using UnityEngine;
using DG.Tweening;

public class PenWriter : MonoBehaviour
{
    [Header("Assign the transform that moves up/down (pen or tip root)")]
    public Transform pen;             // If null, uses this.transform

    [Header("Motion Settings")]
    [Min(0f)] public float minDown = 0.2f; // minimum down stroke depth (in local units)
    [Min(0f)] public float maxDown = 0.6f; // maximum down stroke depth
    [Min(0f)] public float minDur = 0.04f; // min duration per tap
    [Min(0f)] public float maxDur = 0.10f; // max duration per tap
    [Range(0f, 1f)] public float upFraction = 0.35f; // fraction of tap duration for the up motion (snappy up)

    private Vector3 localUpAxis;
    private Vector3 baseLocalPos;
    private bool writing;

    void Awake()
    {
        if (!pen) pen = transform;
        baseLocalPos = pen.localPosition;
        localUpAxis = transform.InverseTransformDirection(Vector3.up);
    }

    public void StartWriting()
    {
        if (writing) return;
        writing = true;

        // Ensure any previous tweens are stopped and we reset to rest
        DOTween.Kill(pen, complete: false);
        pen.localPosition = baseLocalPos;

        // We’ll add a callback that keeps enqueuing the next tap until stopped
        EnqueueNextTap();
    }

    public void StopWriting(bool snapToRest = true)
    {
        writing = false;
        DOTween.Kill(pen);

        if (snapToRest)
            pen.localPosition = baseLocalPos;
        else
        {
            // Smoothly return to rest
            pen.DOLocalMove(baseLocalPos, 0.08f)
               .SetEase(Ease.OutSine);
        }
    }

    private void EnqueueNextTap()
    {
        if (!writing) return;

        float depth = Random.Range(minDown, maxDown);
        float dur = Random.Range(minDur, maxDur);

        Vector3 downPos = baseLocalPos - localUpAxis * depth;

        float upDur = Mathf.Max(0.01f, dur * upFraction);
        float downDur = Mathf.Max(0.01f, dur - upDur);

        // Down (contact), then Up (lift)
        pen.DOLocalMove(downPos, downDur).OnComplete(() =>
        {
            pen.DOLocalMove(baseLocalPos, upDur).OnComplete(() =>
            {
                if (writing) EnqueueNextTap();
            });
        });
    }
}