using System.Buffers.Binary;

namespace AcDream.Core.Net.Messages;

/// <summary>
/// Outbound inventory-manipulation GameActions: stack merge/split, give,
/// drop, shortcuts. All ride in the <c>0xF7B1</c> GameAction envelope.
///
/// <para>
/// References: r08 §3 rows 0x0054-0x0056 / 0x019B-0x019D / 0x00CD.
/// </para>
/// </summary>
public static class InventoryActions
{
    public const uint GameActionEnvelope = 0xF7B1u;

    public const uint StackableMergeOpcode          = 0x0054u;
    public const uint StackableSplitToContainerOpcode = 0x0055u;
    public const uint StackableSplitTo3DOpcode      = 0x0056u;
    public const uint StackableSplitToWieldOpcode   = 0x019Bu;
    public const uint GiveObjectRequestOpcode       = 0x00CDu;
    public const uint AddShortcutOpcode             = 0x019Cu;
    public const uint RemoveShortcutOpcode          = 0x019Du;
    public const uint TeleToPoiOpcode               = 0x00B1u;

    /// <summary>
    /// Merge stack A into stack B of the same item type. Server validates
    /// compatibility; if the merge fails it rolls back via
    /// InventoryServerSaveFailed (0x00A0).
    /// </summary>
    public static byte[] BuildStackableMerge(uint seq, uint mergeFromGuid, uint mergeToGuid, uint amount)
    {
        byte[] body = new byte[24];
        BinaryPrimitives.WriteUInt32LittleEndian(body,            GameActionEnvelope);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(4),  seq);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(8),  StackableMergeOpcode);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(12), mergeFromGuid);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(16), mergeToGuid);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(20), amount);
        return body;
    }

    /// <summary>Split N items off a stack into a container at placement.</summary>
    public static byte[] BuildStackableSplitToContainer(
        uint seq, uint stackGuid, uint containerGuid, uint placement, uint amount)
    {
        byte[] body = new byte[28];
        BinaryPrimitives.WriteUInt32LittleEndian(body,            GameActionEnvelope);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(4),  seq);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(8),  StackableSplitToContainerOpcode);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(12), stackGuid);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(16), containerGuid);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(20), placement);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(24), amount);
        return body;
    }

    /// <summary>Split N items off a stack and drop them on the ground.</summary>
    public static byte[] BuildStackableSplitTo3D(uint seq, uint stackGuid, uint amount)
    {
        byte[] body = new byte[20];
        BinaryPrimitives.WriteUInt32LittleEndian(body,            GameActionEnvelope);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(4),  seq);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(8),  StackableSplitTo3DOpcode);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(12), stackGuid);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(16), amount);
        return body;
    }

    /// <summary>Split N items off a stack into an equip slot.</summary>
    public static byte[] BuildStackableSplitToWield(
        uint seq, uint stackGuid, uint equipLocation, uint amount)
    {
        byte[] body = new byte[24];
        BinaryPrimitives.WriteUInt32LittleEndian(body,            GameActionEnvelope);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(4),  seq);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(8),  StackableSplitToWieldOpcode);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(12), stackGuid);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(16), equipLocation);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(20), amount);
        return body;
    }

    /// <summary>Give an item (or a stack of N) to a target creature/NPC.</summary>
    public static byte[] BuildGiveObjectRequest(
        uint seq, uint targetGuid, uint itemGuid, uint amount)
    {
        byte[] body = new byte[24];
        BinaryPrimitives.WriteUInt32LittleEndian(body,            GameActionEnvelope);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(4),  seq);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(8),  GiveObjectRequestOpcode);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(12), targetGuid);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(16), itemGuid);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(20), amount);
        return body;
    }

    /// <summary>Pin an item / spell to a quickbar slot.</summary>
    public static byte[] BuildAddShortcut(
        uint seq, uint slotIndex, uint objectType, uint targetId)
    {
        byte[] body = new byte[24];
        BinaryPrimitives.WriteUInt32LittleEndian(body,            GameActionEnvelope);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(4),  seq);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(8),  AddShortcutOpcode);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(12), slotIndex);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(16), objectType);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(20), targetId);
        return body;
    }

    /// <summary>Unpin a quickbar slot.</summary>
    public static byte[] BuildRemoveShortcut(uint seq, uint slotIndex)
    {
        byte[] body = new byte[16];
        BinaryPrimitives.WriteUInt32LittleEndian(body,            GameActionEnvelope);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(4),  seq);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(8),  RemoveShortcutOpcode);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(12), slotIndex);
        return body;
    }

    /// <summary>Teleport to a Point of Interest (quest-driven recall).</summary>
    public static byte[] BuildTeleToPoi(uint seq, uint poiId)
    {
        byte[] body = new byte[16];
        BinaryPrimitives.WriteUInt32LittleEndian(body,            GameActionEnvelope);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(4),  seq);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(8),  TeleToPoiOpcode);
        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(12), poiId);
        return body;
    }
}