FORT-BO/Assets/CONTENT/Game/Scripts/Items/NetworkHandItemInteractable.cs

using System.Collections.Generic;
using Unity.Netcode;
using UnityEngine;

public interface IUsableHandItem
{
    string ItemName { get; }
    bool IsHeld { get; }
    bool IsHeldByLocalPlayer { get; }
    void RequestUse();
    void RequestThrow();
}

public abstract class NetworkHandItemInteractable : NetworkInteractable, IUsableHandItem
{
    private const ulong NoHolder = ulong.MaxValue;
    private static readonly HashSet<NetworkHandItemInteractable> SpawnedItems = new();

    [Header("Hand item physics")]
    [SerializeField] private Rigidbody physicsBody;
    [SerializeField] private Collider[] itemColliders;
    [SerializeField, Min(0f)] private float throwForce = 4f;
    [SerializeField, Min(0f)] private float throwUpwardForce = 1f;

    private readonly NetworkVariable<ulong> holderClientId = new(
        NoHolder,
        NetworkVariableReadPermission.Everyone,
        NetworkVariableWritePermission.Server);

    public string ItemName => InteractionLabel;
    public bool IsHeld => holderClientId.Value != NoHolder;
    public bool IsHeldByLocalPlayer =>
        NetworkManager != null && holderClientId.Value == NetworkManager.LocalClientId;

    public override bool IsInteractionAvailable => base.IsInteractionAvailable && !IsHeld;

    protected virtual void Awake()
    {
        if (physicsBody == null)
            physicsBody = GetComponent<Rigidbody>();

        if (itemColliders == null || itemColliders.Length == 0)
            itemColliders = GetComponentsInChildren<Collider>(true);
    }

    public override void OnNetworkSpawn()
    {
        SpawnedItems.Add(this);
        holderClientId.OnValueChanged += HandleHolderChanged;
        ApplyHeldState(IsHeld);
    }

    public override void OnNetworkDespawn()
    {
        holderClientId.OnValueChanged -= HandleHolderChanged;
        SpawnedItems.Remove(this);
        ApplyHeldState(false);
    }

    private void LateUpdate()
    {
        if (!IsSpawned || !IsHeld)
            return;

        if (!TryGetPlayerObject(holderClientId.Value, out NetworkObject holder))
        {
            if (IsServer)
                DropWithoutThrow();

            return;
        }

        PlayerHandController hand = holder.GetComponent<PlayerHandController>();
        if (hand == null || hand.ItemSocket == null)
            return;

        transform.SetPositionAndRotation(
            hand.ItemSocket.position,
            hand.ItemSocket.rotation);
    }

    public void RequestUse()
    {
        if (IsSpawned && IsHeldByLocalPlayer)
            RequestUseServerRpc();
    }

    public void RequestThrow()
    {
        if (IsSpawned && IsHeldByLocalPlayer)
            RequestThrowServerRpc();
    }

    protected override bool CanInteractOnServer(ulong senderClientId) =>
        !IsHeld && !TryGetHeldItem(senderClientId, out _);

    protected override void InteractOnServer(ulong senderClientId, NetworkObject playerObject)
    {
        holderClientId.Value = senderClientId;
        ApplyHeldState(true);
    }

    [Rpc(SendTo.Server, InvokePermission = RpcInvokePermission.Everyone)]
    private void RequestUseServerRpc(RpcParams rpcParams = default)
    {
        ulong senderClientId = rpcParams.Receive.SenderClientId;
        if (holderClientId.Value != senderClientId ||
            !TryGetPlayerObject(senderClientId, out NetworkObject playerObject))
        {
            return;
        }

        UseOnServer(playerObject);
    }

    [Rpc(SendTo.Server, InvokePermission = RpcInvokePermission.Everyone)]
    private void RequestThrowServerRpc(RpcParams rpcParams = default)
    {
        ulong senderClientId = rpcParams.Receive.SenderClientId;
        if (holderClientId.Value != senderClientId ||
            !TryGetPlayerObject(senderClientId, out NetworkObject playerObject))
        {
            return;
        }

        Vector3 throwVelocity = playerObject.transform.forward * throwForce +
            Vector3.up * throwUpwardForce;

        holderClientId.Value = NoHolder;
        ApplyHeldState(false);

        if (physicsBody != null)
            physicsBody.linearVelocity = throwVelocity;
    }

    protected abstract void UseOnServer(NetworkObject playerObject);

    public static bool TryGetHeldItem(
        ulong clientId,
        out NetworkHandItemInteractable heldItem)
    {
        foreach (NetworkHandItemInteractable item in SpawnedItems)
        {
            if (item != null && item.holderClientId.Value == clientId)
            {
                heldItem = item;
                return true;
            }
        }

        heldItem = null;
        return false;
    }

    private void DropWithoutThrow()
    {
        holderClientId.Value = NoHolder;
        ApplyHeldState(false);
    }

    private void HandleHolderChanged(ulong _, ulong currentHolder) =>
        ApplyHeldState(currentHolder != NoHolder);

    private void ApplyHeldState(bool held)
    {
        if (physicsBody != null)
        {
            physicsBody.isKinematic = held || !IsServer;

            if (held)
            {
                physicsBody.linearVelocity = Vector3.zero;
                physicsBody.angularVelocity = Vector3.zero;
            }
        }

        foreach (Collider itemCollider in itemColliders)
        {
            if (itemCollider != null)
                itemCollider.enabled = !held;
        }
    }
}