'use strict';

////////////////////////////////////////////////////////////////////////////////
/// @brief Foxx Template Middleware
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 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 Lucas Dohmen
/// @author Copyright 2013, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

var db = require("@arangodb").db,
  _ = require("lodash");

////////////////////////////////////////////////////////////////////////////////
/// @start Docu Block JSF_foxx_TemplateMiddleware_initializer
///
/// Initialize with the name of a collection or a collection and optionally
/// a set of helper functions.
/// Then use *before* to attach the initialized middleware to your Foxx.Controller
///
/// @EXAMPLES
///
/// ```js
/// templateMiddleware = new TemplateMiddleware("templates", {
///   uppercase: function (x) { return x.toUpperCase(); }
/// });
/// // or without helpers:
/// //templateMiddleware = new TemplateMiddleware("templates");
///
/// app.before(templateMiddleware);
/// ```
/// @end Docu Block
////////////////////////////////////////////////////////////////////////////////

function TemplateMiddleware(templateCollection, helper) {
  var middleware = function (request, response) {
    var responseFunctions,
      _ = require("lodash");

    responseFunctions = {

////////////////////////////////////////////////////////////////////////////////
/// @start Docu Block JSF_foxx_TemplateMiddleware_response_render
///
/// `response.render(templatePath, data)`
///
/// When the TemplateMiddleware is included, you will have access to the
/// *render* function on the response object.
/// If you call render, Controller will look into the this collection and
/// search by the path attribute.  It will then render the template with the
/// given data.
///
/// @EXAMPLES
///
/// ```js
/// response.render("high/way", {username: 'Application'})
/// ```
/// @end Docu Block
////////////////////////////////////////////////////////////////////////////////

      render: function (templatePath, data) {
        var template;

        template = templateCollection.firstExample({path: templatePath });

        if (_.isNull(template)) {
          throw new Error("Template '" + templatePath + "' does not exist");
        }

        if (template.templateLanguage !== "underscore") {
          throw new Error("Unknown template language '" + template.templateLanguage + "'");
        }

        this.body = _.template(template.content)(_.extend(data, helper));
        this.contentType = template.contentType;
      }
    };

    _.extend(response, responseFunctions);
  };

  if (_.isString(templateCollection)) {
    templateCollection = db._collection(templateCollection) ||
      db._create(templateCollection);
  }

  return middleware;
}

exports.TemplateMiddleware = TemplateMiddleware;