#include "ctype.h"
#include "kprintf.h"
#include "shell.h"
#include "string.h"
#include "sys/io.h"
#include "terminal.h"

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

static struct screen screens[TERM_COUNT];
struct screen *screen = &screens[0];

static inline uint8_t vga_entry_color(enum vga_color fg, enum vga_color bg)
{
	return fg | bg << 4;
}

static inline uint16_t vga_entry(unsigned char uc, uint8_t color)
{
	return (uint16_t)uc | (uint16_t)color << 8;
}

void terminal_initialize(void)
{
	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;
			TERM_BUF[index] = vga_entry(' ', VGA_COLOR_WHITE);
		}
	}
	for (int i = 0; i < TERM_COUNT; i++) {
		screens[i].row = 0;
		screens[i].column = 0;
		screens[i].color = vga_entry_color(VGA_COLOR_LIGHT_MAGENTA - i,
		                                   VGA_COLOR_BLACK);
		memcpy(screens[i].buffer, TERM_BUF, sizeof(screen->buffer));
	}
}

void terminal_set_screen(int pos)
{
	memcpy(screen->buffer, TERM_BUF, sizeof(screen->buffer));
	screen = &screens[pos];
	memcpy(TERM_BUF, screen->buffer, sizeof(screen->buffer));
	update_cursor();
	if (TERM_BUF[0] == vga_entry(' ', VGA_COLOR_WHITE))
		kprintf(0, PROMPT);
}

void terminal_setcolor(uint8_t color)
{
	screen->color = color;
}

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

static void terminal_scroll(void)
{
	screen->row--;
	for (size_t i = 0; i < VGA_WIDTH * (VGA_HEIGHT - 1); i++)
		TERM_BUF[i] = TERM_BUF[i + VGA_WIDTH];
	for (size_t i = 0; i < VGA_WIDTH; i++)
		terminal_putentryat(' ', VGA_COLOR_WHITE, i, VGA_HEIGHT - 1);
}

static void terminal_new_line(void)
{
	screen->column = 0;
	if (++screen->row == VGA_HEIGHT)
		terminal_scroll();
}

int terminal_putchar(char c)
{
	if (c == '\r')
		screen->column = 0;
	else if (c == '\n')
		terminal_new_line();
	if (!isprint(c))
		return 1;
	terminal_putentryat(c, screen->color, screen->column, screen->row);
	if (++screen->column == VGA_WIDTH)
		terminal_new_line();
	return 1;
}

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

int terminal_writestring(const char *data)
{
	size_t len = strlen(data);
	terminal_write(data, len);
	return len;
}

int terminal_writelong(long n)
{
	long div = 10;
	int rv = 0;
	if (n < 0) {
		rv += terminal_putchar('-');
		n *= -1;
	}
	div = 1;
	while (div <= n / 10)
		div *= 10;
	while (div > 0) {
		rv += terminal_putchar('0' + n / div % 10);
		div /= 10;
	}
	return rv;
}

void update_cursor(void)
{
	uint16_t pos = screen->row * VGA_WIDTH + screen->column;

	outb(0x3D4, 0x0F);
	outb(0x3D5, pos & 0xFF);
	outb(0x3D4, 0x0E);
	outb(0x3D5, (pos >> 8) & 0xFF);
}

void move_cursor(int direction)
{

	switch (direction) {
	case LEFT:
		if (screen->column) {
			screen->column--;
		} else if (screen->row) {
			screen->column = VGA_WIDTH - 1;
			screen->row--;
		}
		break;
	case RIGHT:
		if (screen->column < VGA_WIDTH - 1) {
			screen->column++;
		} else if (screen->row < VGA_HEIGHT - 1) {
			screen->column = 0;
			screen->row++;
		} else {
			terminal_new_line();
		}
		break;
	case UP:
		break;
	case DOWN:
		break;
	default:
		break;
	}

	uint16_t pos = screen->row * VGA_WIDTH + screen->column;

	outb(0x3D4, 0x0F);
	outb(0x3D5, pos & 0xFF);
	outb(0x3D4, 0x0E);
	outb(0x3D5, (pos >> 8) & 0xFF);
}

struct screen *get_screen(void)
{
	return screen;
}