Mini Kabibi Habibi

Imports Microsoft.VisualBasic
Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.ServiceModel.Syndication
Imports System.Web.UI
Imports System.Xml
Imports DevExpress.Web.ASPxClasses
Imports DevExpress.Web.ASPxSplitter
Imports DevExpress.Web.ASPxGridView
Imports System.Text.RegularExpressions
Imports DevExpress.Data.Filtering
Imports System.Web.UI.WebControls

Partial Public Class Feeds
	Inherits System.Web.UI.Page
	Private Const FeedItemPreviewFormat As String = "<div class='FeedPreview'>" & "<div class='Subject'>{0}</div>" & "<div class='Info'>" & "<span>{1}</span>" & "<a href='{2}' target='_blank'>View on Web</a>" & "</div>" & "<div class='Separator'></div>" & "<div class='Body'>{3}</div>" & "</div>"

	Private Shared ReadOnly FeedRegistry As New Dictionary(Of String, String)()
	Private Shared LastFeedFetchTime As DateTime = DateTime.MinValue
	Private Shared ReadOnly FeedTTL As TimeSpan = TimeSpan.FromHours(2)
	Private Shared FetchedFeeds As New Dictionary(Of String, SyndicationFeed)()
	Private Shared ReadOnly FeedFetchLock As Object = New Object()

	Shared Sub New()
		FeedRegistry("Blogs") = "http://community.devexpress.com/blogs/MainFeed.aspx"
		FeedRegistry("Videos") = "http://tv.devexpress.com/rss.ashx"
		FeedRegistry("Webinars") = "http://www.devexpress.com/rss/webinars/"
		FeedRegistry("News") = "http://www.devexpress.com/rss/news/news20.xml"
		FeedRegistry("BBC News") = "http://feeds.bbci.co.uk/news/rss.xml"
		FeedRegistry("Engadget") = "http://www.engadget.com/rss.xml"
		FeedRegistry("Stack Overflow") = "http://stackoverflow.com/feeds/tag?tagnames=devexpress&sort=newest"
	End Sub

	Protected ReadOnly Property SearchText() As String
		Get
			Return Utils.GetSearchText(Me)
		End Get
	End Property

	Protected Sub Page_PreInit(ByVal sender As Object, ByVal e As EventArgs)
		Utils.ApplyTheme(Me)
	End Sub

	Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
		LoadFeedToGrid()
		PrepareMasterSplitter()
	End Sub

	Protected Sub FeedItemPreviewPanel_Callback(ByVal sender As Object, ByVal e As CallbackEventArgsBase)
		Dim text As String = String.Format("Can't find feed with the key = {0}", e.Parameter)
		If (Not String.IsNullOrEmpty(e.Parameter)) Then
			Dim feedItem = CurrentFeed.Items.FirstOrDefault(Function(i) i.Id = e.Parameter)
			If feedItem IsNot Nothing Then
				text = FormatFeedItem(feedItem)
			End If
		End If
		FeedItemPreviewPanel.Controls.Add(New LiteralControl(text))
	End Sub

	Protected Sub FeedGrid_CustomCallback(ByVal sender As Object, ByVal e As ASPxGridViewCustomCallbackEventArgs)
		If e.Parameters = "FeedChanged" OrElse e.Parameters = "Search" AndAlso String.IsNullOrEmpty(SearchText) Then
			FeedGrid.FilterExpression = ""
		ElseIf e.Parameters = "Search" Then
			FeedGrid.FilterExpression = New GroupOperator(GroupOperatorType.Or, New FunctionOperator(FunctionOperatorType.Contains, New OperandProperty("Title"), SearchText), New FunctionOperator(FunctionOperatorType.Contains, New OperandProperty("From"), SearchText)).ToString()
		End If
	End Sub

	Protected Sub FeedGrid_CustomColumnDisplayText(ByVal sender As Object, ByVal e As ASPxGridViewColumnDisplayTextEventArgs)
		If (Not String.IsNullOrEmpty(SearchText)) AndAlso (e.Column.FieldName = "From" OrElse e.Column.FieldName = "Title") Then
			Dim text As String
			If String.IsNullOrEmpty(e.DisplayText) Then
				text = e.Value.ToString()
			Else
				text = e.DisplayText
			End If
			e.DisplayText = New Regex(SearchText, RegexOptions.IgnoreCase).Replace(text, "<span class='hgl'>$0</span>")
		End If
	End Sub

	Protected Function FormatFeedItem(ByVal feedItem As SyndicationItem) As String
		Return String.Format(FeedItemPreviewFormat, feedItem.Title.Text, GetCreator(CurrentFeed, feedItem), feedItem.Links(0).Uri.AbsoluteUri, feedItem.Summary.Text)
	End Function

	Protected ReadOnly Property CurrentFeed() As SyndicationFeed
		Get
			Return GetFeed(FeedNavBar.SelectedItem.Text)
		End Get
	End Property

	Private Function GetFeed(ByVal key As String) As SyndicationFeed
		If (Not FetchedFeeds.ContainsKey(key)) OrElse DateTime.Now.Subtract(LastFeedFetchTime) > FeedTTL Then
			SyncLock FeedFetchLock
				Using reader = New XmlTextReader(FeedRegistry(key))
					FetchedFeeds(key) = SyndicationFeed.Load(reader)
				End Using
				LastFeedFetchTime = DateTime.Now
			End SyncLock
		End If
		Return FetchedFeeds(key)
	End Function

	Private Sub LoadFeedToGrid()
		Dim data = SelectData()
		If data IsNot Nothing Then
			FeedGrid.DataSource = data
			FeedGrid.DataBind()
		Else
			FeedGrid.SettingsText.EmptyDataRow = String.Format("Please accept our apologies for the inconvenience. The feed URL is currently unavailable: {0}", FeedRegistry(FeedNavBar.SelectedItem.Text))
			FeedGrid.Settings.ShowFooter = False
		End If
	End Sub

	Private Function SelectData() As Object
		Try
			Return _
				From i In CurrentFeed.Items _
				Where (Not i.Summary.Text.Contains("<object")) AndAlso (Not i.Summary.Text.Contains("<embed")) AndAlso (Not i.Summary.Text.Contains("<iframe")) AndAlso (Not i.Summary.Text.Contains("Server Error")) _
				Select New With {Key .ID = i.Id, Key .Date = i.PublishDate, Key .From = GetCreator(CurrentFeed, i), Key .Title = i.Title.Text, Key .Description = i.Summary.Text, Key .Url = i.Links(0).Uri.AbsoluteUri}
		Catch
			Return Nothing
		End Try
	End Function

	Private Function GetCreator(ByVal feed As SyndicationFeed, ByVal item As SyndicationItem) As String
		If item.Authors.Count > 0 Then
			If ((item.Authors(0).Name) IsNot Nothing) Then
				Return item.Authors(0).Name
			Else
				Return item.Authors(0).Email
			End If
		End If
		Dim creator = item.ElementExtensions.FirstOrDefault(Function(e) e.OuterName = "creator")
		If creator IsNot Nothing Then
			Return creator.GetReader().ReadInnerXml()
		End If
		Return feed.Title.Text
	End Function

	Private Sub PrepareMasterSplitter()
		Dim rootHolder = TryCast(Page.Master.Master.FindControl("RootHolder"), ContentPlaceHolder)
		Dim pane = (CType(rootHolder.FindControl("LayoutSplitter"), ASPxSplitter)).GetPaneByName("LeftPane")
		pane.PaneStyle.BorderTop.BorderWidth = 0
	End Sub
End Class