//
// Created by selim on 8/22/23.
//

#ifndef NES_PPU_H
#define NES_PPU_H

#include "Cartridge.h"

#include <cstdint>
#include <memory>
#include <functional>

namespace nes {

    struct Pixel {
        uint8_t R = 0;
        uint8_t G = 0;
        uint8_t B = 0;
        uint8_t A = 0xFF;
    };

    class Ppu {
    public:
        static constexpr uint16_t SCREEN_WIDTH = 256;
        static constexpr uint16_t SCREEN_HEIGHT = 240;

        enum ControlAddress: uint16_t {
            Control     = 0x0000,
            Mask        = 0x0001,
            Status      = 0x0002,
            OamAddress  = 0x0003,
            OamData     = 0x0004,
            Scroll      = 0x0005,
            PpuAddress  = 0x0006,
            PpuData     = 0x0007
        };

        union StatusRegister {
            struct {
                uint8_t unused: 5;
                uint8_t spriteOverflow: 1;
                uint8_t spriteZeroHit: 1;
                uint8_t verticalBlank: 1;
            };
            uint8_t value;
        };

        union ControlRegister {
            struct {
                uint8_t nameTableX: 1;
                uint8_t nameTableY: 1;
                uint8_t incrementMode: 1;
                uint8_t patternSprite: 1;
                uint8_t patternBackground: 1;
                uint8_t spriteSize: 1;
                uint8_t slaveMode: 1;
                uint8_t enableNmi: 1;
            };
            uint8_t value;
        };

        union MaskRegister {
            struct {
                uint8_t grayscale: 1;
                uint8_t renderBackgroundLeft: 1;
                uint8_t renderSpritesLeft: 1;
                uint8_t renderBackground: 1;
                uint8_t renderSprites: 1;
                uint8_t enhanceRed: 1;
                uint8_t enhanceGreen: 1;
                uint8_t enhanceBlue: 1;
            };
            uint8_t value;
        };

        union LoopyRegister {
            struct {
                uint8_t coarseX : 5;
                uint8_t coarseY : 5;
                uint8_t nameTableX : 1;
                uint8_t nameTableY : 1;
                uint8_t fineY : 3;
                uint8_t unused : 1;
            };
            uint16_t value;
        };

    public:
        Ppu();
        bool tick();
        void write(uint16_t address, uint8_t value);
        uint8_t read(uint16_t address);
        void setPixel(uint16_t row, uint16_t column, Pixel pixel);
        void connect(std::shared_ptr<Cartridge> cartridge);

    public:
        std::function<void(const Pixel*)> onNewFrame;

    private:
        uint8_t internalRead(uint16_t address);
        void internalWrite(uint16_t address, uint8_t value);
        Pixel getColor(uint8_t palette, uint8_t pixel);

    private:
        int16_t _column;
        int16_t _scanline;
        StatusRegister _status;
        ControlRegister _control;
        MaskRegister _mask;

        LoopyRegister _vRamAddress;
        LoopyRegister _tRamAddress;
        bool _addressWriteInProgress;
        uint8_t _dataTemp;
        uint8_t _fineX;

    private:
        std::unique_ptr<uint8_t[]> _nameTable;
        std::unique_ptr<Pixel[]> _palette;
        std::unique_ptr<uint8_t[]> _paletteTable;

    private:
        std::unique_ptr<Pixel[]> _frameBuffer;
        std::shared_ptr<Cartridge> _cartridge;
    };

}

#endif //NES_PPU_H