/*jslint indent: 2, nomen: true, maxlen: 100, sloppy: true, vars: true, white: true, plusplus: true */
/*global require, module: true */

////////////////////////////////////////////////////////////////////////////////
/// @brief JavaScript server functions
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2010-2011 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, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

// -----------------------------------------------------------------------------
// --SECTION--                                                            Module
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup V8Module
/// @{
////////////////////////////////////////////////////////////////////////////////

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

function Module (id) {
  this.id = id;
  this.exports = {};
}

////////////////////////////////////////////////////////////////////////////////
/// @brief module cache
////////////////////////////////////////////////////////////////////////////////

Module.prototype.ModuleCache = {};
Module.prototype.ModuleCache["/internal"] = new Module("/internal");
Module.prototype.ModuleCache["/fs"] = new Module("/fs");
Module.prototype.ModuleCache["/console"] = new Module("/console");

////////////////////////////////////////////////////////////////////////////////
/// @brief file exists cache
////////////////////////////////////////////////////////////////////////////////

Module.prototype.ModuleExistsCache = {};

////////////////////////////////////////////////////////////////////////////////
/// @brief loads a file and creates a new module descriptor
////////////////////////////////////////////////////////////////////////////////

Module.prototype.require = function (path) {
  var internal;
  var content;
  var f;
  var module;
  var paths;
  var raw;
  var sandbox;

  internal = this.ModuleCache["/internal"].exports;

  // first get rid of any ".." and "."
  path = this.normalise(path);

  // check if you already know the module, return the exports
  if (this.ModuleCache.hasOwnProperty(path)) {
    return this.ModuleCache[path].exports;
  }

  // locate file and read content
  raw = internal.loadDatabaseFile(path);

  // test for parse errors first and fail early if a parse error detected
  if (! internal.parse(raw.content, path)) {
    throw "Javascript parse error in file '" + path + "'";
  }

  // create a new sandbox and execute
  module = this.ModuleCache[path] = new Module(path);

  content = "(function (module, exports, require, print) {"
          + raw.content 
          + "\n});";
  
  f = internal.execute(content, undefined, path);

  if (f === undefined) {
    throw "cannot create context function";
  }
 
  try {
    f(module,
      module.exports,
      function(path) { return module.require(path); },
      this.ModuleCache["/internal"].exports.print);
  }
  catch (err) {
    delete this.ModuleCache[path];
    throw "Javascript exception in file '" + path + "': " + err.stack;
  }

  return module.exports;
};

////////////////////////////////////////////////////////////////////////////////
/// @brief returns true if require found a file
////////////////////////////////////////////////////////////////////////////////

Module.prototype.exists = function (path) {
  return Module.prototype.ModuleExistsCache[path];
};

////////////////////////////////////////////////////////////////////////////////
/// @brief normalises a path
////////////////////////////////////////////////////////////////////////////////

Module.prototype.normalise = function (path) {
  var i;
  var n;
  var p;
  var q;
  var x;

  if (path === "") {
    return this.id;
  }

  p = path.split('/');

  // relative path
  if (p[0] === "." || p[0] === "..") {
    q = this.id.split('/');
    q.pop();
    q = q.concat(p);
  }

  // absolute path
  else {
    q = p;
  }

  // normalize path
  n = [];

  for (i = 0;  i < q.length;  ++i) {
    x = q[i];

    if (x === "..") {
      if (n.length === 0) {
        throw "cannot cross module top";
      }

      n.pop();
    }
    else if (x !== "" && x !== ".") {
      n.push(x);
    }
  }

  return "/" + n.join('/');
};

////////////////////////////////////////////////////////////////////////////////
/// @brief unloads module
////////////////////////////////////////////////////////////////////////////////

Module.prototype.unload = function (path) {
  if (! path) {
    return;
  }

  var norm = module.normalise(path);

  if (   norm === "/"
      || norm === "/console"
      || norm === "/internal"
      || norm === "/fs"
      || norm === "/org/arangodb"
      || norm === "/org/arangodb/actions") {
    return;
  }

   Module.prototype.ModuleCache["/console"].exports.info("UNLOADING %s", path);
 
  delete this.ModuleCache[norm];
};

////////////////////////////////////////////////////////////////////////////////
/// @brief unloads module
////////////////////////////////////////////////////////////////////////////////

Module.prototype.unloadAll = function () {
  var path;

  for (path in this.ModuleCache) {
    if (this.ModuleCache.hasOwnProperty(path)) {
      this.unload(path);
    }
  }
};

////////////////////////////////////////////////////////////////////////////////
/// @brief top-level module
////////////////////////////////////////////////////////////////////////////////

module = Module.prototype.ModuleCache["/"] = new Module("/");

////////////////////////////////////////////////////////////////////////////////
/// @brief global require function
///
/// @FUN{require(@FA{path})}
///
/// @FN{require} checks if the file specified by @FA{path} has already been
/// loaded.  If not, the content of the file is executed in a new
/// context. Within the context you can use the global variable @LIT{exports}
/// in order to export variables and functions. This variable is returned by
/// @FN{require}.
///
/// Assume that your module file is @LIT{test1.js} and contains
///
/// @verbinclude modules-require-1
///
/// Then you can use @FN{require} to load the file and access the exports.
///
/// @verbinclude modules-require-2
///
/// @FN{require} follows the specification
/// <a href="http://wiki.commonjs.org/wiki/Modules/1.1.1">Modules/1.1.1</a>.
////////////////////////////////////////////////////////////////////////////////

function require (path) {
  return module.require(path);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief global print function
////////////////////////////////////////////////////////////////////////////////

function print () {
  var internal = require("internal");

  internal.print.apply(internal.print, arguments);
}

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

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

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