using System.Collections.Generic;
using UnityEngine;

namespace TKS
{
    /// <summary>아트 리소스 없이 쓰는 도형 스프라이트(원·링·얇은 링·도넛·사각). 프로토타입 전용.</summary>
    public static class ProceduralSprites
    {
        static Sprite circle;
        static Sprite ring;
        static Sprite thinRing;
        static Sprite square;
        static readonly Dictionary<int, Sprite> donuts = new Dictionary<int, Sprite>();

        /// <summary>바깥 지름 1 월드 단위의 얇은 흰 링(두께 3 %) — 사거리 표시용.</summary>
        public static Sprite ThinRing
        {
            get
            {
                if (thinRing == null) thinRing = MakeRing(256, 0.03f);
                return thinRing;
            }
        }

        /// <summary>바깥 지름 1 · 안쪽 지름 innerFrac(0~1) 의 채워진 도넛 — 궁병 공격 가능 범위 표시용.</summary>
        public static Sprite Donut(float innerFrac)
        {
            int key = Mathf.RoundToInt(Mathf.Clamp01(innerFrac) * 1000f);
            Sprite s;
            if (!donuts.TryGetValue(key, out s))
            {
                s = MakeRing(256, 1f - key / 1000f);
                donuts[key] = s;
            }
            return s;
        }

        /// <summary>지름 1 월드 단위의 흰 원.</summary>
        public static Sprite Circle
        {
            get
            {
                if (circle == null) circle = MakeCircle(128);
                return circle;
            }
        }

        /// <summary>바깥 지름 1 월드 단위의 흰 링(두께 12 %).</summary>
        public static Sprite Ring
        {
            get
            {
                if (ring == null) ring = MakeRing(128, 0.12f);
                return ring;
            }
        }

        /// <summary>1×1 월드 단위의 흰 사각형.</summary>
        public static Sprite Square
        {
            get
            {
                if (square == null)
                {
                    var tex = new Texture2D(4, 4, TextureFormat.RGBA32, false);
                    var px = new Color[16];
                    for (int i = 0; i < px.Length; i++) px[i] = Color.white;
                    tex.SetPixels(px);
                    tex.Apply();
                    tex.hideFlags = HideFlags.DontSave;
                    square = Sprite.Create(tex, new Rect(0, 0, 4, 4), new Vector2(0.5f, 0.5f), 4f);
                    square.hideFlags = HideFlags.DontSave;
                }
                return square;
            }
        }

        static Sprite MakeCircle(int size)
        {
            var tex = new Texture2D(size, size, TextureFormat.RGBA32, false);
            tex.wrapMode = TextureWrapMode.Clamp;
            tex.filterMode = FilterMode.Bilinear;
            float half = size * 0.5f;
            var px = new Color[size * size];
            for (int y = 0; y < size; y++)
            {
                for (int x = 0; x < size; x++)
                {
                    float dx = x + 0.5f - half;
                    float dy = y + 0.5f - half;
                    float d = Mathf.Sqrt(dx * dx + dy * dy);
                    float a = Mathf.Clamp01(half - d); // 1 px 안티앨리어싱
                    px[y * size + x] = new Color(1f, 1f, 1f, a);
                }
            }
            tex.SetPixels(px);
            tex.Apply();
            tex.hideFlags = HideFlags.DontSave;
            var s = Sprite.Create(tex, new Rect(0, 0, size, size), new Vector2(0.5f, 0.5f), size);
            s.hideFlags = HideFlags.DontSave;
            return s;
        }

        static Sprite MakeRing(int size, float thicknessFrac)
        {
            var tex = new Texture2D(size, size, TextureFormat.RGBA32, false);
            tex.wrapMode = TextureWrapMode.Clamp;
            tex.filterMode = FilterMode.Bilinear;
            float half = size * 0.5f;
            float inner = half * (1f - thicknessFrac);
            var px = new Color[size * size];
            for (int y = 0; y < size; y++)
            {
                for (int x = 0; x < size; x++)
                {
                    float dx = x + 0.5f - half;
                    float dy = y + 0.5f - half;
                    float d = Mathf.Sqrt(dx * dx + dy * dy);
                    float a = Mathf.Clamp01(half - d) * Mathf.Clamp01(d - inner);
                    px[y * size + x] = new Color(1f, 1f, 1f, a);
                }
            }
            tex.SetPixels(px);
            tex.Apply();
            tex.hideFlags = HideFlags.DontSave;
            var s = Sprite.Create(tex, new Rect(0, 0, size, size), new Vector2(0.5f, 0.5f), size);
            s.hideFlags = HideFlags.DontSave;
            return s;
        }

        public static SpriteRenderer NewSprite(Transform parent, string name, Sprite sprite, Color color, float scale, int sortingOrder)
        {
            var go = new GameObject(name);
            go.transform.SetParent(parent, false);
            var sr = go.AddComponent<SpriteRenderer>();
            sr.sprite = sprite;
            sr.color = color;
            sr.sortingOrder = sortingOrder;
            go.transform.localScale = new Vector3(scale, scale, 1f);
            return sr;
        }
    }
}