using StardewModdingAPI.Framework.StateTracking;

namespace StardewModdingAPI.Framework
{
    /// <summary>A snapshot of a tracked value.</summary>
    /// <typeparam name="T">The tracked value type.</typeparam>
    internal class SnapshotDiff<T>
    {
        /*********
        ** Accessors
        *********/
        /// <summary>Whether the value changed since the last update.</summary>
        public bool IsChanged { get; private set; }

        /// <summary>The previous value.</summary>
        public T? Old { get; private set; }

        /// <summary>The current value.</summary>
        public T? New { get; private set; }


        /*********
        ** Public methods
        *********/
        /// <summary>Update the snapshot.</summary>
        /// <param name="isChanged">Whether the value changed since the last update.</param>
        /// <param name="old">The previous value.</param>
        /// <param name="now">The current value.</param>
        public void Update(bool isChanged, T old, T now)
        {
            this.IsChanged = isChanged;
            this.Old = old;
            this.New = now;
        }

        /// <summary>Update the snapshot.</summary>
        /// <param name="watcher">The value watcher to snapshot.</param>
        public void Update(IValueWatcher<T> watcher)
        {
            this.Update(watcher.IsChanged, watcher.PreviousValue, watcher.CurrentValue);
        }
    }
}