using System.Collections.Generic;
using UnityEngine;

namespace Vanguard.UI
{
    /// <summary>
    /// Процедурные карточные текстуры без внешних артов: цвет клана,
    /// градиент, рубашка. Позже заменяется Addressables-артом.
    /// </summary>
    public static class CardArt
    {
        private static readonly Dictionary<string, Sprite> Cache =
            new Dictionary<string, Sprite>();
        private static Sprite _back;

        public static Color ClanColor(string clan) => clan switch
        {
            "RoyalPaladin" => new Color(0.20f, 0.40f, 0.78f),
            "OracleThinkTank" => new Color(0.72f, 0.58f, 0.22f),
            "Kagero" => new Color(0.68f, 0.18f, 0.18f),
            "Nubatama" => new Color(0.38f, 0.22f, 0.62f),
            "Tachikaze" => new Color(0.22f, 0.56f, 0.34f),
            "NovaGrappler" => new Color(0.78f, 0.40f, 0.16f),
            "SpikeBrothers" => new Color(0.52f, 0.34f, 0.20f),
            "DarkIrregulars" => new Color(0.30f, 0.18f, 0.38f),
            "Granblue" => new Color(0.16f, 0.46f, 0.54f),
            "Megacolony" => new Color(0.40f, 0.48f, 0.18f),
            _ => new Color(0.28f, 0.34f, 0.46f),
        };

        public static Sprite ForClan(string clan)
        {
            var key = "clan:" + clan;
            if (Cache.TryGetValue(key, out var sprite))
                return sprite;

            var color = ClanColor(clan);
            sprite = Gradient(
                Color.Lerp(color, Color.black, 0.55f),
                Color.Lerp(color, Color.white, 0.18f),
                accent: Color.Lerp(color, Color.white, 0.35f),
                variant: 0);
            Cache[key] = sprite;
            return sprite;
        }

        public static Sprite ForCard(string nameId, string clan)
        {
            var key = "card:" + nameId;
            if (Cache.TryGetValue(key, out var sprite))
                return sprite;

            var color = ClanColor(clan);
            var hash = StableHash(nameId ?? string.Empty);
            var accent = Color.HSVToRGB(
                (hash % 360) / 360f,
                0.62f,
                0.98f);
            sprite = Gradient(
                Color.Lerp(color, Color.black, 0.58f),
                Color.Lerp(color, Color.white, 0.16f),
                accent,
                (int)(hash % 5));
            Cache[key] = sprite;
            return sprite;
        }

        private static uint StableHash(string value)
        {
            var hash = 2166136261u;
            foreach (var ch in value)
            {
                hash ^= ch;
                hash *= 16777619u;
            }

            return hash;
        }

        public static Sprite Back
        {
            get
            {
                if (_back != null)
                    return _back;

                _back = BackTexture();
                return _back;
            }
        }

        private static Sprite Gradient(Color bottom, Color top, Color accent, int variant)
        {
            const int width = 32;
            const int height = 48;
            var texture = new Texture2D(width, height, TextureFormat.RGBA32, false)
            {
                filterMode = FilterMode.Bilinear,
                wrapMode = TextureWrapMode.Clamp,
            };

            var pixels = new Color[width * height];
            for (var y = 0; y < height; y++)
            {
                var t = y / (float)(height - 1);
                var row = Color.Lerp(bottom, top, t);
                for (var x = 0; x < width; x++)
                {
                    var stripe = ((x + y + variant * 3) % 11) < 2 ? 0.12f : 0f;
                    var glow = Mathf.Clamp01(1f - Mathf.Abs(x - width * 0.5f) / (width * 0.5f)) * 0.12f;

                    var cx = x - width * 0.5f;
                    var cy = y - height * 0.38f;
                    var radius = 6f + variant;
                    var sigil = Mathf.Abs(cx) + Mathf.Abs(cy) < radius ? 0.22f : 0f;
                    if (variant == 2 && Mathf.Abs(cx) < 2f && Mathf.Abs(cy) < 9f)
                        sigil += 0.18f;

                    pixels[y * width + x] = Color.Lerp(row, accent, Mathf.Clamp01(stripe + glow + sigil));
                }
            }

            texture.SetPixels(pixels);
            texture.Apply();
            return Sprite.Create(
                texture,
                new Rect(0f, 0f, width, height),
                new Vector2(0.5f, 0.5f),
                100f);
        }

        private static Sprite BackTexture()
        {
            const int width = 32;
            const int height = 48;
            var texture = new Texture2D(width, height, TextureFormat.RGBA32, false)
            {
                filterMode = FilterMode.Point,
                wrapMode = TextureWrapMode.Clamp,
            };

            var pixels = new Color[width * height];
            for (var y = 0; y < height; y++)
            {
                for (var x = 0; x < width; x++)
                {
                    var border = x == 0 || y == 0 || x == width - 1 || y == height - 1;
                    var diamond = (x + y) % 8 == 0 || (x - y + 64) % 8 == 0;
                    pixels[y * width + x] = border
                        ? new Color(0.42f, 0.56f, 0.82f)
                        : diamond
                            ? new Color(0.12f, 0.22f, 0.42f)
                            : new Color(0.05f, 0.09f, 0.17f);
                }
            }

            texture.SetPixels(pixels);
            texture.Apply();
            return Sprite.Create(
                texture,
                new Rect(0f, 0f, width, height),
                new Vector2(0.5f, 0.5f),
                100f);
        }
    }
}