#include <arch/irq.h>
#include <arch/ports.h>
#include <arch/serial.h>
#include <mango/libc/stdio.h>
#include <mango/machine/vm.h>
#include <mango/printk.h>

struct vga_console {
	uint16_t *vga_framebuffer;
	unsigned int vga_cursor_x, vga_cursor_y;
	unsigned int vga_screen_width, vga_screen_height;
	uint8_t vga_attrib;
};

static struct vga_console vga_con = {
	.vga_attrib = 0x0F,
	.vga_screen_width = 80,
	.vga_screen_height = 25,
	.vga_framebuffer = (uint16_t *)0xffffffff800b8000,
};

static void vga_console_clear(struct vga_console *con)
{
	size_t len = con->vga_screen_width * con->vga_screen_height;

	for (size_t i = 0; i < len; i++) {
		con->vga_framebuffer[i] = (uint16_t)con->vga_attrib << 8;
	}

	con->vga_cursor_x = 0;
	con->vga_cursor_y = 0;
}

static void vga_console_show_cursor(struct vga_console *con)
{
	size_t start = 0, end = 15;

	outportb(0x3D4, 0x0A);
	outportb(0x3D5, (inportb(0x3D5) & 0xC0) | start);

	outportb(0x3D4, 0x0B);
	outportb(0x3D5, (inportb(0x3D5) & 0xE0) | end);
}

static void vga_console_update_cursor(struct vga_console *con)
{
	uint16_t pos
		= con->vga_cursor_y * con->vga_screen_width + con->vga_cursor_x;

	outportb(0x3D4, 0x0F);
	outportb(0x3D5, (uint8_t)(pos & 0xFF));
	outportb(0x3D4, 0x0E);
	outportb(0x3D5, (uint8_t)((pos >> 8) & 0xFF));
}

static void vga_console_scroll(struct vga_console *con)
{
	uint16_t *src = &con->vga_framebuffer[con->vga_screen_width];
	uint16_t *dest = &con->vga_framebuffer[0];
	size_t len = (con->vga_screen_height - 1) * con->vga_screen_width
	           * sizeof *con->vga_framebuffer;

	memcpy(dest, src, len);

	dest = &con->vga_framebuffer
	                [(con->vga_screen_height - 1) * con->vga_screen_width];
	len = con->vga_screen_width;
	for (size_t i = 0; i < len; i++) {
		dest[i] = (uint16_t)con->vga_attrib << 8;
	}

	con->vga_cursor_x = 0;
	con->vga_cursor_y = con->vga_screen_height - 1;
}

static void vga_console_putc(struct vga_console *con, char c)
{
	switch (c) {
	case '\n':
		con->vga_cursor_x = 0;
		con->vga_cursor_y++;
		break;
	case '\r':
		con->vga_cursor_x = 0;
		break;
	default:
		con->vga_framebuffer
			[con->vga_cursor_y * con->vga_screen_width
		         + con->vga_cursor_x]
			= ((uint16_t)con->vga_attrib << 8) | c;
		con->vga_cursor_x++;
		break;
	}

	if (con->vga_cursor_x >= con->vga_screen_width) {
		con->vga_cursor_x = 0;
		con->vga_cursor_y++;
	}

	if (con->vga_cursor_y >= con->vga_screen_height) {
		vga_console_scroll(con);
	}
}

static void vgacon_write(struct console *con, const char *s, unsigned int len)
{
	for (unsigned int i = 0; i < len; i++) {
		vga_console_putc(&vga_con, s[i]);
	}

	vga_console_update_cursor(&vga_con);
}

static struct console vgacon = {
	.c_name = "vgacon",
	.c_flags = CON_BOOT,
	.c_write = vgacon_write,
	.c_lock = SPIN_LOCK_INIT,
};

void vgacon_init(void)
{
	vga_console_clear(&vga_con);
	vga_console_show_cursor(&vga_con);
	console_register(&vgacon);
}