#include "SharedMemoryAccess.hpp"
#include "internal.hpp"
#include "vkvm.hpp"

#include <csignal>
#include <unistd.h>

namespace vkvm {

    auto initialize(int pid) -> void {
        impl.sharedMemoryPid = pid;
        impl.sharedMemoryKey = 12345;
        impl.sharedMemorySize = 8000;
        initSemaphore();
        setDefaultValues();
    }

    auto setDefaultValues() -> void {
        impl.localMemoryWarn = false;
        if(getSharedMemory() != nullptr) {
            //set default values
            setMode(GraphicMode::RGB);
            setCharactersPerRow(60);
            setCharactersPerColumn(20);
            setHeight(600);
            setWidth(800);
            setMousePosition(42, 42);
            setBackgroundColor(black);
            setForegroundColor(white);
            setRedrawInterval(20);
            setTimerInterruptInterval(10);
            setFont(FontType(3,"",0,0));
        }
        impl.localMemoryWarn = true;
    }

    auto registerEvent(EventType type, const std::function<void()> &handler) -> bool {
        int signum = SIGUSR1 + impl.eventTable.size();
        auto ivt = getInterruptTable();

        lockSharedMemory();

        for(int i = 0; i < impl.interruptEntrysPerEventType;i++){
            auto &entry= ivt[type * impl.interruptEntrysPerEventType + i];
            if (entry.pid == 0) {

                entry.pid = getpid();
                entry.signum = signum;
                impl.eventTable.push_back(handler);

                onSignal(signum, [](int sig){
                    if(sig >= SIGUSR1){
                        if((sig - SIGUSR1) < impl.eventTable.size()){
                            impl.eventTable[sig - SIGUSR1]();
                        }
                    }
                });
                unlockSharedMemory();
                return true;
            }
        }
        unlockSharedMemory();
        return false;
    }

    auto setPixel(int x, int y, Color color) -> bool {
        if(x > getWidth() || y > getHeight()) {
            return false;
        }
        lockSharedMemory();
        auto reg = getRegisters();
        const int bitsPerPixel = 8;

        switch(reg->graphicMode) {
            case Text: {
                int pixelIndex = (y * getWidth() + x);
                unsigned char *ptr = reinterpret_cast<unsigned char *>(getPixelArea()) + (pixelIndex / bitsPerPixel);
                if(color == reg->foreground_color){
                    //set bit to 1
                    ptr[0] |= (1 << (pixelIndex % bitsPerPixel));
                }
                else{
                    //set bit to 0
                    ptr[0] &= ~(1 << (pixelIndex % bitsPerPixel));
                }
                break;
            }
            case TwoColors: {
                int pixelIndex = (y * getWidth() + x);
                unsigned char *ptr = reinterpret_cast<unsigned char *>(getPixelArea()) + (pixelIndex / bitsPerPixel);
                if(color == reg->foreground_color){
                    //set bit to 1
                    ptr[0] |= (1 << (pixelIndex % bitsPerPixel));
                }
                else{
                    //set bit to 0
                    ptr[0] &= ~(1 << (pixelIndex % bitsPerPixel));
                }
                break;
            }
            case Gray_256: {
                unsigned char *ptr = reinterpret_cast<unsigned char *>(getPixelArea()) + (y * getWidth() + x);
                int avg = color.getRed() + color.getGreen() + color.getBlue();
                avg /= 3;
                ptr[0] = avg;
                break;
            }
            case RGB: {
                unsigned char *ptr = reinterpret_cast<unsigned char *>(getPixelArea()) + (y * getWidth() + x) * 3;
                ptr[0] = color.getRed();
                ptr[1] = color.getGreen();
                ptr[2] = color.getBlue();
                break;
            }
        }
        unlockSharedMemory();
        return true;
    }

    auto getPixel(int x, int y) -> Color {
        if(x > getWidth() || y > getHeight()) {
            return getBackgroundColor();
        }

        Color color = Color(0,0,0);
        auto reg = getRegisters();
        const int bitsPerPixel = 8;

        switch(reg->graphicMode) {
            case Text: {
                int pixelIndex = (y * getWidth() + x);
                unsigned char *ptr = reinterpret_cast<unsigned char *>(getPixelArea()) + pixelIndex / bitsPerPixel;
                bool bit = static_cast<bool>(ptr[0] & (1 << (pixelIndex % bitsPerPixel)));
                if(bit){
                    color = reg->foreground_color;
                }else{
                    color =reg->background_color;
                }
                break;
            }
            case TwoColors: {
                int pixelIndex = (y * getWidth() + x);
                unsigned char *ptr = reinterpret_cast<unsigned char *>(getPixelArea()) + (pixelIndex / bitsPerPixel);
                bool bit = static_cast<bool>(ptr[0] & (1 << (pixelIndex % bitsPerPixel)));
                if(bit){
                    color = reg->foreground_color;
                }else{
                    color =reg->background_color;
                }
                break;
            }
            case Gray_256: {
                unsigned char *ptr = reinterpret_cast<unsigned char *>(getPixelArea()) + (y * getWidth() + x) * 1;
                color = {ptr[0], ptr[0], ptr[0]};
                break;
            }
            case RGB: {
                unsigned char *ptr = reinterpret_cast<unsigned char *>(getPixelArea()) + (y * getWidth() + x) * 3;
                color = {ptr[0], ptr[1], ptr[2]};
                break;
            }
        }
        return color;
    }

    auto setText(std::string text) -> bool {
        lockSharedMemory();
        char *ptr = getTextArea();
        for(int i = 0; i < static_cast<int>(text.size());i++){
            if(i >= getCharactersPerColumn() * getCharactersPerRow()){
                break;
            }
            ptr[i] = text[i];
        }
        if(text.size() < getCharactersPerColumn() * getCharactersPerRow()){
            ptr[text.size()] = '\0';
        }
        unlockSharedMemory();
        return true;
    }

    auto getText() -> std::string {
        return std::string (getTextArea());
    }

    auto getLayoutVersion() -> LayoutVersion {
        return static_cast<LayoutVersion>(getRegisters()->layout_version);
    }

    auto reset() -> void {
        //TODO(julian): reset
    }

    auto getWidth() -> int {
        return getRegisters()->width_pixels;
    }

    auto setWidth(int newValue) -> void {
        lockSharedMemory();
        getRegisters()->width_pixels = newValue;
        unlockSharedMemory();
    }

    auto getHeight() -> int {
        return getRegisters()->height_pixels;
    }

    auto setHeight(int newValue) -> void {
        lockSharedMemory();
        getRegisters()->height_pixels = newValue;
        unlockSharedMemory();
    }

    auto getMode() -> GraphicMode {
        return getRegisters()->graphicMode;
    }

    auto setMode(GraphicMode newValue) -> void {
        lockSharedMemory();
        auto reg = getRegisters();
        if(reg->graphicMode != newValue){

            std::vector<Color> pixels;
            int height = reg->height_pixels;
            int width = reg->width_pixels;
            pixels.resize(height * width);

            for(int y = 0; y < height;y++){
                for(int x = 0;x < width;x++){
                    pixels[y * width + x] = getPixel(x,y);
                }
            }

            getRegisters()->graphicMode = newValue;

            unlockSharedMemory();
            for(int y = 0; y < height;y++){
                for(int x = 0;x < width;x++){
                    setPixel(x,y, pixels[y * width + x]);
                }
            }
            lockSharedMemory();
        }else{
            reg->graphicMode = newValue;
        }
        unlockSharedMemory();
    }

    auto getRedrawInterval() -> int {
        return getRegisters()->autoRedrawInterval;
    }

    auto setRedrawInterval(int newValue) -> void {
        lockSharedMemory();
        getRegisters()->autoRedrawInterval = newValue;
        unlockSharedMemory();
    }

    auto getTimerInterruptInterval() -> int {
        return getRegisters()->timerInterruptInterval;
    }

    auto setTimerInterruptInterval(int newValue) -> void {
        lockSharedMemory();
        getRegisters()->timerInterruptInterval = newValue;
        unlockSharedMemory();
    }

    auto getBackgroundColor() -> Color {
        return getRegisters()->background_color;
    }

    auto setBackgroundColor(const Color &newValue) -> void {
        lockSharedMemory();
        getRegisters()->background_color = newValue;
        unlockSharedMemory();
    }

    auto getForegroundColor() -> Color {
        return getRegisters()->foreground_color;
    }

    auto setForegroundColor(const Color &newValue) -> void {
        lockSharedMemory();
        getRegisters()->foreground_color = newValue;
        unlockSharedMemory();
    }

    auto getCharactersPerRow() -> int {
        return getRegisters()->characters_per_row;
    }

    auto getCharactersPerColumn() -> int {
        return getRegisters()->characters_per_column;
    }

    auto getFont() -> FontType {
        //TODO(julian): get font properly
        return {getRegisters()->textMode_font, "", 0, 0};
    }

    auto setFont(const FontType &newValue) -> void {
        //TODO(julian): setFont properly
        lockSharedMemory();
        getRegisters()->textMode_font = newValue.getId();
        unlockSharedMemory();
    }

    auto getMousePosition() -> Coordinates {
        return {getRegisters()->mouse_pos_x, getRegisters()->mouse_pos_y};
    }

    auto getLastPressedKey() -> KeyCode {
        lockSharedMemory();
        auto keyCode = KeyCode(0);
        auto reg = getRegisters();
        if(reg->keyboardBuffer_index_read != reg->keyboardBuffer_index_write) {
            keyCode = static_cast<KeyCode>(reg->keyboardBuffer[reg->keyboardBuffer_index_read++]);
            if (reg->keyboardBuffer_index_read >= sizeof(reg->keyboardBuffer)) {
                reg->keyboardBuffer_index_read = 0;
            }
        }
        unlockSharedMemory();
        return keyCode;
    }

}