean
    private void rebindConfigurationProperties() {
        // 獲取所有@ConfigurationProperties Bean的名稱
        String[] beanNames = applicationContext.getBeanNamesForAnnotation(org.springframework.boot.context.properties.ConfigurationProperties.class);
        for (String beanName : beanNames) {
            // 重新綁定屬性（關(guān)鍵：不重建Bean，只更新屬性值）
            bindingPostProcessor.postProcessBeforeInitialization(
                    applicationContext.getBean(beanName), beanName);
            log.info("刷新配置Bean：{}", beanName);
        }
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }
}

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class HotRefreshConfig {
    @Bean
    public ConfigFileWatcher configFileWatcher(ConfigRefreshHandler refreshHandler) throws IOException {
        return new ConfigFileWatcher(refreshHandler);
    }
}

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

@Data
@Component
@ConfigurationProperties(prefix = "app") // 綁定配置前綴
public class AppConfig {
    private int timeout = 3000; // 默認(rèn)超時(shí)時(shí)間3秒
    private int maxRetries = 2; // 默認(rèn)重試次數(shù)2次
}

package com.example.controller;

import com.example.AppConfig;
import com.example.config.ConfigRefreshedEvent;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.event.EventListener;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@Slf4j
public class ConfigController {
    @Autowired
    private AppConfig appConfig;

    @GetMapping("/config")
    public AppConfig getConfig() {
        return appConfig; // 返回當(dāng)前配置
    }

    // 監(jiān)聽(tīng)配置刷新事件，可進(jìn)行業(yè)務(wù)特殊處理
    @EventListener(ConfigRefreshedEvent.class)
    public void appConfigUpdate(ConfigRefreshedEvent event) {
        event.getChangedKeys().forEach(key -> log.info("配置項(xiàng) {} 發(fā)生變化", key));
    }

}

// 修改ConfigFileWatcher的init方法
@PostConstruct
public void init() throws IOException {
    // 生產(chǎn)環(huán)境建議監(jiān)聽(tīng)外部配置文件（如/opt/app/application.yml）
    Path configPath = Paths.get("/opt/app/application.yml");
    if (Files.exists(configPath)) {
        watchConfigFile(configPath); // 監(jiān)聽(tīng)外部文件
    } else {
        log.warn("外部配置文件不存在，使用默認(rèn)配置");
    }
}

private void watchConfigFile(Path configPath) throws IOException {
    Path configDir = configPath.getParent();
    String fileName = configPath.getFileName().toString();
    // 后續(xù)邏輯同上...
}

// 偽代碼：解密配置
private String decrypt(String value) {
    if (value.startsWith("ENC(")) {
        return jasyptEncryptor.decrypt(value.substring(4, value.length() - 1));
    }
    return value;
}