#include <stdint.h>
#include <stdbool.h>
#include <malloc.h>

#include <coreinit/screen.h>
#include <coreinit/cache.h>
#include <vpad/input.h>
#include <whb/proc.h>

void quit(void);
void welcome(OSScreenID screen);
void drawScreen(OSScreenID screen, VPADTouchData gamepad, int color);

int main(int argc, char **argv)
{
    // initialize ProcUI and OSScreen
    WHBProcInit();
    OSScreenInit();

    // allocate memory to render both displays and align them
    size_t tvBufferSize = OSScreenGetBufferSizeEx(SCREEN_TV);
    size_t drcBufferSize = OSScreenGetBufferSizeEx(SCREEN_DRC);
    void *tvBuffer = memalign(0x100, tvBufferSize);
    void *drcBuffer = memalign(0x100, drcBufferSize);

    // free used video memory and deinitialize OSScreen and ProcUI
    void quit(void)
    {
        if (tvBuffer)
            free(tvBuffer);
        if (drcBuffer)
            free(drcBuffer);
        OSScreenShutdown();
        WHBProcShutdown();
    };

    // check if memory allocation was successful otherwise kill program
    if (!tvBuffer || !drcBuffer)
    {
        quit();
        return 1;
    }

    // tell the screens where the allocated memory is
    OSScreenSetBufferEx(SCREEN_TV, tvBuffer);
    OSScreenSetBufferEx(SCREEN_DRC, drcBuffer);

    // enable control of the displays
    OSScreenEnableEx(SCREEN_TV, true);
    OSScreenEnableEx(SCREEN_DRC, true);

    VPADStatus status;
    VPADReadError error;
    VPADTouchData gamepadTouchScreen;

    bool vpad_fatal = false;
    uint32_t penColor = 0xFFFFFF00;

    // welcome message
    void welcome(OSScreenID screen)
    {
        OSScreenPutFontEx(screen, 0, 0, "Welcome to SimpleDrawU!");
        OSScreenPutFontEx(screen, 0, 1, "A is red.");
        OSScreenPutFontEx(screen, 0, 2, "B is yellow.");
        OSScreenPutFontEx(screen, 0, 3, "X is blue.");
        OSScreenPutFontEx(screen, 0, 4, "Y is green.");
        OSScreenPutFontEx(screen, 0, 5, "Plus is white.");
        OSScreenPutFontEx(screen, 0, 6, "Minus is black (erase).");
        OSScreenPutFontEx(screen, 0, 7, "Press both Plus and Minus");
        OSScreenPutFontEx(screen, 0, 8, "to clear the screen, enjoy!");
    }
    welcome(SCREEN_TV);
    welcome(SCREEN_DRC);

    // define color palette
    enum penColor
    {
        white = 0xFFFFFF00,
        black = 0x00000000,
        red = 0xBF5B5B00,
        yellow = 0xC6B95500,
        blue = 0x3C8D8800,
        green = 0x86B46000,
    };

    // draw pixels to screen
    void drawScreen(OSScreenID screen, VPADTouchData gamepad, int color)
    {
        OSScreenPutPixelEx(screen, gamepad.x - 1, gamepad.y - 1, color);
        OSScreenPutPixelEx(screen, gamepad.x + 1, gamepad.y + 1, color);
        OSScreenPutPixelEx(screen, gamepad.x + 1, gamepad.y, color);
        OSScreenPutPixelEx(screen, gamepad.x - 1, gamepad.y, color);
        OSScreenPutPixelEx(screen, gamepad.x, gamepad.y, color);
        OSScreenPutPixelEx(screen, gamepad.x, gamepad.y + 1, color);
        OSScreenPutPixelEx(screen, gamepad.x, gamepad.y - 1, color);
        OSScreenPutPixelEx(screen, gamepad.x - 1, gamepad.y + 1, color);
        OSScreenPutPixelEx(screen, gamepad.x + 1, gamepad.y - 1, color);
    };

    // while ProcUI is running
    while (WHBProcIsRunning())
    {
        // read gamepad inputs and check if error
        VPADRead(VPAD_CHAN_0, &status, 1, &error);
        switch (error)
        {
        case VPAD_READ_SUCCESS:
        {
            VPADGetTPCalibratedPoint(VPAD_CHAN_0, &gamepadTouchScreen, &status.tpNormal);
            break;
        }
        case VPAD_READ_NO_SAMPLES:
        {
            continue;
        }
        case VPAD_READ_INVALID_CONTROLLER:
        {
            vpad_fatal = true;
            break;
        }
        default:
        {
            vpad_fatal = true;
            break;
        }
        }
        if (vpad_fatal)
            break;

        // clear screen
        if ((status.hold & VPAD_BUTTON_PLUS) && (status.hold & VPAD_BUTTON_MINUS))
        {
            OSScreenClearBufferEx(SCREEN_TV, black);
            OSScreenClearBufferEx(SCREEN_DRC, black);
        }

        // select color
        if (status.hold & VPAD_BUTTON_PLUS)
        {
            penColor = white;
        }
        if (status.hold & VPAD_BUTTON_MINUS)
        {
            penColor = black;
        }
        if (status.hold & VPAD_BUTTON_A)
        {
            penColor = red;
        }
        if (status.hold & VPAD_BUTTON_B)
        {
            penColor = yellow;
        }
        if (status.hold & VPAD_BUTTON_X)
        {
            penColor = blue;
        }
        if (status.hold & VPAD_BUTTON_Y)
        {
            penColor = green;
        }

        // draw on screen
        if (gamepadTouchScreen.touched)
        {
            drawScreen(SCREEN_TV, gamepadTouchScreen, penColor);
            drawScreen(SCREEN_DRC, gamepadTouchScreen, penColor);
        }

        // commit drawing to the screen
        DCFlushRange(tvBuffer, tvBufferSize);
        DCFlushRange(drcBuffer, drcBufferSize);
        OSScreenFlipBuffersEx(SCREEN_TV);
        OSScreenFlipBuffersEx(SCREEN_DRC);
    }

    quit();

    return 0;
}