////////////////////////////////////////////////////////////////////////////////
/// @brief Avocado Query Language
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2010-2012 triagens GmbH, Cologne, Germany
///
/// 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.
///
/// Copyright holder is triAGENS GmbH, Cologne, Germany
///
/// @author Dr. Frank Celler
/// @author Copyright 2012, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

// -----------------------------------------------------------------------------
// --SECTION--                                                      FLUENT QUERY
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// --SECTION--                                      constructors and destructors
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup AQL
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief abstract fluent query constructor
////////////////////////////////////////////////////////////////////////////////

function AvocadoFluentQuery2 () {
  this._execution = null;

  this._skip = 0;
  this._limit = null;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief fluent query constructor for abstract representation
////////////////////////////////////////////////////////////////////////////////

function AvocadoFluentQueryAbstract (collection, query) {
  this._collection = collection;

  this._query = query;
  this._current = 0;
}

AvocadoFluentQueryAbstract.prototype = new AvocadoFluentQuery2();
AvocadoFluentQueryAbstract.prototype.constructor = AvocadoFluentQueryAbstract;

////////////////////////////////////////////////////////////////////////////////
/// @brief fluent query constructor for array representation
////////////////////////////////////////////////////////////////////////////////

function AvocadoFluentQueryArray (collection, documents) {
  this._collection = collection;

  this._documents = documents;
  this._current = 0;
}

AvocadoFluentQueryArray.prototype = new AvocadoFluentQuery2();
AvocadoFluentQueryArray.prototype.constructor = AvocadoFluentQueryArray;

////////////////////////////////////////////////////////////////////////////////
/// @brief fluent query constructor for internal representation
////////////////////////////////////////////////////////////////////////////////

function AvocadoFluentQueryInternal (collection) {
  this._collection = collection;

  this._query = null;

  this._select = null;
  this._joins = null;
  this._where = null;
}

AvocadoFluentQueryInternal.prototype = new AvocadoFluentQuery2();
AvocadoFluentQueryInternal.prototype.constructor = AvocadoFluentQueryInternal;

////////////////////////////////////////////////////////////////////////////////
/// @}
////////////////////////////////////////////////////////////////////////////////

// -----------------------------------------------------------------------------
// --SECTION--                                                      FLUENT QUERY
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// --SECTION--                                                  public functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup AQL
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief looks up a document
///
/// @FUN{document(@FA{document-identifier})}
///
/// The @FN{document} operator finds a document given it's identifier.  It
/// returns the empty result set or a result set containing the document with
/// document identifier @FA{document-identifier}.
///
/// @verbinclude fluent54
///
/// The corresponding AQL query would be:
///
/// @verbinclude fluent54-aql
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQuery2.prototype.document = function (id) {
  var copy;
  var doc;

  if (this._execution != null) {
    throw "query is already executing";
  }

  copy = this.copyQuery();

  // try to find a document
  while (copy.hasNext()) {
    doc = copy.next();

    if (doc._id == id) {
      return new AvocadoFluentQueryArray(this._collection, [ doc ]);
    }
  }

  // nothing found
  return new AvocadoFluentQueryArray(this._collection, []);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief limits an existing query
///
/// @FUN{limit(@FA{number})}
///
/// Limits a result to the first @FA{number} documents. Specifying a limit of
/// @CODE{0} returns no documents at all. If you do not need a limit, just do
/// not add the limit operator. If you specifiy a negtive limit of @CODE{-n},
/// this will return the last @CODE{n} documents instead.
///
/// @verbinclude fluent30
///
/// The corresponding AQL queries would be:
///
/// @verbinclude fluent30-aql
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQuery2.prototype.limit = function (limit) {
  var copy;

  if (this._execution != null) {
    throw "query is already executing";
  }

  if (limit == 0) {
    return new AvocadoFluentQueryArray(this._collection, []);
  }

  copy = this.copyQuery();

  if (limit == null || copy._limit == 0) {
    return copy;
  }

  if (copy._limit == null) {
    copy._limit = limit;
  }
  else if (0 < limit) {
    if (0 < copy._limit && limit < copy._limit) {
      copy._limit = limit;
    }
    else if (copy._limit < 0) {
      copy = new AvocadoFluentQueryArray(copy._collection, copy.toArray());

      copy._limit = limit;
    }
  }
  else {
    if (copy._limit < 0 && copy._limit < limit) {
      copy._limit = limit;
    }
    else if (0 < copy._limit) {
      copy = new AvocadoFluentQueryArray(copy._collection, copy.toArray());

      copy._limit = limit;
    }
  }

  return copy;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief skips an existing query
///
/// @FUN{skip(@FA{number})}
///
/// Skips the first @FA{number} documents.
///
/// @verbinclude fluent31
///
/// The corresponding AQL queries would be:
///
/// @verbinclude fluent31-aql
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQuery2.prototype.skip = function (skip) {
  var copy;

  if (skip == null) {
    skip = 0;
  }

  if (skip < 0) {
    throw "skip must be non-negative";
  }

  if (this._execution != null) {
    throw "query is already executing";
  }

  copy = this.copyQuery();

  if (skip != 0) {
    if (copy._limit == null) {
      copy._skip = copy._skip + skip;
    }
    else {
      copy = new AvocadoFluentQueryAbstract(copy._collection, copy);

      copy._skip = skip;
    }
  }

  return copy;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief converts into an array
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQuery2.prototype.toArray = function () {
  var cursor;
  var result;

  if (this._execution != null) {
    throw "query is already executing";
  }

  result = [];

  while (this.hasNext()) {
    result.push(this.next());
  }

  return result;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief returns all elements
///
/// @FUN{all()}
///
/// Selects all documents of a collection.
///
/// @verbinclude fluent23
///
/// The corresponding AQL query would be:
///
/// @verbinclude fluent23-aql
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQuery2.prototype.all = function () {
  if (this._execution != null) {
    throw "query is already executing";
  }

  return this.copyQuery();
}

////////////////////////////////////////////////////////////////////////////////
/// @}
////////////////////////////////////////////////////////////////////////////////

// -----------------------------------------------------------------------------
// --SECTION--                                           ABSTRACT REPRESENTATION
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// --SECTION--                                                 private functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup AQL
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief copies an abstract fluent query
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryAbstract.prototype.copyQuery = function () {
  var copy;

  copy = new AvocadoFluentQueryAbstract(this._collection, this._query.copyQuery());

  copy._skip = this._skip;
  copy._limit = this._limit;

  return copy;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief executes an abstract fluent query
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryAbstract.prototype.execute = function () {
  if (this._execution == null) {
    if (this._limit < 0) {
      throw "limit must be non-negative";
    }

    this._execution = true;

    if (0 < this._skip) {
      for (var i = 0;  i < this._skip && this._query.hasNext();  ++i) {
        this._query.useNext();
      }
    }

    this._current = 0;
  }
}

////////////////////////////////////////////////////////////////////////////////
/// @}
////////////////////////////////////////////////////////////////////////////////

// -----------------------------------------------------------------------------
// --SECTION--                                                  public functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup AQL
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief checks if the cursor is exhausted
///
/// @FUN{hasNext()}
///
/// The @FN{hasNext} operator returns @LIT{true}, if the cursor still has
/// documents.  In this case the next document can be accessed using the
/// @FN{next} operator, which will advance the cursor.
///
/// @verbinclude fluent3
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryAbstract.prototype.hasNext = function () {
  this.execute();

  if (this._limit != null && this._limit <= this._current) {
    return false;
  }

  if (! this._query.hasNext()) {
    this._limit = 0;
    return false;
  }

  return true;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief returns the next result document
///
/// @FUN{next()}
///
/// If the @FN{hasNext} operator returns @LIT{true}, if the cursor still has
/// documents.  In this case the next document can be accessed using the @FN{next}
/// operator, which will advance the cursor.
///
/// @verbinclude fluent28
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryAbstract.prototype.next = function() {
  this.execute();

  if (this._limit != null) {
    if (this._limit <= this._current) {
      return false;
    }

    ++this._limit;
  }

  return this._query.next();
}

////////////////////////////////////////////////////////////////////////////////
/// @brief returns the next result document
///
/// @FUN{nextRef()}
///
/// If the @FN{hasNext} operator returns @LIT{true}, if the cursor still has
/// documents.  In this case the next document reference can be
/// accessed using the @FN{nextRef} operator, which will advance the
/// cursor.
///
/// @verbinclude fluent51
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryAbstract.prototype.nextRef = function() {
  this.execute();

  if (this._limit != null) {
    if (this._limit <= this._current) {
      return false;
    }

    ++this._limit;
  }

  return this._query.nextRef();
}

////////////////////////////////////////////////////////////////////////////////
/// @brief uses the next document
///
/// @FUN{useNext()}
///
/// If the @FN{hasNext} operator returns @LIT{true}, then the cursor still has
/// documents.  In this case the next document can be skipped using the
/// @FN{useNext} operator, which will advance the cursor and return @LIT{true}.
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryAbstract.prototype.useNext = function() {
  this.execute();

  if (this._limit != null) {
    if (this._limit <= this._current) {
      return;
    }

    ++this._limit;
  }

  this._query.useNext();
}

////////////////////////////////////////////////////////////////////////////////
/// @}
////////////////////////////////////////////////////////////////////////////////

// -----------------------------------------------------------------------------
// --SECTION--                                              ARRAY REPRESENTATION
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// --SECTION--                                                 private functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup AQL
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief copies an array fluent query
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryArray.prototype.copyQuery = function() {
  var copy;

  copy = new AvocadoFluentQueryArray(this._collection, this._documents);

  copy._skip = this._skip;
  copy._limit = this._limit;

  return copy;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief executes an array fluent query
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryArray.prototype.execute = function () {
  if (this._execution == null) {
    this._execution = true;

    if (this._skip == null || this._skip <= 0) {
      this._skip = 0;
    }

    if (this._skip != 0 && this._limit == null) {
      this._current = this._skip;
    }
    else if (this._limit != null) {
      var documents;
      var start;
      var end;

      if (0 == this._limit) {
        start = 0;
        end = 0;
      }
      else if (0 < this._limit) {
        start = this._skip;
        end = this._skip + this._limit;
      }
      else {
        start = this._documents.length + this._limit - this._skip;
        end = this._documents.length - this._skip;
      }

      if (start < 0) {
        start = 0;
      }

      if (this._documents.length < end) {
        end = this._documents.length;
      }

      documents = [];

      for (var i = start;  i < end;  ++i) {
        documents.push(this._documents[i]);
      }

      this._documents = documents;
      this._skip = 0;
      this._limit = null;
    }
  }
}

////////////////////////////////////////////////////////////////////////////////
/// @}
////////////////////////////////////////////////////////////////////////////////

// -----------------------------------------------------------------------------
// --SECTION--                                                  public functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup AQL
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief checks if the cursor is exhausted
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryArray.prototype.hasNext = function () {
  this.execute();

  return this._current < this._documents.length;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief returns the next result document
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryArray.prototype.next = function() {
  this.execute();

  if (this._current < this._documents.length) {
    return this._documents[this._current++];
  }
  else {
    return undefined;
  }
}

////////////////////////////////////////////////////////////////////////////////
/// @brief returns the next result document
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryArray.prototype.nextRef = function() {
  this.execute();

  if (this._current < this._documents.length) {
    return this._documents[this._current++]._id;
  }
  else {
    return undefined;
  }
}

////////////////////////////////////////////////////////////////////////////////
/// @brief uses the next document
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryArray.prototype.useNext = function() {
  this.execute();

  if (this._current < this._documents.length) {
    this._current++;
  }
}

////////////////////////////////////////////////////////////////////////////////
/// @}
////////////////////////////////////////////////////////////////////////////////

// -----------------------------------------------------------------------------
// --SECTION--                                           INTERNAL REPRESENTATION
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// --SECTION--                                                 private functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup AQL
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief copies an internal fluent query
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryInternal.prototype.copyQuery = function() {
  var copy;

  copy = new AvocadoFluentQueryInternal(this._collection);

  copy._select = this._select;
  copy._joins = this._joins;
  copy._where = this._where;
  copy._skip = this._skip;
  copy._limit = this._limit;

  return copy;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief executes an internal fluent query
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryInternal.prototype.execute = function () {
  if (this._execution == null) {
    this._query = AQL_SELECT(this._select,
                             "$",
                             this._collection,
                             this._joins,
                             this._where,
                             this._skip,
                             this._limit);

    this._execution = this._query.execute();
  }
}

////////////////////////////////////////////////////////////////////////////////
/// @}
////////////////////////////////////////////////////////////////////////////////

// -----------------------------------------------------------------------------
// --SECTION--                                                  public functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup AQL
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief checks if the cursor is exhausted
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryInternal.prototype.hasNext = function () {
  this.execute();

  return this._execution.hasNext();
}

////////////////////////////////////////////////////////////////////////////////
/// @brief returns the next result document
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryInternal.prototype.next = function () {
  this.execute();

  return this._execution.next();
}

////////////////////////////////////////////////////////////////////////////////
/// @brief returns the next result document
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryInternal.prototype.nextRef = function () {
  this.execute();

  return this._execution.nextRef();
}

////////////////////////////////////////////////////////////////////////////////
/// @brief uses the next document
////////////////////////////////////////////////////////////////////////////////

AvocadoFluentQueryInternal.prototype.useNext = function () {
  this.execute();

  return this._execution.useNext();
}

////////////////////////////////////////////////////////////////////////////////
/// @}
////////////////////////////////////////////////////////////////////////////////

// -----------------------------------------------------------------------------
// --SECTION--                                                        COLLECTION
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// --SECTION--                                                  public functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup AQL
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief returns all elements
////////////////////////////////////////////////////////////////////////////////

AvocadoCollection.prototype.T_all = function () {
  return new AvocadoFluentQueryInternal(this);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief looks up a document
////////////////////////////////////////////////////////////////////////////////

AvocadoCollection.prototype.T_document = function (id) {
  var query;

  query = new AvocadoFluentQueryInternal(this);
  query._where = AQL_WHERE_PRIMARY_CONST(id);

  return query;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief limits an existing query
////////////////////////////////////////////////////////////////////////////////

AvocadoCollection.prototype.T_limit = function (limit) {
  var query;

  query = new AvocadoFluentQueryInternal(this);
  query._limit = limit;

  return query;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief skips an existing query
////////////////////////////////////////////////////////////////////////////////

AvocadoCollection.prototype.T_skip = function (skip) {
  var query;

  if (skip < 0) {
    throw "skip must be non-negative";
  }

  query = new AvocadoFluentQueryInternal(this);
  query._skip = skip;

  return query;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief converts into an array
////////////////////////////////////////////////////////////////////////////////

AvocadoCollection.prototype.T_toArray = function () {
  var cursor;
  var result;

  cursor = this.T_all();
  result = [];

  while (cursor.hasNext()) {
    result.push(cursor.next());
  }

  return result;
}

////////////////////////////////////////////////////////////////////////////////
/// @}
////////////////////////////////////////////////////////////////////////////////

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