#include <lib.h>
#include <comus/asm.h>
#include <comus/memory.h>
#include <comus/drivers/pci.h>
#include <comus/drivers/gpu/bochs.h>

#define INDEX 0x1CE
#define DATA 0x1CF

#define INDEX_ID 0
#define INDEX_XRES 1
#define INDEX_YRES 2
#define INDEX_BPP 3
#define INDEX_ENABLE 4
#define INDEX_BANK 5
#define INDEX_VIRT_WIDTH 6
#define INDEX_VIRT_HEIGHT 7
#define INDEX_X_OFFSET 8
#define INDEX_Y_OFFSET 9

#define DATA_DISP_DISABLE 0x00
#define DATA_DISP_ENABLE 0x01
#define DATA_LFB_ENABLE 0x40
#define DATA_NO_CLEAR_MEM 0x80

#define BOCHS_PCI_VENDOR 0x1234
#define BOCHS_PCI_DEVICE 0x1111

#define BOCHS_WIDTH 1024
#define BOCHS_HEIGHT 768
#define BOCHS_BIT_DEPTH 32

static volatile uint32_t *framebuffer;
static uint16_t width = BOCHS_WIDTH;
static uint16_t height = BOCHS_HEIGHT;
static uint8_t bit_depth = BOCHS_BIT_DEPTH;

static void write(uint16_t index, uint16_t data)
{
	outw(INDEX, index);
	outw(DATA, data);
}

static uint16_t read(uint16_t value)
{
	outw(INDEX, value);
	return inw(DATA);
}

static int is_available(void)
{
	return (read(INDEX_ID) == 0xB0C5);
}

static void set_mode(uint16_t width, uint16_t height, uint16_t bit_depth,
					 int lfb, int clear)
{
	write(INDEX_ENABLE, DATA_DISP_DISABLE);
	write(INDEX_XRES, width);
	write(INDEX_YRES, height);
	write(INDEX_BPP, bit_depth);
	write(INDEX_ENABLE, DATA_DISP_ENABLE | (lfb ? DATA_LFB_ENABLE : 0) |
							(clear ? 0 : DATA_NO_CLEAR_MEM));
}

int bochs_init(void)
{
	struct pci_device bochs = { 0 };
	bool found =
		pci_findby_id(&bochs, BOCHS_PCI_DEVICE, BOCHS_PCI_VENDOR, NULL);
	if (!found)
		return 1;

	set_mode(width, height, bit_depth, true, true);
	if (!is_available())
		return 1;

	uint32_t bar0 = pci_rcfg_d(bochs, PCI_BAR0_D);
	uint32_t *addr = (uint32_t *)(uintptr_t)bar0;
	framebuffer = kmapaddr(addr, NULL, width * height * bit_depth, F_WRITEABLE);

	return 0;
}

uint32_t bochs_width(void)
{
	return width;
}

uint32_t bochs_height(void)
{
	return height;
}

uint8_t bochs_bit_depth(void)
{
	return bit_depth;
}

void bochs_set_pixel(uint32_t x, uint32_t y, uint32_t r, uint32_t g, uint32_t b)
{
	uint32_t index = x + y * width;
	framebuffer[index] = (b << 0) | (g << 8) | (r << 16);
}