Add IBuddyList (#1261)

Dalamud/Plugin/Services/IBuddyList.cs

@@ -0,0 +1,61 @@
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+
+using Dalamud.Game.ClientState.Buddy;
+
+namespace Dalamud.Plugin.Services;
+
+/// <summary>
+/// This collection represents the buddies present in your squadron or trust party.
+/// It does not include the local player.
+/// </summary>
+public interface IBuddyList : IReadOnlyCollection<BuddyMember>
+{
+    /// <summary>
+    /// Gets the amount of battle buddies the local player has.
+    /// </summary>
+    public int Length { get; }
+    
+    /// <summary>
+    /// Gets the active companion buddy.
+    /// </summary>
+    public BuddyMember? CompanionBuddy { get; }
+    
+    /// <summary>
+    /// Gets the active pet buddy.
+    /// </summary>
+    public BuddyMember? PetBuddy { get; }
+    
+    /// <summary>
+    /// Gets a battle buddy at the specified spawn index.
+    /// </summary>
+    /// <param name="index">Spawn index.</param>
+    /// <returns>A <see cref="BuddyMember"/> at the specified spawn index.</returns>
+    public BuddyMember? this[int index] { get; }
+
+    /// <summary>
+    /// Gets the address of the companion buddy.
+    /// </summary>
+    /// <returns>The memory address of the companion buddy.</returns>
+    public nint GetCompanionBuddyMemberAddress();
+
+    /// <summary>
+    /// Gets the address of the pet buddy.
+    /// </summary>
+    /// <returns>The memory address of the pet buddy.</returns>
+    public nint GetPetBuddyMemberAddress();
+
+    /// <summary>
+    /// Gets the address of the battle buddy at the specified index of the buddy list.
+    /// </summary>
+    /// <param name="index">The index of the battle buddy.</param>
+    /// <returns>The memory address of the battle buddy.</returns>
+    public nint GetBattleBuddyMemberAddress(int index);
+
+    /// <summary>
+    /// Create a reference to a buddy.
+    /// </summary>
+    /// <param name="address">The address of the buddy in memory.</param>
+    /// <returns><see cref="BuddyMember"/> object containing the requested data.</returns>
+    public BuddyMember? CreateBuddyMemberReference(nint address);
+}