////////////////////////////////////////////////////////////////////////////////
/// @brief blueprints graph api
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 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 Achim Brandt
/// @author Jan Steemann
/// @author Copyright 2012, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

(function() {
  var actions = require("org/arangodb/actions");
  var graph = require("graph");

// -----------------------------------------------------------------------------
// --SECTION--                                                  global variables
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup ArangoAPI
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief url prefix
////////////////////////////////////////////////////////////////////////////////

  var BLUEPRINTS_URL = "_api/blueprints";

////////////////////////////////////////////////////////////////////////////////
/// @brief context
////////////////////////////////////////////////////////////////////////////////

  var BLUEPRINTS_CONTEXT = "api";

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

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

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup ArangoAPI
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief get graph by request parameter (throws exception)
////////////////////////////////////////////////////////////////////////////////

  function blueprints_graph_by_request_parameter (req) {
    var name = req.parameters['graph'];    

    if (name == undefined) {
      throw "missing graph name";
    }

    return new graph.Graph(name);
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief get graph by request parameter (throws exception)
////////////////////////////////////////////////////////////////////////////////

  function blueprints_graph_by_request (req) {
    var id = req.suffix[0];

    if (req.suffix.length > 1) {
      id += "/" + req.suffix[1];
    }
      
    var g = new graph.Graph(id);
      
    if (g._properties == null) {
      throw "no graph found for: " + id;
    }
    
    return g;
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief get vertex by request (throws exception)
////////////////////////////////////////////////////////////////////////////////

  function blueprints_vertex_by_request (graph, req) {
    var id = req.suffix[0];

    if (req.suffix.length > 1) {
      id += "/" + req.suffix[1];
    }

    var vertex = graph.getVertex(id);

    if (vertex == undefined || vertex._properties == undefined) {
      throw "no vertex found for: " + id;
    }
    
    return vertex;
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief get edge by request (throws exception)
////////////////////////////////////////////////////////////////////////////////

  function blueprints_edge_by_request (graph, req) {
    var id = req.suffix[0];
    if (req.suffix.length > 1) {
      id += "/" + req.suffix[1];
    }

    var edge = graph.getEdge(id);

    if (edge == undefined || edge._properties == undefined) {
      throw "no edge found for: " + id;
    }
    
    return edge;
  }


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

// -----------------------------------------------------------------------------
// --SECTION--                                                   graph functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup ArangoAPI
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief create a blueprint graph
///
/// @RESTHEADER{POST /_api/blueprints/graph,create graph}
///
/// @REST{POST /_api/blueprints/graph}
///
////////////////////////////////////////////////////////////////////////////////
///
/// Creates a new graph.
///
/// The call expects a JSON hash array as body with the following attributes:
///
/// - @LIT{name}: The identifier or name of the new graph.
///
/// - @LIT{verticesName}: The name of the vertices collection.
///
/// - @LIT{edgesName}: The name of the egge collection.
///
/// Returns an object with an attribute @LIT{graph} containing a 
/// list of all graph properties.
///
/// @EXAMPLES
///
/// @verbinclude api-blueprints-create-graph
////////////////////////////////////////////////////////////////////////////////

  function POST_blueprints_graph (req, res) {
    try {    
      var json = actions.getJsonBody(req, res, actions.ERROR_GRAPH_COULD_NOT_CREATE_GRAPH);
      
      if (json === undefined) {
        return;
      }
      
      var name = json['name'];
      var vertices = json['verticesName'];
      var edges = json['edgesName'];
      
      var g = new graph.Graph(name, vertices, edges);
      
      if (g._properties == null) {
        throw "no properties of graph found";
      }
      
      actions.resultOk(req, res, actions.HTTP_OK, { "graph" : g._properties} );
    }
    catch (err) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_COULD_NOT_CREATE_GRAPH, err);
    }
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief get blueprint graph properties
///
/// @RESTHEADER{GET /_api/blueprints/graph/@FA{graph-identifier},get graph properties}
///
/// @REST{GET /_api/blueprints/graph/@FA{graph-identifier}}
///
////////////////////////////////////////////////////////////////////////////////
///
/// Returns an object with an attribute @LIT{graph} containing a 
/// list of all graph properties.
//
/// @EXAMPLES
///
/// get graph by name
/// 
/// @verbinclude api-blueprints-get-graph
/// 
/// get graph by document id
///
/// @verbinclude api-blueprints-get-graph-by-id
////////////////////////////////////////////////////////////////////////////////

  function GET_blueprints_graph (req, res) {
    if (req.suffix.length < 1) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_GRAPH, "graph not found");
      return;
    }
    
    try {    
      var g = blueprints_graph_by_request(req);
      
      actions.resultOk(req, res, actions.HTTP_OK, { "graph" : g._properties} );
    }
    catch (err) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_GRAPH, err);
    }
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief deletes a blueprint graph
///
/// @RESTHEADER{DELETE /_api/blueprints/graph/@FA{graph-identifier},delete graph}
///
/// @REST{DELETE /_api/blueprints/graph/@FA{graph-identifier}}
///
/// Deletes graph, edges and vertices
///
/// @EXAMPLES
///
/// @verbinclude api-blueprints-delete-graph
////////////////////////////////////////////////////////////////////////////////

  function DELETE_blueprints_graph (req, res) {
    if (req.suffix.length < 1) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_GRAPH, "graph not found");
      return;
    }
    
    try {    
      var g = blueprints_graph_by_request(req);
      
      g.drop();
      
      actions.resultOk(req, res, actions.HTTP_OK, { "deleted" : true} );
    }
    catch (err) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_GRAPH, err);
    }
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief actions gateway 
////////////////////////////////////////////////////////////////////////////////

  actions.defineHttp({
    url : BLUEPRINTS_URL + "/graph",
    context : BLUEPRINTS_CONTEXT,

    callback : function (req, res) {
      try {
        switch (req.requestType) {
          case (actions.POST) :
            POST_blueprints_graph(req, res); 
            break;

          case (actions.GET) :
            GET_blueprints_graph(req, res); 
            break;

          case (actions.DELETE) :
            DELETE_blueprints_graph(req, res); 
            break;

          default:
            actions.resultUnsupported(req, res);
        }
      }
      catch (err) {
        actions.resultException(req, res, err);
      }
    }
  });

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

// -----------------------------------------------------------------------------
// --SECTION--                                                  vertex functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup ArangoAPI
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief creates a blueprint graph vertex
///
/// @RESTHEADER{POST /_api/blueprints/vertex?graph=@FA{graph-identifier},create vertex}
///
/// @REST{POST /_api/blueprints/vertex?graph=@FA{graph-identifier}}
///
////////////////////////////////////////////////////////////////////////////////
///
/// Creates a vertex in a graph.
///
/// The call expects a JSON hash array as body with the vertex properties:
///
/// - @LIT{$id}: The identifier or name of the vertex (optional).
///
/// - further optional attributes.
///
/// Returns an object with an attribute @LIT{vertex} containing a
/// list of all vertex properties.
///
/// @EXAMPLES
///
/// @verbinclude api-blueprints-create-vertex
////////////////////////////////////////////////////////////////////////////////

  function POST_blueprints_vertex (req, res) {
    try {
      var g = blueprints_graph_by_request_parameter(req);
      var json = actions.getJsonBody(req, res);
      var id = undefined;

      if (json) {
        id = json["$id"];
      }

      var v = g.addVertex(id, json);      

      if (v == undefined || v._properties == undefined) {
        throw "could not create vertex";
      }

      actions.resultOk(req, res, actions.HTTP_OK, { "vertex" : v._properties } );
    }
    catch (err) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_COULD_NOT_CREATE_VERTEX, err);
    }
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief get vertex properties
///
/// @RESTHEADER{GET /_api/blueprints/vertex/@FA{vertex-identifier}?graph=@FA{graph-identifier},get vertex}
///
/// @REST{GET /_api/blueprints/vertex/@FA{vertex-identifier}?graph=@FA{graph-identifier}}
///
/// Returns an object with an attribute @LIT{vertex} containing a
/// list of all vertex properties.
///
/// @EXAMPLES
///
/// get vertex properties by $id
///
/// @verbinclude api-blueprints-get-vertex
///
/// get vertex properties by document id
///
/// @verbinclude api-blueprints-get-vertex-by-id
////////////////////////////////////////////////////////////////////////////////

  function GET_blueprints_vertex (req, res) {
    if (req.suffix.length < 1) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_VERTEX, "vertex not found");
      return;
    }

    try {    
      var g = blueprints_graph_by_request_parameter(req);
      var v = blueprints_vertex_by_request(g, req);

      actions.resultOk(req, res, actions.HTTP_OK, { "vertex" : v._properties} );
    }
    catch (err) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_VERTEX, err);
    }
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief delete vertex
///
/// @RESTHEADER{DELETE /_api/blueprints/vertex/@FA{vertex-identifier}?graph=@FA{graph-identifier},delete vertex}
///
/// @REST{DELETE /_api/blueprints/vertex/@FA{vertex-identifier}?graph=@FA{graph-identifier}}
///
/// Deletes vertex and all in and out edges of the vertex
///
/// @EXAMPLES
///
/// @verbinclude api-blueprints-delete-vertex
////////////////////////////////////////////////////////////////////////////////

  function DELETE_blueprints_vertex (req, res) {
    if (req.suffix.length < 1) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_VERTEX, "vertex not found");
      return;
    }

    try {    
      var g = blueprints_graph_by_request_parameter(req);
      var v = blueprints_vertex_by_request(g, req);

      g.removeVertex(v);

      actions.resultOk(req, res, actions.HTTP_OK, { "deleted" : true} );
    }
    catch (err) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_VERTEX, err);
    }
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief updates a vertex
///
/// @RESTHEADER{PUT /_api/blueprints/vertex/@FA{vertex-identifier}?graph=@FA{graph-identifier},update vertex}
///
/// @REST{PUT /_api/blueprints/vertex/@FA{vertex-identifier}?graph=@FA{graph-identifier}}
///
////////////////////////////////////////////////////////////////////////////////
///
/// Replaces the vertex properties.
///
/// The call expects a JSON hash array as body with the new vertex properties:
///
/// - @LIT{$id}: The identifier or name of the vertex (not changeable).
///
/// - further optional attributes.
///
/// Returns an object with an attribute @LIT{vertex} containing a
/// list of all vertex properties.
///
/// @EXAMPLES
///
/// @verbinclude api-blueprints-change-vertex
////////////////////////////////////////////////////////////////////////////////

  function PUT_blueprints_vertex (req, res) {
    if (req.suffix.length < 1) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_COULD_NOT_CHANGE_VERTEX, "vertex not found");
      return;
    }

    try {    
      var g = blueprints_graph_by_request_parameter(req);
      var v = blueprints_vertex_by_request(g, req);

      var json = actions.getJsonBody(req, res, actions.ERROR_GRAPH_COULD_NOT_CHANGE_VERTEX);

      if (json === undefined) {
        return;
      }

      var shallow = json.shallowCopy;
      shallow.$id = v._properties.$id;

      var id2 = g._vertices.replace(v._properties, shallow);
      var result = g._vertices.document(id2);

      actions.resultOk(req, res, actions.HTTP_OK, { "vertex" : result} );
    }
    catch (err) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_COULD_NOT_CHANGE_VERTEX, err);
    }
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief actions gateway 
////////////////////////////////////////////////////////////////////////////////

  actions.defineHttp({
    url : BLUEPRINTS_URL + "/vertex",
    context : BLUEPRINTS_CONTEXT,

    callback : function (req, res) {
      try {
        switch (req.requestType) {
          case (actions.POST) :
            POST_blueprints_vertex(req, res); 
            break;

          case (actions.DELETE) :
            DELETE_blueprints_vertex(req, res); 
            break;

          case (actions.GET) :
            GET_blueprints_vertex(req, res); 
            break;

          case (actions.PUT) :
            PUT_blueprints_vertex(req, res); 
            break;

          default:
            actions.resultUnsupported(req, res);
        }
      }
      catch (err) {
        actions.resultException(req, res, err);
      }
    }
  });

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

// -----------------------------------------------------------------------------
// --SECTION--                                                vertices functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup ArangoAPI
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief get graph vertices
///
/// @RESTHEADER{POST /_api/blueprints/vertices?graph=@FA{graph-identifier},get vertices}
///
/// @REST{POST /_api/blueprints/vertices?graph=@FA{graph-identifier}}
///
/// Returns a a cursor.
///
/// The call expects a JSON hash array as body to filter the edges:
///
/// - @LIT{vertex}: the identifier or name of a vertex. This selects inbound and 
///   outbound neighbors of a vertex. If a vertex is given the edge direction
///   can be filterd by @LIT{direction} and labels of edges can be filterd by 
///   @LIT{labels}.
///
/// - @LIT{direction}: Filter for inbound (value "in") or outbound (value "out") 
///   neighbors. Default value is "any".
///
/// - @LIT{key}: filter the result vertices by a key value pair
///
/// - @LIT{value}: the value of the @LIT{key}
///
/// - @LIT{labels}: filter by an array of edge labels
///
/// - @LIT{batchSize}: the batch size of the returned cursor
///
/// @EXAMPLES
///
/// Select all vertices
///
/// @verbinclude api-blueprints-get-vertices
///
/// Select of all neighbors of a vertex.
///
/// @verbinclude api-blueprints-get-vertices2
///
/// Select of all outbound neighbors of a vertex.
///
/// @verbinclude api-blueprints-get-outbound-vertices
//
/// Select of all neighbors of a vertex by a edge label.
///
/// @verbinclude api-blueprints-get-vertices-label
///
/// Select of vertices by key value
///
/// @verbinclude api-blueprints-get-vertices-key
///
////////////////////////////////////////////////////////////////////////////////

  function POST_blueprints_vertices (req, res) {
    if (req.suffix.length != 0) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_VERTEX, "vertex not found");
      return;
    }    

    var json = actions.getJsonBody(req, res);

    if (json === undefined) {
      json = {};
    }
    
    
    try {    
      var g = blueprints_graph_by_request_parameter(req);
      var selectEdge = "";
      var vertexFilter = "";
      var edgeFilter = "";
      var bindVars = {"@vertexColl" : g._properties.verticesName };          

      if (json.vertex != undefined) {
        // get neighbors
        var v = g.getVertex(json.vertex);
        
        if (v == undefined || v._properties == undefined) {
          actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_VERTEX, "vertex not found");
          return;          
        }
        selectEdge = "FOR e IN @@edgeColl";

        // get inbound neighbors
        if (json.direction == "in") {
          edgeFilter = " FILTER e._to == @id";
          vertexFilter = " FILTER e._from == v._id";
        }
        // get outbound neighbors
        else if (json.direction == "out") {
          edgeFilter = " FILTER e._from == @id";
          vertexFilter = " FILTER e._to == v._id";
        }
        // get all neighbors
        else {          
          vertexFilter = " FILTER ((e._from == @id && e._to == v._id) || (e._to == @id && e._from == v._id))";
        }

        bindVars["@edgeColl"] = g._properties.edgesName;
        bindVars["id"] = v._id;
                  
        // filter edge labels
        if (json.labels != undefined && json.labels instanceof Array) {
          if (edgeFilter == "") { edgeFilter = " FILTER"; } else { edgeFilter += " &&";}
          edgeFilter += ' e["$label"] IN @labels';
          bindVars["labels"] = json.labels;
        }

      }

      // filter key/value pairs labels
      if (json.key != undefined) {
        // get all with key=value
        if (vertexFilter == "") { vertexFilter = " FILTER"; } else { vertexFilter += " &&";}
        vertexFilter += " v[@key] == @value";        
        bindVars["key"] = json.key;
        bindVars["value"] = json.value;
      }

      // build aql query
      var query = selectEdge + edgeFilter + " FOR v IN @@vertexColl" + vertexFilter + " RETURN v";

      var cursor = AHUACATL_RUN(query, 
                            bindVars, 
                            (json.count != undefined ? json.count : false),
                            json.batchSize, 
                            (json.batchSize == undefined));  

      // error occurred
      if (cursor instanceof ArangoError) {
        actions.resultBad(req, res, cursor.errorNum, cursor.errorMessage);
        return;
      }
      
      // this might dispose or persist the cursor
      actions.resultCursor(req, res, cursor, actions.HTTP_CREATED, { countRequested: json.count ? true : false });      
    }
    catch (err) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_VERTEX, err);
    }
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief actions gateway 
////////////////////////////////////////////////////////////////////////////////

  actions.defineHttp({
    url : BLUEPRINTS_URL + "/vertices",
    context : BLUEPRINTS_CONTEXT,

    callback : function (req, res) {
      try {
        switch (req.requestType) {
          case (actions.POST) :
            POST_blueprints_vertices(req, res); 
            break;

          default:
            actions.resultUnsupported(req, res);
        }
      }
      catch (err) {
        actions.resultException(req, res, err);
      }
    }
  });

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

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

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup ArangoAPI
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief creates a blueprint graph edge
///
/// @RESTHEADER{POST /_api/blueprints/edge?graph=@FA{graph-identifier},create edge}
///
/// @REST{POST /_api/blueprints/edge?graph=@FA{graph-identifier}}
///
////////////////////////////////////////////////////////////////////////////////
///
/// Creates an edge in a graph.
///
/// The call expects a JSON hash array as body with the edge properties:
///
/// - @LIT{$id}: The identifier or name of the edge.
///
/// - @LIT{_from}: The identifier or name of the from vertex.
///
/// - @LIT{_to}: The identifier or name of the to vertex.
///
/// - @LIT{$label}: A label for the edge (optional).
///
/// - further optional attributes.
///
/// Returns an object with an attribute @LIT{edge} containing the
/// list of all edge properties.
///
/// @EXAMPLES
///
/// @verbinclude api-blueprints-create-edge
////////////////////////////////////////////////////////////////////////////////

  function POST_blueprints_edge (req, res) {
    try {
      var g = blueprints_graph_by_request_parameter(req);
      var json = actions.getJsonBody(req, res, actions.ERROR_GRAPH_COULD_NOT_CREATE_EDGE);

      if (json === undefined) {
        return;
      }

      var id = json["$id"];    
      var out = g.getVertex(json["_from"]);
      var ine = g.getVertex(json["_to"]);
      var label = json["$label"];    

      var e = g.addEdge(out, ine, id, label, json);      

      if (e == undefined || e._properties == undefined) {
        throw "could not create edge";
      }

      actions.resultOk(req, res, actions.HTTP_OK, { "edge" : e._properties } );
    }
    catch (err) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_COULD_NOT_CREATE_EDGE, err);
    }
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief get edge properties
///
/// @RESTHEADER{GET /_api/blueprints/edge/@FA{edge-identifier}?graph=@FA{graph-identifier},get edge}
///
/// @REST{GET /_api/blueprints/edge/@FA{edge-identifier}?graph=@FA{graph-identifier}}
///
/// Returns an object with an attribute @LIT{edge} containing a
/// list of all edge properties.
///
/// @EXAMPLES
///
/// @verbinclude api-blueprints-get-edge
////////////////////////////////////////////////////////////////////////////////

  function GET_blueprints_edge (req, res) {
    if (req.suffix.length < 1) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_EDGE, "edge not found");
      return;
    }

    try {    
      var g = blueprints_graph_by_request_parameter(req);
      var e = blueprints_edge_by_request(g, req);

      actions.resultOk(req, res, actions.HTTP_OK, { "edge" : e._properties} );
    }
    catch (err) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_EDGE, err);
    }
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief deletes an edge
///
/// @RESTHEADER{DELETE /_api/blueprints/edge/@FA{edge-identifier}?graph=@FA{graph-identifier},delete edge}
///
/// @REST{DELETE /_api/blueprints/edge/@FA{edge-identifier}?graph=@FA{graph-identifier}}
///
/// Deletes an edges of the graph
///
/// @EXAMPLES
///
/// @verbinclude api-blueprints-delete-edge
////////////////////////////////////////////////////////////////////////////////

  function DELETE_blueprints_edge (req, res) {
    if (req.suffix.length < 1) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_EDGE, "edge not found");
      return;
    }

    try {    
      var g = blueprints_graph_by_request_parameter(req);
      var e = blueprints_edge_by_request(g, req);

      g.removeEdge(e);

      actions.resultOk(req, res, actions.HTTP_OK, { "deleted" : true} );
    }
    catch (err) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_EDGE, err);
    }
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief updates an edge
///
/// @RESTHEADER{PUT /_api/blueprints/edge/@FA{edge-identifier}?graph=@FA{graph-identifier},update edge}
///
/// @REST{PUT /_api/blueprints/edge/@FA{edge-identifier}?graph=@FA{graph-identifier}}
///
////////////////////////////////////////////////////////////////////////////////
///
/// Replaces the optional edge properties.
///
/// The call expects a JSON hash array as body with the new edge properties.
///
/// Returns an object with an attribute @LIT{edge} containing a
/// list of all edge properties.
///
/// @EXAMPLES
///
/// @verbinclude api-blueprints-change-edge
////////////////////////////////////////////////////////////////////////////////

  function PUT_blueprints_edge(req, res) {
    if (req.suffix.length < 1) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_COULD_NOT_CHANGE_EDGE, "edge not found");
      return;
    }

    try {    
      var g = blueprints_graph_by_request_parameter(req);
      var e = blueprints_edge_by_request(g, req);

      var json = actions.getJsonBody(req, res, actions.ERROR_GRAPH_COULD_NOT_CHANGE_EDGE);

      if (json === undefined) {
        return;
      }

      var shallow = json.shallowCopy;
      shallow.$id = e._properties.$id;
      shallow.$label = e._properties.$label;

      var id2 = g._edges.replace(e._properties, shallow);
      var result = g._edges.document(id2);

      actions.resultOk(req, res, actions.HTTP_OK, { "edge" : result} );
    }
    catch (err) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_COULD_NOT_CHANGE_EDGE, err);
    }
  }

////////////////////////////////////////////////////////////////////////////////
/// @brief actions gateway 
////////////////////////////////////////////////////////////////////////////////

  actions.defineHttp({
    url : BLUEPRINTS_URL + "/edge",
    context : BLUEPRINTS_CONTEXT,

    callback : function (req, res) {
      try {
        switch (req.requestType) {
          case (actions.POST) :
            POST_blueprints_edge(req, res); 
            break;

          case (actions.GET) :
            GET_blueprints_edge(req, res); 
            break;

          case (actions.DELETE) :
            DELETE_blueprints_edge(req, res); 
            break;

          case (actions.PUT) :
            PUT_blueprints_edge(req, res); 
            break;
 
          default:
            actions.resultUnsupported(req, res);
        }
      }
      catch (err) {
        actions.resultException(req, res, err);
      }
    }
  });

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

// -----------------------------------------------------------------------------
// --SECTION--                                                   edges functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup ArangoAPI
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief get graph edges
///
/// @RESTHEADER{POST /_api/blueprints/edges?graph=@FA{graph-identifier},get edges}
///
/// @REST{POST /_api/blueprints/edges?graph=@FA{graph-identifier}}
/// 
/// Returns a a cursor.
/// 
/// The call expects a JSON hash array as body to filter the edges:
///
/// - @LIT{vertex}: the identifier or name of a vertex. This selects inbound and 
///   outbound edges of a vertex. If a vertex is given the edge direction
///   can be filterd by @LIT{direction}.
///
/// - @LIT{direction}: Filter for inbound (value "in") or outbound (value "out") 
///   edges. Default value is "any".
///
/// - @LIT{labels}: filter by an array of edge labels
///
/// - @LIT{key}: filter the by a key value pair
///
/// - @LIT{value}: the value of the @LIT{key}
///
/// - @LIT{batchSize}: the batch size of the returned cursor
///
/// @EXAMPLES
///
/// Select all edges
///
/// @verbinclude api-blueprints-get-edges
///
/// Select of all inbound and outbound edges of a vertex.
///
/// @verbinclude api-blueprints-get-edges-by-vertex
///
/// Select of all outbound edges of a vertex.
///
/// @verbinclude api-blueprints-get-out-edges-by-vertex
///
/// Select of all edges of a vertex by a label.
///
/// @verbinclude api-blueprints-get-in-edges-by-vertex
////////////////////////////////////////////////////////////////////////////////

  function POST_blueprints_edges (req, res) {
    if (req.suffix.length != 0) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_VERTEX, "edges not found");
      return;
    }    

    var json = actions.getJsonBody(req, res);

    if (json === undefined) {
      json = {};
    }
        
    try {    
      var g = blueprints_graph_by_request_parameter(req);
      var filter = "";
      var bindVars = {"@edgeColl" : g._properties.edgesName};

      if (json.vertex != undefined) {
        // get edges of a vertex
        var v = g.getVertex(json.vertex);
        
        if (v == undefined || v._properties == undefined) {
          actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_VERTEX, "vertex not found");
          return;          
        }

        if (json.direction == "in") {
          filter = " FILTER e._to == @id ";
        }
        else if (json.direction == "out") {
          filter = " FILTER e._from == @id ";
        }
        else {
          filter = " FILTER (e._from == @id || e._to == @id)";
        }

        bindVars["id"] = v._id;
      }

      if (json.key != undefined) {
        // get all with key=value
        if (filter == "") {filter = " FILTER";} else {filter += " &&";}
        filter += " e[@key] == @value";
        bindVars["key"] = json.key;
        bindVars["value"] = json.value;
      }

      if (json.labels != undefined && json.labels instanceof Array) {
        // get all with $lable=value
        if (filter == "") {filter = " FILTER";} else {filter += " &&";}
        filter += ' e["$label"] IN @labels';
        bindVars["labels"] = json.labels;
      }

      var query = "FOR e IN @@edgeColl" + filter + " RETURN e";

      var cursor = AHUACATL_RUN(query, 
                            bindVars, 
                            (json.count != undefined ? json.count : false),
                            json.batchSize, 
                            (json.batchSize == undefined));  

      // error occurred
      if (cursor instanceof ArangoError) {
        actions.resultBad(req, res, cursor.errorNum, cursor.errorMessage);
        return;
      }
      
      // this might dispose or persist the cursor
      actions.resultCursor(req, res, cursor, actions.HTTP_CREATED, { countRequested: json.count ? true : false });      
    }
    catch (err) {
      actions.resultBad(req, res, actions.ERROR_GRAPH_INVALID_VERTEX, err + query);
    }
  }
////////////////////////////////////////////////////////////////////////////////
/// @brief actions gateway 
////////////////////////////////////////////////////////////////////////////////

  actions.defineHttp({
    url : BLUEPRINTS_URL + "/edges",
    context : BLUEPRINTS_CONTEXT,

    callback : function (req, res) {
      try {
        switch (req.requestType) {
          case (actions.POST) :
            POST_blueprints_edges(req, res); 
            break;

          default:
            actions.resultUnsupported(req, res);
        }
      }
      catch (err) {
        actions.resultException(req, res, err);
      }
    }
  });

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

})();

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