define([
  'angular',
  'underscore',
  'config',
],
function(angular, _, config) {
  'use strict';

  if (!config.unsaved_changes_warning) {
    return;
  }

  var module = angular.module('kibana.services');

  module.service('unsavedChangesSrv', function($rootScope, $modal, $q, $location, $timeout) {

    var self = this;
    var modalScope = $rootScope.$new();

    $rootScope.$on("dashboard-loaded", function(event, newDashboard) {
      self.original = angular.copy(newDashboard);
      self.current = newDashboard;
    });

    $rootScope.$on("dashboard-saved", function(event, savedDashboard) {
      self.original = angular.copy(savedDashboard);
      self.current = savedDashboard;
    });

    $rootScope.$on("$routeChangeSuccess", function() {
      self.original = null;
    });

    window.onbeforeunload = function() {
      if (self.has_unsaved_changes()) {
        return "There are unsaved changes to this dashboard";
      }
    };

    this.init = function() {
      $rootScope.$on("$locationChangeStart", function(event, next) {
        if (self.has_unsaved_changes()) {
          event.preventDefault();
          self.next = next;
          self.open_modal();
        }
      });
    };

    this.open_modal = function() {
      var confirmModal = $modal({
          template: './app/partials/unsaved-changes.html',
          persist: true,
          show: false,
          scope: modalScope,
          keyboard: false
        });

      $q.when(confirmModal).then(function(modalEl) {
        modalEl.modal('show');
      });
    };

    this.has_unsaved_changes = function() {
      if (!self.original) {
        return false;
      }

      var current = angular.copy(self.current);
      var original = self.original;

      // ignore timespan changes
      current.services.filter.time = original.services.filter.time = {};

      current.refresh = original.refresh;

      var currentTimepicker = _.findWhere(current.nav, { type: 'timepicker' });
      var originalTimepicker = _.findWhere(original.nav, { type: 'timepicker' });

      if (currentTimepicker && originalTimepicker) {
        currentTimepicker.now = originalTimepicker.now;
      }

      var currentJson = angular.toJson(current);
      var originalJson = angular.toJson(original);

      if (currentJson !== originalJson) {
        return true;
      }

      return false;
    };

    this.goto_next = function() {
      var baseLen = $location.absUrl().length - $location.url().length;
      var nextUrl = self.next.substring(baseLen);
      $location.url(nextUrl);
    };

    modalScope.ignore = function() {
      self.original = null;
      self.goto_next();
    };

    modalScope.save = function() {
      var unregister = $rootScope.$on('dashboard-saved', function() {
        self.goto_next();
      });

      $timeout(unregister, 2000);

      $rootScope.$emit('save-dashboard');
    };

  }).run(function(unsavedChangesSrv) {
    unsavedChangesSrv.init();
  });
});