#include <kernel/font.h>
#include <kernel/devices/display.h>
#include <kernel/atomic.h>

// Font bitmap.
static const uint8_t kernel_font_bitmap[] = {
	0xee, 0xee, 0xee, 0xee, 0xee, 0xee, 0xee, 0xee, 0xee, 0xee, 0xee, 0xee,
	0xee, 0xee, 0xee, 0xef, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55,
	0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x56, 0xaa, 0xaa, 0xaa, 0xaa,
	0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xad,
	0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55,
	0x55, 0x55, 0x55, 0x5e, 0xee, 0xee, 0xee, 0xee, 0xee, 0xee, 0xee, 0xee,
	0xee, 0xee, 0xee, 0xee, 0xee, 0xee, 0xee, 0xe0, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
	0x2a, 0x92, 0x11, 0x11, 0x28, 0x00, 0x00, 0x38, 0xbb, 0xab, 0xbb, 0xbb,
	0x80, 0x08, 0x23, 0x02, 0x57, 0x31, 0x52, 0x41, 0x22, 0x00, 0x01, 0x51,
	0x11, 0x54, 0x41, 0x55, 0x22, 0x27, 0x21, 0x04, 0x0a, 0xc4, 0x40, 0x82,
	0xae, 0x0e, 0x04, 0xa2, 0xee, 0xee, 0xe2, 0xee, 0x00, 0x80, 0x24, 0x00,
	0x1c, 0xd1, 0x41, 0x04, 0x08, 0x80, 0x11, 0x45, 0x04, 0x45, 0x45, 0x44,
	0x88, 0x9c, 0x80, 0x10, 0x2b, 0x09, 0x81, 0x10, 0x02, 0x01, 0x03, 0x8b,
	0xb8, 0xbb, 0x8b, 0xb8, 0x20, 0x82, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0c, 0xee,
	0xec, 0xee, 0xea, 0xee, 0xa8, 0xae, 0xee, 0xee, 0x6e, 0xaa, 0xaa, 0xae,
	0xe0, 0xe4, 0x05, 0x55, 0x15, 0x11, 0x14, 0x89, 0x51, 0xd5, 0x55, 0x55,
	0x09, 0x55, 0x55, 0x45, 0x10, 0x54, 0x0b, 0xb2, 0x2b, 0xba, 0xb9, 0x13,
	0x22, 0xaa, 0xba, 0xb3, 0x92, 0xaa, 0x91, 0x12, 0x10, 0x80, 0x55, 0x54,
	0x54, 0x45, 0x52, 0x25, 0x45, 0x55, 0x47, 0x51, 0x25, 0x57, 0x52, 0x44,
	0x11, 0x00, 0xca, 0xee, 0xce, 0x8e, 0xae, 0xca, 0xea, 0xae, 0x8e, 0xac,
	0x4e, 0x4a, 0xa4, 0xee, 0x0e, 0x0e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x12, 0x00,
	0x90, 0x9a, 0x11, 0x23, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x19,
	0x30, 0x39, 0x14, 0x31, 0x52, 0x54, 0x00, 0x42, 0x76, 0x26, 0x35, 0x37,
	0x55, 0x55, 0x57, 0x22, 0x20, 0x70, 0x6c, 0x86, 0xee, 0x6c, 0xc4, 0xa4,
	0xea, 0xaa, 0xac, 0xc4, 0xaa, 0xa4, 0xa4, 0x84, 0x26, 0xe1, 0x55, 0x15,
	0x08, 0x54, 0x89, 0x89, 0x55, 0x58, 0xd0, 0x49, 0x55, 0xd4, 0x90, 0x88,
	0x99, 0xc1, 0xb1, 0x99, 0x93, 0x2b, 0xb2, 0x9a, 0xa9, 0x20, 0xa3, 0x19,
	0x92, 0xa9, 0x39, 0x93, 0x03, 0x80
};


static void font_draw_core(struct font_block_s *fblock)
{
	extern uint32_t vram[256];
	uint8_t vram_offset_y;
	uint32_t pixel_cursor;
	uint8_t pixel_test;
	int x;
	int y;

	// Calculate VRAM buffer starting position.
	// @note:
	// 	The screen width size is always 128 and we
	// use 4-aligned Video RAM so 32 pixels per "slot"
	// and 128 / 32 = 4.
	// y * 4 can be optimised by used shift operator,
	// this is why we use y << 2 because 2^2 = 4.
	vram_offset_y = fblock->y << 2;

	// Start atomic operations
	atomic_start();

	// Draw character, pixer per pixel... (x_x)
	// TODO: update me !!
	y = -1;
	while (++y < fblock->height)
	{
		x = -1;
		while (++x < fblock->width)
		{
			// Get bitmap pixel test.
			pixel_cursor = fblock->bitmap.x + fblock->bitmap.y + x;
			pixel_test = 0x80 >> (pixel_cursor & 0x07);

			// Check if the pixel is block or white.
			if (pixel_test & kernel_font_bitmap[pixel_cursor >> 3])
			{
				vram[((fblock->x + x) >> 5) + vram_offset_y] |=
					0x80000000 >> ((fblock->x + x) & 31);
			}
		}

		// Update internal offset.
		fblock->bitmap.y = fblock->bitmap.y + KERNEL_FONT_BITMAP_WIDTH; 
		vram_offset_y = vram_offset_y + 4;
	}

	// Stop atomic operations
	atomic_stop();
}


void font_draw(int x, int y, char c)
{
	struct font_block_s fblock;

	// Check obvious error.
	if (x > DISPLAY_SCREEN_WIDTH || y > DISPLAY_SCREEN_HEIGHT)
		return;

	// Calculate the charactere position (bitmap)
	fblock.bitmap.y = (c / KERNEL_FONT_NB_CHAR_X) * (KERNEL_FONT_BITMAP_WIDTH * KERNEL_FONT_BITMAP_CHEIGHT);
	fblock.bitmap.x = (c - ((c / KERNEL_FONT_NB_CHAR_X) * KERNEL_FONT_NB_CHAR_X)) * KERNEL_FONT_BITMAP_CWIDTH;


	// Check X axis culling
	// and get font "block" width.
	if (x < 0)
	{
		fblock.bitmap.x = fblock.bitmap.x + x;
		fblock.width = KERNEL_FONT_REAL_WIDTH + x;
		fblock.x = 0;
	} else {
		fblock.width =
			(x + KERNEL_FONT_REAL_WIDTH >= DISPLAY_SCREEN_WIDTH)
			? DISPLAY_SCREEN_WIDTH - x - 1
			: KERNEL_FONT_REAL_WIDTH;
		fblock.x = x;
	}

	// Check Y axis culling.
	// and get font "block" height.
	if (y < 0)
	{
		fblock.height = KERNEL_FONT_REAL_HEIGHT + y;
		fblock.bitmap.y = fblock.bitmap.y + ((-y) * KERNEL_FONT_BITMAP_WIDTH);
		fblock.y = 0;
	} else {
		fblock.height = 
			(y + KERNEL_FONT_REAL_HEIGHT >= DISPLAY_SCREEN_HEIGHT)
			? DISPLAY_SCREEN_HEIGHT - y - 1
			: KERNEL_FONT_REAL_HEIGHT;
		fblock.y = y;
	}

	// Check useless draw.
	if (fblock.width < 0 || fblock.height < 0)
		return;

	// Draw ASCII character.
	font_draw_core(&fblock);
}