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#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>

#include <kernel/tty.h>

#include "vga.h"

static const size_t VGA_WIDTH = 80;
static const size_t VGA_HEIGHT = 25;
static uint16_t* const VGA_MEMORY = (uint16_t*) 0xB8000;

static size_t terminal_row;
static size_t terminal_column;
static uint8_t terminal_color;
static uint16_t* terminal_buffer;

void terminal_initialize(void) {
	terminal_row = 0;
	terminal_column = 0;
	terminal_color = vga_entry_color(VGA_COLOR_GREEN, VGA_COLOR_BLACK);
	terminal_buffer = VGA_MEMORY;
	for (size_t y = 0; y < VGA_HEIGHT; y++) {
		for (size_t x = 0; x < VGA_WIDTH; x++) {
			const size_t index = y * VGA_WIDTH + x;
			terminal_buffer[index] = vga_entry(' ', terminal_color);
		}
	}
}

void terminal_setcolor(uint8_t color) {
	terminal_color = color;
}

void terminal_putentryat(unsigned char c, uint8_t color, size_t x, size_t y) {
	const size_t index = y * VGA_WIDTH + x;
	terminal_buffer[index] = vga_entry(c, color);
}

void terminal_scroll(void) {
	for(size_t y = 0; y < VGA_HEIGHT; y++) {
		for (size_t x = 0; x < VGA_WIDTH; x++) {
			terminal_buffer[y * VGA_WIDTH + x] = terminal_buffer[(y + 1) * VGA_WIDTH + x];
        }
    }
}

void terminal_update(void) {
	memmove(VGA_MEMORY, terminal_buffer);
}
void terminal_putchar(char c) {
	unsigned char uc = c;
	if (c == '\n') {
		terminal_row++;
		terminal_column = 0;
	}
	else {
		terminal_putentryat(uc, terminal_color, terminal_column, terminal_row);
		if (++terminal_column == VGA_WIDTH) {
			terminal_column = 0;
			if (++terminal_row == VGA_HEIGHT) {
			terminal_scroll();
		terminal_update();
			}
		}
	}
}

void terminal_write(const char* data, size_t size) {
	for (size_t i = 0; i < size; i++)
		terminal_putchar(data[i]);
}

void terminal_writestring(const char* data) {
	terminal_write(data, strlen(data));
}