/*
Crafter®.Graphics
Copyright (C) 2025 Catcrafts®
catcrafts.net

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License version 3.0 as published by the Free Software Foundation;

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
*/

module;
#define STB_IMAGE_IMPLEMENTATION
#include "../lib/stb_image.h"
export module Crafter.Graphics:RenderingElement;
import std;
import :Transform;
import :Types;
import :Image;
import :Window;

export namespace Crafter {
    struct RenderElementScalingOwning {
        std::vector<Pixel_BU8_GU8_RU8_AU8> scalingBuffer;
        std::uint_fast32_t bufferWidth;
        std::uint_fast32_t bufferHeight;
        bool bufferUpdated = true;
        RenderElementScalingOwning() = default;
        RenderElementScalingOwning(std::uint_fast32_t bufferWidth, std::uint_fast32_t bufferHeight) : scalingBuffer(bufferWidth*bufferHeight), bufferWidth(bufferWidth), bufferHeight(bufferHeight) {
            
        }
    };

    struct RenderElementScalingNonOwning {
        Pixel_BU8_GU8_RU8_AU8* scalingBuffer;
        std::uint_fast32_t bufferWidth;
        std::uint_fast32_t bufferHeight;
        bool bufferUpdated = true;
        RenderElementScalingNonOwning() = default;
        RenderElementScalingNonOwning(Pixel_BU8_GU8_RU8_AU8* scalingBuffer, std::uint_fast32_t bufferWidth, std::uint_fast32_t bufferHeight) : scalingBuffer(scalingBuffer), bufferWidth(bufferWidth), bufferHeight(bufferHeight) {
            
        }
    };

    struct RenderElementRotating {
        std::uint_fast32_t rotation;
        bool rotationUpdated = true;
        RenderElementRotating() = default;
        RenderElementRotating(std::uint_fast32_t rotation) : rotation(rotation) {

        }
    };


    struct EmptyScalingBase {};
    struct EmptyRotatingBase {};

    template<bool Scaling, bool Owning>
    using ScalingBase =
        std::conditional_t<
            Scaling,
            std::conditional_t<Owning,
                RenderElementScalingOwning,
                RenderElementScalingNonOwning>,
            EmptyScalingBase
        >;

    template<bool Rotating>
    using RotatingBase =
        std::conditional_t<
            Rotating,
            RenderElementRotating,
            EmptyRotatingBase
        >;

    class RenderingElementBase : public Transform  {
    public:
        std::vector<Pixel_BU8_GU8_RU8_AU8> buffer;
        OpaqueType opaque;
        RenderingElementBase(Anchor anchor) : Transform(anchor) {
            scaled.width = 0;
        }
        RenderingElementBase(Anchor anchor, OpaqueType opaque) : Transform(anchor), opaque(opaque) {
            scaled.width = 0;
        }
    };

    template<bool Scaling, bool Owning, bool Rotating> requires ((!Rotating || Scaling) && (!Owning || Scaling))
    class RenderingElement : public RenderingElementBase, public ScalingBase<Scaling, Owning>, public RotatingBase<Rotating> {
    public:        
        RenderingElement() = default;
        RenderingElement(Anchor anchor, OpaqueType opaque) : RenderingElementBase(anchor, opaque) {

        }
        RenderingElement(Anchor anchor, OpaqueType opaque, std::uint_fast32_t rotation) requires(Rotating) : RenderingElementBase(anchor, opaque), RotatingBase<Rotating>(rotation) {

        }

        RenderingElement(Anchor anchor, const std::string_view imagePath) : RenderingElementBase(anchor) {
            LoadImage(imagePath);
        }
        RenderingElement(Anchor anchor, const std::string_view imagePath, std::uint_fast32_t rotation) requires(Rotating) : RenderingElementBase(anchor), RotatingBase<Rotating>(rotation) {
            LoadImage(imagePath);
        }

        RenderingElement(Anchor anchor, const std::string_view imagePath, OpaqueType opaque) : RenderingElementBase(anchor, opaque) {
            LoadImageNoOpaqueCheck(imagePath);
        }
        RenderingElement(Anchor anchor, const std::string_view imagePath, OpaqueType opaque, std::uint_fast32_t rotation) requires(Rotating) : RenderingElementBase(anchor, opaque), RotatingBase<Rotating>(rotation) {
            LoadImageNoOpaqueCheck(imagePath);
        }

        RenderingElement(Anchor anchor, OpaqueType opaque, std::uint_fast32_t bufferWidth, std::uint_fast32_t bufferHeight, Pixel_BU8_GU8_RU8_AU8* scalingBuffer) requires(Scaling && !Owning) : RenderingElementBase(anchor, opaque), ScalingBase<Scaling, Owning>(bufferWidth, bufferHeight, scalingBuffer) {

        }
        RenderingElement(Anchor anchor, OpaqueType opaque, std::uint_fast32_t bufferWidth, std::uint_fast32_t bufferHeight, Pixel_BU8_GU8_RU8_AU8* scalingBuffer, std::uint_fast32_t rotation) requires(Scaling && !Owning && Rotating) : RenderingElementBase(anchor, opaque), ScalingBase<Scaling, Owning>(bufferWidth, bufferHeight, scalingBuffer), RotatingBase<Rotating>(rotation) {

        }

        RenderingElement(Anchor anchor, OpaqueType opaque, Image& image) requires(Scaling && !Owning) : RenderingElementBase(anchor, opaque), ScalingBase<Scaling, Owning>(image.buffer.data(), image.width, image.height) {

        }
        RenderingElement(Anchor anchor, OpaqueType opaque, Image& image, std::uint_fast32_t rotation) requires(Scaling && !Owning && Rotating) : RenderingElementBase(anchor, opaque), ScalingBase<Scaling, Owning>(image.buffer.data(), image.width, image.height), RotatingBase<Rotating>(rotation) {

        }

        RenderingElement(Anchor anchor, Image& image) requires(Scaling && !Owning) : RenderingElementBase(anchor, image.opaque), ScalingBase<Scaling, Owning>(image.buffer.data(), image.width, image.height) {

        }
        RenderingElement(Anchor anchor, Image& image, std::uint_fast32_t rotation) requires(Scaling && !Owning && Rotating) : RenderingElementBase(anchor, image.opaque), ScalingBase<Scaling, Owning>(image.buffer.data(), image.width, image.height), RotatingBase<Rotating>(rotation) {

        }

        RenderingElement(Anchor anchor, OpaqueType opaque, std::uint_fast32_t bufferWidth, std::uint_fast32_t bufferHeight) requires(Owning) : RenderingElementBase(anchor, opaque), ScalingBase<Scaling, Owning>(bufferWidth, bufferHeight) {

        }
        RenderingElement(Anchor anchor, OpaqueType opaque, std::uint_fast32_t bufferWidth, std::uint_fast32_t bufferHeight, std::uint_fast32_t rotation) requires(Owning && Rotating) : RenderingElementBase(anchor, opaque), ScalingBase<Scaling, Owning>(bufferWidth, bufferHeight) , RotatingBase<Rotating>(rotation) {

        }

        RenderingElement(RenderingElement&) = delete;
        RenderingElement& operator=(RenderingElement&) = delete;

        void ScaleNearestNeighbor() requires(Scaling) {
            for (std::uint_fast32_t y = 0; y < scaled.height; y++) {
                std::uint_fast32_t srcY = y * ScalingBase<true, Owning>::bufferHeight / scaled.height;
                for (std::uint_fast32_t x = 0; x < scaled.width; x++) {
                    std::uint_fast32_t srcX = x * ScalingBase<true, Owning>::bufferWidth / scaled.width;
                    buffer[y * scaled.width + x] = ScalingBase<true, Owning>::scalingBuffer[srcY * ScalingBase<true, Owning>::bufferWidth + srcX];
                }
            }
        }

        void ScaleRotating() requires(Scaling) {
            const double rad = (static_cast<double>(RotatingBase<true>::rotation) / static_cast<double>(std::numeric_limits<std::uint_fast32_t>::max())) * 2.0 * std::numbers::pi;

            const std::uint_fast32_t dstWidth  = scaled.width;
            const std::uint_fast32_t dstHeight = scaled.height;

            const double c2 = std::abs(std::cos(rad));
            const double s2 = std::abs(std::sin(rad));

            const double rotatedWidth  = dstWidth  * c2 + dstHeight * s2;
            const double rotatedHeight = dstWidth  * s2 + dstHeight * c2;

            const std::uint_fast32_t diffX = static_cast<std::uint_fast32_t>(std::ceil((rotatedWidth  - dstWidth)  * 0.5));
            const std::uint_fast32_t diffY = static_cast<std::uint_fast32_t>(std::ceil((rotatedHeight - dstHeight) * 0.5));

            scaled.width += diffX + diffX;
            scaled.height += diffY + diffY;

            scaled.x -= diffX;
            scaled.y -= diffY;

            buffer.clear();
            buffer.resize(scaled.width * scaled.height);

            // Destination center
            const double dstCx = (static_cast<double>(scaled.width)  - 1.0) * 0.5;
            const double dstCy = (static_cast<double>(scaled.height) - 1.0) * 0.5;

            // Source center
            const double srcCx = (static_cast<double>(ScalingBase<true, Owning>::bufferWidth)  - 1.0) * 0.5;
            const double srcCy = (static_cast<double>(ScalingBase<true, Owning>::bufferHeight) - 1.0) * 0.5;

            const double c = std::cos(rad);
            const double s = std::sin(rad);

            // Scale factors (destination → source)
            const double scaleX = static_cast<double>(ScalingBase<true, Owning>::bufferWidth)  / dstWidth;
            const double scaleY = static_cast<double>(ScalingBase<true, Owning>::bufferHeight) / dstHeight;

            for (std::uint_fast32_t yB = 0; yB < scaled.height; ++yB) {
                for (std::uint_fast32_t xB = 0; xB < scaled.width; ++xB) {

                    // ---- Destination pixel relative to center ----
                    const double dx = (static_cast<double>(xB) - dstCx) * scaleX;
                    const double dy = (static_cast<double>(yB) - dstCy) * scaleY;

                    // ---- Inverse rotation ----
                    const double sx =  (c * dx - s * dy) + srcCx;
                    const double sy =  (s * dx + c * dy) + srcCy;

                    // ---- Nearest neighbour sampling ----
                    const std::int_fast32_t srcX = static_cast<std::int_fast32_t>(std::round(sx));
                    const std::int_fast32_t srcY = static_cast<std::int_fast32_t>(std::round(sy));

                    if (srcX >= 0 && srcX < ScalingBase<true, Owning>::bufferWidth && srcY >= 0 && srcY < ScalingBase<true, Owning>::bufferHeight) {
                        buffer[yB * scaled.width + xB] = ScalingBase<true, Owning>::scalingBuffer[srcY * ScalingBase<true, Owning>::bufferWidth + srcX];
                    }
                }
            }
        }
        
        void UpdatePosition(Window& window, ScaleData oldScale) {
            if constexpr(Scaling && !Rotating) {
                if(oldScale.width != scaled.width || oldScale.height != scaled.height) {
                    buffer.resize(scaled.width * scaled.height);
                    ScaleNearestNeighbor();
                    window.AddDirtyRect(oldScale);
                    window.AddDirtyRect(scaled);
                } else if(oldScale.x != scaled.x || oldScale.y != scaled.y) {
                    window.AddDirtyRect(oldScale);
                    window.AddDirtyRect(scaled);
                    if(ScalingBase<true, Owning>::bufferUpdated) {
                        ScaleNearestNeighbor();
                        ScalingBase<true, Owning>::bufferUpdated = false;
                    }
                } else if(ScalingBase<true, Owning>::bufferUpdated) {
                    ScaleNearestNeighbor();
                    ScalingBase<true, Owning>::bufferUpdated = false;
                }
            } else if constexpr(Rotating) {
                if(oldScale.width != scaled.width || oldScale.height != scaled.height) {
                    buffer.resize(scaled.width * scaled.height);
                    ScaleNearestNeighbor();
                    window.AddDirtyRect(oldScale);
                    window.AddDirtyRect(scaled);
                } else if(oldScale.x != scaled.x || oldScale.y != scaled.y) {
                    window.AddDirtyRect(oldScale);
                    window.AddDirtyRect(scaled);
                    if(ScalingBase<true, Owning>::bufferUpdated) {
                        ScaleRotating();
                        ScalingBase<true, Owning>::bufferUpdated = false;
                        RotatingBase<true>::rotationUpdated = false;
                    }
                } else if(ScalingBase<true, Owning>::bufferUpdated || RotatingBase<true>::rotationUpdated) {
                    ScaleRotating();
                    ScalingBase<true, Owning>::bufferUpdated = false;
                    RotatingBase<true>::rotationUpdated = false;
                }
            } else {
                if(oldScale.width != scaled.width || oldScale.height != scaled.height) {
                    buffer.resize(scaled.width * scaled.height);
                    window.AddDirtyRect(oldScale);
                    window.AddDirtyRect(scaled);
                }
                if(oldScale.x != scaled.x || oldScale.y != scaled.y) {
                    window.AddDirtyRect(oldScale);
                    window.AddDirtyRect(scaled);
                }
            }
        }

        void UpdatePosition(Window& window) override {
            ScaleData oldScale = scaled;
            window.ScaleElement(*this);
            UpdatePosition(window, oldScale);
            for(Transform* child : children) {
                child->UpdatePosition(window, *this);
            }
        }

        void UpdatePosition(Window& window, Transform& parent) override {
            ScaleData oldScale = scaled;
            window.ScaleElement(*this, parent);
            UpdatePosition(window, oldScale);
            for(Transform* child : children) {
                child->UpdatePosition(window, *this);
            }
}

        void LoadImage(const std::string_view imagePath) {
            std::filesystem::path abs = std::filesystem::absolute(imagePath);
            int xSize;
            int ySize;
            unsigned char* bgData = stbi_load(abs.string().c_str(), &xSize, &ySize, nullptr, 4);

            if constexpr(Scaling && !Owning) {
                ScalingBase<true, false>::bufferUpdated = true;
            } else if constexpr(Scaling && Owning) {
                ScalingBase<true, true>::bufferWidth = xSize;
                ScalingBase<true, true>::bufferHeight = ySize;
                ScalingBase<true, true>::bufferUpdated = true;
                ScalingBase<true, Owning>::scalingBuffer.resize(xSize*ySize);
            } else {
                buffer.resize(xSize*ySize);
            }

            opaque = OpaqueType::FullyOpaque;

            if constexpr(Scaling) {
                for(std::uint_fast32_t x = 0; x < xSize; x++) {
                    for(std::uint_fast32_t y = 0; y < ySize; y++) {
                        std::uint_fast32_t idx = (x*ySize+y)*4;
                        ScalingBase<true, Owning>::scalingBuffer[x*ySize+y].r = bgData[idx];
                        ScalingBase<true, Owning>::scalingBuffer[x*ySize+y].g = bgData[idx+1];
                        ScalingBase<true, Owning>::scalingBuffer[x*ySize+y].b = bgData[idx+2];
                        ScalingBase<true, Owning>::scalingBuffer[x*ySize+y].a = bgData[idx+3];
                    }
                }

                for(std::uint_fast32_t i = 0; i < xSize*ySize; i++) {
                    if(ScalingBase<true, Owning>::scalingBuffer[i].a != 255) {
                        opaque = OpaqueType::SemiOpaque;
                        for(std::uint_fast32_t i2 = 0; i2 < xSize*ySize; i2++) {
                            if(ScalingBase<true, Owning>::scalingBuffer[i2].a != 0 && ScalingBase<true, Owning>::scalingBuffer[i2].a != 255) {
                                opaque = OpaqueType::Transparent;
                                return;
                            }
                        }
                        return;
                    }
                }
            } else {
                for(std::uint_fast32_t x = 0; x < xSize; x++) {
                    for(std::uint_fast32_t y = 0; y < ySize; y++) {
                        std::uint_fast32_t idx = (x*ySize+y)*4;
                        buffer[x*ySize+y].r = bgData[idx];
                        buffer[x*ySize+y].g = bgData[idx+1];
                        buffer[x*ySize+y].b = bgData[idx+2];
                        buffer[x*ySize+y].a = bgData[idx+3];
                    }
                }

                for(std::uint_fast32_t i = 0; i < xSize*ySize; i++) {
                    if(buffer[i].a != 255) {
                        opaque = OpaqueType::SemiOpaque;
                        for(std::uint_fast32_t i2 = 0; i2 < xSize*ySize; i2++) {
                            if(buffer[i2].a != 0 && buffer[i2].a != 255) {
                                opaque = OpaqueType::Transparent;
                                return;
                            }
                        }
                        return;
                    }
                }
            }
        }
        void LoadImageNoOpaqueCheck(const std::string_view imagePath) {
            std::filesystem::path abs = std::filesystem::absolute(imagePath);
            int xSize;
            int ySize;
            unsigned char* bgData = stbi_load(abs.string().c_str(), &xSize, &ySize, nullptr, 4);


            if constexpr(Scaling && !Owning) {
                ScalingBase<true, false>::bufferUpdated = true;
            } else if constexpr(Scaling && Owning) {
                ScalingBase<true, true>::bufferWidth = xSize;
                ScalingBase<true, true>::bufferHeight = ySize;
                ScalingBase<true, true>::bufferUpdated = true;
                ScalingBase<true, Owning>::scalingBuffer.resize(xSize*ySize);
            } else {
                buffer.resize(xSize*ySize);
            }


            if constexpr(Scaling) {
                for(std::uint_fast32_t x = 0; x < xSize; x++) {
                    for(std::uint_fast32_t y = 0; y < ySize; y++) {
                        std::uint_fast32_t idx = (x*ySize+y)*4;
                        ScalingBase<true, Owning>::scalingBuffer[x*ySize+y].r = bgData[idx];
                        ScalingBase<true, Owning>::scalingBuffer[x*ySize+y].g = bgData[idx+1];
                        ScalingBase<true, Owning>::scalingBuffer[x*ySize+y].b = bgData[idx+2];
                        ScalingBase<true, Owning>::scalingBuffer[x*ySize+y].a = bgData[idx+3];
                    }
                }
            } else {
                for(std::uint_fast32_t x = 0; x < xSize; x++) {
                    for(std::uint_fast32_t y = 0; y < ySize; y++) {
                        std::uint_fast32_t idx = (x*ySize+y)*4;
                        buffer[x*ySize+y].r = bgData[idx];
                        buffer[x*ySize+y].g = bgData[idx+1];
                        buffer[x*ySize+y].b = bgData[idx+2];
                        buffer[x*ySize+y].a = bgData[idx+3];
                    }
                }
            }
        }
    };
}