using UnityEngine;

namespace Vanguard.Board3D
{
    /// <summary>Процедурная рубашка и запасное лицо карты без внешних ассетов.</summary>
    internal static class BoardTextures
    {
        private const int BackWidth = 256;
        private const int BackHeight = 356;

        private static Texture2D _back;
        private static Texture2D _white;

        public static Texture2D White
        {
            get
            {
                if (_white == null)
                {
                    _white = new Texture2D(2, 2, TextureFormat.RGBA32, false)
                    {
                        name = "Board White",
                        filterMode = FilterMode.Bilinear,
                        wrapMode = TextureWrapMode.Clamp,
                        hideFlags = HideFlags.DontSave,
                    };
                    _white.SetPixels(new[] { Color.white, Color.white, Color.white, Color.white });
                    _white.Apply(false, true);
                }

                return _white;
            }
        }

        public static Texture2D Back
        {
            get
            {
                if (_back != null)
                    return _back;

                _back = Resources.Load<Texture2D>("CardArt/vanguard_back");
                if (_back == null)
                    _back = BuildBack();
                return _back;
            }
        }

        public static Color AccentFor(string printingId)
        {
            var hash = 2166136261u;
            if (!string.IsNullOrEmpty(printingId))
            {
                foreach (var ch in printingId)
                {
                    hash ^= ch;
                    hash *= 16777619u;
                }
            }

            var hue = (hash % 360u) / 360f;
            return Color.HSVToRGB(hue, 0.42f, 0.62f);
        }

        private static Texture2D BuildBack()
        {
            var texture = new Texture2D(
                BackWidth,
                BackHeight,
                TextureFormat.RGBA32,
                false)
            {
                name = "Board Card Back",
                filterMode = FilterMode.Bilinear,
                wrapMode = TextureWrapMode.Clamp,
                hideFlags = HideFlags.DontSave,
            };

            var pixels = new Color[BackWidth * BackHeight];
            var dark = new Color(0.035f, 0.055f, 0.11f);
            var mid = new Color(0.10f, 0.18f, 0.36f);
            var edge = new Color(0.72f, 0.56f, 0.22f);

            for (var y = 0; y < BackHeight; y++)
            {
                for (var x = 0; x < BackWidth; x++)
                {
                    var u = (x + 0.5f) / BackWidth;
                    var v = (y + 0.5f) / BackHeight;
                    var border = Mathf.Min(
                        Mathf.Min(u, 1f - u) * BackWidth,
                        Mathf.Min(v, 1f - v) * BackHeight);

                    var color = Color.Lerp(dark, mid, v * 0.55f + u * 0.15f);
                    var diagonal = Mathf.Abs(((u + v) % 0.5f) - 0.25f);
                    if (diagonal < 0.018f)
                        color = Color.Lerp(color, mid, 0.45f);

                    var dx = Mathf.Abs(u - 0.5f) * BackWidth;
                    var dy = Mathf.Abs(v - 0.5f) * BackHeight;
                    if (dx + dy < 34f)
                        color = Color.Lerp(color, edge, 0.65f);

                    if (border < 4f)
                        color = edge;

                    pixels[(y * BackWidth) + x] = color;
                }
            }

            texture.SetPixels(pixels);
            texture.Apply(false, true);
            return texture;
        }
    }
}