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package com.appcrossings.config;

import java.net.InetAddress;
import java.net.UnknownHostException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.EnvironmentAware;
import org.springframework.core.env.Environment;
import org.springframework.util.StringUtils;

import com.google.common.base.Throwables;

public class EnvironmentUtil implements EnvironmentAware {

  private final static Logger log = LoggerFactory.getLogger(EnvironmentUtil.class);
  protected Environment springProfiles;
  protected String environmentName;
  protected String hostName;

  /**
   * Attempt to detect environment of the application.
   * 
   * @return environment string
   */
  public String detectEnvironment() {

    String env = this.environmentName; // initialize to configured environment

    if (StringUtils.isEmpty(env)) {

      if (springProfiles != null && springProfiles.getActiveProfiles() != null
          && springProfiles.getActiveProfiles().length > 0) {
        env = springProfiles.getActiveProfiles()[0];
      }

      env = StringUtils.hasText(env) ? env : System.getProperty("env");
      env = StringUtils.hasText(env) ? env : System.getProperty("ENV");
      env = StringUtils.hasText(env) ? env : System.getProperty("environment");
      env = StringUtils.hasText(env) ? env : System.getProperty("ENVIRONMENT");

      if (!StringUtils.hasText(env)) {
        log.info("No environment variable detected under 'spring.profiles' or system properties 'env', 'ENV', 'environment', 'ENVIRONMENT'");
      } else {
        log.info("Detected environment: " + env);
      }
    }

    return env;
  }

  /**
   * Reads the underlying host's name. This is used to match this host against its configuration.
   * You can programmatically override the hostname value by setting System.setProperty("hostname",
   * "value").
   * 
   * @return hostname
   */
  public String detectHostName() {

    String hostName = this.hostName; // initialize to configured host name

    if (StringUtils.isEmpty(hostName)) {

      try {

        hostName =
            StringUtils.hasText(System.getProperty("hostname")) ? System.getProperty("hostname")
                : InetAddress.getLocalHost().getHostName();

        hostName = StringUtils.hasText(hostName) ? hostName : System.getProperty("HOSTNAME");

        if (!StringUtils.hasText(hostName)) {
          throw new UnknownHostException(
              "Unable to resolve host in order to resolve hosts file config. Searched system property 'hostname', 'HOSTNAME' and localhost.hostName");
        }

        if (hostName.contains(".")) {
          hostName = hostName.substring(0, hostName.indexOf("."));
        }

        log.info("Resolved hostname to: " + hostName);

      } catch (UnknownHostException ex) {
        log.error("Can't resolve hostname", ex);
        Throwables.propagate(ex);
      }
    }

    return hostName;
  }

  public void setHostName(String hostName) {
    this.hostName = hostName;
  }

  public void setEnvironmentName(String environmentName) {
    this.environmentName = environmentName;
  }

  @Override
  public void setEnvironment(Environment environment) {
    this.springProfiles = environment;
  }

}