package com.meltmedia.jgroups.aws;
   
   import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
   import com.fasterxml.jackson.annotation.JsonProperty;
   import com.fasterxml.jackson.databind.ObjectMapper;
   import org.apache.http.HttpResponse;
   import org.apache.http.HttpStatus;
   import org.apache.http.client.HttpClient;
   import org.apache.http.client.methods.HttpGet;
  import org.apache.http.util.EntityUtils;
  
  import java.io.IOException;
  import java.net.URI;
  import java.net.URISyntaxException;
  import java.util.Objects;
  
  @JsonIgnoreProperties(ignoreUnknown = true)
  public class InstanceIdentity {
    private static String INSTANCE_IDENTITY_URL = "http://instance-data/latest/dynamic/instance-identity/document";
    private static URI INSTANCE_IDENTITY_URI;
  
    static {
      try {
        INSTANCE_IDENTITY_URI = new URI(INSTANCE_IDENTITY_URL);
      } catch (URISyntaxException e) {
        throw new RuntimeException("this should never happen");
      }
    }
  
  
    public final String availabilityZone;
    public final String privateIp;
    public final String instanceId;
    public final String instanceType;
    public final String imageId;
    public final String architecture;
    public final String region;
  
    public InstanceIdentity(
        @JsonProperty("availabilityZone") final String availabilityZone,
        @JsonProperty("privateIp") final String privateIp,
        @JsonProperty("instanceId") final String instanceId,
        @JsonProperty("instanceType") final String instanceType,
        @JsonProperty("imageId") final String imageId,
        @JsonProperty("architecture") final String architecture,
        @JsonProperty("region") final String region) {
      this.availabilityZone = Objects.requireNonNull(availabilityZone, "availabilityZone cannot be null");
      this.privateIp = Objects.requireNonNull(privateIp, "privateIp cannot be null");
      this.instanceId = Objects.requireNonNull(instanceId, "instanceId cannot be null");
      this.instanceType = Objects.requireNonNull(instanceType, "instanceType cannot be null");
      this.imageId = Objects.requireNonNull(imageId, "imageId cannot be null");
      this.architecture = Objects.requireNonNull(architecture, "architecture cannot be null");
      this.region = Objects.requireNonNull(region, "region cannot be null");
    }
  
    public static InstanceIdentity getIdentity(final HttpClient client) throws IOException {
      return new ObjectMapper().readValue(getIdentityDocument(client), InstanceIdentity.class);
    }
  
    /**
     * Gets the body of the content returned from a GET request to uri.
     *
     * @param client
     * @return the body of the message returned from the GET request.
     * @throws IOException if there is an error encountered while getting the content.
     */
    private static String getIdentityDocument(final HttpClient client) throws IOException {
      try {
        final HttpGet getInstance = new HttpGet();
        getInstance.setURI(INSTANCE_IDENTITY_URI);
        final HttpResponse response = client.execute(getInstance);
        if (response.getStatusLine().getStatusCode() != HttpStatus.SC_OK) {
          throw new IOException("failed to get instance identity, tried: " + INSTANCE_IDENTITY_URL + ", response: " + response.getStatusLine().getReasonPhrase());
        }
        return EntityUtils.toString(response.getEntity());
      } catch (Exception e) {
        throw new IOException("failed to get instance identity", e);
      }
    }
  }