using System; using System.Collections.Generic; using System.Linq; namespace StardewModdingAPI.Utilities { /// <summary>Manages a separate value for each player in split-screen mode. This can safely be used in non-split-screen mode too, it'll just have a single state in that case.</summary> /// <typeparam name="T">The state class.</typeparam> public class PerScreen<T> { /********* ** Fields *********/ /// <summary>Create the initial value for a screen.</summary> private readonly Func<T> CreateNewState; /// <summary>The tracked values for each screen.</summary> private readonly IDictionary<int, T> States = new Dictionary<int, T>(); /// <summary>The last <see cref="Context.LastRemovedScreenId"/> value for which this instance was updated.</summary> private int LastRemovedScreenId; /********* ** Accessors *********/ /// <summary>The value for the current screen.</summary> /// <remarks>The value is initialized the first time it's requested for that screen, unless it's set manually first.</remarks> public T Value { get => this.GetValueForScreen(Context.ScreenId); set => this.SetValueForScreen(Context.ScreenId, value); } /********* ** Public methods *********/ /// <summary>Construct an instance.</summary> public PerScreen() : this(null) { } /// <summary>Construct an instance.</summary> /// <param name="createNewState">Create the initial state for a screen.</param> public PerScreen(Func<T> createNewState) { this.CreateNewState = createNewState ?? (() => default); } /// <summary>Get all active values by screen ID. This doesn't initialize the value for a screen ID if it's not created yet.</summary> public IEnumerable<KeyValuePair<int, T>> GetActiveValues() { this.RemoveDeadScreens(); return this.States.ToArray(); } /// <summary>Get the value for a given screen ID, creating it if needed.</summary> /// <param name="screenId">The screen ID to check.</param> public T GetValueForScreen(int screenId) { this.RemoveDeadScreens(); return this.States.TryGetValue(screenId, out T state) ? state : this.States[screenId] = this.CreateNewState(); } /// <summary>Set the value for a given screen ID.</summary> /// <param name="screenId">The screen ID whose value set.</param> /// <param name="value">The value to set.</param> public void SetValueForScreen(int screenId, T value) { this.RemoveDeadScreens(); this.States[screenId] = value; } /// <summary>Remove all active values.</summary> public void ResetAllScreens() { this.RemoveScreens(p => true); } /********* ** Private methods *********/ /// <summary>Remove screens which are no longer active.</summary> private void RemoveDeadScreens() { if (this.LastRemovedScreenId == Context.LastRemovedScreenId) return; this.LastRemovedScreenId = Context.LastRemovedScreenId; this.RemoveScreens(id => !Context.HasScreenId(id)); } /// <summary>Remove screens matching a condition.</summary> /// <param name="shouldRemove">Returns whether a screen ID should be removed.</param> private void RemoveScreens(Func<int, bool> shouldRemove) { foreach (var pair in this.States.ToArray()) { if (shouldRemove(pair.Key)) this.States.Remove(pair.Key); } } } }