feat(sidebar): Add sidebar controls to add and remove categories

Summary:
- Refactors account-sidebar internal package:
  - Separates into smaller react components
  - Makes DisclosureTriangle its own independent component
  - Adds data to AccountSidebarStore to allow removal or addition of items for a
    specific section of the sidebar
- Adds button and input and css styles to create categories
- Adds context menu to destroy a category
- Adds new method to CategoryStore to get the icon name for the categories of
  the current account
- Removes some unused code

Test Plan: Manual

Reviewers: evan, bengotow

Reviewed By: bengotow

Differential Revision: https://phab.nylas.com/D2283

internal_packages/account-sidebar/lib/account-sidebar-item.cjsx

@@ -1,18 +1,80 @@
 React                      = require 'react'
-{Actions} = require("nylas-exports")
+{WorkspaceStore}           = require 'nylas-exports'
+SidebarSheetItem           = require './account-sidebar-sheet-item'
+AccountSidebarMailViewItem = require './account-sidebar-mail-view-item'
+{DisclosureTriangle}       = require 'nylas-component-kit'
+
 
 class AccountSidebarItem extends React.Component
   @displayName: "AccountSidebarItem"
 
-  render: =>
+  @propTypes: {
-    className = "item " + if @props.select then " selected" else ""
+    item: React.PropTypes.object.isRequired
-    <div className={className} onClick={@_onClick} id={@props.item.id}>
+    selected: React.PropTypes.object.isRequired
-      <div className="name">{@props.item.displayName}</div>
+    onToggleCollapsed: React.PropTypes.func.isRequired
-    </div>
+    collapsed: React.PropTypes.bool
+    onDestroyItem: React.PropTypes.func
+  }
 
-  _onClick: (event) =>
+  @defaultProps: {
-    event.preventDefault()
+    collapsed: false
-    Actions.selectView(@props.item.view)
+  }
 
+  componentDidMount: ->
+    if @props.onDestroyItem?
+      React.findDOMNode(@).addEventListener('contextmenu', @_onShowContextMenu)
+
+  componentWillUnmount: ->
+    if @props.onDestroyItem?
+      React.findDOMNode(@).removeEventListener('contextmenu', @_onShowContextMenu)
+
+  _itemComponent: (item) ->
+    unless item instanceof WorkspaceStore.SidebarItem
+      throw new Error("AccountSidebar:_itemComponents: sections contained an \
+                       item which was not a SidebarItem")
+    if item.component
+      Component = item.component
+      <Component
+        item={item}
+        select={item.id is @props.selected?.id } />
+
+    else if item.mailViewFilter
+      <AccountSidebarMailViewItem
+        item={item}
+        mailView={item.mailViewFilter}
+        select={item.mailViewFilter.isEqual(@props.selected)} />
+
+    else if item.sheet
+      <SidebarSheetItem
+        item={item}
+        select={item.sheet.id is @props.selected?.id} />
+
+    else
+      throw new Error("AccountSidebarItem: each item must have a \
+                       custom component, or a sheet or mailViewFilter")
+
+  _onShowContextMenu: =>
+    item = @props.item
+    label = item.name
+    remote = require 'remote'
+    Menu = remote.require 'menu'
+    MenuItem = remote.require 'menu-item'
+
+    menu = new Menu()
+    menu.append(new MenuItem({
+      label: "Delete #{label}"
+      click: => @props.onDestroyItem?(item)
+    }))
+    menu.popup(remote.getCurrentWindow())
+
+  render: ->
+    item = @props.item
+    <span  className="item-container">
+      <DisclosureTriangle
+        collapsed={@props.collapsed}
+        visible={item.children.length > 0}
+        onToggleCollapsed={ => @props.onToggleCollapsed(item.id)} />
+      {@_itemComponent(item)}
+    </span>
 
 module.exports = AccountSidebarItem

internal_packages/account-sidebar/lib/account-sidebar-mail-view-item.cjsx

@@ -2,7 +2,6 @@ React = require 'react'
 classNames = require 'classnames'
 {Actions,
  Utils,
- ThreadCountsStore,
  WorkspaceStore,
  AccountStore,
  FocusedMailViewStore,
@@ -17,7 +16,6 @@ class AccountSidebarMailViewItem extends React.Component
   @propTypes:
     select: React.PropTypes.bool
     item: React.PropTypes.object.isRequired
-    itemUnreadCount: React.PropTypes.number
     mailView: React.PropTypes.object.isRequired
 
   constructor: (@props) ->
@@ -27,10 +25,13 @@ class AccountSidebarMailViewItem extends React.Component
     !Utils.isEqualReact(@props, nextProps) or !Utils.isEqualReact(@state, nextState)
 
   render: =>
+    isDeleted = @props.mailView?.category?.isDeleted is true
+
     containerClass = classNames
       'item': true
       'selected': @props.select
       'dropping': @state.isDropping
+      'deleted': isDeleted
 
     <DropZone className={containerClass}
          onClick={@_onClick}
@@ -44,10 +45,10 @@ class AccountSidebarMailViewItem extends React.Component
     </DropZone>
 
   _renderUnreadCount: =>
-    return false if @props.itemUnreadCount is 0
+    return false unless @props.item.unreadCount
     className = 'item-count-box '
     className += @props.mailView.category?.name
-    <div className={className}>{@props.itemUnreadCount}</div>
+    <div className={className}>{@props.item.unreadCount}</div>
 
   _renderIcon: ->
     <RetinaImg name={@props.mailView.iconName} fallback={'folder.png'} mode={RetinaImg.Mode.ContentIsMask} />

internal_packages/account-sidebar/lib/account-sidebar-section.cjsx

@@ -0,0 +1,98 @@
+React              = require 'react'
+_                  = require 'underscore'
+_str               = require 'underscore.string'
+{RetinaImg}        = require 'nylas-component-kit'
+AccountSidebarItem = require './account-sidebar-item'
+
+
+class AccountSidebarSection extends React.Component
+  @displayName: "AccountSidebarSection"
+
+  @propTypes: {
+    section: React.PropTypes.object.isRequired
+    collapsed: React.PropTypes.object.isRequired
+    selected: React.PropTypes.object.isRequired
+    onToggleCollapsed: React.PropTypes.func.isRequired
+  }
+
+  constructor: (@props) ->
+    @state = {showCreateInput: false}
+
+  render: ->
+    section     = @props.section
+    showInput   = @state.showCreateInput
+    allowCreate = section.createItem?
+
+    <section>
+      <div className="heading">{section.label}</div>
+      {@_createItemButton(section) if allowCreate}
+      {@_createItemInput(section) if allowCreate and showInput}
+      {@_itemComponents(section.items)}
+    </section>
+
+  _createItemButton: ({label}) ->
+    <div
+      className="add-item-button"
+      onClick={@_onCreateButtonClicked.bind(@, label)}>
+      <RetinaImg
+        url="nylas://account-sidebar/assets/icon-sidebar-addcategory@2x.png"
+        fallback="icon-sidebar-addcategory.png"
+        style={height: 14, width: 14}
+        mode={RetinaImg.Mode.ContentPreserve} />
+    </div>
+
+  _createItemInput: (section) ->
+    label = _str.decapitalize section.label[...-1]
+    placeholder = "Create new #{label}"
+    <span className="item-container">
+      <div className="item add-item-container">
+        <div className="icon">
+          <RetinaImg
+            name="#{section.iconName}"
+            fallback="folder.png"
+            mode={RetinaImg.Mode.ContentIsMask} />
+        </div>
+        <input
+          type="text"
+          tabIndex="1"
+          className="input-bordered add-item-input"
+          autoFocus={true}
+          onKeyDown={_.partial @_onInputKeyDown, _, section}
+          placeholder={placeholder}/>
+      </div>
+    </span>
+
+  _itemComponents: (items) =>
+    components = []
+
+    items.forEach (item) =>
+      components.push(
+        <AccountSidebarItem
+          key={item.id}
+          item={item}
+          collapsed={@props.collapsed[item.id]}
+          selected={@props.selected}
+          onDestroyItem={@props.section.destroyItem}
+          onToggleCollapsed={@props.onToggleCollapsed} />
+      )
+
+      if item.children.length and not @props.collapsed[item.id]
+        components.push(
+          <section key={"#{item.id}-children"}>
+            {@_itemComponents(item.children)}
+          </section>
+        )
+
+    components
+
+  _onCreateButtonClicked: (sectionLabel) =>
+    @setState(showCreateInput: not @state.showCreateInput)
+
+  _onInputKeyDown: (event, section) =>
+    if event.key is 'Escape'
+      @setState(showCreateInput: false)
+    if event.key in ['Enter', 'Return']
+      @props.section.createItem?(event.target.value)
+      @setState(showCreateInput: false)
+
+module.exports = AccountSidebarSection

internal_packages/account-sidebar/lib/account-sidebar-store.coffee

@@ -4,6 +4,7 @@ _ = require 'underscore'
  DatabaseStore,
  CategoryStore,
  AccountStore,
+ ThreadCountsStore,
  WorkspaceStore,
  DraftCountStore,
  Actions,
@@ -12,7 +13,8 @@ _ = require 'underscore'
  Message,
  MailViewFilter,
  FocusedMailViewStore,
- NylasAPI,
+ SyncbackCategoryTask,
+ DestroyCategoryTask,
  Thread} = require 'nylas-exports'
 
 class AccountSidebarStore extends NylasStore
@@ -38,7 +40,9 @@ class AccountSidebarStore extends NylasStore
     @listenTo CategoryStore, @_refreshSections
     @listenTo WorkspaceStore, @_refreshSections
     @listenTo DraftCountStore, @_refreshSections
+    @listenTo ThreadCountsStore, @_refreshSections
     @listenTo FocusedMailViewStore, => @trigger()
+    @configSubscription = NylasEnv.config.observe('core.workspace.showUnreadForAllCategories', @_refreshSections)
 
   _refreshSections: =>
     account = AccountStore.current()
@@ -111,6 +115,9 @@ class AccountSidebarStore extends NylasStore
     @_sections.push
       label: CategoryStore.categoryLabel()
       items: userCategoryItemsHierarchical
+      iconName: CategoryStore.categoryIconName()
+      createItem: @_createCategory
+      destroyItem: @_destroyCategory
 
     @trigger()
 
@@ -125,5 +132,23 @@ class AccountSidebarStore extends NylasStore
       id: category.id,
       name: shortenedName || category.displayName
       mailViewFilter: MailViewFilter.forCategory(category)
+      unreadCount: @_itemUnreadCount(category)
+
+  _createCategory: (displayName) ->
+    CategoryClass = AccountStore.current().categoryClass()
+    category = new CategoryClass
+      displayName: displayName
+      accountId: AccountStore.current().id
+    Actions.queueTask(new SyncbackCategoryTask({category}))
+
+  _destroyCategory: (sidebarItem) ->
+    category = sidebarItem.mailViewFilter.category
+    Actions.queueTask(new DestroyCategoryTask({category}))
+
+  _itemUnreadCount: (category) =>
+    unreadCountEnabled = NylasEnv.config.get('core.workspace.showUnreadForAllCategories')
+    if category and (category.name is 'inbox' or unreadCountEnabled)
+      return ThreadCountsStore.unreadCountForCategoryId(category.id)
+    return 0
 
 module.exports = new AccountSidebarStore()

internal_packages/account-sidebar/lib/account-sidebar.cjsx

@@ -1,26 +1,8 @@
 React = require 'react'
 _ = require 'underscore'
-{Actions, MailViewFilter, WorkspaceStore, ThreadCountsStore} = require("nylas-exports")
+{ScrollRegion} = require 'nylas-component-kit'
-{ScrollRegion, Flexbox} = require("nylas-component-kit")
+AccountSidebarStore = require './account-sidebar-store'
-SidebarDividerItem = require("./account-sidebar-divider-item")
+AccountSidebarSection = require './account-sidebar-section'
-SidebarSheetItem = require("./account-sidebar-sheet-item")
-AccountSidebarStore = require ("./account-sidebar-store")
-AccountSidebarMailViewItem = require("./account-sidebar-mail-view-item")
-{RetinaImg} = require 'nylas-component-kit'
-
-class DisclosureTriangle extends React.Component
-  @displayName: 'DisclosureTriangle'
-
-  @propTypes:
-    collapsed: React.PropTypes.bool
-    visible: React.PropTypes.bool
-    onToggleCollapsed: React.PropTypes.func.isRequired
-
-  render: ->
-    classnames = "disclosure-triangle"
-    classnames += " visible" if @props.visible
-    classnames += " collapsed" if @props.collapsed
-    <div className={classnames} onClick={@props.onToggleCollapsed}><div></div></div>
 
 
 class AccountSidebar extends React.Component
@@ -38,12 +20,9 @@ class AccountSidebar extends React.Component
   componentDidMount: =>
     @unsubscribers = []
     @unsubscribers.push AccountSidebarStore.listen @_onStoreChange
-    @unsubscribers.push ThreadCountsStore.listen @_onStoreChange
-    @configSubscription = NylasEnv.config.observe('core.workspace.showUnreadForAllCategories', @_onStoreChange)
 
   componentWillUnmount: =>
     unsubscribe() for unsubscribe in @unsubscribers
-    @configSubscription?.dispose()
 
   render: =>
     <ScrollRegion style={flex:1} id="account-sidebar">
@@ -54,67 +33,12 @@ class AccountSidebar extends React.Component
 
   _sections: =>
     @state.sections.map (section) =>
-      <section key={section.label}>
+      <AccountSidebarSection
-        <div className="heading">{section.label}</div>
+        key={section.label}
-        {@_itemComponents(section.items)}
+        section={section}
-      </section>
+        collapsed={@state.collapsed}
-
+        selected={@state.selected}
-  _itemComponents: (items) =>
+        onToggleCollapsed={@_onToggleCollapsed} />
-    components = []
-
-    items.forEach (item) =>
-      components.push(
-        <span key={item.id} className="item-container">
-          <DisclosureTriangle
-            collapsed={@state.collapsed[item.id]}
-            visible={item.children.length > 0}
-            onToggleCollapsed={ => @_onToggleCollapsed(item.id)}/>
-          {@_itemComponent(item)}
-        </span>
-      )
-
-      if item.children.length and not @state.collapsed[item.id]
-        components.push(
-          <section key={"#{item.id}-children"}>
-            {@_itemComponents(item.children)}
-          </section>
-        )
-
-    components
-
-  _itemUnreadCount: (item) =>
-    category = item.mailViewFilter.category
-    if category and (category.name is 'inbox' or @state.unreadCountsForAll)
-      return @state.unreadCounts[category.id]
-    return 0
-
-  _itemComponent: (item) =>
-    unless item instanceof WorkspaceStore.SidebarItem
-      throw new Error("AccountSidebar:_itemComponents: sections contained an \
-                       item which was not a SidebarItem")
-
-    if item.component
-      Component = item.component
-      <Component
-        item={item}
-        select={item.id is @state.selected?.id } />
-
-    else if item.mailViewFilter
-      <AccountSidebarMailViewItem
-        item={item}
-        itemUnreadCount={@_itemUnreadCount(item)}
-        mailView={item.mailViewFilter}
-        select={item.mailViewFilter.isEqual(@state.selected)} />
-
-    else if item.sheet
-      <SidebarSheetItem
-        item={item}
-        select={item.sheet.id is @state.selected?.id} />
-
-    else
-      throw new Error("AccountSidebar:_itemComponents: each item must have a \
-                       custom component, or a sheet or mailViewFilter")
-
   _onStoreChange: =>
     @setState @_getStateFromStores()
 
@@ -127,8 +51,5 @@ class AccountSidebar extends React.Component
   _getStateFromStores: =>
     sections: AccountSidebarStore.sections()
     selected: AccountSidebarStore.selected()
-    unreadCounts: ThreadCountsStore.unreadCounts()
-    unreadCountsForAll: NylasEnv.config.get('core.workspace.showUnreadForAllCategories')
-
 
 module.exports = AccountSidebar

internal_packages/account-sidebar/spec/account-sidebar-store-spec.coffee

@@ -115,6 +115,7 @@ describe "AccountSidebarStore", ->
         },
         {
           label: 'Folders',
+          iconName: 'folder.png',
           items: [
             {
               id: 'a',

internal_packages/account-sidebar/stylesheets/account-sidebar.less

@@ -23,6 +23,27 @@
     padding-left:@padding-small-horizontal;
     padding-top:@padding-small-horizontal;
     letter-spacing: -0.2px;
+    display: inline-block;
+  }
+
+  .add-item-button {
+    display: inline-block;
+    margin-left: @padding-small-horizontal;
+    cursor: pointer;
+  }
+
+  .add-item-container {
+    padding-left: @padding-small-horizontal;
+    align-items: center;
+
+    .add-item-input {
+      order: 2;
+      font-size: @font-size-small;
+      margin-left: @padding-small-horizontal * 0.85;
+      height: 22px;
+      text-indent: 4px;
+      width: 85%;
+    }
   }
 
   .item-container {
@@ -112,6 +133,9 @@
       color: @source-list-active-color;
       img.content-mask { background-color: @source-list-active-color; }
     }
+    &.deleted {
+      opacity: 0.5;
+    }
 
     &:hover {
       cursor: default;

spec/tasks/destroy-category-task-spec.coffee

@@ -0,0 +1,106 @@
+DestroyCategoryTask = require "../../src/flux/tasks/destroy-category-task"
+NylasAPI = require "../../src/flux/nylas-api"
+Task = require '../../src/flux/tasks/task'
+{APIError} = require '../../src/flux/errors'
+{Label, Folder, DatabaseStore} = require "nylas-exports"
+
+describe "DestroyCategoryTask", ->
+  pathOf = (fn) ->
+    fn.calls[0].args[0].path
+
+  methodOf = (fn) ->
+    fn.calls[0].args[0].method
+
+  accountIdOf = (fn) ->
+    fn.calls[0].args[0].accountId
+
+  nameOf = (fn) ->
+    fn.calls[0].args[0].body.display_name
+
+  makeTask = (CategoryClass) ->
+    category = new CategoryClass
+      displayName: "important emails"
+      accountId: "account 123"
+      serverId: "server-444"
+    new DestroyCategoryTask
+      category: category
+
+  describe "performLocal", ->
+    beforeEach ->
+      spyOn(DatabaseStore, 'persistModel')
+
+    it "sets an is deleted flag and persists the category", ->
+      task = makeTask(Folder)
+      task.performLocal()
+
+      expect(DatabaseStore.persistModel).toHaveBeenCalled()
+      model = DatabaseStore.persistModel.calls[0].args[0]
+      expect(model.serverId).toEqual "server-444"
+      expect(model.isDeleted).toBe true
+
+  describe "performRemote", ->
+    it "throws error when no category present", ->
+      waitsForPromise ->
+        task = makeTask(Label)
+        task.category = null
+        task.performRemote()
+        .then ->
+          throw new Error('The promise should reject')
+        .catch Error, (err) ->
+          expect(err).toBeDefined()
+
+    it "throws error when category does not have a serverId", ->
+      waitsForPromise ->
+        task = makeTask(Label)
+        task.category.serverId = undefined
+        task.performRemote()
+        .then ->
+          throw new Error('The promise should reject')
+        .catch Error, (err) ->
+          expect(err).toBeDefined()
+
+    describe "when request succeeds", ->
+      beforeEach ->
+        spyOn(NylasAPI, "makeRequest").andCallFake -> Promise.resolve("null")
+
+      it "sends API req to /labels if user uses labels", ->
+        task = makeTask(Label)
+        task.performRemote()
+        expect(pathOf(NylasAPI.makeRequest)).toBe "/labels/server-444"
+
+      it "sends API req to /folders if user uses folders", ->
+        task = makeTask(Folder)
+        task.performRemote()
+        expect(pathOf(NylasAPI.makeRequest)).toBe "/folders/server-444"
+
+      it "sends DELETE request", ->
+        task = makeTask(Folder)
+        task.performRemote()
+        expect(methodOf(NylasAPI.makeRequest)).toBe "DELETE"
+
+      it "sends the account id", ->
+        task = makeTask(Label)
+        task.performRemote()
+        expect(accountIdOf(NylasAPI.makeRequest)).toBe "account 123"
+
+    describe "when request fails", ->
+      beforeEach ->
+        spyOn(NylasEnv, 'emitError')
+        spyOn(DatabaseStore, 'persistModel').andCallFake ->
+          Promise.resolve()
+        spyOn(NylasAPI, 'makeRequest').andCallFake ->
+          Promise.reject(new APIError({statusCode: 403}))
+
+      it "updates the isDeleted flag for the category and notifies error", ->
+        waitsForPromise ->
+          task = makeTask(Folder)
+          spyOn(task, "_notifyUserOfError")
+
+          task.performRemote().then (status) ->
+            expect(status).toEqual Task.Status.Failed
+            expect(task._notifyUserOfError).toHaveBeenCalled()
+            expect(NylasEnv.emitError).toHaveBeenCalled()
+            expect(DatabaseStore.persistModel).toHaveBeenCalled()
+            model = DatabaseStore.persistModel.calls[0].args[0]
+            expect(model.serverId).toEqual "server-444"
+            expect(model.isDeleted).toBe false

src/components/disclosure-triangle.cjsx

@@ -0,0 +1,17 @@
+React = require 'react'
+
+class DisclosureTriangle extends React.Component
+  @displayName: 'DisclosureTriangle'
+
+  @propTypes:
+    collapsed: React.PropTypes.bool
+    visible: React.PropTypes.bool
+    onToggleCollapsed: React.PropTypes.func.isRequired
+
+  render: ->
+    classnames = "disclosure-triangle"
+    classnames += " visible" if @props.visible
+    classnames += " collapsed" if @props.collapsed
+    <div className={classnames} onClick={@props.onToggleCollapsed}><div></div></div>
+
+module.exports = DisclosureTriangle

src/flux/models/category.coffee

@@ -32,9 +32,9 @@ class Category extends Model
       modelKey: 'displayName'
       jsonKey: 'display_name'
 
-    'unread': Attributes.Number
+    'isDeleted': Attributes.Boolean
-      queryable: true
+      modelKey: 'isDeleted'
-      modelKey: 'unread'
+      jsonKey: 'is_deleted'
 
   hue: ->
     return 0 unless @displayName

src/flux/nylas-api.coffee

@@ -10,7 +10,7 @@ async = require 'async'
 # A 0 code is when an error returns without a status code. These are
 # things like "ESOCKETTIMEDOUT"
 TimeoutErrorCode = 0
-PermanentErrorCodes = [400, 404, 500]
+PermanentErrorCodes = [400, 403, 404, 500]
 CancelledErrorCode = -123
 SampleTemporaryErrorCode = 504
 

src/flux/stores/category-store.coffee

@@ -61,6 +61,18 @@ class CategoryStore extends NylasStore
     else
       return "Unknown"
 
+  categoryIconName: ->
+    account = AccountStore.current()
+    return "folder.png" unless account
+
+    if account.usesFolders()
+      return "folder.png"
+    else if account.usesLabels()
+      return "tag.png"
+    else
+      return null
+
+
   # Public: Returns {Folder} or {Label}, depending on the current provider.
   #
   categoryClass: ->

src/flux/stores/draft-store.coffee

@@ -533,14 +533,7 @@ class DraftStore
       # don't delay the modal may come up in a state where the draft looks
       # like it hasn't been restored or has been lost.
       _.delay ->
-        remote = require('remote')
+        NylasEnv.showErrorDialog(errorMessage)
-        dialog = remote.require('dialog')
-        dialog.showMessageBox remote.getCurrentWindow(), {
-          type: 'warning'
-          buttons: ['Okay'],
-          message: "Error"
-          detail: errorMessage
-        }
       , 100
 
  module.exports = new DraftStore()

src/flux/stores/workspace-store.coffee

@@ -10,7 +10,7 @@ Location = {}
 SidebarItems = {}
 
 class WorkspaceSidebarItem
-  constructor: ({@id, @component, @icon, @name, @sheet, @mailViewFilter, @section, @children}) ->
+  constructor: ({@id, @component, @icon, @name, @sheet, @mailViewFilter, @section, @children, @unreadCount}) ->
     if not @sheet and not @mailViewFilter and not @component
       throw new Error("WorkspaceSidebarItem: You must provide either a sheet \
                        component, or a mailViewFilter for the sidebar item named #{@name}")

src/flux/tasks/destroy-category-task.coffee

@@ -0,0 +1,79 @@
+DatabaseStore = require '../stores/database-store'
+Label = require '../models/label'
+Folder = require '../models/folder'
+Task = require './task'
+ChangeFolderTask = require './change-folder-task'
+ChangeLabelTask = require './change-labels-task'
+SyncbackCategoryTask = require './syncback-category-task'
+NylasAPI = require '../nylas-api'
+{APIError} = require '../errors'
+
+class DestroyCategoryTask extends Task
+
+  constructor: ({@category}={}) ->
+    super
+
+  label: ->
+    name = @category.displayName
+    if @category instanceof Label
+      "Deleting label #{name}..."
+    else
+      "Deleting folder #{name}..."
+
+  isDependentTask: (other) ->
+    (other instanceof ChangeFolderTask) or
+    (other instanceof ChangeLabelTask) or
+    (other instanceof SyncbackCategoryTask)
+
+  performLocal: ->
+    if not @category
+      return Promise.reject(new Error("Attempt to call DestroyCategoryTask.performLocal without @category."))
+    @category.isDeleted = true
+    DatabaseStore.persistModel @category
+
+  performRemote: ->
+    if not @category
+      return Promise.reject(new Error("Attempt to call DestroyCategoryTask.performRemote without @category."))
+
+    if not @category.serverId
+      return Promise.reject(new Error("Attempt to call DestroyCategoryTask.performRemote without @category.serverId."))
+
+    if @category instanceof Label
+      path = "/labels/#{@category.serverId}"
+    else
+      path = "/folders/#{@category.serverId}"
+
+    NylasAPI.makeRequest
+      path: path
+      method: 'DELETE'
+      accountId: @category.accountId
+      returnsModel: false
+    .then ->
+      return Promise.resolve(Task.Status.Success)
+    .catch APIError, (err) =>
+      if err.statusCode in NylasAPI.PermanentErrorCodes
+        # Revert isDeleted flag
+        @category.isDeleted = false
+        DatabaseStore.persistModel(@category).then =>
+          NylasEnv.emitError(
+            new Error("Deleting category responded with #{err.statusCode}!")
+          )
+          @_notifyUserOfError()
+          return Promise.resolve(Task.Status.Failed)
+      else
+        return Promise.resolve(Task.Status.Retry)
+
+  _notifyUserOfError: (category = @category) ->
+    displayName = category.displayName
+    label = if category instanceof Label
+      'label'
+    else
+      'folder'
+
+    msg = "The #{label} #{displayName} could not be deleted."
+    if label is 'folder'
+      msg += " Make sure the folder you want to delete is empty before deleting it."
+
+    NylasEnv.showErrorDialog(msg)
+
+module.exports = DestroyCategoryTask

src/global/nylas-component-kit.coffee

@@ -30,6 +30,7 @@ class NylasComponentKit
   @load "InjectedComponentSet", 'injected-component-set'
   @load "TimeoutTransitionGroup", 'timeout-transition-group'
   @load "ConfigPropContainer", "config-prop-container"
+  @load "DisclosureTriangle", "disclosure-triangle"
 
   @load "ScrollRegion", 'scroll-region'
   @load "ResizableRegion", 'resizable-region'

src/global/nylas-exports.coffee

@@ -86,6 +86,7 @@ class NylasExports
   @require "ChangeLabelsTask", 'flux/tasks/change-labels-task'
   @require "ChangeFolderTask", 'flux/tasks/change-folder-task'
   @require "SyncbackCategoryTask", 'flux/tasks/syncback-category-task'
+  @require "DestroyCategoryTask", 'flux/tasks/destroy-category-task'
   @require "ChangeUnreadTask", 'flux/tasks/change-unread-task'
   @require "SyncbackDraftTask", 'flux/tasks/syncback-draft'
   @require "ChangeStarredTask", 'flux/tasks/change-starred-task'

src/mail-view-filter.coffee

@@ -140,10 +140,8 @@ class CategoryMailViewFilter extends MailViewFilter
 
     if cat.name
       @iconName = "#{cat.name}.png"
-    else if AccountStore.current().usesLabels()
-      @iconName = "tag.png"
     else
-      @iconName = "folder.png"
+      @iconName = CategoryStore.categoryIconName()
 
     @
 

src/nylas-env.coffee

@@ -843,6 +843,15 @@ class NylasEnvConstructor extends Model
     dialog = remote.require('dialog')
     dialog.showSaveDialog(@getCurrentWindow(), {title: 'Save File', defaultPath}, callback)
 
+  showErrorDialog: (message) ->
+    dialog = remote.require('dialog')
+    dialog.showMessageBox null, {
+      type: 'warning'
+      buttons: ['Okay'],
+      message: "Error"
+      detail: message
+    }
+
   saveSync: ->
     stateString = JSON.stringify(@savedState)
     if statePath = @constructor.getStatePath()