using Unity.Netcode;
using UnityEngine;

/// <summary>
/// Replicates the visual body state that the disabled-on-remote controller / pose system would
/// otherwise drive: the owner publishes its selected pose index, resolved locomotion category
/// (idle / walk / run / fall) AND the wall-lean / ground-raise / ceiling mesh offset, so a remote
/// avatar shows the same pose, walk/run/fall animation and leans into walls / raises off the ground
/// like the owner — not just a sliding, upright idle.
///
/// Body position/rotation come from the NetworkTransform; this only carries the small extra state on
/// top. Pose index and locomotion change rarely (a pose cycle, a locomotion transition), so those
/// NetworkVariables send a delta only when the value actually changes. The mesh offset is the visual
/// model's child-local position (<see cref="PlayerCharacterController.MeshOffsetTarget"/>) — a tiny
/// vector the owner eases continuously; the remote eases onto the replicated value so it doesn't
/// tick-step (the body itself is already interpolated by the NetworkTransform).
///
/// Runs after the PlayerPoseController (execution order 100) so the owner reads this frame's resolved
/// state; remote avatars apply via OnValueChanged / per-frame easing, independent of frame order.
/// </summary>
[RequireComponent(typeof(PlayerPoseController))]
[RequireComponent(typeof(PlayerCharacterController))]
[DisallowMultipleComponent]
[DefaultExecutionOrder(200)]
public class PlayerAnimationSync : NetworkBehaviour
{
    [Tooltip("How fast a remote avatar eases its mesh lean/raise offset onto the replicated value " +
             "(1/second). Higher = tighter follow, lower = smoother. The body itself is interpolated " +
             "by the NetworkTransform; this only smooths the small child-local lean offset.")]
    [SerializeField] private float meshOffsetFollow = 18f;

    private readonly NetworkVariable<int> _poseIndex =
        new(0, NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Owner);

    // Locomotion category stored as a byte (PlayerPoseController.Locomotion has only a handful of values).
    private readonly NetworkVariable<byte> _locomotion =
        new(0, NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Owner);

    // Visual model's child-local lean/raise offset: wall lean + ground raise + ceiling lean, all folded
    // by the controller into MeshOffsetTarget.localPosition. Owner-authoritative like the rest. Already in
    // the root's local space, so it stays correct under the synced body rotation (wall/ceiling) as-is.
    private readonly NetworkVariable<Vector3> _meshOffset =
        new(Vector3.zero, NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Owner);

    private PlayerPoseController _pose;
    private PlayerCharacterController _controller;
    private Transform _offsetTarget;

    void Awake()
    {
        _pose = GetComponent<PlayerPoseController>();
        _controller = GetComponent<PlayerCharacterController>();
    }

    public override void OnNetworkSpawn()
    {
        // Resolved after all Awakes ran: the controller resolves MeshOffsetTarget in its own Awake.
        _offsetTarget = _controller ? _controller.MeshOffsetTarget : null;

        if (IsOwner)
            return;

        // Remote avatar: stop reading local input/physics and drive the pose from replicated state.
        _pose.EnableNetworkDrive();
        _poseIndex.OnValueChanged += OnPoseIndexChanged;
        _locomotion.OnValueChanged += OnLocomotionChanged;
        ApplyRemote(); // spawn-time values are already replicated

        // Seed the lean offset to the replicated value so a mid-lean late join doesn't pop from base.
        if (_offsetTarget) _offsetTarget.localPosition = _meshOffset.Value;
    }

    public override void OnNetworkDespawn()
    {
        _poseIndex.OnValueChanged -= OnPoseIndexChanged;
        _locomotion.OnValueChanged -= OnLocomotionChanged;
    }

    void Update()
    {
        if (IsOwner)
        {
            if (!_pose)
                return;

            // Publish the owner's resolved animation state. Assigning the same value is a no-op for
            // replication (the NetworkVariable dirties only on an actual change).
            int index = _pose.CurrentIndex;
            byte loco = (byte)_pose.CurrentLocomotion;
            if (_poseIndex.Value != index) _poseIndex.Value = index;
            if (_locomotion.Value != loco) _locomotion.Value = loco;

            // Mesh lean/raise offset: the controller owns MeshOffsetTarget.localPosition (sole writer),
            // so this frame's value is final by execution order 200.
            if (_offsetTarget)
            {
                Vector3 lp = _offsetTarget.localPosition;
                if (_meshOffset.Value != lp) _meshOffset.Value = lp;
            }
            return;
        }

        // Remote avatar: ease the visual model onto the replicated lean/raise offset. The controller is
        // disabled here, so this is the sole writer of MeshOffsetTarget.localPosition on the remote (the
        // pose reset already excludes that node). Easing avoids tick-rate stepping on the small offset.
        if (_offsetTarget)
        {
            float k = 1f - Mathf.Exp(-meshOffsetFollow * Time.deltaTime);
            _offsetTarget.localPosition = Vector3.Lerp(_offsetTarget.localPosition, _meshOffset.Value, k);
        }
    }

    private void OnPoseIndexChanged(int previous, int current) => ApplyRemote();
    private void OnLocomotionChanged(byte previous, byte current) => ApplyRemote();

    private void ApplyRemote() =>
        _pose.SetNetworkState(_poseIndex.Value, (PlayerPoseController.Locomotion)_locomotion.Value);
}