From c667c722ec081dfb651d3583236d7aa429c56941 Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Thu, 13 May 2021 15:53:08 +0800
Subject: feat: Posts pagination.

---
 .../Timeline/Services/Timeline/ITimelinePostService.cs |  4 +++-
 .../Timeline/Services/Timeline/Resource.Designer.cs    | 18 ++++++++++++++++++
 BackEnd/Timeline/Services/Timeline/Resource.resx       |  6 ++++++
 .../Timeline/Services/Timeline/TimelinePostService.cs  | 14 +++++++++++++-
 4 files changed, 40 insertions(+), 2 deletions(-)

(limited to 'BackEnd/Timeline/Services')

diff --git a/BackEnd/Timeline/Services/Timeline/ITimelinePostService.cs b/BackEnd/Timeline/Services/Timeline/ITimelinePostService.cs
index 92984938..c0edf857 100644
--- a/BackEnd/Timeline/Services/Timeline/ITimelinePostService.cs
+++ b/BackEnd/Timeline/Services/Timeline/ITimelinePostService.cs
@@ -16,9 +16,11 @@ namespace Timeline.Services.Timeline
         /// <param name="timelineId">The id of the timeline.</param>
         /// <param name="modifiedSince">The time that posts have been modified since.</param>
         /// <param name="includeDeleted">Whether include deleted posts.</param>
+        /// <param name="page">The page number. Starts from 0. If null, do not do pagination.</param>
+        /// <param name="numberPerPage">Count of entities per page. If null, 20.</param>
         /// <returns>A list of all posts.</returns>
         /// <exception cref="EntityNotExistException">Thrown when timeline does not exist.</exception>
-        Task<List<TimelinePostEntity>> GetPostsAsync(long timelineId, DateTime? modifiedSince = null, bool includeDeleted = false);
+        Task<List<TimelinePostEntity>> GetPostsAsync(long timelineId, DateTime? modifiedSince = null, bool includeDeleted = false, int? page = null, int? numberPerPage = null);
 
         /// <summary>
         /// Get a post of a timeline.
diff --git a/BackEnd/Timeline/Services/Timeline/Resource.Designer.cs b/BackEnd/Timeline/Services/Timeline/Resource.Designer.cs
index 5ad03011..f5112cd9 100644
--- a/BackEnd/Timeline/Services/Timeline/Resource.Designer.cs
+++ b/BackEnd/Timeline/Services/Timeline/Resource.Designer.cs
@@ -105,6 +105,24 @@ namespace Timeline.Services.Timeline {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Number per page can&apos;t be zero or negative..
+        /// </summary>
+        internal static string ExceptionNumberPerPageZeroOrNegative {
+            get {
+                return ResourceManager.GetString("ExceptionNumberPerPageZeroOrNegative", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Page number can&apos;t be negative..
+        /// </summary>
+        internal static string ExceptionPageNegative {
+            get {
+                return ResourceManager.GetString("ExceptionPageNegative", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Image validation failed..
         /// </summary>
diff --git a/BackEnd/Timeline/Services/Timeline/Resource.resx b/BackEnd/Timeline/Services/Timeline/Resource.resx
index cc293d05..1d61a1bb 100644
--- a/BackEnd/Timeline/Services/Timeline/Resource.resx
+++ b/BackEnd/Timeline/Services/Timeline/Resource.resx
@@ -132,6 +132,12 @@
   <data name="ExceptionGeneralTimelineNameBadFormat" xml:space="preserve">
     <value>This timeline name is neither a valid personal timeline name nor a valid ordinary timeline name. {0}</value>
   </data>
+  <data name="ExceptionNumberPerPageZeroOrNegative" xml:space="preserve">
+    <value>Number per page can't be zero or negative.</value>
+  </data>
+  <data name="ExceptionPageNegative" xml:space="preserve">
+    <value>Page number can't be negative.</value>
+  </data>
   <data name="ExceptionPostDataImageInvalid" xml:space="preserve">
     <value>Image validation failed.</value>
   </data>
diff --git a/BackEnd/Timeline/Services/Timeline/TimelinePostService.cs b/BackEnd/Timeline/Services/Timeline/TimelinePostService.cs
index a0961a8d..ee1002e0 100644
--- a/BackEnd/Timeline/Services/Timeline/TimelinePostService.cs
+++ b/BackEnd/Timeline/Services/Timeline/TimelinePostService.cs
@@ -64,8 +64,14 @@ namespace Timeline.Services.Timeline
             });
         }
 
-        public async Task<List<TimelinePostEntity>> GetPostsAsync(long timelineId, DateTime? modifiedSince = null, bool includeDeleted = false)
+        public async Task<List<TimelinePostEntity>> GetPostsAsync(long timelineId, DateTime? modifiedSince = null, bool includeDeleted = false, int? page = null, int? numberPerPage = null)
         {
+            if (page.HasValue && page < 0)
+                throw new ArgumentOutOfRangeException(nameof(page), Resource.ExceptionPageNegative);
+            if (numberPerPage.HasValue && numberPerPage <= 0)
+                throw new ArgumentOutOfRangeException(nameof(numberPerPage), Resource.ExceptionNumberPerPageZeroOrNegative);
+
+
             await _basicTimelineService.ThrowIfTimelineNotExist(timelineId);
 
             modifiedSince = modifiedSince?.MyToUtc();
@@ -84,6 +90,12 @@ namespace Timeline.Services.Timeline
 
             query = query.OrderBy(p => p.Time);
 
+            if (page.HasValue)
+            {
+                var npp = numberPerPage.GetValueOrDefault(20);
+                query = query.Skip(npp * (page.Value - 1)).Take(npp);
+            }
+
             return await query.ToListAsync();
         }
 
-- 
cgit v1.2.3