/*jshint strict: false */
/*global ArangoClusterComm, ArangoClusterInfo, require, exports, module */

////////////////////////////////////////////////////////////////////////////////
/// @brief ArangoCollection
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2011-2013 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 2011-2013, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

module.isSystem = true;

var internal = require("internal");

////////////////////////////////////////////////////////////////////////////////
/// @brief builds an example query
////////////////////////////////////////////////////////////////////////////////

function buildExampleQuery (collection, example, limit) {
  var parts = [ ]; 
  var bindVars = { "@collection" : collection.name() };
  var keys = Object.keys(example);

  for (var i = 0; i < keys.length; ++i) {
    var key = keys[i];
    parts.push("doc.@att" + i + " == @value" + i);
    bindVars["att" + i] = key;
    bindVars["value" + i] = example[key];
  }
  
  var query = "FOR doc IN @@collection";
  if (parts.length > 0) {
    query += " FILTER " + parts.join(" && ", parts);
  }
  if (limit > 0) {
    query += " LIMIT " + parseInt(limit, 10);
  }

  return { query: query, bindVars: bindVars };
}

////////////////////////////////////////////////////////////////////////////////
/// @brief add options from arguments to index specification
////////////////////////////////////////////////////////////////////////////////

function addIndexOptions (body, parameters) {
  body.fields = [ ];

  var setOption = function(k) {
    if (! body.hasOwnProperty(k)) {
      body[k] = parameters[i][k];
    }
  };

  var i;
  for (i = 0; i < parameters.length; ++i) {
    if (typeof parameters[i] === "string") {
      // set fields
      body.fields.push(parameters[i]);
    }
    else if (typeof parameters[i] === "object" && 
             ! Array.isArray(parameters[i]) &&
             parameters[i] !== null) {
      // set arbitrary options
      Object.keys(parameters[i]).forEach(setOption);
      break;
    }
  }

  return body;
}

// -----------------------------------------------------------------------------
// --SECTION--                                                  ArangoCollection
// -----------------------------------------------------------------------------

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

////////////////////////////////////////////////////////////////////////////////
/// @brief constructor
////////////////////////////////////////////////////////////////////////////////

var ArangoCollection = internal.ArangoCollection;
exports.ArangoCollection = ArangoCollection;

// must be called after exporting ArangoCollection
require("@arangodb/arango-collection-common");

var simple = require("@arangodb/simple-query");
var ArangoError = require("@arangodb").ArangoError;
var ArangoDatabase = require("@arangodb/arango-database").ArangoDatabase;

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

////////////////////////////////////////////////////////////////////////////////
/// @brief converts collection into an array
/// @startDocuBlock collectionToArray
/// `collection.toArray()`
///
/// Converts the collection into an array of documents. Never use this call
/// in a production environment.
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.toArray = function () {
  var cluster = require("@arangodb/cluster");

  if (cluster.isCoordinator()) {
    return this.all().toArray();
  }

  return this.ALL(null, null).documents;
};

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

////////////////////////////////////////////////////////////////////////////////
/// @brief truncates a collection
/// @startDocuBlock collectionTruncate
/// `collection.truncate()`
///
/// Truncates a *collection*, removing all documents but keeping all its
/// indexes.
///
/// @EXAMPLES
///
/// Truncates a collection:
///
/// @EXAMPLE_ARANGOSH_OUTPUT{collectionTruncate}
/// ~ db._create("example");
///   col = db.example;
///   col.save({ "Hello" : "World" });
///   col.count();
///   col.truncate();
///   col.count();
/// ~ db._drop("example");
/// @END_EXAMPLE_ARANGOSH_OUTPUT
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.truncate = function () {
  var cluster = require("@arangodb/cluster");

  if (cluster.isCoordinator()) {
    if (this.status() === ArangoCollection.STATUS_UNLOADED) {
      this.load();
    }
    var dbName = require("internal").db._name();
    var shards = cluster.shardList(dbName, this.name());
    var coord = { coordTransactionID: ArangoClusterInfo.uniqid() };
    var options = { coordTransactionID: coord.coordTransactionID, timeout: 360 };

    shards.forEach(function (shard) {
      ArangoClusterComm.asyncRequest("put",
                                     "shard:" + shard,
                                     dbName,
                                     "/_api/collection/" + encodeURIComponent(shard) + "/truncate",
                                     "",
                                     { },
                                     options);
    });

    cluster.wait(coord, shards);
    return;
  }

  return this.TRUNCATE();
};

// -----------------------------------------------------------------------------
// --SECTION--                                                   index functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief finds an index of a collection
///
/// @FUN{@FA{collection}.index(@FA{index-handle})}
///
/// Returns the index with @FA{index-handle} or null if no such index exists.
///
/// *Examples*
///
/// @code
/// arango> db.example.getIndexes().map(function(x) { return x.id; });
/// ["example/0"]
/// arango> db.example.index("93013/0");
/// { "id" : "example/0", "type" : "primary", "fields" : ["_id"] }
/// @endcode
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.index = function (id) {
  var indexes = this.getIndexes();
  var i;

  if (typeof id === "object" && id.hasOwnProperty("id")) {
    id = id.id;
  }

  if (typeof id === "string") {
    var pa = ArangoDatabase.indexRegex.exec(id);

    if (pa === null) {
      id = this.name() + "/" + id;
    }
  }
  else if (typeof id === "number") {
    // stringify the id
    id = this.name() + "/" + id;
  }

  for (i = 0;  i < indexes.length;  ++i) {
    var index = indexes[i];

    if (index.id === id) {
      return index;
    }
  }

  var err = new ArangoError();
  err.errorNum = internal.errors.ERROR_ARANGO_INDEX_NOT_FOUND.code;
  err.errorMessage = internal.errors.ERROR_ARANGO_INDEX_NOT_FOUND.message;

  throw err;
};

// -----------------------------------------------------------------------------
// --SECTION--                                                    edge functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief returns connected edges
////////////////////////////////////////////////////////////////////////////////

function getEdges (collection, vertex, direction) {
  var cluster = require("@arangodb/cluster");

  if (cluster.isCoordinator()) {
    var dbName = require("internal").db._name();
    var shards = cluster.shardList(dbName, collection.name());
    var coord = { coordTransactionID: ArangoClusterInfo.uniqid() };
    var options = { coordTransactionID: coord.coordTransactionID, timeout: 360 };
    var body;

    if (vertex !== null &&
        typeof vertex === "object" &&
        vertex.hasOwnProperty("_id")) {
      vertex = vertex._id;
    }
    if (Array.isArray(vertex)) {
      var idList = vertex.map(function (v) {
        if (v !== null) {
          if (typeof v === "object" &&
              v.hasOwnProperty("_id")) {
            return v._id;
          }
          if (typeof v === "string") {
            return v;
          }
        }
      });
      body = JSON.stringify(idList);
      shards.forEach(function (shard) {
        var url = "/_api/edges/" + encodeURIComponent(shard) +
                  "?direction=" + encodeURIComponent(direction);

        ArangoClusterComm.asyncRequest("post",
                                       "shard:" + shard,
                                       dbName,
                                       url,
                                       body,
                                       { },
                                       options);
      });

    }
    else {
      shards.forEach(function (shard) {
        var url = "/_api/edges/" + encodeURIComponent(shard) +
                  "?direction=" + encodeURIComponent(direction) +
                  "&vertex=" + encodeURIComponent(vertex);

        ArangoClusterComm.asyncRequest("get",
                                       "shard:" + shard,
                                       dbName,
                                       url,
                                       "",
                                       { },
                                       options);
      });
    }

    var results = cluster.wait(coord, shards), i;
    var edges = [ ];

    for (i = 0; i < results.length; ++i) {
      body = JSON.parse(results[i].body);

      edges = edges.concat(body.edges);
    }

    return edges;
  }

  if (direction === "in") {
    return collection.INEDGES(vertex);
  }
  if (direction === "out") {
    return collection.OUTEDGES(vertex);
  }

  return collection.EDGES(vertex);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief returns all edges connected to a vertex
/// @startDocuBlock collectionEdgesAll
/// `collection.edges(vertex-id)`
///
/// Returns all edges connected to the vertex specified by *vertex-id*.
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.edges = function (vertex) {
  return getEdges(this, vertex, "any");
};

////////////////////////////////////////////////////////////////////////////////
/// @brief returns inbound edges connected to a vertex
/// @startDocuBlock collectionEdgesInbound
/// `collection.inEdges(vertex-id)`
///
/// Returns inbound edges connected to the vertex specified by *vertex-id*.
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.inEdges = function (vertex) {
  return getEdges(this, vertex, "in");
};

////////////////////////////////////////////////////////////////////////////////
/// @brief returns outbound edges connected to a vertex
/// @startDocuBlock collectionEdgesOutbound
/// `collection.outEdges(vertex-id)`
///
/// Returns outbound edges connected to the vertex specified by *vertex-id*.
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.outEdges = function (vertex) {
  return getEdges(this, vertex, "out");
};

// -----------------------------------------------------------------------------
// --SECTION--                                                document functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief returns any document from a collection
/// @startDocuBlock documentsCollectionAny
/// `collection.any()`
///
/// Returns a random document from the collection or *null* if none exists.
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.any = function () {
  var cluster = require("@arangodb/cluster");

  if (cluster.isCoordinator()) {
    var dbName = require("internal").db._name();
    var shards = cluster.shardList(dbName, this.name());
    var coord = { coordTransactionID: ArangoClusterInfo.uniqid() };
    var options = { coordTransactionID: coord.coordTransactionID, timeout: 360 };

    shards.forEach(function (shard) {
      ArangoClusterComm.asyncRequest("put",
                                     "shard:" + shard,
                                     dbName,
                                     "/_api/simple/any",
                                     JSON.stringify({
                                       collection: shard
                                     }),
                                     { },
                                     options);
    });

    var results = cluster.wait(coord, shards), i;
    for (i = 0; i < results.length; ++i) {
      var body = JSON.parse(results[i].body);
      if (body.document !== null) {
        return body.document;
      }
    }

    return null;
  }

  return this.ANY();
};

////////////////////////////////////////////////////////////////////////////////
/// @brief selects the n first documents in the collection
/// @startDocuBlock documentsCollectionFirst
/// `collection.first(count)`
///
/// The *first* method returns the n first documents from the collection, in
/// order of document insertion/update time.
///
/// If called with the *count* argument, the result is a list of up to
/// *count* documents. If *count* is bigger than the number of documents
/// in the collection, then the result will contain as many documents as there
/// are in the collection.
/// The result list is ordered, with the "oldest" documents being positioned at
/// the beginning of the result list.
///
/// When called without an argument, the result is the first document from the
/// collection. If the collection does not contain any documents, the result
/// returned is *null*.
///
/// **Note**: this method is not supported in sharded collections with more than
/// one shard.
///
/// @EXAMPLES
///
/// @EXAMPLE_ARANGOSH_OUTPUT{documentsCollectionFirst}
/// ~ db._create("example");
/// ~ db.example.save({ Hello : "world" });
/// ~ db.example.save({ Foo : "bar" });
///   db.example.first(1);
/// ~ db._drop("example");
/// @END_EXAMPLE_ARANGOSH_OUTPUT
///
/// @EXAMPLE_ARANGOSH_OUTPUT{documentsCollectionFirstNull}
/// ~ db._create("example");
/// ~ db.example.save({ Hello : "world" });
///   db.example.first();
/// ~ db._drop("example");
/// @END_EXAMPLE_ARANGOSH_OUTPUT
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.first = function (count) {
  var cluster = require("@arangodb/cluster");

  if (cluster.isCoordinator()) {
    var dbName = require("internal").db._name();
    var shards = cluster.shardList(dbName, this.name());

    if (shards.length !== 1) {
      var err = new ArangoError();
      err.errorNum = internal.errors.ERROR_CLUSTER_UNSUPPORTED.code;
      err.errorMessage = "operation is not supported in sharded collections";

      throw err;
    }

    var coord = { coordTransactionID: ArangoClusterInfo.uniqid() };
    var options = { coordTransactionID: coord.coordTransactionID, timeout: 360 };
    var shard = shards[0];

    ArangoClusterComm.asyncRequest("put",
                                   "shard:" + shard,
                                   dbName,
                                   "/_api/simple/first",
                                   JSON.stringify({
                                     collection: shard,
                                     count: count
                                   }),
                                   { },
                                   options);

    var results = cluster.wait(coord, shards);

    if (results.length) {
      var body = JSON.parse(results[0].body);
      return body.result || null;
    }
  }
  else {
    return this.FIRST(count);
  }

  return null;
};

////////////////////////////////////////////////////////////////////////////////
/// @brief selects the n last documents in the collection
///
/// @startDocuBlock documentsCollectionLast
/// `collection.last(count)`
///
/// The *last* method returns the n last documents from the collection, in
/// order of document insertion/update time.
///
/// If called with the *count* argument, the result is a list of up to
/// *count* documents. If *count* is bigger than the number of documents
/// in the collection, then the result will contain as many documents as there
/// are in the collection.
/// The result list is ordered, with the "latest" documents being positioned at
/// the beginning of the result list.
///
/// When called without an argument, the result is the last document from the
/// collection. If the collection does not contain any documents, the result
/// returned is *null*.
///
/// **Note**: this method is not supported in sharded collections with more than
/// one shard.
///
/// @EXAMPLES
///
/// @EXAMPLE_ARANGOSH_OUTPUT{documentsCollectionLast}
/// ~ db._create("example");
/// ~ db.example.save({ Hello : "world" });
/// ~ db.example.save({ Foo : "bar" });
///   db.example.last(2);
/// ~ db._drop("example");
/// @END_EXAMPLE_ARANGOSH_OUTPUT
///
/// @EXAMPLE_ARANGOSH_OUTPUT{documentsCollectionLastNull}
/// ~ db._create("example");
/// ~ db.example.save({ Hello : "world" });
///   db.example.last(1);
/// ~ db._drop("example");
/// @END_EXAMPLE_ARANGOSH_OUTPUT
///
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.last = function (count) {
  var cluster = require("@arangodb/cluster");

  if (cluster.isCoordinator()) {
    var dbName = require("internal").db._name();
    var shards = cluster.shardList(dbName, this.name());

    if (shards.length !== 1) {
      var err = new ArangoError();
      err.errorNum = internal.errors.ERROR_CLUSTER_UNSUPPORTED.code;
      err.errorMessage = "operation is not supported in sharded collections";

      throw err;
    }

    var coord = { coordTransactionID: ArangoClusterInfo.uniqid() };
    var options = { coordTransactionID: coord.coordTransactionID, timeout: 360 };
    var shard = shards[0];

    ArangoClusterComm.asyncRequest("put",
                                   "shard:" + shard,
                                   dbName,
                                   "/_api/simple/last",
                                   JSON.stringify({
                                     collection: shard,
                                     count: count
                                   }),
                                   { },
                                   options);

    var results = cluster.wait(coord, shards);

    if (results.length) {
      var body = JSON.parse(results[0].body);
      return body.result || null;
    }
  }
  else {
    return this.LAST(count);
  }

  return null;
};

////////////////////////////////////////////////////////////////////////////////
/// @brief constructs a query-by-example for a collection
///
/// @startDocuBlock collectionFirstExample
/// `collection.firstExample(example)`
///
/// Returns the first document of a collection that matches the specified
/// example. If no such document exists, *null* will be returned. 
/// The example has to be specified as paths and values.
/// See *byExample* for details.
///
/// `collection.firstExample(path1, value1, ...)`
///
/// As alternative you can supply an array of paths and values.
///
/// @EXAMPLES
///
/// @EXAMPLE_ARANGOSH_OUTPUT{collectionFirstExample}
/// ~ db._create("users");
/// ~ db.users.save({ name: "Gerhard" });
/// ~ db.users.save({ name: "Helmut" });
/// ~ db.users.save({ name: "Angela" });
///   db.users.firstExample("name", "Angela");
/// ~ db._drop("users");
/// @END_EXAMPLE_ARANGOSH_OUTPUT
///
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.firstExample = function (example) {
  var e;
  var i;

  // example is given as only argument
  if (arguments.length === 1) {
    e = example;
  }

  // example is given as list
  else {
    e = {};

    for (i = 0;  i < arguments.length;  i += 2) {
      e[arguments[i]] = arguments[i + 1];
    }
  }

  var documents = (new simple.SimpleQueryByExample(this, e)).limit(1).toArray();
  if (documents.length > 0) {
    return documents[0];
  }

  return null;
};

////////////////////////////////////////////////////////////////////////////////
/// @brief removes documents matching an example
/// @param example a json object which is used as sample for finding docs that
///        this example matches
/// @param waitForSync (optional) a boolean value or a json object
/// @param limit (optional) an integer value, the max number of to deleting docs
/// @example remove("{a : 1 }")
/// @example remove("{a : 1 }", true)
/// @example remove("{a : 1 }", false)
/// @example remove("{a : 1 }", {waitForSync: false, limit: 12})
/// @throws "too many parameters" when waiitForSyn is a Json object and limit
///         is given
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.removeByExample = function (example,
                                                       waitForSync,
                                                       limit) {
  if (limit === 0) {
    return 0;
  }
  if (typeof waitForSync === "object") {
    if (typeof limit !== "undefined") {
      throw "too many parameters";
    }
    var tmp_options = waitForSync === null ? {} : waitForSync;
    // avoiding jslint error
    // see: http://jslinterrors.com/unexpected-sync-method-a/
    waitForSync = tmp_options.waitForSync;
    limit = tmp_options.limit;
  }
  var i;
  var cluster = require("@arangodb/cluster");

  if (cluster.isCoordinator()) {
    var dbName = require("internal").db._name();
    var shards = cluster.shardList(dbName, this.name());
    var coord = { coordTransactionID: ArangoClusterInfo.uniqid() };
    var options = { coordTransactionID: coord.coordTransactionID, timeout: 360 };

    if (limit > 0 && shards.length > 1) {
      var err = new ArangoError();
      err.errorNum = internal.errors.ERROR_CLUSTER_UNSUPPORTED.code;
      err.errorMessage = "limit is not supported in sharded collections";

      throw err;
    }

    shards.forEach(function (shard) {
      ArangoClusterComm.asyncRequest("put",
                                     "shard:" + shard,
                                     dbName,
                                     "/_api/simple/remove-by-example",
                                     JSON.stringify({
                                       collection: shard,
                                       example: example,
                                       waitForSync: waitForSync,
                                       limit: limit || undefined
                                     }),
                                     { },
                                     options);
    });

    var deleted = 0;
    var results = cluster.wait(coord, shards);
    for (i = 0; i < results.length; ++i) {
      var body = JSON.parse(results[i].body);

      deleted += (body.deleted || 0);
    }

    return deleted;
  }

  var query = buildExampleQuery(this, example, limit);
  var opts = { waitForSync : waitForSync };
  query.query += " REMOVE doc IN @@collection OPTIONS " + JSON.stringify(opts);

  return require("internal").db._query(query).getExtra().stats.writesExecuted; 
};

////////////////////////////////////////////////////////////////////////////////
/// @brief replaces documents matching an example
/// @param example the json object for finding documents which matches this
///        example
/// @param newValue the json object which replaces the matched documents
/// @param waitForSync (optional) a boolean value or a json object which
///        contains the options
/// @param limit (optional) an integer value, the max number of to deleting docs
/// @throws "too many parameters" when waitForSync is a json object and limit
///        was given
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.replaceByExample = function (example,
                                                        newValue,
                                                        waitForSync,
                                                        limit) {
  if (limit === 0) {
    return 0;
  }

  if (typeof newValue !== "object" || Array.isArray(newValue)) {
    var err1 = new ArangoError();
    err1.errorNum = internal.errors.ERROR_BAD_PARAMETER.code;
    err1.errorMessage = "invalid value for parameter 'newValue'";

    throw err1;
  }

  if (typeof waitForSync === "object") {
    if (typeof limit !== "undefined") {
      throw "too many parameters";
    }
    var tmp_options = waitForSync === null ? {} : waitForSync;
    // avoiding jslint error
    // see: http://jslinterrors.com/unexpected-sync-method-a/
        waitForSync = tmp_options.waitForSync;
    limit = tmp_options.limit;
  }

  var cluster = require("@arangodb/cluster");

  if (cluster.isCoordinator()) {
    var dbName = require("internal").db._name();
    var shards = cluster.shardList(dbName, this.name());
    var coord = { coordTransactionID: ArangoClusterInfo.uniqid() };
    var options = { coordTransactionID: coord.coordTransactionID, timeout: 360 };

    if (limit > 0 && shards.length > 1) {
      var err2 = new ArangoError();
      err2.errorNum = internal.errors.ERROR_CLUSTER_UNSUPPORTED.code;
      err2.errorMessage = "limit is not supported in sharded collections";

      throw err2;
    }

    shards.forEach(function (shard) {
      ArangoClusterComm.asyncRequest("put",
                                     "shard:" + shard,
                                     dbName,
                                     "/_api/simple/replace-by-example",
                                     JSON.stringify({
                                       collection: shard,
                                       example: example,
                                       newValue: newValue,
                                       waitForSync: waitForSync,
                                       limit: limit || undefined
                                     }),
                                     { },
                                     options);
    });

    var replaced = 0;
    var results = cluster.wait(coord, shards), i;
    for (i = 0; i < results.length; ++i) {
      var body = JSON.parse(results[i].body);

      replaced += (body.replaced || 0);
    }

    return replaced;
  }

  var query = buildExampleQuery(this, example, limit);
  var opts = { waitForSync : waitForSync };
  query.query += " REPLACE doc WITH @newValue IN @@collection OPTIONS " + JSON.stringify(opts);
  query.bindVars.newValue = newValue;

  return require("internal").db._query(query).getExtra().stats.writesExecuted; 
};

////////////////////////////////////////////////////////////////////////////////
/// @brief partially updates documents matching an example
/// @param example the json object for finding documents which matches this
///        example
/// @param newValue the json object which replaces the matched documents
/// @param keepNull (optional) true or a json object which
///        contains the options
/// @param waitForSync (optional) a boolean value
/// @param limit (optional) an integer value, the max number of to deleting docs
/// @throws "too many parameters" when keepNull is  a json object and limit
///        was given
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.updateByExample = function (example,
                                                       newValue,
                                                       keepNull,
                                                       waitForSync,
                                                       limit) {

  if (limit === 0) {
    return 0;
  }

  if (typeof newValue !== "object" || Array.isArray(newValue)) {
    var err1 = new ArangoError();
    err1.errorNum = internal.errors.ERROR_BAD_PARAMETER.code;
    err1.errorMessage = "invalid value for parameter 'newValue'";

    throw err1;
  }

  if (typeof keepNull === "object") {
    if (typeof waitForSync !== "undefined") {
      throw "too many parameters";
    }
    var tmp_options = keepNull === null ? {} : keepNull;

    // avoiding jslint error
    // see: http://jslinterrors.com/unexpected-sync-method-a/
        keepNull = tmp_options.keepNull;
    waitForSync = tmp_options.waitForSync;
    limit = tmp_options.limit;
  }

  var cluster = require("@arangodb/cluster");

  if (cluster.isCoordinator()) {
    var dbName = require("internal").db._name();
    var shards = cluster.shardList(dbName, this.name());
    var coord = { coordTransactionID: ArangoClusterInfo.uniqid() };
    var options = { coordTransactionID: coord.coordTransactionID, timeout: 360 };

    if (limit > 0 && shards.length > 1) {
      var err2 = new ArangoError();
      err2.errorNum = internal.errors.ERROR_CLUSTER_UNSUPPORTED.code;
      err2.errorMessage = "limit is not supported in sharded collections";

      throw err2;
    }

    shards.forEach(function (shard) {
      ArangoClusterComm.asyncRequest("put",
                                     "shard:" + shard,
                                     dbName,
                                     "/_api/simple/update-by-example",
                                     JSON.stringify({
                                       collection: shard,
                                       example: example,
                                       newValue: newValue,
                                       waitForSync: waitForSync,
                                       keepNull: keepNull,
                                       limit: limit || undefined
                                     }),
                                     { },
                                     options);
    });

    var updated = 0;
    var results = cluster.wait(coord, shards), i;
    for (i = 0; i < results.length; ++i) {
      var body = JSON.parse(results[i].body);

      updated += (body.updated || 0);
    }

    return updated;
  }

  var query = buildExampleQuery(this, example, limit);
  var opts = { waitForSync : waitForSync, keepNull: keepNull };
  query.query += " UPDATE doc WITH @newValue IN @@collection OPTIONS " + JSON.stringify(opts);
  query.bindVars.newValue = newValue;

  return require("internal").db._query(query).getExtra().stats.writesExecuted; 
};

////////////////////////////////////////////////////////////////////////////////
/// @brief ensures that a cap constraint exists
/// @startDocuBlock collectionEnsureCapConstraint
/// `collection.ensureIndex({ type: "cap", size: size, byteSize: byteSize })`
///
/// Creates a size restriction aka cap for the collection of `size`
/// documents and/or `byteSize` data size. If the restriction is in place
/// and the (`size` plus one) document is added to the collection, or the
/// total active data size in the collection exceeds `byteSize`, then the
/// least recently created or updated documents are removed until all
/// constraints are satisfied.
///
/// It is allowed to specify either `size` or `byteSize`, or both at
/// the same time. If both are specified, then the automatic document removal
/// will be triggered by the first non-met constraint.
///
/// Note that at most one cap constraint is allowed per collection. Trying
/// to create additional cap constraints will result in an error. Creating
/// cap constraints is also not supported in sharded collections with more
/// than one shard.
///
/// Note that this does not imply any restriction of the number of revisions
/// of documents.
///
/// @EXAMPLES
///
/// Restrict the number of document to at most 10 documents:
///
/// @EXAMPLE_ARANGOSH_OUTPUT{collectionEnsureCapConstraint}
/// ~db._create('examples');
///  db.examples.ensureIndex({ type: "cap", size: 10 });
///  for (var i = 0;  i < 20;  ++i) { var d = db.examples.save( { n : i } ); }
///  db.examples.count();
/// ~db._drop('examples');
/// @END_EXAMPLE_ARANGOSH_OUTPUT
///
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.ensureCapConstraint = function (size, byteSize) {
  'use strict';

  return this.ensureIndex({
    type: "cap",
    size: size || undefined,
    byteSize: byteSize || undefined
  });
};

////////////////////////////////////////////////////////////////////////////////
/// @brief ensures that a unique skiplist index exists
/// @startDocuBlock ensureUniqueSkiplist
/// `collection.ensureIndex({ type: "skiplist", fields: [ "field1", ..., "fieldn" ], unique: true })`
///
/// Creates a unique skiplist index on all documents using *field1*, ... *fieldn*
/// as attribute paths. At least one attribute path has to be given. The index will
/// be non-sparse by default.
///
/// All documents in the collection must differ in terms of the indexed 
/// attributes. Creating a new document or updating an existing document will
/// will fail if the attribute uniqueness is violated. 
///
/// To create a sparse unique index, set the *sparse* attribute to `true`:
/// 
/// `collection.ensureIndex({ type: "skiplist", fields: [ "field1", ..., "fieldn" ], unique: true, sparse: true })`
/// 
/// In a sparse index all documents will be excluded from the index that do not 
/// contain at least one of the specified index attributes or that have a value 
/// of `null` in any of the specified index attributes. Such documents will
/// not be indexed, and not be taken into account for uniqueness checks.
///
/// In a non-sparse index, these documents will be indexed (for non-present
/// indexed attributes, a value of `null` will be used) and will be taken into
/// account for uniqueness checks.
///
/// In case that the index was successfully created, an object with the index
/// details, including the index-identifier, is returned.
///
/// @EXAMPLE_ARANGOSH_OUTPUT{ensureUniqueSkiplist}
/// ~db._create("ids");
/// db.ids.ensureIndex({ type: "skiplist", fields: [ "myId" ], unique: true });
/// db.ids.save({ "myId": 123 });
/// db.ids.save({ "myId": 456 });
/// db.ids.save({ "myId": 789 });
/// db.ids.save({ "myId": 123 });  // xpError(ERROR_ARANGO_UNIQUE_CONSTRAINT_VIOLATED)
/// ~db._drop("ids");
/// @END_EXAMPLE_ARANGOSH_OUTPUT
/// @EXAMPLE_ARANGOSH_OUTPUT{ensureUniqueSkiplistMultiColmun}
/// ~db._create("ids");
/// db.ids.ensureIndex({ type: "skiplist", fields: [ "name.first", "name.last" ], unique: true });
/// db.ids.save({ "name" : { "first" : "hans", "last": "hansen" }});
/// db.ids.save({ "name" : { "first" : "jens", "last": "jensen" }});
/// db.ids.save({ "name" : { "first" : "hans", "last": "jensen" }});
/// | db.ids.save({ "name" : { "first" : "hans", "last": "hansen" }}); 
/// ~ // xpError(ERROR_ARANGO_UNIQUE_CONSTRAINT_VIOLATED)
/// ~db._drop("ids");
/// @END_EXAMPLE_ARANGOSH_OUTPUT
///
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.ensureUniqueSkiplist = function () {
  'use strict';

  return this.ensureIndex(addIndexOptions({
    type: "skiplist",
    unique: true
  }, arguments));
};

////////////////////////////////////////////////////////////////////////////////
/// @brief ensures that a non-unique skiplist index exists
/// @startDocuBlock ensureSkiplist
/// `collection.ensureIndex({ type: "skiplist", fields: [ "field1", ..., "fieldn" ] })`
///
/// Creates a non-unique skiplist index on all documents using *field1*, ...
/// *fieldn* as attribute paths. At least one attribute path has to be given.
/// The index will be non-sparse by default.
///
/// To create a sparse unique index, set the *sparse* attribute to `true`.
///
/// In case that the index was successfully created, an object with the index
/// details, including the index-identifier, is returned.
///
/// @EXAMPLE_ARANGOSH_OUTPUT{ensureSkiplist}
/// ~db._create("names");
/// db.names.ensureIndex({ type: "skiplist", fields: [ "first" ] });
/// db.names.save({ "first" : "Tim" });
/// db.names.save({ "first" : "Tom" });
/// db.names.save({ "first" : "John" });
/// db.names.save({ "first" : "Tim" });
/// db.names.save({ "first" : "Tom" });
/// ~db._drop("names");
/// @END_EXAMPLE_ARANGOSH_OUTPUT
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.ensureSkiplist = function () {
  'use strict';

  return this.ensureIndex(addIndexOptions({
    type: "skiplist"
  }, arguments));
};

////////////////////////////////////////////////////////////////////////////////
/// @brief ensures that a fulltext index exists
/// @startDocuBlock ensureFulltextIndex
/// `collection.ensureIndex({ type: "fulltext", fields: [ "field" ], minLength: minLength })`
///
/// Creates a fulltext index on all documents on attribute *field*.
///
/// Fulltext indexes are implicitly sparse: all documents which do not have 
/// the specified *field* attribute or that have a non-qualifying value in their 
/// *field* attribute will be ignored for indexing.
///
/// Only a single attribute can be indexed. Specifying multiple attributes is 
/// unsupported.
///
/// The minimum length of words that are indexed can be specified via the
/// *minLength* parameter. Words shorter than minLength characters will 
/// not be indexed. *minLength* has a default value of 2, but this value might
/// be changed in future versions of ArangoDB. It is thus recommended to explicitly
/// specify this value.
///
/// In case that the index was successfully created, an object with the index
/// details is returned.
///
/// @EXAMPLE_ARANGOSH_OUTPUT{ensureFulltextIndex}
/// ~db._create("example");
/// db.example.ensureIndex({ type: "fulltext", fields: [ "text" ], minLength: 3 });
/// db.example.save({ text : "the quick brown", b : { c : 1 } });
/// db.example.save({ text : "quick brown fox", b : { c : 2 } });
/// db.example.save({ text : "brown fox jums", b : { c : 3 } });
/// db.example.save({ text : "fox jumps over", b : { c : 4 } });
/// db.example.save({ text : "jumps over the", b : { c : 5 } });
/// db.example.save({ text : "over the lazy", b : { c : 6 } });
/// db.example.save({ text : "the lazy dog", b : { c : 7 } });
/// db._query("FOR document IN FULLTEXT(example, 'text', 'the') RETURN document");
/// ~db._drop("example");
/// @END_EXAMPLE_ARANGOSH_OUTPUT
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.ensureFulltextIndex = function (field, minLength) {
  'use strict';

  if (! Array.isArray(field)) {
    field = [ field ];
  }

  return this.ensureIndex({
    type: "fulltext",
    minLength: minLength || undefined,
    fields: field
  });
};

////////////////////////////////////////////////////////////////////////////////
/// @brief ensures that a unique constraint exists
/// @startDocuBlock ensureUniqueConstraint
/// `collection.ensureIndex({ type: "hash", fields: [ "field1", ..., "fieldn" ], unique: true })`
///
/// Creates a unique hash index on all documents using *field1*, ... *fieldn*
/// as attribute paths. At least one attribute path has to be given.
/// The index will be non-sparse by default.
///
/// All documents in the collection must differ in terms of the indexed 
/// attributes. Creating a new document or updating an existing document will
/// will fail if the attribute uniqueness is violated. 
///
/// To create a sparse unique index, set the *sparse* attribute to `true`:
/// 
/// `collection.ensureIndex({ type: "hash", fields: [ "field1", ..., "fieldn" ], unique: true, sparse: true })`
/// 
/// In case that the index was successfully created, the index identifier is returned.
/// 
/// Non-existing attributes will default to `null`.
/// In a sparse index all documents will be excluded from the index for which all
/// specified index attributes are `null`. Such documents will not be taken into account
/// for uniqueness checks.
///
/// In a non-sparse index, **all** documents regardless of `null` - attributes will be
/// indexed and will be taken into account for uniqueness checks.
///
/// In case that the index was successfully created, an object with the index
/// details, including the index-identifier, is returned.
///
/// @EXAMPLE_ARANGOSH_OUTPUT{ensureUniqueConstraint}
/// ~db._create("test");
/// db.test.ensureIndex({ type: "hash", fields: [ "a", "b.c" ], unique: true });
/// db.test.save({ a : 1, b : { c : 1 } });
/// db.test.save({ a : 1, b : { c : 1 } }); // xpError(ERROR_ARANGO_UNIQUE_CONSTRAINT_VIOLATED)
/// db.test.save({ a : 1, b : { c : null } });
/// db.test.save({ a : 1 });  // xpError(ERROR_ARANGO_UNIQUE_CONSTRAINT_VIOLATED)
/// ~db._drop("test");
/// @END_EXAMPLE_ARANGOSH_OUTPUT
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.ensureUniqueConstraint = function () {
  'use strict';

  return this.ensureIndex(addIndexOptions({
    type: "hash",
    unique: true
  }, arguments));
};

////////////////////////////////////////////////////////////////////////////////
/// @brief ensures that a non-unique hash index exists
/// @startDocuBlock ensureHashIndex
/// `collection.ensureIndex({ type: "hash", fields: [ "field1", ..., "fieldn" ] })`
///
/// Creates a non-unique hash index on all documents using  *field1*, ... *fieldn*
/// as attribute paths. At least one attribute path has to be given.
/// The index will be non-sparse by default.
///
/// To create a sparse unique index, set the *sparse* attribute to `true`:
/// 
/// `collection.ensureIndex({ type: "hash", fields: [ "field1", ..., "fieldn" ], sparse: true })`
///
/// In case that the index was successfully created, an object with the index
/// details, including the index-identifier, is returned.
///
/// @EXAMPLE_ARANGOSH_OUTPUT{ensureHashIndex}
/// ~db._create("test");
/// db.test.ensureIndex({ type: "hash", fields: [ "a" ] });
/// db.test.save({ a : 1 });
/// db.test.save({ a : 1 });
/// db.test.save({ a : null });
/// ~db._drop("test");
/// @END_EXAMPLE_ARANGOSH_OUTPUT
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.ensureHashIndex = function () {
  'use strict';

  return this.ensureIndex(addIndexOptions({
    type: "hash"
  }, arguments));
};

////////////////////////////////////////////////////////////////////////////////
/// @brief ensures that a geo index exists
/// @startDocuBlock collectionEnsureGeoIndex
/// `collection.ensureIndex({ type: "geo", fields: [ "location" ] })`
///
/// Creates a geo-spatial index on all documents using *location* as path to
/// the coordinates. The value of the attribute has to be an array with at least two
/// numeric values. The array must contain the latitude (first value) and the
/// longitude (second value).
/// 
/// All documents, which do not have the attribute path or have a non-conforming
/// value in it are excluded from the index.
///
/// A geo index is implicitly sparse, and there is no way to control its sparsity.
///
/// In case that the index was successfully created, an object with the index
/// details, including the index-identifier, is returned.
///
/// To create a geo on an array attribute that contains longitude first, set the
/// *geoJson* attribute to `true`. This corresponds to the format described in
/// [positions](http://geojson.org/geojson-spec.html)
///
/// `collection.ensureIndex({ type: "geo", fields: [ "location" ], geoJson: true })`
///
/// To create a geo-spatial index on all documents using *latitude* and
/// *longitude* as separate attribute paths, two paths need to be specified
/// in the *fields* array:
///
/// `collection.ensureIndex({ type: "geo", fields: [ "latitude", "longitude" ] })`
///
/// In case that the index was successfully created, an object with the index
/// details, including the index-identifier, is returned.
///
/// @EXAMPLES
///
/// Create a geo index for an array attribute:
///
/// @EXAMPLE_ARANGOSH_OUTPUT{geoIndexCreateForArrayAttribute}
/// ~db._create("geo")
///  db.geo.ensureIndex({ type: "geo", fields: [ "loc" ] });
/// | for (i = -90;  i <= 90;  i += 10) {
/// |     for (j = -180; j <= 180; j += 10) {
/// |         db.geo.save({ name : "Name/" + i + "/" + j, loc: [ i, j ] });
/// |     }
///   }	
/// db.geo.count();
/// db.geo.near(0, 0).limit(3).toArray();
/// db.geo.near(0, 0).count();
/// ~db._drop("geo")
/// @END_EXAMPLE_ARANGOSH_OUTPUT
///
/// Create a geo index for a hash array attribute:
/// 
/// @EXAMPLE_ARANGOSH_OUTPUT{geoIndexCreateForArrayAttribute2}
/// ~db._create("geo2")
/// db.geo2.ensureIndex({ type: "geo", fields: [ "location.latitude", "location.longitude" ] });
/// | for (i = -90;  i <= 90;  i += 10) {
/// |     for (j = -180; j <= 180; j += 10) {
/// |         db.geo2.save({ name : "Name/" + i + "/" + j, location: { latitude : i, longitude : j } });
/// |     }
///   }	
/// db.geo2.near(0, 0).limit(3).toArray();
/// ~db._drop("geo2")
/// @END_EXAMPLE_ARANGOSH_OUTPUT
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.ensureGeoIndex = function (lat, lon) {
  'use strict';

  if (typeof lat !== "string") {
    throw "usage: ensureGeoIndex(<lat>, <lon>) or ensureGeoIndex(<loc>[, <geoJson>])";
  }

  if (typeof lon === "boolean") {
    return this.ensureIndex({
      type : "geo1",
      fields : [ lat ],
      geoJson : lon
    });
  }

  if (lon === undefined) {
    return this.ensureIndex({
      type : "geo1",
      fields : [ lat ],
      geoJson : false
    });
  }

  return this.ensureIndex({
    type : "geo2",
    fields : [ lat, lon ]
  });
};

////////////////////////////////////////////////////////////////////////////////
/// @brief ensures that a geo constraint exists
/// @startDocuBlock collectionEnsureGeoConstraint
/// `collection.ensureIndex({ type: "geo", fields: [ "location" ] })`
///
/// Since ArangoDB 2.5, this method is an alias for *ensureGeoIndex* since 
/// geo indexes are always sparse, meaning that documents that do not contain
/// the index attributes or have non-numeric values in the index attributes
/// will not be indexed.
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.ensureGeoConstraint = function (lat, lon) {
  'use strict';

  return this.ensureGeoIndex(lat, lon);
};

////////////////////////////////////////////////////////////////////////////////
/// @brief looks up a unique constraint
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.lookupUniqueConstraint = function () {
  'use strict';

  return this.lookupIndex({
    type: "hash",
    fields: Array.prototype.slice.call(arguments),
    unique: true
  });
};

////////////////////////////////////////////////////////////////////////////////
/// @brief looks up a hash index
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.lookupHashIndex = function () {
  'use strict';

  return this.lookupIndex({
    type: "hash",
    fields: Array.prototype.slice.call(arguments)
  });
};

////////////////////////////////////////////////////////////////////////////////
/// @brief looks up a unique skiplist index
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.lookupUniqueSkiplist = function () {
  'use strict';

  return this.lookupIndex({
    type: "skiplist",
    fields: Array.prototype.slice.call(arguments),
    unique: true
  });
};

////////////////////////////////////////////////////////////////////////////////
/// @brief looks up a skiplist index
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.lookupSkiplist = function () {
  'use strict';

  return this.lookupIndex({
    type: "skiplist",
    fields: Array.prototype.slice.call(arguments)
  });
};

////////////////////////////////////////////////////////////////////////////////
/// @brief looks up a fulltext index
/// @startDocuBlock lookUpFulltextIndex
/// `collection.lookupFulltextIndex(attribute, minLength)`
///
/// Checks whether a fulltext index on the given attribute *attribute* exists.
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////

ArangoCollection.prototype.lookupFulltextIndex = function (field, minLength) {
  'use strict';

  if (! Array.isArray(field)) {
    field = [ field ];
  }

  return this.lookupIndex({
    type: "fulltext",
    fields: field,
    minLength: minLength || undefined
  });
};

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// --SECTION--                                                       END-OF-FILE
// -----------------------------------------------------------------------------

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