using System;
using System.Collections.Generic;

namespace AcDream.Core.Items;

/// <summary>
/// Mutable client-side model of retail <c>ShortCutManager::shortCuts_[18]</c>
/// (<c>acclient.h:36492</c>). Every present entry retains all three raw
/// <see cref="ShortcutEntry"/> fields, including non-object records that the object-only
/// <c>gmToolbarUI</c> does not render.
/// </summary>
public sealed class ShortcutStore
{
    public const int SlotCount = 18;
    private readonly ShortcutEntry?[] _entries = new ShortcutEntry?[SlotCount];

    /// <summary>
    /// Replace all slots from packed entries. Invalid signed indices are rejected exactly
    /// like <c>ShortCutManager::AddShortCut @ 0x005D5790</c>; valid entries are retained
    /// even when their object id is zero.
    /// </summary>
    public void Load(IEnumerable<ShortcutEntry> entries)
    {
        Array.Clear(_entries);
        foreach (var entry in entries)
            Set(entry);
    }

    /// <summary>Raw entry at <paramref name="slot"/>, or null for absent/out-of-range.</summary>
    public ShortcutEntry? GetEntry(int slot)
        => (uint)slot < SlotCount ? _entries[slot] : null;

    /// <summary>Detached raw snapshot for planning a complete mutation before applying it.</summary>
    public ShortcutEntry?[] Snapshot() => (ShortcutEntry?[])_entries.Clone();

    /// <summary>Visible object id at <paramref name="slot"/>, or zero.</summary>
    public uint Get(int slot) => GetEntry(slot)?.ObjectId ?? 0u;

    /// <summary>
    /// Visual availability used by <c>gmToolbarUI</c>. A retained non-object entry remains
    /// invisible and therefore counts as an empty toolbar cell.
    /// </summary>
    public bool IsEmpty(int slot) => Get(slot) == 0u;

    public void Set(ShortcutEntry entry)
    {
        if ((uint)entry.Index < SlotCount)
            _entries[entry.Index] = entry;
    }

    /// <summary>Create/replace a retail object shortcut; toolbar-created records use spell word zero.</summary>
    public void SetItem(int slot, uint objectId) => Set(new ShortcutEntry(slot, objectId, 0u));

    public void Remove(int slot)
    {
        if ((uint)slot < SlotCount)
            _entries[slot] = null;
    }
}