using System;
using UnityEngine;

public class HomingBullet : BulletBase
{
    [SerializeField] float rotSpeed = 100.0f;
    [SerializeField] float factorByAngleDiff = 0f;

    public Transform Target { get; private set; }

    public bool IsHoming => Target != null;

    public Action OnUpdate;

    protected override bool UpdateBullet(float deltaTime)
    {
        if(Target is null) return false;

        Vector2 toTarget = Target.position - transform.position;

        float targetAngle = Utility.GetAngle2D(toTarget);
        float currentAngle = Utility.GetAngle2D(HeadDirection);

        float factor = 1.0f;
        if(toTarget.sqrMagnitude < 3.0f * 3.0f)
        {
            factor = 0f;
        }

        if(factorByAngleDiff > 0)
        {
            factor *= Mathf.Abs(currentAngle - targetAngle) * factorByAngleDiff;
        }

        transform.rotation = Quaternion.RotateTowards(Quaternion.Euler(0, 0, currentAngle), Quaternion.Euler(0, 0, targetAngle), rotSpeed * factor * deltaTime);
        transform.position += (Vector3)HeadDirection * Speed * deltaTime;

        return true;
    }

    public override void Fire(Transform target = null, bool resetLifeTime = true)
    {
        if (target is null) return;

        base.Fire(target, resetLifeTime);

        Target = target;
    }
}