// 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.module.backend;

import static google.registry.model.registry.Registries.assertTldExists;
import static google.registry.model.registry.Registries.assertTldsExist;
import static google.registry.request.RequestParameters.extractOptionalDatetimeParameter;
import static google.registry.request.RequestParameters.extractOptionalParameter;
import static google.registry.request.RequestParameters.extractRequiredParameter;
import static google.registry.request.RequestParameters.extractSetOfParameters;

import com.google.common.collect.ImmutableSet;
import dagger.Module;
import dagger.Provides;
import google.registry.batch.ExpandRecurringBillingEventsAction;
import google.registry.request.HttpException.BadRequestException;
import google.registry.request.Parameter;
import google.registry.request.RequestParameters;
import google.registry.util.Clock;
import java.util.Optional;
import javax.servlet.http.HttpServletRequest;
import org.joda.time.DateTime;
import org.joda.time.YearMonth;
import org.joda.time.format.DateTimeFormat;
import org.joda.time.format.DateTimeFormatter;

/**
 * Dagger module for injecting common settings for all Backend tasks.
 */
@Module
public class BackendModule {

  private static final String PARAM_YEAR_MONTH = "yearMonth";

  @Provides
  @Parameter(RequestParameters.PARAM_TLD)
  static String provideTld(HttpServletRequest req) {
    return assertTldExists(extractRequiredParameter(req, RequestParameters.PARAM_TLD));
  }

  @Provides
  @Parameter(RequestParameters.PARAM_TLD)
  static ImmutableSet<String> provideTlds(HttpServletRequest req) {
    ImmutableSet<String> tlds = extractSetOfParameters(req, RequestParameters.PARAM_TLD);
    assertTldsExist(tlds);
    return tlds;
  }

  @Provides
  @Parameter("cursorTime")
  static Optional<DateTime> provideCursorTime(HttpServletRequest req) {
    return extractOptionalDatetimeParameter(
        req, ExpandRecurringBillingEventsAction.PARAM_CURSOR_TIME);
  }

  /** Extracts an optional YearMonth in yyyy-MM format from the request. */
  @Provides
  @Parameter(PARAM_YEAR_MONTH)
  static Optional<YearMonth> provideYearMonthOptional(HttpServletRequest req) {
    DateTimeFormatter formatter = DateTimeFormat.forPattern("yyyy-MM");
    Optional<String> optionalYearMonthStr = extractOptionalParameter(req, PARAM_YEAR_MONTH);
    try {
      return optionalYearMonthStr.map(s -> YearMonth.parse(s, formatter));
    } catch (IllegalArgumentException e) {
      throw new BadRequestException(
          String.format(
              "yearMonth must be in yyyy-MM format, got %s instead",
              optionalYearMonthStr.orElse("UNSPECIFIED YEARMONTH")));
    }
  }

  /**
   * Provides the yearMonth in yyyy-MM format, if not specified in the request, defaults to one
   * month prior to run time.
   */
  @Provides
  static YearMonth provideYearMonth(
      @Parameter(PARAM_YEAR_MONTH) Optional<YearMonth> yearMonthOptional, Clock clock) {
    return yearMonthOptional.orElseGet(() -> new YearMonth(clock.nowUtc().minusMonths(1)));
  }
}