using FloodSWE.TileGraph;
using UnityEngine;

namespace FloodSWE.Streaming
{
    public static class HeightmapExtractor
    {
        public static HeightmapPacket CreatePacketFromHeights(int frameId, TileId tile, int resolution, float[] heights)
        {
            return HeightmapPacket.FromHeights(frameId, tile, resolution, heights);
        }

        public static HeightmapPacket CreateMockPacket(int frameId, TileId tile, int resolution, float timeSeconds, float baseHeight, float amplitude)
        {
            int sampleCount = resolution * resolution;
            float[] heights = new float[sampleCount];
            float invRes = 1.0f / Mathf.Max(1, resolution - 1);

            int index = 0;
            for (int y = 0; y < resolution; y++)
            {
                float fy = y * invRes;
                for (int x = 0; x < resolution; x++)
                {
                    float fx = x * invRes;
                    float wave = Mathf.Sin((fx + timeSeconds * 0.2f) * Mathf.PI * 2.0f) *
                                 Mathf.Cos((fy + timeSeconds * 0.15f) * Mathf.PI * 2.0f);
                    heights[index++] = baseHeight + (amplitude * wave);
                }
            }

            return HeightmapPacket.FromHeights(frameId, tile, resolution, heights);
        }

        public static bool TryExtractFromTexture2D(Texture2D texture, int frameId, TileId tile, out HeightmapPacket packet)
        {
            packet = default;

            if (texture == null)
            {
                return false;
            }

            if (!texture.isReadable)
            {
                Debug.LogWarning("HeightmapExtractor: texture is not readable.");
                return false;
            }

            int width = texture.width;
            int height = texture.height;
            if (width != height)
            {
                Debug.LogWarning("HeightmapExtractor: texture must be square.");
                return false;
            }

            Color[] pixels = texture.GetPixels();
            float[] heights = new float[pixels.Length];
            for (int i = 0; i < pixels.Length; i++)
            {
                heights[i] = pixels[i].r;
            }

            packet = HeightmapPacket.FromHeights(frameId, tile, width, heights);
            return true;
        }

        public static bool TryExtractFromRenderTexture(RenderTexture source, int frameId, TileId tile, out HeightmapPacket packet)
        {
            packet = default;

            if (source == null)
            {
                return false;
            }

            int width = source.width;
            int height = source.height;
            if (width != height)
            {
                Debug.LogWarning("HeightmapExtractor: render texture must be square.");
                return false;
            }

            RenderTexture previous = RenderTexture.active;
            RenderTexture.active = source;

            Texture2D temp = new Texture2D(width, height, TextureFormat.RFloat, false, true);
            temp.ReadPixels(new Rect(0, 0, width, height), 0, 0);
            temp.Apply(false, true);

            RenderTexture.active = previous;

            bool success = TryExtractFromTexture2D(temp, frameId, tile, out packet);
            Object.Destroy(temp);
            return success;
        }
    }
}