/*
    * 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 org.basepom.mojo.propertyhelper.definitions;
  
  import static com.google.common.base.Preconditions.checkNotNull;
  
  import org.basepom.mojo.propertyhelper.FieldContext;
  import org.basepom.mojo.propertyhelper.ValueCache;
  import org.basepom.mojo.propertyhelper.ValueProvider;
  import org.basepom.mojo.propertyhelper.fields.DateField;
  
  import java.io.IOException;
  import java.time.Instant;
  import java.time.ZoneId;
  import java.time.ZonedDateTime;
  import java.time.format.DateTimeFormatter;
  import java.time.format.DateTimeParseException;
  import java.util.Optional;
  import java.util.StringJoiner;
  import java.util.function.Function;
  
  import com.google.common.annotations.VisibleForTesting;
  
  public class DateDefinition extends FieldDefinition<ZonedDateTime> {
  
      /**
       * Timezone for this date. Field injected by Maven.
       */
      String timezone = null;
  
      /**
       * Value for this date. Field injected by Maven.
       */
      Long value = null;
  
      public DateDefinition() {
      }
  
      @VisibleForTesting
      DateDefinition(String id) {
          super(id);
      }
  
      public ZoneId getTimezone() {
          return Optional.ofNullable(timezone)
              .map(ZoneId::of)
              .orElse(ZoneId.systemDefault());
      }
  
      public Optional<Long> getValue() {
          return Optional.ofNullable(value);
      }
  
      @Override
      public DateField createField(FieldContext context, ValueCache valueCache) throws IOException {
          checkNotNull(context, "context is null");
          checkNotNull(valueCache, "valueCache is null");
  
          check();
  
          final ValueProvider dateValue = valueCache.getValueProvider(this);
          return new DateField(this, dateValue, context);
      }
  
      @Override
      public Function<ZonedDateTime, String> getPreFormat() {
          DateTimeFormatter dateTimeFormatter = getFormatter().orElseGet(this::getFallbackFormatter);
          return v -> v == null ? "" : dateTimeFormatter.format(v);
      }
  
      @Override
      public Function<String, String> getPostFormat() {
          return Function.identity();
      }
  
      public Function<String, ZonedDateTime> getParser() {
          return value -> getFormatter().map(f -> {
              try {
                  return ZonedDateTime.parse(value, f);
              } catch (DateTimeParseException e) {
                  return null;
              }
          }).orElseGet(() -> parseLong(value).map(getLongParser())
              .orElseGet(() -> ZonedDateTime.parse(value, getFallbackFormatter())));
      }
  
      private Optional<Long> parseLong(String value) {
         try {
             return Optional.of(Long.parseLong(value));
         } catch (NumberFormatException e) {
             return Optional.empty();
         }
     }
 
     public Function<Long, ZonedDateTime> getLongParser() {
         return longValue -> ZonedDateTime.ofInstant(Instant.ofEpochMilli(longValue), getTimezone());
     }
 
     public Optional<DateTimeFormatter> getFormatter() {
         return Optional.ofNullable(format)
             .map(DateTimeFormatter::ofPattern)
             .map(formatter -> formatter.withZone(getTimezone()));
     }
 
     public DateTimeFormatter getFallbackFormatter() {
         return DateTimeFormatter.ISO_DATE_TIME.withZone(getTimezone());
     }
 
     @Override
     public String toString() {
         return new StringJoiner(", ", DateDefinition.class.getSimpleName() + "[", "]")
             .add("timezone='" + timezone + "'")
             .add("value=" + value)
             .add(super.toString())
             .toString();
     }
 }