#include "video.h"

static uint8_t *const video = (uint8_t *) 0xB8000;
static const int width = 80;
static const int height = 25;
static int currentX = 0;
static int currentY = 0;

int limitX[2] = {0, 80};
int limitY[2] = {0, 25};

void increment() {
    currentX++;
    if (currentX == limitX[1]) {
        currentY++;
        currentX = limitX[0];
        if (currentY >= limitY[1]) {
            scroll();
            currentY = limitY[1] - 1;
        }
    }
}

char checkIfEscapeSequence(const char *bufferAux) {
    if (*bufferAux == '\e') {
        bufferAux++;
        if (*bufferAux == '\f') {
            clear();
        }
        return 1;
    }
    return 0;
}

void scroll() {
    for (int i = limitY[0]; i < limitY[1] - 1; i++) {
        for (int j = limitX[0]; j < limitX[1]; j++) {
            *(video + i * width * 2 + j * 2) = *(video + (i + 1) * width * 2 + j * 2);
            *(video + i * width * 2 + j * 2 + 1) = *(video + (i + 1) * width * 2 + j * 2 + 1);
        }
    }
    for (int j = limitX[0]; j < limitX[1]; j++) {
        *(video + (limitY[1] - 1) * width * 2 + j * 2) = ' ';
    }
}

int printStringLen(int color, const char *string, int maxLen) {
    int i = 0;

    while (*string != '\0' && i <= maxLen) {
        if (*string == '\n') {
            new_line();
            string++;
            i++;
            continue;
        } else if (*string == '\b') {
            backspace();
            return i;
        } else if (checkIfEscapeSequence(string)) {
            return i;
        }

        *(video + currentY * width * 2 + currentX * 2) = *string++;
        *(video + currentY * width * 2 + currentX * 2 + 1) = color;
        increment();
        i++;
    }

    return i;
}

void backspace() {
    if (video + currentY * width * 2 + currentX * 2 > video) {
        currentX--;
        if (currentX < limitX[0]) {
            currentX = limitX[1];
            if (currentY > limitY[0])
                currentY--;
        }
    }
    *(video + currentY * width * 2 + currentX * 2) = ' ';
}

void new_line() {
    currentX = limitX[0];
    currentY++;
    if (currentY == limitY[1]) {
        scroll();
        currentY = limitY[1] - 1;
    }
}

void clear() {
    currentX = limitX[0];
    currentY = limitY[0];
    for (int i = limitY[0]; i < limitY[1]; i++) {
        for (int j = limitX[0]; j < limitX[1]; j++) {
            *(video + i * width * 2 + j * 2) = ' ';
        }
    }
}