From d934c1273bc20533683eaad858a1c499c7729a28 Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Thu, 17 Dec 2020 20:08:33 +0800
Subject: ...

---
 .../Timeline/Services/HighlightTimelineService.cs  | 85 +++++++++++++++++++++-
 1 file changed, 82 insertions(+), 3 deletions(-)

(limited to 'BackEnd/Timeline/Services/HighlightTimelineService.cs')

diff --git a/BackEnd/Timeline/Services/HighlightTimelineService.cs b/BackEnd/Timeline/Services/HighlightTimelineService.cs
index 0f4e5488..ea3e4c7e 100644
--- a/BackEnd/Timeline/Services/HighlightTimelineService.cs
+++ b/BackEnd/Timeline/Services/HighlightTimelineService.cs
@@ -9,10 +9,25 @@ using Timeline.Services.Exceptions;
 
 namespace Timeline.Services
 {
+
+    [Serializable]
+    public class InvalidHighlightTimelineException : Exception
+    {
+        public InvalidHighlightTimelineException() { }
+        public InvalidHighlightTimelineException(string message) : base(message) { }
+        public InvalidHighlightTimelineException(string message, Exception inner) : base(message, inner) { }
+        protected InvalidHighlightTimelineException(
+          System.Runtime.Serialization.SerializationInfo info,
+          System.Runtime.Serialization.StreamingContext context) : base(info, context) { }
+    }
+
+    /// <summary>
+    /// Service that controls highlight timeline.
+    /// </summary>
     public interface IHighlightTimelineService
     {
         /// <summary>
-        /// Get all highlight timelines.
+        /// Get all highlight timelines in order.
         /// </summary>
         /// <returns>A list of all highlight timelines.</returns>
         Task<List<TimelineInfo>> GetHighlightTimelines();
@@ -39,6 +54,21 @@ namespace Timeline.Services
         /// <exception cref="TimelineNotExistException">Thrown when timeline with given name does not exist.</exception>
         /// <exception cref="UserNotExistException">Thrown when user with given operator id does not exist.</exception>
         Task<bool> RemoveHighlightTimeline(string timelineName, long? operatorId);
+
+        /// <summary>
+        /// Move a highlight timeline to a new position.
+        /// </summary>
+        /// <param name="timelineName">The timeline name.</param>
+        /// <param name="newPosition">The new position. Starts at 1.</param>
+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="timelineName"/> is null.</exception>
+        /// <exception cref="ArgumentException">Thrown when <paramref name="timelineName"/> is not a valid timeline name.</exception>
+        /// <exception cref="TimelineNotExistException">Thrown when timeline with given name does not exist.</exception>
+        /// <exception cref="InvalidHighlightTimelineException">Thrown when given timeline is not a highlight timeline.</exception>
+        /// <remarks>
+        /// If <paramref name="newPosition"/> is smaller than 1. Then move the timeline to head.
+        /// If <paramref name="newPosition"/> is bigger than total count. Then move the timeline to tail.
+        /// </remarks>
+        Task MoveHighlightTimeline(string timelineName, long newPosition);
     }
 
     public class HighlightTimelineService : IHighlightTimelineService
@@ -72,13 +102,13 @@ namespace Timeline.Services
 
             if (alreadyIs) return;
 
-            _database.HighlightTimelines.Add(new HighlightTimelineEntity { TimelineId = timelineId, OperatorId = operatorId, AddTime = _clock.GetCurrentTime() });
+            _database.HighlightTimelines.Add(new HighlightTimelineEntity { TimelineId = timelineId, OperatorId = operatorId, AddTime = _clock.GetCurrentTime(), Order = await _database.HighlightTimelines.CountAsync() + 1 });
             await _database.SaveChangesAsync();
         }
 
         public async Task<List<TimelineInfo>> GetHighlightTimelines()
         {
-            var entities = await _database.HighlightTimelines.Select(t => new { t.Id }).ToListAsync();
+            var entities = await _database.HighlightTimelines.OrderBy(t => t.Order).Select(t => new { t.Id }).ToListAsync();
 
             var result = new List<TimelineInfo>();
 
@@ -106,10 +136,59 @@ namespace Timeline.Services
 
             if (entity == null) return false;
 
+            await using var transaction = await _database.Database.BeginTransactionAsync();
+
+            var order = entity.Order;
+
             _database.HighlightTimelines.Remove(entity);
             await _database.SaveChangesAsync();
 
+            await _database.Database.ExecuteSqlRawAsync("UPDATE highlight_timelines SET `order` = `order` - 1 WHERE `order` > {0}", order);
+
+            await transaction.CommitAsync();
+
             return true;
         }
+
+        public async Task MoveHighlightTimeline(string timelineName, long newPosition)
+        {
+            if (timelineName == null)
+                throw new ArgumentNullException(nameof(timelineName));
+
+            var timelineId = await _timelineService.GetTimelineIdByName(timelineName);
+
+            var entity = await _database.HighlightTimelines.SingleOrDefaultAsync(t => t.TimelineId == timelineId);
+
+            if (entity == null) throw new InvalidHighlightTimelineException("You can't move a non-highlight timeline.");
+
+            var oldPosition = entity.Order;
+
+            if (newPosition < 1)
+            {
+                newPosition = 1;
+            }
+            else
+            {
+                var totalCount = await _database.HighlightTimelines.CountAsync();
+                if (newPosition > totalCount) newPosition = totalCount;
+            }
+
+            if (oldPosition == newPosition) return;
+
+            await using var transaction = await _database.Database.BeginTransactionAsync();
+
+            if (newPosition > oldPosition)
+            {
+                await _database.Database.ExecuteSqlRawAsync("UPDATE highlight_timelines SET `order` = `order` - 1 WHERE `order` BETWEEN {0} AND {1}", oldPosition + 1, newPosition);
+                await _database.Database.ExecuteSqlRawAsync("UPDATE highlight_timelines SET `order` = {0} WHERE id = {1}", newPosition, entity.Id);
+            }
+            else
+            {
+                await _database.Database.ExecuteSqlRawAsync("UPDATE highlight_timelines SET `order` = `order` + 1 WHERE `order` BETWEEN {0} AND {1}", newPosition, oldPosition - 1);
+                await _database.Database.ExecuteSqlRawAsync("UPDATE highlight_timelines SET `order` = {0} WHERE id = {1}", newPosition, entity.Id);
+            }
+
+            await transaction.CommitAsync();
+        }
     }
 }
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