canvas-lms/app/helpers/application_helper.rb

#
# Copyright (C) 2011 Instructure, Inc.
#
# This file is part of Canvas.
#
# Canvas is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the Free
# Software Foundation, version 3 of the License.
#
# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License along
# with this program. If not, see <http://www.gnu.org/licenses/>.
#

# Methods added to this helper will be available to all templates in the application.
module ApplicationHelper
  include TextHelper
  include LocaleSelection
  
  # Admins of the given context can see the User.name attribute,
  # but everyone else sees the User.short_name attribute.
  def context_user_name(context, user, last_name_first=false)
    return nil unless user
    return user.short_name if !context && user.respond_to?(:short_name)
    context_code = context
    context_code = context.asset_string if context.respond_to?(:asset_string)
    context_code ||= "no_context"
    user_id = user
    user_id = user.id if user.is_a?(User) || user.is_a?(OpenObject)
    Rails.cache.fetch(['context_user_name', context_code, user_id, last_name_first].cache_key, {:expires_in=>15.minutes}) do
      user = User.find_by_id(user_id)
      res = user.short_name || user.name
      res
    end
  end
  
  def keyboard_navigation(keys)
    content = "<ul class='navigation_list' tabindex='-1'>\n"
    keys.each do |hash|
      content += "  <li>\n"
      content += "    <span class='keycode'>#{h(hash[:key])}</span>\n"
      content += "    <span class='colon'>:</span>\n"
      content += "    <span class='description'>#{h(hash[:description])}</span>\n"
      content += "  </li>\n"
    end
    content += "</ul>"
    content_for(:keyboard_navigation) { raw(content) }
  end
  
  def context_prefix(code)
    return "/{{ context_type_pluralized }}/{{ context_id }}" unless code
    split = code.split(/_/)
    id = split.pop
    type = split.join('_')
    "/#{type.pluralize}/#{id}"
  end
  
  def cached_context_short_name(code)
    return nil unless code
    @cached_context_names ||= {}
    @cached_context_names[code] ||= Rails.cache.fetch(['short_name_lookup', code].cache_key) do
      Context.find_by_asset_string(code).short_name rescue ""
    end
  end

  def lock_explanation(hash, type, context=nil)
    res = "This #{type} "
    hash ||= {}
    if hash[:lock_at]
      res += "was locked #{datetime_string(hash[:lock_at])}"
    elsif hash[:unlock_at]
      res += "is locked until #{datetime_string(hash[:unlock_at])}"
    elsif hash[:context_module]
      obj = hash[:context_module].is_a?(ContextModule) ? hash[:context_module] : OpenObject.new(hash[:context_module])
      res += "hasn't been unlocked yet.  It is part of the module <b>#{obj.name}</b>."
      if context
        res += "<br/><a href='#{context_url(context, :context_context_modules_url)}'>Visit the #{context.class.to_s.downcase} modules page for information on how to unlock this content.</a>"
        res += "<a href='#{context_url(context, :context_context_module_prerequisites_needing_finishing_url, obj.id, hash[:asset_string])}' style='display: none;' id='module_prerequisites_lookup_link'>&nbsp;</a>"
        jammit_js :prerequisites_lookup
      end
    else
      res += "is currently locked"
    end
    raw(res)
  end
  
  def avatar_image(user_id, height=50)
    if session["reported_#{user_id}"]
      image_tag "no_pic.gif"
    else
      image_tag(avatar_image_url(user_id || 0), :style => "height: #{height}px;", :alt => '')
    end
  end
  
  def avatar(user_id, context_code, height=50)
    if service_enabled?(:avatars)
      link_to(avatar_image(user_id, height), "#{context_prefix(context_code)}/users/#{user_id}", :style => 'z-index: 2; position: relative;')
    end
  end
  
  def slugify(text="")
    text.gsub(/[^\w]/, "_").downcase
  end
  
  def count_if_any(count=nil)
    if count && count > 0
      "(#{count})"
    else
      ""
    end
  end

  # Used to generate context_specific urls, as in:
  # context_url(@context, :context_assignments_url)
  # context_url(@context, :controller => :assignments, :action => :show)
  def context_url(context, *opts)
    @context_url_lookup ||= {}
    context_name = (context ? context.class.base_ar_class : context.class).name.underscore
    lookup = [context ? context.id : nil, context_name, *opts]
    return @context_url_lookup[lookup] if @context_url_lookup[lookup]
    res = nil
    if opts.length > 1 || (opts[0].is_a? String) || (opts[0].is_a? Symbol)
      name = opts.shift.to_s
      name = name.sub(/context/, context_name)
      opts.unshift context.id
      opts.push({}) unless opts[-1].is_a?(Hash)
      ajax = opts[-1].delete :ajax rescue nil
      opts[-1][:only_path] = true unless opts[-1][:only_path] == false
      res = self.send name, *opts
    elsif opts[0].is_a? Hash
      opts = opts[0]
      ajax = opts[0].delete :ajax rescue nil
      opts[:only_path] = true
      opts["#{context_name}_id"] = context.id
      res = self.url_for opts
    else
      res = context_name.to_s + opts.to_json.to_s
    end
    @context_url_lookup[lookup] = res
  end
  
  def hidden(include_style=false)
    include_style ? "style='display:none;'" : "display: none;"
  end

  # Helper for easily checking vender/plugins/adheres_to_policy.rb
  # policies from within a view.  Caches the response, but basically
  # user calls object.grants_right?(user, nil, action)
  def can_do(object, user, action)
    return false unless object
    if object.is_a?(OpenObject) && object.type
      obj = object.temporary_instance
      if !obj
        obj = object.type.classify.constantize.new
        obj.instance_variable_set("@attributes", object.instance_variable_get("@table").with_indifferent_access)
        obj.instance_variable_set("@new_record", false)
        object.temporary_instance = obj
      end
      return can_do(obj, user, action)
    end
    if (object == @context || object.is_a?(Course)) && user == @current_user
      @context_all_permissions ||= {}
      @context_all_permissions[object.asset_string] ||= object.grants_rights?(user, session, nil)
      return @context_all_permissions[object.asset_string][action]
    end
    @permissions_lookup ||= {}
    lookup = [object ? object.asset_string : nil, user ? user.id : nil, action]
    return @permissions_lookup[lookup] if @permissions_lookup[lookup] != nil
    res = false
    begin
      res = object.grants_right?(user, session, action)
    rescue => e
      logger.warn "#{object.inspect} raised an error while granting rights.  #{e.inspect}" if logger
      false 
    end
    @permissions_lookup[lookup] = res
  end
  
  # Loads up the lists of files needed for the wiki_sidebar.  Called from
  # within the cached code so won't be loaded unless needed.
  def load_wiki_sidebar
    return if @wiki_sidebar_data
    logger.warn "database lookups happening in view code instead of controller code for wiki sidebar (load_wiki_sidebar)"
    @wiki_sidebar_data = {}
    includes = [:default_wiki_wiki_pages, :active_assignments, :active_discussion_topics, :active_quizzes, :active_context_modules]
    includes.each{|i| @wiki_sidebar_data[i] = @context.send(i).scoped({:limit => 150}) if @context.respond_to?(i) }
    includes.each{|i| @wiki_sidebar_data[i] ||= [] }
    @wiki_sidebar_data[:root_folders] = Folder.root_folders(@context)
    @wiki_sidebar_data
  end
  
  # js_block captures the content of what you pass it and render_js_blocks will 
  # render all of the blocks that were captured by js_block inside of a <script> tag
  # if you are in the development environment it will also print out a javascript // comment
  # that shows the file and line number of where this block of javascript came from.
  def js_block(options = {}, &block)
    js_blocks << options.merge(
      :file_and_line => block.to_s,
      :contents => capture(&block)
    )
  end
  def js_blocks; @js_blocks ||= []; end
  def render_js_blocks
    output = js_blocks.inject('') do |str, e|
      add_i18n_scoping!(e[:i18n_scope].to_s, e[:contents]) if e[:i18n_scope]
      # print file and line number for debugging in development mode.
      value = ""
      value << "<!-- BEGIN SCRIPT BLOCK FROM: " + e[:file_and_line] + " --> \n" if Rails.env == "development"
      value << e[:contents]
      value << "<!-- END SCRIPT BLOCK FROM: " + e[:file_and_line] + " --> \n" if Rails.env == "development"
      str << value
    end
    raw(output)
  end

  class << self
    attr_accessor :cached_translation_blocks
  end

  def add_i18n_scoping!(scope, contents)
    @included_i18n_scopes ||= []
    translations = unless @included_i18n_scopes.include?(scope)
      @included_i18n_scopes << scope
      js_translations_for(scope)
    end
    contents.gsub!(/(<script[^>]*>)([^<].*?)(<\/script>)/m, "\\1\n#{translations}I18n.scoped(#{scope.inspect}, function(I18n){\n\\2\n});\n\\3")
  end

  def js_translations_for(scope)
    scope = [I18n.locale] + scope.split(/\./).map(&:to_sym)
    (ApplicationHelper.cached_translation_blocks ||= {})[scope] ||=
    if scoped_translations = scope.inject(I18n.backend.send(:translations)) { |hash, key| hash && hash[key] }
      last_key = scope.last
      translations = {}
      scope[0..scope.size-2].inject(translations) { |hash, key|
        hash[key] ||= {}
      }[last_key] = scoped_translations
      <<-TRANSLATIONS
var I18n = I18n || {};
(function($) {
  var translations = #{translations.to_json};
  if (I18n.translations) {
    $.extend(true, I18n.translations, translations);
  } else {
    I18n.translations = translations;
  }
})(jQuery);
      TRANSLATIONS
    else
      ''
    end
  end

  def jammit_js_bundles; @jammit_js_bundles ||= []; end
  def jammit_js(*args)
    Array(args).flatten.each do |bundle| 
      jammit_js_bundles << bundle unless jammit_js_bundles.include? bundle
    end
  end
    
  def jammit_css_bundles; @jammit_css_bundles ||= []; end
  def jammit_css(*args)
    Array(args).flatten.each do |bundle| 
      jammit_css_bundles << bundle unless jammit_css_bundles.include? bundle
    end
  end

  def section_tabs
    @section_tabs ||= begin
      if @context 
        Rails.cache.fetch([@context, @current_user, "section_tabs", I18n.locale].cache_key) do
          if @context.respond_to?(:tabs_available) && !(tabs = @context.tabs_available(@current_user)).empty?
            html = []
            html << '<nav role="navigation"><ul id="section-tabs">'
            tabs = tabs.select do |tab|
              if (tab[:id] == @context.class::TAB_CHAT rescue false)
                tab[:href] && tab[:label] && feature_enabled?(:tinychat)
              elsif (tab[:id] == @context.class::TAB_COLLABORATIONS rescue false)
                tab[:href] && tab[:label] && Collaboration.any_collaborations_configured?
              elsif (tab[:id] == @context.class::TAB_CONFERENCES rescue false)
                tab[:href] && tab[:label] && feature_enabled?(:web_conferences)
              else
                tab[:href] && tab[:label]
              end
            end
            tabs.each do |tab|
              path = tab[:no_args] ? send(tab[:href]) : send(tab[:href], @context)
              html << "<li class='section #{"hidden" if tab[:hidden] || tab[:hidden_unused] }'>" + link_to(tab[:label], path, :class => tab[:css_class].to_css_class) + "</li>" if tab[:href]
            end
            html << "</ul></nav>"
            html.join("")
          end
        end
      end
    end
    raw(@section_tabs)
  end
  
  def sortable_tabs
    tabs = @context.tabs_available(@current_user)
    tabs.select do |tab| 
      if (tab[:id] == @context.class::TAB_CHAT rescue false)
        feature_enabled?(:tinychat)
      elsif (tab[:id] == @context.class::TAB_COLLABORATIONS rescue false)
        Collaboration.any_collaborations_configured?
      elsif (tab[:id] == @context.class::TAB_CONFERENCES rescue false)
        feature_enabled?(:web_conferences)
      else
        tab[:id] != (@context.class::TAB_SETTINGS rescue nil)
      end
    end
  end
  
  def license_help_link
    @include_license_dialog = true
    link_to(image_tag('help.png'), '#', :class => 'license_help_link no-hover', :title => "Help with content licensing")
  end
  
  def equella_enabled?
    @equella_settings ||= @context.equella_settings if @context.respond_to?(:equella_settings)
    @equella_settings ||= @domain_root_account.try(:equella_settings)
    !!@equella_settings
  end

  def show_user_create_course_button(user)
    return false if user.nil?
    root_account = @domain_root_account || user.account.root_account || user.account
    
    # admins can always create courses
    return true if root_account.account_users.find_by_user_id(user.id)
    
    if root_account.settings[:teachers_can_create_courses] != false
      count = user.enrollments.scoped(:select=>'id', :conditions=>"enrollments.type IN ('TeacherEnrollment', 'DesignerEnrollment') AND (enrollments.workflow_state != 'deleted') AND root_account_id = #{root_account.id}").count
      return true if count > 0
    end
    if root_account.settings[:students_can_create_courses] != false
      count = user.enrollments.scoped(:select=>'id', :conditions=>"enrollments.type IN ('StudentEnrollment', 'ObserverEnrollment') AND (enrollments.workflow_state != 'deleted') AND root_account_id = #{root_account.id}").count
      return true if count > 0
    end
    if root_account.settings[:no_enrollments_can_create_courses] != false
      count = user.enrollments.scoped(:select=>'id', :conditions=>"enrollments.workflow_state != 'deleted' AND root_account_id = #{root_account.id}").count
      return true if count == 0
    end
    
    false
  end
  
  def hash_get(hash, key, default=nil)
    if hash
      if hash[key.to_s] != nil
        hash[key.to_s]
      elsif hash[key.to_sym] != nil
        hash[key.to_sym]
      else
        default
      end
    else
      default
    end
  end
  
  def safe_cache_key(*args)
    key = args.cache_key
    if key.length > 200
      key = Digest::MD5.hexdigest(key)
    end
    key
  end
  
  def inst_env
    global_inst_object = { :environment =>  Rails.env }
    {
      :allowMediaComments     => Kaltura::ClientV3.config && @context.try_rescue(:allow_media_comments?),
      :kalturaSettings        => Kaltura::ClientV3.config.try(:slice, 'domain', 'resource_domain', 'partner_id', 'subpartner_id', 'player_ui_conf', 'player_cache_st', 'kcw_ui_conf', 'upload_ui_conf', 'max_file_size_bytes'),
      :equellaEnabled         => !!equella_enabled?,
      :googleAnalyticsAccount => Setting.get_cached('google_analytics_key', nil),
      :http_status            => @status,
      :error_id               => @error && @error.id,
      :disableGooglePreviews  => !service_enabled?(:google_docs_previews), 
      :disableScribdPreviews  => !feature_enabled?(:scribd),
      :logPageViews           => !@body_class_no_headers,
    }.each do |key,value|
      # dont worry about keys that are nil or false because in javascript: if (INST.featureThatIsUndefined ) { //won't happen }
      global_inst_object[key] = value if value
    end
    global_inst_object
  end

  def nbsp
    raw("&nbsp;")
  end

  # translate a URL intended for an iframe into an alternative URL, if one is
  # avavailable. Right now the only supported translation is for youtube
  # videos. Youtube video pages can no longer be embedded, but we can translate
  # the URL into the player iframe data.
  def iframe(src, html_options = {})
    uri = URI.parse(src) rescue nil
    if uri
      query = Rack::Utils.parse_query(uri.query)
      if uri.host == 'www.youtube.com' && uri.path == '/watch' && query['v'].present?
        src = "//www.youtube.com/embed/#{query['v']}"
        html_options.merge!({:title => 'Youtube video player', :width => 640, :height => 480, :frameborder => 0, :allowfullscreen => 'allowfullscreen'})
      end
    end
    content_tag('iframe', '', { :src => src }.merge(html_options))
  end

  # returns a time object at 00:00:00 tomorrow
  def tomorrow_at_midnight
    1.day.from_now.to_date.to_time
  end
  
  # you should supply :all_folders to avoid a db lookup on every iteration
  def folders_as_options(folders, opts = {})
    opts[:indent_width] ||= 3
    opts[:depth] ||= 0
    opts[:options_so_far] ||= []
    folders.each do |folder|
      opts[:options_so_far] << %{<option value="#{folder.id}" #{'selected' if opts[:selected_folder_id] == folder.id}>#{"&nbsp;" * opts[:indent_width] * opts[:depth]}#{"- " if opts[:depth] > 0}#{html_escape folder.name}</option>}
      child_folders = if opts[:all_folders]
                        opts[:all_folders].select {|f| f.parent_folder_id == folder.id }
                      else
                        folder.active_sub_folders
                      end
      if opts[:max_depth].nil? || opts[:depth] < opts[:max_depth]
        folders_as_options(child_folders, opts.merge({:depth => opts[:depth] + 1}))
      end
    end
    opts[:depth] == 0 ? raw(opts[:options_so_far].join("\n")) : nil
  end

  # this little helper just allows you to do <% ot(...) %> and have it output the same as <%= t(...) %>. The upside though, is you can interpolate whole blocks of HTML, like:
  # <% ot 'some_key', 'For %{a} select %{b}', :a => capture { %>
  # <div>...</div>
  # <% }, :b => capture { %>
  # <select>...</select>
  # <% } %>
  def ot(*args)
    concat(t(*args))
  end

  def join_title(*parts)
    parts.join(t('#title_separator', ': '))
  end

  def cache(name = {}, options = nil, &block)
    unless options && options[:no_locale]
      name = name.cache_key if name.respond_to?(:cache_key)
      name = name + "/#{I18n.locale}" if name.is_a?(String)
    end
    super
  end
end