/**
    * This file Copyright (c) 2017-2018 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.rest.delivery.jcr;
  
  import static info.magnolia.rest.delivery.jcr.Operator.*;
  import static java.util.stream.Collectors.joining;
  
  import java.time.LocalDate;
  import java.time.LocalTime;
  import java.time.ZoneId;
  import java.time.ZonedDateTime;
  import java.time.format.DateTimeFormatter;
  import java.time.format.DateTimeParseException;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  import java.util.stream.Collectors;
  
  import javax.ws.rs.BadRequestException;
  
  import org.apache.commons.lang3.StringUtils;
  import org.apache.commons.lang3.math.NumberUtils;
  
  /**
   * This class is used to get filtering condition SQL.
   */
  public class FilteringCondition {
  
      private static final String NAME_PROPERTY = "@name";
      private static final String PARENT_PROPERTY = "@ancestor";
  
      static final DateTimeFormatter DATE_TIME_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");
      static final DateTimeFormatter DATE_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd");
  
      private static final String VALUES_SPLITTER = "\\|";
  
      private static final String OPERATOR_OPEN = "[";
      private static final String OPERATOR_CLOSE = "]";
  
      private static final String RANGE_SYMBOL = "~";
  
      private final String INVALID_VALUE_STRING = "Value string is invalid.";
  
      private final String property;
      private final Operator operator;
      private final String[] values;
  
      private boolean isDateQuery = false;
  
      /**
       * Ranges are inclusive.
       * For example, "price[in]=100~200" is translated into "price >= 100 AND price <= 200".
       */
      private final List<String[]> rangeValues;
  
      public FilteringCondition(String propertyString, String valueString) {
          if (StringUtils.isEmpty(propertyString)) {
              throw new IllegalArgumentException("Property string is invalid.");
          }
  
          operator = extractOperator(propertyString);
          property = StringUtils.substringBeforeLast(propertyString, OPERATOR_OPEN);
          values = valueString.split(VALUES_SPLITTER);
  
          validateValueString();
  
          isDateQuery = isDateQuery();
  
         if (isDateQuery) {
             rangeValues = extractDateRangeValues(values);
         } else {
             rangeValues = extractRangeValues(values);
         }
     }
 
     private void validateValueString() {
         // If any value containing range symbol but not having enough 2 bounds, exception thrown.
         if (Arrays.stream(values)
                 .anyMatch(value -> value.contains(RANGE_SYMBOL)
                         && value.split(RANGE_SYMBOL).length != 2)) {
             throw new BadRequestException(INVALID_VALUE_STRING);
         }
 
         // If date and range of dates are mixed, exception thrown.
         if (Arrays.stream(values)
                 .anyMatch(value -> dateMatches(DATE_FORMATTER, value))
                 && Arrays.stream(values)
                 .anyMatch(value -> value.contains(RANGE_SYMBOL))) {
             throw new BadRequestException(INVALID_VALUE_STRING);
         }
     }
 
     private List<String[]> extractDateRangeValues(String[] values) {
         List<String[]> rangeValues = new ArrayList<>();
         for (String value : values) {
             if (value.contains(RANGE_SYMBOL)) {
                 String[] bounds = value.split(RANGE_SYMBOL);
                 rangeValues.add(bounds);
             } else {
                 String[] bounds = new String[] { value, value };
                 rangeValues.add(bounds);
             }
         }
         return rangeValues;
     }
 
     private boolean isDateQuery() {
         // If all values are dates, the condition is a date query.
         if (Arrays.stream(values)
                 .allMatch(value -> dateMatches(DATE_FORMATTER, value))) {
             return true;
         }
 
         // If any value having invalid range value, the condition is not a date query.
         for (String value : values) {
             if (Arrays.stream(value.split(RANGE_SYMBOL))
                     .anyMatch(bound -> !dateMatches(DATE_FORMATTER, bound))) {
                 return false;
             }
         }
 
         return true;
     }
 
     private Operator extractOperator(String propertyString) {
         if (!propertyString.contains(OPERATOR_OPEN) && !propertyString.contains(OPERATOR_CLOSE)) {
             return Operator.EQ;
         }
         return Operator.from(StringUtils.substringBetween(propertyString, OPERATOR_OPEN, OPERATOR_CLOSE));
     }
 
     private List<String[]> extractRangeValues(String[] values) {
         return Arrays.stream(values)
                 .map(value -> value.split(RANGE_SYMBOL))
                 .filter(bounds -> bounds.length == 2)
                 .collect(Collectors.toList());
     }
 
     public String asSqlString() {
         if (operator == NULL) {
             return String.format("[%s] IS %sNULL", property, "true".equalsIgnoreCase(values[0]) ? "" : "NOT ");
         }
 
         if (isDateQuery) {
             return rangeValues.stream()
                     .map(this::getDateConditionClause)
                     .collect(joining(" OR "));
         }
         if (operator == IN) {
             return rangeValues.stream()
                     .map(this::getInConditionClause)
                     .collect(joining(" OR "));
         }
         if (operator == NOT_IN) {
             return rangeValues.stream()
                     .map(this::getNotInConditionClause)
                     .collect(joining(" OR "));
         }
         return Arrays.stream(values)
                 .map(this::getConditionClause)
                 .collect(joining(" OR "));
     }
 
     private String getInConditionClause(String[] bounds) {
         return String.format("[%s] >= %s AND [%s] <= %s", property, resolveValue(bounds[0]), property, resolveValue(bounds[1]));
     }
 
     private String getNotInConditionClause(String[] bounds) {
         return String.format("[%s] < %s OR [%s] > %s", property, resolveValue(bounds[0]), property, resolveValue(bounds[1]));
     }
 
     private String getDateConditionClause(String[] bounds) {
         switch (operator) {
         case GT:
             rangeIsNotSupported(bounds);
             return String.format("[%s] > %s", property, resolveDateValue(bounds[0], true));
         case LT:
             rangeIsNotSupported(bounds);
             return String.format("[%s] < %s", property, resolveDateValue(bounds[0], false));
         case GTE:
             rangeIsNotSupported(bounds);
             return String.format("[%s] >= %s", property, resolveDateValue(bounds[0], false));
         case LTE:
             rangeIsNotSupported(bounds);
             return String.format("[%s] <= %s", property, resolveDateValue(bounds[0], true));
         case NE:
             rangeIsNotSupported(bounds);
             return String.format("[%s] < %s OR [%s] > %s", property, resolveDateValue(bounds[0], false),
                     property, resolveDateValue(bounds[0], true));
         default:
             String lowerBound = resolveDateValue(bounds[0], false);
             String upperBound = resolveDateValue(bounds[1], true);
 
             if (operator == IN) {
                 return String.format("[%s] >= %s AND [%s] <= %s", property, lowerBound, property, upperBound);
             } else if (operator == NOT_IN) {
                 return String.format("[%s] < %s OR [%s] > %s", property, lowerBound, property, upperBound);
             }
 
             rangeIsNotSupported(bounds);
             return String.format("[%s] >= %s AND [%s] <= %s", property, lowerBound, property, upperBound);
         }
     }
 
     private void rangeIsNotSupported(String[] bounds) {
         if (bounds.length == 2 && !bounds[0].equals(bounds[1])) {
             throw new BadRequestException("Range is not supported.");
         }
     }
 
     private String getConditionClause(String value) {
         if (PARENT_PROPERTY.equalsIgnoreCase(property)) {
             return String.format("ISDESCENDANTNODE('%s')", value);
         }
 
         /**
          * By testing, "LOCALNAME" must go with "LIKE" to give correct results.
          * This use of "LIKE" is equivalent to "=".
          */
         if (NAME_PROPERTY.equalsIgnoreCase(property)) {
             return String.format("LOWER(LOCALNAME(t)) LIKE '%s'", value);
         }
 
         return String.format("[%s] %s %s", property, operator.asSqlString(), resolveValue(value));
     }
 
     private String resolveValue(String value) {
         if (NumberUtils.isNumber(value)) {
             return value;
         }
 
         if (dateMatches(DATE_TIME_FORMATTER, value)) {
             return String.format("CAST('%s' AS DATE)", value);
         }
 
         // Remove the escape characters, treat as String.
         if (value.startsWith("\"") && value.endsWith("\"")) {
             value = value.substring(1, value.length() - 1);
         }
 
         return String.format("'%s'", value);
     }
 
     private String resolveDateValue(String value, boolean upperBound) {
         if (dateMatches(DATE_FORMATTER, value)) {
             if (upperBound) {
                 return String.format("CAST('%s' AS DATE)", getEndOfDay(value));
             } else {
                 return String.format("CAST('%s' AS DATE)", getBeginningOfDay(value));
             }
         }
         return String.format("CAST('%s' AS DATE)", value);
     }
 
     private boolean dateMatches(DateTimeFormatter dateTimeFormatter, String value) {
         try {
             dateTimeFormatter.parse(value);
             return true;
         } catch (DateTimeParseException e) {
             return false;
         }
     }
 
     private static String getBeginningOfDay(String date) {
         LocalDate localDate = LocalDate.parse(date, DATE_FORMATTER);
         ZonedDateTime zonedDateTime = localDate.atStartOfDay(ZoneId.systemDefault());
         return zonedDateTime.format(DATE_TIME_FORMATTER);
     }
 
     private static String getEndOfDay(String date) {
         LocalDate localDate = LocalDate.parse(date, DATE_FORMATTER);
         ZonedDateTime zonedDateTime = localDate.atTime(LocalTime.MAX).atZone(ZoneId.systemDefault());
         return zonedDateTime.format(DATE_TIME_FORMATTER);
     }
 
     @Override
     public String toString() {
         return asSqlString();
     }
 }