/*jshint strict: false */

////////////////////////////////////////////////////////////////////////////////
/// @brief traversal actions
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2014 ArangoDB 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 ArangoDB GmbH, Cologne, Germany
///
/// @author Jan Steemann
/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
/// @author Copyright 2013, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

var arangodb = require("@arangodb");
var actions = require("@arangodb/actions");
var db = require("internal").db;
var traversal = require("@arangodb/graph/traversal");
var Traverser = traversal.Traverser;
var graph = require("@arangodb/general-graph");


////////////////////////////////////////////////////////////////////////////////
/// @brief create a "bad parameter" error
////////////////////////////////////////////////////////////////////////////////

function badParam (req, res, message) {
  actions.resultBad(req,
                    res,
                    arangodb.ERROR_HTTP_BAD_PARAMETER,
                    message);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief create a "not found" error
////////////////////////////////////////////////////////////////////////////////

function notFound (req, res, code, message) {
  actions.resultNotFound(req,
                         res,
                         code,
                         message);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief was docuBlock JSF_HTTP_API_TRAVERSAL
////////////////////////////////////////////////////////////////////////////////

function post_api_traversal(req, res) {
  /*jshint evil: true */
  var json = actions.getJsonBody(req, res);

  if (json === undefined) {
    return badParam(req, res);
  }

  // check start vertex
  // -----------------------------------------

  if (json.startVertex === undefined ||
      typeof json.startVertex !== "string") {
    return badParam(req, res, "missing or invalid startVertex");
  }

  var doc;
  try {
    doc = db._document(json.startVertex);
  }
  catch (err) {
    return notFound(req, res, arangodb.ERROR_ARANGO_DOCUMENT_NOT_FOUND, "invalid startVertex");
  }

  var datasource;
  var edgeCollection;

  if (json.graphName === undefined) {
    // check edge collection
    // -----------------------------------------

    if (json.edgeCollection === undefined) {
      return badParam(req, res, "missing graphname");
    }
    if (typeof json.edgeCollection !== "string") {
      return notFound(req, res, "invalid edgecollection");
    }

    try {
      edgeCollection = db._collection(json.edgeCollection);
      datasource = traversal.collectionDatasourceFactory(edgeCollection);
    }
    catch (ignore) {
    }

    if (edgeCollection === undefined ||
        edgeCollection === null) {
        return notFound(req, res, arangodb.ERROR_ARANGO_COLLECTION_NOT_FOUND,
          "invalid edgeCollection");
    }

  } else {
    if (typeof json.graphName !== "string" || !graph._exists(json.graphName)) {
      return notFound(req, res, arangodb.ERROR_GRAPH_NOT_FOUND,
        "invalid graphname");
    }
    datasource = traversal.generalGraphDatasourceFactory(json.graphName);
  }


  // set up filters
  // -----------------------------------------

  var filters = [ ];
  if (json.minDepth !== undefined) {
    filters.push(traversal.minDepthFilter);
  }
  if (json.maxDepth !== undefined) {
    filters.push(traversal.maxDepthFilter);
  }
  if (json.filter) {
    try {
      filters.push(new Function('config', 'vertex', 'path', json.filter));
    }
    catch (err3) {
      return badParam(req, res, "invalid filter function");
    }
  }

  // if no filter given, use the default filter (does nothing)
  if (filters.length === 0) {
    filters.push(traversal.visitAllFilter);
  }

  // set up visitor
  // -----------------------------------------

  var visitor;

  if (json.visitor !== undefined) {
    try {
      visitor = new Function('config', 'result', 'vertex', 'path', 'connected', json.visitor);
    }
    catch (err4) {
      return badParam(req, res, "invalid visitor function");
    }
  }
  else {
    visitor = traversal.trackingVisitor;
  }

  // set up expander
  // -----------------------------------------

  var expander;

  if (json.direction !== undefined) {
    expander = json.direction;
  }
  else if (json.expander !== undefined) {
    try {
      expander = new Function('config', 'vertex', 'path', json.expander);
    }
    catch (err5) {
      return badParam(req, res, "invalid expander function");
    }
  }

  if (expander === undefined) {
    return badParam(req, res, "missing or invalid expander");
  }

  // set up sort
  // -----------------------------------------

  var sort;

  if (json.sort !== undefined) {
    try {
      sort = new Function('l', 'r', json.sort);
    }
    catch (err6) {
      return badParam(req, res, "invalid sort function");
    }
  }

  // assemble config object
  // -----------------------------------------

  var config = {
    params: json,
    datasource: datasource,
    strategy: json.strategy,
    order: json.order,
    itemOrder: json.itemOrder,
    expander: expander,
    sort: sort,
    visitor: visitor,
    filter: filters,
    minDepth: json.minDepth,
    maxDepth: json.maxDepth,
    maxIterations: json.maxIterations,
    uniqueness: json.uniqueness
  };

  if (edgeCollection !== undefined) {
    config.edgeCollection = edgeCollection;
  }

  // assemble result object
  // -----------------------------------------

  var result = {
    visited: {
      vertices: [ ],
      paths: [ ]
    }
  };

  if (json.init !== undefined) {
    try {
      var init = new Function('result', json.init);
      init(result);
    }
    catch (err7) {
      return badParam(req, res, "invalid init function");
    }
  }

  // run the traversal
  // -----------------------------------------

  var traverser;
  try {
    traverser = new Traverser(config);
    traverser.traverse(result, doc);
    actions.resultOk(req, res, actions.HTTP_OK, { result : result });
  }
  catch (err8) {
    if (traverser === undefined) {
      // error during traversal setup
      return badParam(req, res, err8);
    }
    actions.resultException(req, res, err8, undefined, false);
  }
}


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

actions.defineHttp({
  url : "_api/traversal",

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

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