using UnityEngine;
using BumpCombat.Constants;

namespace BumpCombat.Defense
{
    [DisallowMultipleComponent]
    public sealed class DefenseSpriteSequence : MonoBehaviour
    {
        private SpriteRenderer target;
        private Sprite[] frames;
        private string key;
        private float frameRemaining;
        private int frame;
        private Sprite[] nextFrames;
        private string nextKey;
        private bool destroyWhenFinished;
        private float delayRemaining;
        private bool animationFinished;
        private Vector2 travelStart;
        private Vector2 travelEnd;
        private float travelDuration;
        private float travelElapsed;
        private bool fitsLightningBeam;
        private Vector2 beamStart;
        private Vector2 beamEnd;
        private float beamThickness;
        private bool centersImpactWave;
        private Vector2 impactWaveCenter;
        private float impactWaveScale;

        public void Play(SpriteRenderer renderer, string sequenceKey, Sprite[] sequenceFrames,
            bool destroyOnFinish, string followingKey = null,
            Sprite[] followingFrames = null, float startDelay = 0f)
        {
            target = renderer;
            key = sequenceKey;
            frames = sequenceFrames;
            destroyWhenFinished = destroyOnFinish;
            nextKey = followingKey;
            nextFrames = followingFrames;
            delayRemaining = Mathf.Max(0f, startDelay);
            if (target == null || frames == null || frames.Length == 0)
            {
                enabled = false;
                if (destroyWhenFinished) Destroy(gameObject);
                return;
            }
            frame = 0;
            target.sprite = frames[frame];
            target.enabled = delayRemaining <= 0f;
            frameRemaining = DefenseTowerArt.FrameSeconds(key, frame);
            UpdateVisualAlignment();
        }

        public void FitLightningBeam(Vector2 start, Vector2 end, float thickness)
        {
            fitsLightningBeam = true;
            beamStart = start;
            beamEnd = end;
            beamThickness = thickness;
            UpdateVisualAlignment();
        }

        public void CenterImpactWave(Vector2 center, float uniformScale)
        {
            centersImpactWave = true;
            impactWaveCenter = center;
            impactWaveScale = uniformScale;
            UpdateVisualAlignment();
        }

        public void Travel(Vector2 start, Vector2 end, float duration)
        {
            travelStart = start;
            travelEnd = end;
            travelDuration = Mathf.Max(0.001f, duration);
            travelElapsed = 0f;
            transform.position = start;
        }

        private void Update()
        {
            if (target == null || frames == null || frames.Length == 0)
            {
                FinishSequence();
                return;
            }
            if (delayRemaining > 0f)
            {
                delayRemaining -= Time.deltaTime;
                if (delayRemaining > 0f) return;
                target.enabled = true;
            }
            if (travelDuration > 0f && travelElapsed < travelDuration)
            {
                travelElapsed += Time.deltaTime;
                transform.position = Vector2.Lerp(
                    travelStart, travelEnd, Mathf.Clamp01(travelElapsed / travelDuration));
            }
            if (animationFinished)
            {
                if (travelDuration <= 0f || travelElapsed >= travelDuration) FinishSequence();
                return;
            }

            frameRemaining -= Time.deltaTime;
            while (frameRemaining <= 0f)
            {
                frame++;
                if (frame >= frames.Length)
                {
                    if (nextFrames != null && nextFrames.Length > 0)
                    {
                        frames = nextFrames;
                        key = nextKey;
                        nextFrames = null;
                        frame = 0;
                    }
                    else
                    {
                        animationFinished = true;
                        if (travelDuration <= 0f || travelElapsed >= travelDuration) FinishSequence();
                        return;
                    }
                }
                target.sprite = frames[frame];
                UpdateVisualAlignment();
                frameRemaining += DefenseTowerArt.FrameSeconds(key, frame);
            }
        }

        private void UpdateVisualAlignment()
        {
            if (target == null || target.sprite == null) return;
            if (fitsLightningBeam)
            {
                Vector2 direction = beamEnd - beamStart;
                float distance = direction.magnitude;
                Vector2Int bounds = DefenseTowerArtBounds.LightningBeamXBounds(frame);
                float pixelsPerUnit = target.sprite.pixelsPerUnit;
                float visibleWidth = (bounds.y - bounds.x) / pixelsPerUnit;
                float scaleX = distance <= 0f || visibleWidth <= 0f
                    ? 0f : distance / visibleWidth;
                float localStart = (bounds.x - target.sprite.pivot.x) / pixelsPerUnit * scaleX;
                transform.rotation = Quaternion.Euler(0f, 0f,
                    distance > 0f ? Mathf.Atan2(direction.y, direction.x) * Mathf.Rad2Deg : 0f);
                transform.position = beamStart - (Vector2)(transform.right * localStart);
                transform.localScale = new Vector3(scaleX, beamThickness, 1f);
            }
            if (centersImpactWave)
            {
                transform.localScale = Vector3.one * impactWaveScale;
                Vector2 localCenter = (DefenseTowerArtBounds.ImpactWaveCenterPixels(frame, target.sprite)
                    - target.sprite.pivot) / target.sprite.pixelsPerUnit;
                transform.position = impactWaveCenter - (Vector2)transform.TransformVector(localCenter);
            }
        }

        private void FinishSequence()
        {
            if (destroyWhenFinished)
            {
                Destroy(gameObject);
            }
            else
            {
                if (target != null) target.enabled = false;
                enabled = false;
            }
        }
    }
}