From 8316abc300d56f876a5fe3b511dc202556ad776c Mon Sep 17 00:00:00 2001
From: Konstantin
Date: Wed, 24 Oct 2012 23:38:06 +0400
Subject: loading data on scrolling at bottom

---
 Juick/ViewModels/MessageListViewModelBase.cs | 126 ++++++++++++++++-----------
 1 file changed, 73 insertions(+), 53 deletions(-)

(limited to 'Juick/ViewModels/MessageListViewModelBase.cs')

diff --git a/Juick/ViewModels/MessageListViewModelBase.cs b/Juick/ViewModels/MessageListViewModelBase.cs
index 2cf5157..5dc8aed 100644
--- a/Juick/ViewModels/MessageListViewModelBase.cs
+++ b/Juick/ViewModels/MessageListViewModelBase.cs
@@ -1,37 +1,45 @@
 using System;
-using System.ComponentModel;
 using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Net;
-using System.Runtime.Serialization.Json;
 using System.Collections.ObjectModel;
+using System.ComponentModel;
+using System.Net;
 using System.Windows;
-using System.Windows.Controls;
 using System.Windows.Media.Imaging;
 using Juick.Api;
 using RestSharp;
+using System.Windows.Input;
+using Juick.Classes;
 
 namespace Juick.ViewModels
 {
     public class MessageListViewModelBase : INotifyPropertyChanged
     {
+        bool isDataLoading;
+
         public MessageListViewModelBase()
         {
-            this.Items = new ObservableCollection<MessageViewModel>();
+            Items = new ObservableCollection<MessageViewModel>();
+            LoadMessagesPageCommand = new DelegateCommand(LoadData, () => !IsDataLoading);
         }
 
         public string RestUri { get; set; }
-        
+
         /// <summary>
         /// A collection for MessageViewModel objects.
         /// </summary>
         public ObservableCollection<MessageViewModel> Items { get; private set; }
-        
-        public bool IsDataLoaded
+
+        public DelegateCommand LoadMessagesPageCommand { get; private set; }
+
+        public bool IsDataLoading
         {
-            get;
-            private set;
+            get { return isDataLoading; }
+            set
+            {
+                isDataLoading = value;
+                NotifyPropertyChanged("IsDataLoading");
+                LoadMessagesPageCommand.NotifyCanExecuteChanged();
+            }
         }
 
         /// <summary>
@@ -39,57 +47,69 @@ namespace Juick.ViewModels
         /// </summary>
         public void LoadData()
         {
+            if (IsDataLoading) {
+                return;
+            }
+
+            const int PageSize = 1;
+
             if (string.IsNullOrEmpty(RestUri))
             {
                 RestUri = "/home?1=1";
             }
-            var request = new RestRequest(RestUri +"&rnd=" + Environment.TickCount);
+
+            // super-костыли
+            // todo: rewrite
+            else if (RestUri.StartsWith("/home?", StringComparison.InvariantCulture) && Items.Count > 0)
+            {
+                var lastItem = Items[Items.Count - 1];
+                RestUri = string.Format("/home?before_mid={0}&page={1}", lastItem.MID, PageSize);
+            }
+            else if (RestUri.StartsWith("/messages?", StringComparison.InvariantCulture) && Items.Count > 0)
+            {
+                var lastItem = Items[Items.Count - 1];
+                RestUri = string.Format("/messages?before_mid={0}&page={1}", lastItem.MID, PageSize);
+            }
+
+            var request = new RestRequest(RestUri + "&rnd=" + Environment.TickCount);
             App.Client.Authenticator = new HttpBasicAuthenticator(App.Account.Credentials.UserName, App.Account.Credentials.Password);
-            App.Client.ExecuteAsync<List<Message>>(request, response => 
-                                                 {
-                                                     if (response.StatusCode != HttpStatusCode.OK)
-                                                     {
-                                                         MessageBox.Show(response.StatusCode.ToString());
-                                                         return;
-                                                     }
-
-                                                     var messages = response.Data;
-                                                     Items.Clear();
-                                                     messages.ForEach(post =>
-                                                                          {
-                                                                              var item = new MessageViewModel(post)
-                                                                                             {
-                                                                                                 Status =
-                                                                                                     string.Format(
-                                                                                                         "Posted on: {0}, replies: {1}",
-                                                                                                         post.Timestamp,
-                                                                                                         post.Replies)
-                                                                                             };
-                                                                              Items.Add(item);
-                                                                              var imageUri = new Uri(string.Format("http://i.juick.com/as/{0}.png", post.User.Uid), UriKind.Absolute);
-                                                                              item.UserAvatar = new BitmapImage
-                                                                                                    {
-                                                                                                        UriSource = imageUri
-                                                                                                    };
-                                                                              if (post.Photo != null)
-                                                                              {
-                                                                                  item.Attachment = new BitmapImage { UriSource = new Uri(post.Photo.Small, UriKind.Absolute) };
-                                                                              }
-                                                                              
-                                                                          });
-                                                         NotifyPropertyChanged("Items");
-                                                 });
+            App.Client.ExecuteAsync<List<Message>>(request, ProcessResponse);
+            IsDataLoading = true;
+        }
+
+        void ProcessResponse(IRestResponse<List<Message>> response)
+        {
+            IsDataLoading = false;
+            if (response.StatusCode != HttpStatusCode.OK)
+            {
+                MessageBox.Show(response.StatusCode.ToString());
+                return;
+            }
+
+            //Items.Clear();
+            foreach (var post in response.Data)
+            {
+                var status = string.Format("Posted on: {0}, replies: {1}", post.Timestamp, post.Replies);
+                var item = new MessageViewModel(post) { Status = status };
+                Items.Add(item);
+                var imageUri = new Uri(string.Format("http://i.juick.com/as/{0}.png", post.User.Uid), UriKind.Absolute);
+                item.UserAvatar = new BitmapImage { UriSource = imageUri };
+                if (post.Photo != null)
+                {
+                    item.Attachment = new BitmapImage { UriSource = new Uri(post.Photo.Small, UriKind.Absolute) };
+                }
+            }
         }
 
-       
+
         public event PropertyChangedEventHandler PropertyChanged;
-        public void NotifyPropertyChanged(String propertyName)
+
+        public void NotifyPropertyChanged(string propertyName)
         {
-            PropertyChangedEventHandler handler = PropertyChanged;
-            if (null != handler)
+            if (PropertyChanged != null)
             {
-                handler(this, new PropertyChangedEventArgs(propertyName));
+                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
             }
         }
     }
-}
\ No newline at end of file
+}
-- 
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