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using System;
using System.Collections.Generic;
using System.Linq;
using StardewModdingAPI.Framework;
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>
/// <remarks><strong>Limitation with nullable reference types:</strong> when the underlying type <typeparamref name="T"/> is nullable, this sets the default value to null regardless of whether you marked the type parameter nullable. To avoid that, set the default value with the 'createNewState' argument instead.</remarks>
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)
{
// ReSharper disable once ConditionIsAlwaysTrueOrFalse -- required for backwards compatibility
if (createNewState is null)
{
SCore.DeprecationManager.Warn(
SCore.DeprecationManager.GetSourceNameFromStack(),
$"calling the {nameof(PerScreen<T>)} constructor with null",
"3.14.0",
DeprecationLevel.Notice
);
createNewState = (() => default!);
}
this.CreateNewState = createNewState;
}
/// <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(_ => 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);
}
}
}
}
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