#pragma once

#include <glm/glm.hpp>
#include <vulkan/vulkan_core.h>
#include <vector>
#include <string>
#include <set>


namespace gz::vk {
    /**
     * @brief Describes an area in the textureImage that is not in use
     */
    struct TextureImageArea {
        // topleft slot
        uint16_t x;
        uint16_t y;
        // in slots
        uint16_t width;
        uint16_t height;
        std::string toString() const;
    };
    /// strict weak ordering comparison, true if a < b
    inline auto freeAreaCmp = [](const TextureImageArea& a, const TextureImageArea& b) {
        // if a size < b size
        if (a.width * a.height < b.width * b.height) { return true; }
        if (a.width * a.height != b.width * b.height) { return false; }
        // if a size == b size, return true if a is toplefter
        if (a.x + a.y < b.x + b.y) { return true; }
        if (a.x + a.y != b.x + b.y) { return false; }
        // if both are same topleft return if a is lefter
        return a.x < b.x;
    };

    /// Defined in vulkan_instance.hpp
    class VulkanInstance;
    class TextureAtlas {
        public:
            /**
             * @brief Create a texture atlas
             * @details
             *  -# @ref VulkanInstance::registerCleanupCallback "register" @ref cleanup() "cleanup callback"
             *  -# @ref createImageResources "create texture image, view and sampler"
             *
             *  The textureImage will have the dimensions slotWidth * slotCountX, slotHeight * slotCountY
             */
            TextureAtlas(VulkanInstance& instance, uint16_t slotWidth, uint16_t slotHeight, uint16_t slotCountX, uint16_t slotCountY);
            /**
             * @brief Add a texture to the atlas
             * @param textureWidth Width in pixels
             * @param textureHeight Height in pixels
             * @returns The topleft and bottomright texture coordinates in the image of the atlas
             * @throws Exception when there is no space in the atlas to add the texture
             */
            std::pair<glm::vec2, glm::vec2> addTexture(uint8_t* pixels, uint16_t textureWidth, uint16_t textureHeight);
			const VkImageView& getTextureImageView() const { return textureImageView; }
			const VkSampler& getTextureSampler() const { return textureSampler; }

            std::string toString() const;

        private:
            VulkanInstance& vk;
            /**
             * @brief Destroy all vulkan objects owned by this object
             */
            void cleanup();
            void blitTextureOnImage(uint8_t* pixels, uint16_t slotX, uint16_t slotY, uint16_t textureWidth, uint16_t textureHeight);
            /**
             * @brief Create textureImage, textureImageView and textureSampler
             * @details
             *  the textureImage is created with missingTextureColor and then transitioned to SHADER_READ_ONLY_OPTIMAL layout.
             */
            void createImageResources();
            VkImage textureImage;
            VkDeviceMemory textureImageMemory;
            VkImageView textureImageView;
            VkSampler textureSampler;

            std::set<TextureImageArea, decltype(freeAreaCmp)> freeAreas;
            /**
             * @todo implement merge
             */
            void mergeFreeAreas();


            uint16_t slotWidth;
            uint16_t slotHeight;
            uint16_t slotCountX;
            uint16_t slotCountY;
    };
}  // namespace gz::vk