using System;
using System.Globalization;
using UnityEngine;

namespace GeometryTD.CustomUtility
{
    public static class TowerIconComposeUtility
    {
        public static Sprite Compose(
            Sprite muzzleSprite,
            Color muzzleColor,
            Sprite bearingSprite,
            Color bearingColor,
            Sprite baseSprite,
            Color baseColor)
        {
            if (muzzleSprite == null || bearingSprite == null || baseSprite == null)
            {
                return null;
            }

            Sprite referenceSprite = muzzleSprite ?? bearingSprite ?? baseSprite;
            if (referenceSprite == null)
            {
                return null;
            }

            int width = Mathf.RoundToInt(referenceSprite.rect.width);
            int height = Mathf.RoundToInt(referenceSprite.rect.height);
            if (width <= 0 || height <= 0)
            {
                return null;
            }

            return ComposeWithRenderTexture(
                muzzleSprite,
                muzzleColor,
                bearingSprite,
                bearingColor,
                baseSprite,
                baseColor,
                width,
                height,
                referenceSprite);
        }

        public static string BuildCacheKey(
            long muzzleId,
            long bearingId,
            long baseId,
            Color muzzleColor,
            Color bearingColor,
            Color baseColor)
        {
            return string.Format(
                CultureInfo.InvariantCulture,
                "v2|{0}|{1}|{2}|{3}|{4}|{5}",
                muzzleId,
                bearingId,
                baseId,
                ToColorKey(muzzleColor),
                ToColorKey(bearingColor),
                ToColorKey(baseColor));
        }

        private static Sprite ComposeWithRenderTexture(
            Sprite muzzleSprite,
            Color muzzleColor,
            Sprite bearingSprite,
            Color bearingColor,
            Sprite baseSprite,
            Color baseColor,
            int width,
            int height,
            Sprite referenceSprite)
        {
            RenderTexture rt = RenderTexture.GetTemporary(width, height, 0, RenderTextureFormat.ARGB32);
            RenderTexture previous = RenderTexture.active;
            try
            {
                RenderTexture.active = rt;
                GL.PushMatrix();
                GL.LoadPixelMatrix(0f, width, 0f, height);
                GL.Clear(true, true, Color.clear);

                DrawSpriteToRenderTarget(baseSprite, baseColor, width, height);
                DrawSpriteToRenderTarget(bearingSprite, bearingColor, width, height);
                DrawSpriteToRenderTarget(muzzleSprite, muzzleColor, width, height);

                GL.PopMatrix();

                Texture2D composedTexture = new Texture2D(width, height, TextureFormat.RGBA32, false);
                composedTexture.ReadPixels(new Rect(0f, 0f, width, height), 0, 0);
                composedTexture.Apply(false, false);
                return CreateSprite(composedTexture, referenceSprite);
            }
            catch (Exception)
            {
                return null;
            }
            finally
            {
                RenderTexture.active = previous;
                RenderTexture.ReleaseTemporary(rt);
            }
        }

        private static void DrawSpriteToRenderTarget(Sprite sprite, Color color, int width, int height)
        {
            if (sprite == null || sprite.texture == null)
            {
                return;
            }

            Rect textureRect = sprite.textureRect;
            Texture texture = sprite.texture;
            Rect uvRect = new Rect(
                textureRect.x / texture.width,
                textureRect.y / texture.height,
                textureRect.width / texture.width,
                textureRect.height / texture.height);

            Graphics.DrawTexture(new Rect(0f, 0f, width, height), texture, uvRect, 0, 0, 0, 0, color);
        }

        private static Sprite CreateSprite(Texture2D texture, Sprite referenceSprite)
        {
            if (texture == null || referenceSprite == null)
            {
                return null;
            }

            float width = Mathf.Max(1f, referenceSprite.rect.width);
            float height = Mathf.Max(1f, referenceSprite.rect.height);
            Vector2 pivot = new Vector2(referenceSprite.pivot.x / width, referenceSprite.pivot.y / height);
            return Sprite.Create(texture, new Rect(0f, 0f, texture.width, texture.height), pivot, referenceSprite.pixelsPerUnit);
        }

        private static string ToColorKey(Color color)
        {
            Color32 c = color;
            return c.r.ToString("X2", CultureInfo.InvariantCulture) +
                   c.g.ToString("X2", CultureInfo.InvariantCulture) +
                   c.b.ToString("X2", CultureInfo.InvariantCulture) +
                   c.a.ToString("X2", CultureInfo.InvariantCulture);
        }
    }
}