using UnityEngine;

public class FlowIntroRouteMotion : MonoBehaviour
{
    public Vector2[] points;
    public Vector2 offset;
    public float duration = 7.5f;

    private RectTransform rectTransform;
    private Vector3 baseScale = Vector3.one;

    private void Awake()
    {
        rectTransform = GetComponent<RectTransform>();
        if(rectTransform != null)
        {
            baseScale = rectTransform.localScale;
        }
    }

    private void OnEnable()
    {
        if(rectTransform == null)
        {
            rectTransform = GetComponent<RectTransform>();
        }

        if(rectTransform != null)
        {
            baseScale = rectTransform.localScale;
        }
    }

    private void Update()
    {
        if(rectTransform == null || points == null || points.Length < 2 || duration <= 0f)
        {
            return;
        }

        float totalLength = GetTotalLength();
        if(totalLength <= 0f)
        {
            return;
        }

        float distance = Mathf.Repeat(Time.unscaledTime / duration, 1f) * totalLength;
        Vector2 position = points[0];
        Vector2 direction = Vector2.right;

        for(int i = 0; i < points.Length - 1; i++)
        {
            Vector2 from = points[i];
            Vector2 to = points[i + 1];
            Vector2 delta = to - from;
            float segmentLength = delta.magnitude;

            if(distance <= segmentLength)
            {
                float t = segmentLength > 0f ? distance / segmentLength : 0f;
                position = Vector2.Lerp(from, to, t);
                direction = delta.normalized;
                break;
            }

            distance -= segmentLength;
        }

        rectTransform.anchoredPosition = position + offset;

        if(direction.sqrMagnitude > 0.0001f)
        {
            Vector2 displayDirection = direction;
            Vector3 displayScale = baseScale;

            if(displayDirection.x < 0f)
            {
                displayDirection.x = -displayDirection.x;
                displayScale.x = -Mathf.Abs(baseScale.x);
            }
            else
            {
                displayScale.x = Mathf.Abs(baseScale.x);
            }

            rectTransform.localScale = displayScale;
            rectTransform.localRotation = Quaternion.Euler(0f, 0f, Mathf.Atan2(displayDirection.y, displayDirection.x) * Mathf.Rad2Deg - 12f);
        }
    }

    private float GetTotalLength()
    {
        float totalLength = 0f;

        for(int i = 0; i < points.Length - 1; i++)
        {
            totalLength += Vector2.Distance(points[i], points[i + 1]);
        }

        return totalLength;
    }
}