using System;
using System.Collections.Generic;
using UnityEngine;

public class Bullet : MonoBehaviour
{
    [SerializeField] private Collider2D collisionDetector;
    [SerializeField] private float speed = 10.0f;

    float maxFlyDistance = 0.0f;
    float currentFlyDistance = 0.0f;

    HashSet<CreatureBase> collided = new HashSet<CreatureBase>();

    Action<Bullet, CreatureBase> OnCollide;
    Action<Bullet> OnCompleteToTarget;

    public Transform Target { get; private set; } = null;
    public bool IsFired { get; private set; } = false;

    public float Speed
    {
        get => speed;
        set => speed = value;
    }

    public Vector2 HeadDirection
    {
        get
        {
            var zAngle = transform.eulerAngles.z;
            return new Vector2(Mathf.Cos(zAngle * Mathf.Deg2Rad), Mathf.Sin(zAngle * Mathf.Deg2Rad)).normalized;
        }
        set
        {
            transform.eulerAngles = new Vector3(0, 0, Mathf.Atan2(value.y, value.x) * Mathf.Rad2Deg);
        }
    }

    private void Update()
    {
        if(!IsFired) return;

        float sqrtDistanceToTarget = float.MaxValue;

        if (Target != null)
        {
            var ignoreZOfThis = transform.position;
            ignoreZOfThis.z = 0.0f;

            var ignoreZOfTarget = Target.position;
            ignoreZOfTarget.z = 0.0f;

            var toVec = ignoreZOfTarget - ignoreZOfThis;

            HeadDirection = toVec;
            sqrtDistanceToTarget = toVec.sqrMagnitude;
        }

        float moveUnit = speed * Time.deltaTime;
        if (sqrtDistanceToTarget < moveUnit * moveUnit)
        {
            transform.position = Target.position;
            BattleMgr.LoopAllCreatures(HandleCollide);
            OnCompleteToTarget?.Invoke(this);
            IsFired = false;
        }
        else if(maxFlyDistance > 0.0f && currentFlyDistance >= maxFlyDistance)
        {
            BattleMgr.LoopAllCreatures(HandleCollide);
            OnCompleteToTarget?.Invoke(this);
            IsFired = false;
        }
        else
        {
            transform.position += (Vector3)HeadDirection * moveUnit;
            currentFlyDistance += moveUnit;
            BattleMgr.LoopAllCreatures(HandleCollide);
        }
    }

    public void Fire(float maxFlyDistance, Action<Bullet, CreatureBase> onCollide, Action<Bullet> onCompleteToTarget)
    {
        this.maxFlyDistance = maxFlyDistance;
        currentFlyDistance = 0.0f;
        OnCollide = onCollide;
        OnCompleteToTarget = onCompleteToTarget;
        collided.Clear();
        IsFired = true;
    }

    public void Fire(Transform target, Action<Bullet, CreatureBase> onCollide, Action<Bullet> onCompleteToTarget)
    {
        maxFlyDistance = 0.0f;
        currentFlyDistance = 0.0f;
        Target = target;
        OnCollide = onCollide;
        OnCompleteToTarget = onCompleteToTarget;
        collided.Clear();
        IsFired = true;
    }

    private bool HandleCollide(CreatureBase creature)
    {
        var ignoreZOfBounds = collisionDetector.bounds;
        ignoreZOfBounds.extents = new Vector3(ignoreZOfBounds.extents.x, ignoreZOfBounds.extents.y, 0.0f);

        var ignoreZOfCreature = creature.transform.position;
        ignoreZOfCreature.z = 0.0f;

        if (collided.Contains(creature))
        {
            if (!ignoreZOfBounds.Contains(ignoreZOfCreature))
            {
                collided.Remove(creature);
            }

            return true;
        }

        if (ignoreZOfBounds.Contains(ignoreZOfCreature))
        {
            collided.Add(creature);
            OnCollide.Invoke(this, creature);
            return false;
        }

        return true;
    }

    private void OnDrawGizmosSelected()
    {
        Logger.DrawArrow2D(transform.position, HeadDirection, 5.0f, Color.cyan);
    }
}