using System;
using System.Collections;
using UnityEngine;

namespace TKS
{
    /// <summary>간단한 연출(이동 트윈·돌진·화살·피해 숫자). 코루틴 실행자는 BattleManager. 가상 실행(Sim.Active · 적 AI 예측) 중 = 이동·대기 즉시 · 팝업·터짐 없음.</summary>
    public static class Fx
    {
        public static MonoBehaviour Runner;

        public static Coroutine Run(IEnumerator routine)
        {
            if (Sim.Active)
            {
                Sim.Run(routine); // 가상 실행 = 그 자리에서 끝까지(병렬 밀기 등)
                return null;
            }
            if (Runner == null) return null;
            return Runner.StartCoroutine(routine);
        }

        public static IEnumerator Wait(float seconds)
        {
            if (Sim.Active) yield break;
            float t = 0f;
            while (t < seconds)
            {
                t += Time.deltaTime;
                yield return null;
            }
        }

        /// <summary>from → to 이동(기본 = 감속 · easeOut false = 등속 → 부딪히는 순간까지 속도를 유지). onDistance 에는 지금까지 지나온 거리를 넘긴다.</summary>
        public static IEnumerator MoveAlong(Transform tr, Vector2 from, Vector2 to, float speed, Action<float> onDistance, bool easeOut = true)
        {
            float total = Vector2.Distance(from, to);
            if (total < 1e-4f) yield break;
            if (Sim.Active)
            {
                tr.position = new Vector3(to.x, to.y, 0f);
                if (onDistance != null) onDistance(total);
                yield break;
            }
            float duration = Mathf.Max(0.12f, total / Mathf.Max(0.1f, speed));
            float el = 0f;
            while (el < duration)
            {
                el += Time.deltaTime;
                float k = Mathf.Clamp01(el / duration);
                float e = easeOut ? 1f - (1f - k) * (1f - k) : k;
                var p = Vector2.Lerp(from, to, e);
                tr.position = new Vector3(p.x, p.y, 0f);
                if (onDistance != null) onDistance(e * total);
                yield return null;
            }
            tr.position = new Vector3(to.x, to.y, 0f);
            if (onDistance != null) onDistance(total);
        }

        /// <summary>근접 공격 돌진(짧게 찌르고 복귀).</summary>
        public static IEnumerator Lunge(Unit a, Vector2 toward)
        {
            if (Sim.Active) yield break;
            Vector2 start = a.Position;
            Vector2 dir = (toward - start);
            if (dir.sqrMagnitude < 1e-4f) yield break;
            dir.Normalize();
            Vector2 peak = start + dir * 0.3f;
            yield return MoveAlong(a.transform, start, peak, 6f, null);
            yield return MoveAlong(a.transform, peak, start, 4f, null);
            a.Position = start;
        }

        public static readonly Color ArrowColor = new Color(1f, 0.95f, 0.75f);
        public static readonly Color StrategistShotColor = new Color(0.75f, 0.55f, 1f);
        public static readonly Color SplashColor = new Color(0.7f, 0.45f, 1f, 0.45f);
        public static readonly Color FriendlyFireColor = new Color(1f, 0.3f, 0.3f);

        /// <summary>화살(가늘고 긴 사각형) 날리기.</summary>
        public static IEnumerator Arrow(Vector2 from, Vector2 to)
        {
            return Arrow(from, to, ArrowColor);
        }

        /// <summary>투사체(가늘고 긴 사각형) 날리기 — 궁병 화살 · 책사 계략(색만 다름).</summary>
        public static IEnumerator Arrow(Vector2 from, Vector2 to, Color color)
        {
            if (Sim.Active) yield break;
            var go = new GameObject("Arrow");
            var sr = go.AddComponent<SpriteRenderer>();
            sr.sprite = ProceduralSprites.Square;
            sr.color = color;
            sr.sortingOrder = 8;
            Vector2 d = to - from;
            float ang = Mathf.Atan2(d.y, d.x) * Mathf.Rad2Deg;
            go.transform.rotation = Quaternion.Euler(0f, 0f, ang);
            go.transform.localScale = new Vector3(0.5f, 0.06f, 1f);
            float dur = Mathf.Max(0.12f, d.magnitude / 14f);
            float t = 0f;
            while (t < dur)
            {
                t += Time.deltaTime;
                var p = Vector2.Lerp(from, to, Mathf.Clamp01(t / dur));
                go.transform.position = new Vector3(p.x, p.y, 0f);
                yield return null;
            }
            UnityEngine.Object.Destroy(go);
        }

        /// <summary>광역 터짐(반지름 radius 원이 짧게 커지며 사라짐 · 책사 광역).</summary>
        public static void Burst(Vector2 center, float radius, Color color)
        {
            if (Sim.Active) return;
            Run(BurstRoutine(center, radius, color));
        }

        static IEnumerator BurstRoutine(Vector2 center, float radius, Color color)
        {
            var sr = ProceduralSprites.NewSprite(null, "Burst", ProceduralSprites.Circle, color, radius * 2f, 7);
            sr.transform.position = new Vector3(center.x, center.y, 0f);
            float t = 0f;
            const float dur = 0.35f;
            while (t < dur)
            {
                t += Time.deltaTime;
                float k = Mathf.Clamp01(t / dur);
                float s = radius * 2f * (0.6f + 0.4f * k);
                sr.transform.localScale = new Vector3(s, s, 1f);
                var c = color;
                c.a = color.a * (1f - k);
                sr.color = c;
                yield return null;
            }
            UnityEngine.Object.Destroy(sr.gameObject);
        }

        public static void Popup(Vector2 pos, string text, Color color)
        {
            if (Sim.Active) return;
            Run(PopupRoutine(pos, text, color));
        }

        static IEnumerator PopupRoutine(Vector2 pos, string text, Color color)
        {
            var tm = TextUtil.CreateWorldText(null, text, 0.42f, color, 20);
            tm.gameObject.name = "Popup";
            var tr = tm.transform;
            float t = 0f;
            const float dur = 0.75f;
            while (t < dur)
            {
                t += Time.deltaTime;
                float k = Mathf.Clamp01(t / dur);
                tr.position = new Vector3(pos.x, pos.y + 0.55f + 0.7f * k, 0f);
                var c = color;
                c.a = 1f - k * k;
                tm.color = c;
                yield return null;
            }
            UnityEngine.Object.Destroy(tm.gameObject);
        }
    }
}