using System.Collections;
using UnityEngine;

/// <summary>
/// Drives visibility, position, and animation of the FPS climb hand.
///
/// Default state: hidden, PARENTED to <see cref="handRestPos"/> (local identity), Animator on Idle.
///
/// Flow (all driven by events from <see cref="PlayerMovement"/>, no polling):
///   1. Climb prompt appears (player looks at a climbable wall while airborne)
///      -> hand becomes visible, unparents, tweens handRestPos -> fpsHandPos over moveDuration,
///         then re-parents to fpsHandPos (so it stays locked to it, e.g. if it sways with the camera).
///   2. Player actually sticks to the wall (ClimbKey pressed & leap completes)
///      -> hand unparents and is positioned at the wall hit point (+ a small right-hand offset),
///         crossfades to the stick animation, plays once, freezes on the last frame.
///   3. Wall stick ends (timer ran out, key toggled off, wall jump, grounded, etc.)
///      -> crossfade back to Idle, tween wall-position -> handRestPos, then re-parent + hide.
///   4. Climb prompt disappears without ever sticking (player looked away)
///      -> tween back to handRestPos, re-parent, hide. Same as #3 minus the animation swap.
/// </summary>
public class ClimbHandController : MonoBehaviour
{
    [Header("References")]
    [Tooltip("The PlayerMovement script driving climb state. Auto-found on parent/scene if left empty.")]
    [SerializeField] private PlayerMovement playerMovement;
    [Tooltip("Renderers to toggle for visibility. Auto-found in children if left empty.")]
    [SerializeField] private Renderer[] handRenderers;
    [Tooltip("Animator component ON THE HAND PREFAB (drag the hand GameObject itself.")]
    [SerializeField] private Animator handAnimator;
    [Tooltip("Empty transform: where the hand parents/hides when not climbing.")]
    [SerializeField] private Transform handRestPos;
    [Tooltip("Empty transform: where the hand parents while the climb prompt is shown / before sticking.")]
    [SerializeField] private Transform fpsHandPos;

    [Header("Mirroring (for reusing a right-hand prefab as a left hand)")]
    [Tooltip("If true, applies a negative scale on the chosen axis to flip this hand's mesh/animation visually. No remodeling or reanimation needed. Only the wrapper's scale is mirrored.")]
    [SerializeField] private bool mirrorHand = false;
    [Tooltip("Which local axis to negate when mirroring. X is the usual choice for a left/right hand flip.")]
    [SerializeField] private MirrorAxis mirrorAxis = MirrorAxis.X;

    private enum MirrorAxis { X, Y, Z }

    [Header("Wall Stick Offset")]
    [Tooltip("Local offset applied at the wall-stick position (in the hand's own local axes, after rotation).")]
    [SerializeField] private Vector3 stickPositionOffset = new Vector3(0f, 0.5f, 0f);
    [Tooltip("Rotation (Euler) applied so the hand faces the wall along its -Y axis.")]
    [SerializeField] private Vector3 wallFacingRotationEuler = new Vector3(-90f, 0f, 0f);

    [Header("Animator State Names")]
    [Tooltip("Must exactly match the state name in the Animator Controller's Base Layer (index 0).")]
    [SerializeField] private string idleStateName = "Idle R Hand";
    [SerializeField] private string stickStateName = "stckHandR 1";
    [SerializeField] private int animatorLayer = 0;

    [Header("Timing")]
    [Tooltip("How long the hand takes to move between rest and FPS position.")]
    [SerializeField] private float moveDuration = 0.7f;
    [SerializeField] private float animCrossfadeDuration = 0.1f;

    [Header("Debug")]
    [SerializeField] private bool debugLogging = false;

    private Coroutine moveRoutine;
    private Coroutine stickAnimRoutine;
    private bool isVisible;

    private void Reset()
    {
        playerMovement = GetComponentInParent<PlayerMovement>();
        handAnimator = GetComponentInChildren<Animator>();
        handRenderers = GetComponentsInChildren<Renderer>();
    }

    private void Awake()
    {
        if (playerMovement == null) playerMovement = GetComponentInParent<PlayerMovement>();
        if (playerMovement == null) playerMovement = FindObjectOfType<PlayerMovement>();
        if (handAnimator == null) handAnimator = GetComponentInChildren<Animator>();
        if (handRenderers == null || handRenderers.Length == 0) handRenderers = GetComponentsInChildren<Renderer>();

        if (handAnimator == null)
            Debug.LogWarning("[ClimbHandController] No Animator found/assigned. Animations will not play.");
        else if (handAnimator.runtimeAnimatorController == null)
            Debug.LogWarning("[ClimbHandController] The assigned Animator has no Controller asset plugged into it. Assign the Animator Controller on the Animator component itself (not on this script).");

        ReapplyMirrorScale();
    }

    private void OnEnable()
    {
        if (playerMovement != null)
        {
            playerMovement.OnClimbPromptChanged += HandleClimbPromptChanged;
            playerMovement.OnWallStickStarted += HandleWallStickStarted;
            playerMovement.OnWallStickEnded += HandleWallStickEnded;
        }
        else
        {
            Debug.LogWarning("[ClimbHandController] No PlayerMovement reference found - hand will stay hidden.");
        }

        SnapToRestAndHide();
    }

    private void OnDisable()
    {
        if (playerMovement != null)
        {
            playerMovement.OnClimbPromptChanged -= HandleClimbPromptChanged;
            playerMovement.OnWallStickStarted -= HandleWallStickStarted;
            playerMovement.OnWallStickEnded -= HandleWallStickEnded;
        }

        if (moveRoutine != null) StopCoroutine(moveRoutine);
        if (stickAnimRoutine != null) StopCoroutine(stickAnimRoutine);
    }

    private void ReapplyMirrorScale()
    {
        if (!mirrorHand) return;
        Vector3 scale = transform.localScale;
        switch (mirrorAxis)
        {
            case MirrorAxis.X: scale.x = -Mathf.Abs(scale.x); break;
            case MirrorAxis.Y: scale.y = -Mathf.Abs(scale.y); break;
            case MirrorAxis.Z: scale.z = -Mathf.Abs(scale.z); break;
        }
        transform.localScale = scale;
    }

    // --- Event Handlers -----------------------------------------------------

    private void HandleClimbPromptChanged(bool shown)
    {
        if (playerMovement.IsWallSticking) return; // stick events own the hand while sticking

        if (shown) ShowAndMoveToFPS();
        else MoveToRestThenHide();
    }

    private void HandleWallStickStarted(Vector3 wallHitPoint, Vector3 wallNormal)
    {
        Log("Wall stick started - positioning at wall hit point.");

        if (moveRoutine != null) { StopCoroutine(moveRoutine); moveRoutine = null; }

        SetVisible(true);
        transform.SetParent(null, true);
        ReapplyMirrorScale();

        // Face the wall along the hand's own -Y axis, with the configured rotation offset applied on top.
        Quaternion targetRot = Quaternion.LookRotation(-wallNormal) * Quaternion.Euler(wallFacingRotationEuler);

        // Push along all three of the hand's own local axes (post-rotation) by stickPositionOffset.
        Vector3 targetPos = wallHitPoint + (targetRot * stickPositionOffset);

        transform.position = targetPos;
        transform.rotation = targetRot;

        PlayStickAnimationAndFreeze();
    }

    private void HandleWallStickEnded()
    {
        Log("Wall stick ended - returning to idle and rest position.");

        if (stickAnimRoutine != null) { StopCoroutine(stickAnimRoutine); stickAnimRoutine = null; }

        ReturnToIdleAnimation();
        MoveToRestThenHide();
    }

    // --- Movement / Parenting -----------------------------------------------

    private void ShowAndMoveToFPS()
    {
        SetVisible(true);
        transform.SetParent(null, true); // unparent from rest so we can tween in world space
        StartMove(transform.position, transform.rotation, fpsHandPos, () =>
        {
            // Lock to fpsHandPos so it tracks it (e.g. if it sways with camera bob).
            transform.SetParent(fpsHandPos, true);
            transform.localPosition = Vector3.zero;
            transform.localRotation = Quaternion.identity;
            ReapplyMirrorScale();
        });
    }

    private void MoveToRestThenHide()
    {
        if (!isVisible) return;

        transform.SetParent(null, true);
        StartMove(transform.position, transform.rotation, handRestPos, () =>
        {
            transform.SetParent(handRestPos, true);
            transform.localPosition = Vector3.zero;
            transform.localRotation = Quaternion.identity;
            ReapplyMirrorScale();
            SetVisible(false);
        });
    }

    private void StartMove(Vector3 fromPos, Quaternion fromRot, Transform target, System.Action onComplete)
    {
        if (moveRoutine != null) StopCoroutine(moveRoutine);
        moveRoutine = StartCoroutine(MoveRoutine(fromPos, fromRot, target, onComplete));
    }

    private IEnumerator MoveRoutine(Vector3 startPos, Quaternion startRot, Transform target, System.Action onComplete)
    {
        float elapsed = 0f;
        while (elapsed < moveDuration)
        {
            elapsed += Time.deltaTime;
            float t = Mathf.Clamp01(elapsed / moveDuration);
            t = t * t * (3f - 2f * t); // smoothstep

            transform.position = Vector3.Lerp(startPos, target.position, t);
            transform.rotation = Quaternion.Slerp(startRot, target.rotation, t);
            yield return null;
        }

        transform.position = target.position;
        transform.rotation = target.rotation;

        moveRoutine = null;
        onComplete?.Invoke();
    }

    private void SetVisible(bool visible)
    {
        if (isVisible == visible) return;
        isVisible = visible;

        foreach (Renderer r in handRenderers)
        {
            if (r != null) r.enabled = visible;
        }
    }

    private void SnapToRestAndHide()
    {
        if (moveRoutine != null) { StopCoroutine(moveRoutine); moveRoutine = null; }

        if (handRestPos != null)
        {
            transform.SetParent(handRestPos, true);
            transform.localPosition = Vector3.zero;
            transform.localRotation = Quaternion.identity;
            ReapplyMirrorScale();
        }

        SetVisible(false);
        ReturnToIdleAnimation(instant: true);
    }

    // --- Animation ------------------------------------------------------------

    private void PlayStickAnimationAndFreeze()
    {
        if (handAnimator == null)
        {
            Log("Cannot play stick animation - no Animator assigned/found.");
            return;
        }

        if (stickAnimRoutine != null) StopCoroutine(stickAnimRoutine);
        stickAnimRoutine = StartCoroutine(PlayStickRoutine());
    }

    private IEnumerator PlayStickRoutine()
    {
        handAnimator.speed = 1f;
        handAnimator.CrossFadeInFixedTime(stickStateName, animCrossfadeDuration, animatorLayer);

        // Wait for the crossfade to finish and confirm we actually landed on the target state.
        // (During the crossfade itself, GetCurrentAnimatorStateInfo may still report the previous state.)
        float safetyTimer = 0f;
        const float safetyLimit = 2f;

        while (!handAnimator.GetCurrentAnimatorStateInfo(animatorLayer).IsName(stickStateName))
        {
            safetyTimer += Time.deltaTime;
            if (safetyTimer > safetyLimit)
            {
                Debug.LogWarning($"[ClimbHandController] Timed out waiting to enter state '{stickStateName}'. " +
                                  "Check that the Animator state name matches EXACTLY (case-sensitive) and lives on layer " + animatorLayer + ".");
                yield break;
            }
            yield return null;
        }

        Log($"Entered '{stickStateName}', playing until it completes.");

        // Play forward until the clip completes once.
        AnimatorStateInfo state = handAnimator.GetCurrentAnimatorStateInfo(animatorLayer);
        while (state.normalizedTime < 1f)
        {
            yield return null;
            state = handAnimator.GetCurrentAnimatorStateInfo(animatorLayer);

            // If something transitioned us away (e.g. Any State override), bail safely.
            if (!state.IsName(stickStateName)) yield break;
        }

        // Freeze on the last frame.
        handAnimator.speed = 0f;
        Log($"'{stickStateName}' finished - frozen on last frame.");
    }

    private void ReturnToIdleAnimation(bool instant = false)
    {
        if (handAnimator == null) return;

        handAnimator.speed = 1f;

        if (instant)
        {
            handAnimator.Play(idleStateName, animatorLayer, 0f);
        }
        else
        {
            handAnimator.CrossFadeInFixedTime(idleStateName, animCrossfadeDuration, animatorLayer);
        }
    }

    private void Log(string msg)
    {
        if (debugLogging) Debug.Log($"[ClimbHandController] {msg}");
    }
}