/*
 * Copyright (c) 2011-2016 The original author or authors
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Apache License v2.0 which accompanies this distribution.
 *
 *      The Eclipse Public License is available at
 *      http://www.eclipse.org/legal/epl-v10.html
 *
 *      The Apache License v2.0 is available at
 *      http://www.opensource.org/licenses/apache2.0.php
 *
 * You may elect to redistribute this code under either of these licenses.
 */

package io.vertx.servicediscovery.docker;

import io.vertx.core.CompositeFuture;
import io.vertx.core.Future;
import io.vertx.core.Handler;
import io.vertx.core.Promise;
import io.vertx.core.Vertx;
import io.vertx.core.json.JsonObject;
import io.vertx.core.logging.Logger;
import io.vertx.core.logging.LoggerFactory;
import io.vertx.servicediscovery.Record;
import io.vertx.servicediscovery.spi.ServiceImporter;
import io.vertx.servicediscovery.spi.ServicePublisher;
import io.vertx.servicediscovery.spi.ServiceType;
import io.vertx.servicediscovery.types.HttpEndpoint;
import io.vertx.servicediscovery.types.HttpLocation;

import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

A discovery bridge analyzing environment variables to detect Docker links. It imports found links as services in
the discovery infrastructure. As they are mapped from environment variable the set of imported service does not
change after the initialization.
Author:
Clement Escoffier/**
 * A discovery bridge analyzing environment variables to detect Docker links. It imports found links as services in
 * the discovery infrastructure. As they are mapped from environment variable the set of imported service does not
 * change after the initialization.
 *
 * @author <a href="http://escoffier.me">Clement Escoffier</a>
 */
public class DockerLinksServiceImporter implements ServiceImporter {
  
The service discovery instance. Immutable once set.
/**
   * The service discovery instance. Immutable once set.
   */
  private ServicePublisher publisher;

  
The list of records that are imported. Content staled once initialized.
/**
   * The list of records that are imported. Content staled once initialized.
   */
  private List<Record> records = new ArrayList<>();

  private final static Logger LOGGER = LoggerFactory.getLogger(DockerLinksServiceImporter.class);

  @Override
  public void start(Vertx vertx, ServicePublisher publisher, JsonObject configuration,
                    Promise<Void> completion) {
    this.publisher = publisher;

    synchronized (this) {
      lookup(completion);
    }
  }

  private void lookup(Promise<Void> completion) {
    Map<String, String> variables = getVariables();

    // Find names
    List<String> links = variables.keySet().stream()
        .filter(key -> key.endsWith("_NAME"))
        .map(key -> extractLinkName(key, variables))
        .filter(key -> key != null)
        .collect(Collectors.toList());

    LOGGER.info("Docker links: " + links);

    for (String link : links) {
      try {
        Record record = createRecord(link,
            variables.entrySet().stream()
                .filter(entry -> entry.getKey().startsWith(link + "_"))
                .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue)));

        LOGGER.info("Record created from link " + link + " : " + record);
        publisher.publish(record, ar -> {
          if (ar.succeeded()) {
            records.add(ar.result());
            LOGGER.info("Service imported from Docker link : " + link + " with endpoint set to "
                + ar.result().getLocation().getString(Record.ENDPOINT));
          } else {
            LOGGER.error("Publication of the docker link " + link + " as a service failed", ar.cause());
          }
        });
      } catch (URISyntaxException e) {
        if (completion != null) {
          completion.fail(e);
        } else {
          throw new IllegalStateException("Cannot extract service record from variables for " + link, e);
        }
      }
    }

    if (completion != null) {
      completion.complete();
    }
  }

  private String extractLinkName(String key, Map<String, String> variables) {
    // We know it ends with _NAME;
    String name = key.substring(0, key.length() - "_NAME".length());
    if (name.isEmpty()) {
      // Weird case the key is just _NAME
      return null;
    } else {
      String port = name + "_PORT";
      if (variables.containsKey(port)) {
        return name;
      } else {
        // Not a valid link
        return null;
      }
    }
  }

  private Map<String, String> getVariables() {
    LinkedHashMap<String, String> vars = new LinkedHashMap<>();
    vars.putAll(System.getenv());
    System.getProperties().entrySet().forEach(entry ->
        vars.put(entry.getKey().toString(), entry.getValue().toString()));
    return vars;
  }

  @Override
  public void close(Handler<Void> completionHandler) {
    List<Future> list = new ArrayList<>();
    for (Record record : records) {
      publisher.unpublish(record.getRegistration(),
          v -> list.add(v.succeeded() ? Future.succeededFuture() : Future.failedFuture(v.cause())));
    }

    CompositeFuture.all(list).setHandler(ar -> {
          if (ar.succeeded()) {
            LOGGER.info("Successfully closed the service importer " + this);
          } else {
            LOGGER.error("A failure has been caught while stopping " + this, ar.cause());
          }
          if (completionHandler != null) {
            completionHandler.handle(null);
          }
        }
    );
  }

  private Record createRecord(String name, Map<String, String> variables) throws URISyntaxException {
    Record record = new Record()
        .setName(name);

    // Add as metadata all entries
    variables.entrySet().forEach(entry -> {
      if (entry.getKey().startsWith(name + "_")) {
        String label = entry.getKey().substring((name + "_").length());
        record.getMetadata().put(label, entry.getValue());
      }
    });

    String type = variables.get(name + "_ENV_SERVICE_TYPE");
    if (type == null) {
      type = ServiceType.UNKNOWN;
    } else {
      LOGGER.info("Service type for " + name + " : " + type);
    }

    URI url = new URI(variables.get(name + "_PORT"));
    switch (type) {
      case "http-endpoint":
        HttpLocation http = new HttpLocation();
        http.setHost(url.getHost());
        http.setPort(url.getPort());
        if (isTrue(variables, name + "_ENV_SSL")) {
          http.setSsl(true);
        }
        record.setType(HttpEndpoint.TYPE);
        record.setLocation(http.toJson());
        break;
      default:
        JsonObject location = new JsonObject();
        location
            .put("endpoint", url.toString())
            .put("port", url.getPort())
            .put("host", url.getHost())
            .put("proto", url.getScheme());
        record.setType(type);
        record.setLocation(location);
    }

    return record;
  }

  private static boolean isTrue(Map<String, String> labels, String key) {
    return labels != null && "true".equalsIgnoreCase(labels.get(key));
  }
}