/**
    * Copyright 2005-2011 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.rice.krad.service.impl;
  
  import org.kuali.rice.core.api.criteria.Predicate;
  import org.kuali.rice.core.api.search.SearchOperator;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  import java.util.Map;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import static org.kuali.rice.core.api.criteria.PredicateFactory.*;
  
  /**
   * Contains methods used in the predicate factory related to the lookup framework.
   * ***************************************************************************************************************
   * FIXME: issues to talk to the group about.
   * http://kuali.org/rice/documentation/1.0.3/UG_Global/Documents/lookupwildcards.htm
   *
   * 1) Should we support isNotNull, isNull, as wildcards?  Then do we still translate
   * null values into isNull predicates.  I believe the lookup framework right now
   * barfs on null values but that is a guess.
   *
   * 2) We need to support case insensitivity in the old lookup framework.  Right now the lookup
   * framework looks at Data dictionary entries.  This can still be configured in the DD
   * but should be placed in the lookup criteria. We could have a "flag" section on a
   * lookup sequence like foo.bar=(?i)ba*|bing
   *
   * This would translate to
   *
   * or(like("foo.bar", "ba*"), equalsIgnoreCase("foo.bar", "bing"))
   *
   * Btw.  My flag format was stolen from regex but we could use anything really.
   * http://download.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html#CASE_INSENSITIVE
   *
   * I'm currently supporting this.
   *
   * 3) In the above example, I used a case insensitive flag but Like doesn't support case
   * insensitive.  Should it?
   *
   * 4) Do we need to support escaping in the lookup framework & criteria api.  Right now the
   * lookup framework looks at Data dictionary entries.  This can still be configured in the DD
   * but should be placed in the lookup criteria.  Escaping is tricky and I worry if we support
   * it in the criteria api then it will make the criteria service much harder to make custom
   * implementations.  To me it seems it's better to make escaping behavior undefined.
   *
   * If we do support an escape character then we should probably also support a flag to treat
   * escape chars as literal like (?l) (that doesn't exist in java regex)
   *
   * http://download.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html#LITERAL
   *
   * 5) Maybe we should just support what is in the {@link org.kuali.rice.core.framework.logic.SearchOperator} class
   *
   * 6) Maybe the predicate class could have a toLookupString, toLookupMap() methods on them to translate
   * to various formats of criteria?  Or maybe this factory method & related methods should get placed into
   * krad or somewhere else?
   * ***************************************************************************************************************
   */
  class PredicateFactoryLookup {
  
      private static final Pattern FLAGS_PATTERN = Pattern.compile("^\\(\\?[a-z]+\\)");
  
      private PredicateFactoryLookup() {
          throw new IllegalArgumentException("do not call");
      }
  
      /**
       * This take a criteria map that is commonly used in krad-based
       * applications and transforms it to a predicate.
       *
       * The incoming map takes the form of the following possibilities:
       *
       * <ul>
       * <li>propertyPath=value</li>
       * <li>propertyPath=criteriaSequence</li>
       * </ul>
       *
       * <p>
       * The values in the map can either be a String or a Collection<Object>.
       * A String value is directly parsed into predicates.  If a collection
       * is found it is recursively parsed into predicates where each entry in the Collection
       * is anded together.
       * </p>
      *
      * <p>
      * Note: that the Collection can contain other collections or strings
      * but eventually must resolve to a string value or string criteria sequence.
      * </p>
      *
      * a simple example of a propertyPath=value:
      * <pre>
      * foo.bar=baz
      * </pre>
      * would yield
      * <pre>
      * equals("foo.bar", "baz")
      * </pre>
      *
      * a simple example of a propertyPath=criteriaSequence
      * <pre>
      * foo.bar=ba*|bing
      * </pre>
      * would yield
      * <pre>
      * or(like("foo.bar", "ba*"), equals("foo.bar", "bing"))
      * </pre>
      *
      * a compound example of a of a propertyPath=criteriaSequence
      * <pre>
      * foo.bar=[ba*,bing]      * note: [] shows a collection literal
      * </pre>
      * would yield
      * <pre>
      * and(like("foo.bar", "ba*"), equals("foo.bar", "bing"))
      * </pre>
      *
      * <p>
      * Related to null values:  Null values will be translated to isNull predicates.
      * </p>
      *
      * The criteria string may also contain flags similar to regex flags.  The current
      * supported flags are:
      *
      * <ul>
      *     <li>(?i) case insensitive</li>
      * </ul>
      *
      * To use the 'i' and 'm' flags prepend them to the criteria value, for example:
      *
      * (?im)foo
      *
      * Only the first flag sequence will be honored.  All others will be treated as literals.
      *
      * @param the root class to build the predicate on.  Cannot be null.
      * @param criteria the crtieria map.  Cannot be null or empty.
      * @throws IllegalArgumentException if clazz is null or criteria is null or empty
      */
     static Predicate fromCriteriaMap(Class<?> clazz, Map<String, ?> criteria) {
         if (clazz == null) {
             throw new IllegalArgumentException("clazz is null");
         }
 
         if (criteria == null || criteria.isEmpty()) {
             throw new IllegalArgumentException("criteria is null or empty");
         }
 
         final List<Predicate> toAnd = new ArrayList<Predicate>();
         for (Map.Entry<String, ?> entry : criteria.entrySet()) {
             final String key = entry.getKey();
             if (key == null) {
                 throw new IllegalArgumentException("criteria contains a null key");
             }
             toAnd.add(createPredicate(clazz, key, entry.getValue()));
         }
 
         return and(toAnd.toArray(new Predicate[]{}));
     }
 
     private static Predicate createPredicate(Class<?> clazz, final String key, final Object value) {
         if (value == null) {
             return isNull(key);
         } else if (value instanceof String) {
             final String flagStr = getFlagsStr((String) value);
             final String strValue = removeFlag((String) value, flagStr);
             return containsOperator(strValue) ? createFromComplexCriteriaValue(clazz, key, strValue, flagStr) :
                     createFromSimpleCriteriaValue(clazz, key, strValue, flagStr);
         } else if (value instanceof Collection) {
             final List<Predicate> ps = new ArrayList<Predicate>();
             for (Object v : (Collection<?>) value) {
                 //recurs
                 ps.add(createPredicate(clazz, key, v));
             }
             return and(ps.toArray(new Predicate[]{}));
         } else {
             throw new IllegalArgumentException(
                     "criteria map contained a value that was non supported :" + value.getClass().getName());
         }
     }
 
     private static Predicate createFromComplexCriteriaValue(Class<?> clazz, final String key, final String strValue,
             final String flagStr) {
         final boolean caseInsensitive = isCaseInsensitive(flagStr);
 
         return null;
     }
 
     private static Predicate createFromSimpleCriteriaValue(Class<?> clazz, final String key, final String strValue,
             final String flagStr) {
         final boolean caseInsensitive = isCaseInsensitive(flagStr);
         return caseInsensitive ? equalIgnoreCase(key, strValue) : equal(key, strValue);
     }
 
     private static String removeFlag(final String strValue, final String flagStr) {
         return flagStr.length() > 1 ? (strValue).substring(flagStr.length() - 1) : strValue;
     }
 
     //does not handle escaping, assumes non-null
     private static boolean containsOperator(String value) {
         for (SearchOperator o : SearchOperator.values()) {
             if (value.contains(o.op())) {
                 return true;
             }
         }
         return false;
     }
 
     private static String getFlagsStr(String criteria) {
         Matcher m = FLAGS_PATTERN.matcher(criteria);
         if (m.find()) {
             return m.group();
         }
         return "";
     }
 
     private static boolean isCaseInsensitive(String flagStr) {
         return flagStr.contains("i");
     }
 }