Merge pull request #686 from wartech0/chest-tracking

Add chest items changed event

1 files changed, 143 insertions, 0 deletions

diff --git a/src/SMAPI/Framework/StateTracking/FieldWatchers/NetListWatcher.cs b/src/SMAPI/Framework/StateTracking/FieldWatchers/NetListWatcher.cs
new file mode 100644
index 00000000..0b4d3030
--- /dev/null
+++ b/src/SMAPI/Framework/StateTracking/FieldWatchers/NetListWatcher.cs
@@ -0,0 +1,143 @@
+using System.Collections.Generic;
+using Netcode;
+using StardewModdingAPI.Framework.StateTracking.Comparers;
+
+namespace StardewModdingAPI.Framework.StateTracking.FieldWatchers
+{
+    /// <summary>A watcher which detects changes to a net list field.</summary>
+    /// <typeparam name="TValue">The list value type.</typeparam>
+    internal class NetListWatcher<TValue> : BaseDisposableWatcher, ICollectionWatcher<TValue>
+        where TValue : class, INetObject<INetSerializable>
+    {
+        /*********
+        ** Fields
+        *********/
+        /// <summary>The field being watched.</summary>
+        private readonly NetList<TValue, NetRef<TValue>> Field;
+
+        /// <summary>The pairs added since the last reset.</summary>
+        private readonly ISet<TValue> AddedImpl = new HashSet<TValue>(new ObjectReferenceComparer<TValue>());
+
+        /// <summary>The pairs removed since the last reset.</summary>
+        private readonly ISet<TValue> RemovedImpl = new HashSet<TValue>(new ObjectReferenceComparer<TValue>());
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>Whether the collection changed since the last reset.</summary>
+        public bool IsChanged => this.AddedImpl.Count > 0 || this.RemovedImpl.Count > 0;
+
+        /// <summary>The values added since the last reset.</summary>
+        public IEnumerable<TValue> Added => this.AddedImpl;
+
+        /// <summary>The values removed since the last reset.</summary>
+        public IEnumerable<TValue> Removed => this.RemovedImpl;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="field">The field to watch.</param>
+        public NetListWatcher(NetList<TValue, NetRef<TValue>> field)
+        {
+            this.Field = field;
+            field.OnElementChanged += this.OnElementChanged;
+            field.OnArrayReplaced += this.OnArrayReplaced;
+        }
+
+        /// <summary>Set the current value as the baseline.</summary>
+        public void Reset()
+        {
+            this.AddedImpl.Clear();
+            this.RemovedImpl.Clear();
+        }
+
+        /// <summary>Update the current value if needed.</summary>
+        public void Update()
+        {
+            this.AssertNotDisposed();
+        }
+
+        /// <summary>Stop watching the field and release all references.</summary>
+        public override void Dispose()
+        {
+            if (!this.IsDisposed)
+            {
+                this.Field.OnElementChanged -= this.OnElementChanged;
+                this.Field.OnArrayReplaced -= this.OnArrayReplaced;
+            }
+
+            base.Dispose();
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>A callback invoked when the value list is replaced.</summary>
+        /// <param name="list">The net field whose values changed.</param>
+        /// <param name="oldValues">The previous list of values.</param>
+        /// <param name="newValues">The new list of values.</param>
+        private void OnArrayReplaced(NetList<TValue, NetRef<TValue>> list, IList<TValue> oldValues, IList<TValue> newValues)
+        {
+            ISet<TValue> oldSet = new HashSet<TValue>(oldValues, new ObjectReferenceComparer<TValue>());
+            ISet<TValue> changed = new HashSet<TValue>(newValues, new ObjectReferenceComparer<TValue>());
+
+            foreach (TValue value in oldSet)
+            {
+                if (!changed.Contains(value))
+                    this.Remove(value);
+            }
+            foreach (TValue value in changed)
+            {
+                if (!oldSet.Contains(value))
+                    this.Add(value);
+            }
+        }
+
+        /// <summary>A callback invoked when an entry is replaced.</summary>
+        /// <param name="list">The net field whose values changed.</param>
+        /// <param name="index">The list index which changed.</param>
+        /// <param name="oldValue">The previous value.</param>
+        /// <param name="newValue">The new value.</param>
+        private void OnElementChanged(NetList<TValue, NetRef<TValue>> list, int index, TValue oldValue, TValue newValue)
+        {
+            this.Remove(oldValue);
+            this.Add(newValue);
+        }
+
+        /// <summary>Track an added item.</summary>
+        /// <param name="value">The value that was added.</param>
+        private void Add(TValue value)
+        {
+            if (value == null)
+                return;
+
+            if (this.RemovedImpl.Contains(value))
+            {
+                this.AddedImpl.Remove(value);
+                this.RemovedImpl.Remove(value);
+            }
+            else
+                this.AddedImpl.Add(value);
+        }
+
+        /// <summary>Track a removed item.</summary>
+        /// <param name="value">The value that was removed.</param>
+        private void Remove(TValue value)
+        {
+            if (value == null)
+                return;
+
+            if (this.AddedImpl.Contains(value))
+            {
+                this.AddedImpl.Remove(value);
+                this.RemovedImpl.Remove(value);
+            }
+            else
+                this.RemovedImpl.Add(value);
+        }
+    }
+}