// Copyright 2017 The Nomulus Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package google.registry.flows;

import static com.google.common.io.BaseEncoding.base64;
import static google.registry.xml.XmlTransformer.prettyPrint;
import static java.util.Collections.EMPTY_LIST;

import com.google.common.base.Ascii;
import com.google.common.base.Optional;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import google.registry.flows.FlowModule.ClientId;
import google.registry.flows.FlowModule.InputXml;
import google.registry.flows.annotations.ReportingSpec;
import google.registry.model.eppcommon.Trid;
import google.registry.model.eppinput.EppInput;
import google.registry.util.FormattingLogger;
import javax.inject.Inject;
import org.json.simple.JSONValue;

/** Reporter used by {@link FlowRunner} to record flow execution data for reporting. */
public class FlowReporter {

  /**
   * Log signature for recording flow EPP input data.
   *
   * <p><b>WARNING:<b/> DO NOT CHANGE this value unless you want to break reporting.
   */
  private static final String EPPINPUT_LOG_SIGNATURE = "FLOW-LOG-SIGNATURE-EPPINPUT";

  /**
   * Log signature for recording flow metadata (anything beyond or derived from the raw EPP input).
   *
   * <p><b>WARNING:<b/> DO NOT CHANGE this value unless you want to break reporting.
   */
  private static final String METADATA_LOG_SIGNATURE = "FLOW-LOG-SIGNATURE-METADATA";

  private static final FormattingLogger logger = FormattingLogger.getLoggerForCallerClass();

  @Inject Trid trid;
  @Inject @ClientId String clientId;
  @Inject @InputXml byte[] inputXmlBytes;
  @Inject EppInput eppInput;
  @Inject Class<? extends Flow> flowClass;
  @Inject FlowReporter() {}

  /** Records information about the current flow execution in the GAE request logs. */
  public void recordToLogs() {
    // WARNING: These log statements are parsed by reporting pipelines - be careful when changing.
    // It should be safe to add new keys, but be very cautious in changing existing keys.
    logger.infofmt(
        "%s: %s",
        EPPINPUT_LOG_SIGNATURE,
        JSONValue.toJSONString(ImmutableMap.<String, Object>of(
            "xml", prettyPrint(inputXmlBytes),
            "xmlBytes", base64().encode(inputXmlBytes))));
    // Explicitly log flow metadata separately from the EPP XML itself so that it stays compact
    // enough to be sure to fit in a single log entry (the XML part in rare cases could be long
    // enough to overflow into multiple log entries, breaking routine parsing of the JSON format).
    String resourceType = eppInput.getResourceType().or("");
    boolean isDomain = "domain".equals(resourceType);
    String singleTargetId = eppInput.getSingleTargetId().or("");
    ImmutableList<String> targetIds = eppInput.getTargetIds();
    logger.infofmt(
        "%s: %s",
        METADATA_LOG_SIGNATURE,
        JSONValue.toJSONString(new ImmutableMap.Builder<String, Object>()
            .put("serverTrid", trid.getServerTransactionId())
            .put("clientId", clientId)
            .put("commandType", eppInput.getCommandType())
            .put("resourceType", resourceType)
            .put("flowClassName", flowClass.getSimpleName())
            .put("targetId", singleTargetId)
            .put("targetIds", targetIds)
            .put("tld", isDomain ? extractTld(singleTargetId).or("") : "")
            .put("tlds", isDomain ? extractTlds(targetIds).asList() : EMPTY_LIST)
            .put("icannActivityReportField", extractActivityReportField(flowClass))
            .build()));
  }

  /**
   * Returns the guessed TLD of the given domain name, assuming a second-level domain name, or
   * absent if no TLD could be detected.
   *
   * <p>This method is quick and dirty and doesn't attempt to validate the domain name in any way;
   * it just takes anything after the first period to be the TLD and converts ASCII to lowercase.
   * We want quick and dirty here because this will be called on not-yet-validated EPP XML where
   * just about anything could be supplied, and there's no reason to validate twice when this just
   * needs to be roughly correct.
   */
  private static final Optional<String> extractTld(String domainName) {
    int index = domainName.indexOf('.');
    return index == -1
        ? Optional.<String>absent()
        : Optional.of(Ascii.toLowerCase(domainName.substring(index + 1)));
  }

  /**
   * Returns the set of unique results of {@link #extractTld} applied to each given domain name,
   * excluding any absent results (i.e. cases where no TLD was detected).
   */
  private static final ImmutableSet<String> extractTlds(Iterable<String> domainNames) {
    ImmutableSet.Builder<String> set = new ImmutableSet.Builder<>();
    for (String domainName : domainNames) {
      Optional<String> extractedTld = extractTld(domainName);
      if (extractedTld.isPresent()) {
        set.add(extractedTld.get());
      }
    }
    return set.build();
  }

  /**
   * Returns the ICANN activity report field for the given flow class, or the empty string if no
   * activity report field specification is found.
   */
  private static final String extractActivityReportField(Class<? extends Flow> flowClass) {
    ReportingSpec reportingSpec = flowClass.getAnnotation(ReportingSpec.class);
    if (reportingSpec != null) {
      return reportingSpec.value().getFieldName();
    }
    return "";
  }
}