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package apollo.spring.boot;

import apollo.Config;
import apollo.ConfigService;
import apollo.spring.config.ConfigPropertySourceFactory;
import apollo.spring.config.PropertySourcesConstants;
import apollo.spring.util.SpringInjector;
import com.google.common.base.Splitter;
import com.google.common.base.Strings;
import framework.apollo.core.ConfigConsts;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.env.EnvironmentPostProcessor;
import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.env.CompositePropertySource;
import org.springframework.core.env.ConfigurableEnvironment;

import java.util.List;

/**
 * Initialize apollo system properties and inject the Apollo config in Spring Boot bootstrap phase
 *
 * Configuration example:
 *  *   # set app.id
 *   app.id = 100004458
 *   # enable apollo bootstrap config and inject 'application' appNamespace in bootstrap phase
 *   apollo.bootstrap.enabled = true
 * 
 *
 * or
 *
 *  *   # set app.id
 *   app.id = 100004458
 *   # enable apollo bootstrap config
 *   apollo.bootstrap.enabled = true
 *   # will inject 'application' and 'FX.apollo' namespaces in bootstrap phase
 *   apollo.bootstrap.namespaces = application,FX.apollo
 * 
 *
 *
 * If you want to load Apollo configurations even before Logging System Initialization Phase,
 *  add
 *  *   # set apollo.bootstrap.eagerLoad.enabled
 *   apollo.bootstrap.eagerLoad.enabled = true
 * 
 *
 *  This would be very helpful when your logging configurations is set by Apollo.
 *
 *  for example, you have defined logback-spring.xml in your project, and you want to inject some attributes into logback-spring.xml.
 *
 */
public class ApolloApplicationContextInitializer implements
        ApplicationContextInitializer, EnvironmentPostProcessor {
  private static final Logger logger = LoggerFactory.getLogger(ApolloApplicationContextInitializer.class);
  private static final Splitter NAMESPACE_SPLITTER = Splitter.on(",").omitEmptyStrings().trimResults();
  private static final String[] APOLLO_SYSTEM_PROPERTIES = {"app.id", ConfigConsts.APOLLO_CLUSTER_KEY,
      "apollo.cacheDir", ConfigConsts.APOLLO_META_KEY};

  private final ConfigPropertySourceFactory configPropertySourceFactory = SpringInjector
      .getInstance(ConfigPropertySourceFactory.class);

  @Override
  public void initialize(ConfigurableApplicationContext context) {
    ConfigurableEnvironment environment = context.getEnvironment();

    String enabled = environment.getProperty(PropertySourcesConstants.APOLLO_BOOTSTRAP_ENABLED, "false");
    if (!Boolean.valueOf(enabled)) {
      logger.debug("Apollo bootstrap config is not enabled for context {}, see property: ${{}}", context, PropertySourcesConstants.APOLLO_BOOTSTRAP_ENABLED);
      return;
    }
    logger.debug("Apollo bootstrap config is enabled for context {}", context);

    initialize(environment);
  }


  /**
   * Initialize Apollo Configurations Just after environment is ready.
   *
   * @param environment
   */
  protected void initialize(ConfigurableEnvironment environment) {

    if (environment.getPropertySources().contains(PropertySourcesConstants.APOLLO_BOOTSTRAP_PROPERTY_SOURCE_NAME)) {
      //already initialized
      return;
    }

    String namespaces = environment.getProperty(PropertySourcesConstants.APOLLO_BOOTSTRAP_NAMESPACES, ConfigConsts.NAMESPACE_APPLICATION);
    logger.debug("Apollo bootstrap namespaces: {}", namespaces);
    List namespaceList = NAMESPACE_SPLITTER.splitToList(namespaces);

    //获取到所有这个app的优先启动的namespace

    CompositePropertySource composite = new CompositePropertySource(PropertySourcesConstants.APOLLO_BOOTSTRAP_PROPERTY_SOURCE_NAME);
    for (String namespace : namespaceList) {
      Config config = ConfigService.getConfig(namespace);

      composite.addPropertySource(configPropertySourceFactory.getConfigPropertySource(namespace, config));
    }

    environment.getPropertySources().addFirst(composite);
  }

  /**
   * To fill system properties from environment config
   */
  void initializeSystemProperty(ConfigurableEnvironment environment) {
    for (String propertyName : APOLLO_SYSTEM_PROPERTIES) {
      fillSystemPropertyFromEnvironment(environment, propertyName);
    }
  }

  private void fillSystemPropertyFromEnvironment(ConfigurableEnvironment environment, String propertyName) {
    if (System.getProperty(propertyName) != null) {
      return;
    }

    String propertyValue = environment.getProperty(propertyName);

    if (Strings.isNullOrEmpty(propertyValue)) {
      return;
    }

    System.setProperty(propertyName, propertyValue);
  }

  /**
   *
   * In order to load Apollo configurations as early as even before Spring loading logging system phase,
   * this EnvironmentPostProcessor can be called Just After ConfigFileApplicationListener has succeeded.
   *
   * 

   * The processing sequence would be like this: 

   * Load Bootstrap properties and application properties -----> load Apollo configuration properties ----> Initialize Logging systems
   *
   * @param configurableEnvironment
   * @param springApplication
   */
  @Override
  public void postProcessEnvironment(ConfigurableEnvironment configurableEnvironment, SpringApplication springApplication) {

    // should always initialize system properties like app.id in the first place
    initializeSystemProperty(configurableEnvironment);

    Boolean eagerLoadEnabled = configurableEnvironment.getProperty(PropertySourcesConstants.APOLLO_BOOTSTRAP_EAGER_LOAD_ENABLED, Boolean.class, false);

    //EnvironmentPostProcessor should not be triggered if you don't want Apollo Loading before Logging System Initialization
    if (!eagerLoadEnabled) {
      return;
    }

    Boolean bootstrapEnabled = configurableEnvironment.getProperty(PropertySourcesConstants.APOLLO_BOOTSTRAP_ENABLED, Boolean.class, false);

    if (bootstrapEnabled) {
      initialize(configurableEnvironment);
    }

  }
}