#include "vga.h"

#include "stdio.h"
#include "stdlib.h"

#include "kernel.h"

#include "vga_font.h"

#undef DEBUG

static vga_vtable_t const vga_vtable = {
	{
	vga_activate,
	vga_deactivate,
	vga_deinit,
	vga_print_info
	}
};

void vga_init( vga_t *vga, interrupt_t *interrupt, void *context )
{
	memset( vga, 0, sizeof( vga_t ) );
	
	driver_init( (driver_t *)vga, DRIVER_TYPE_VIDEO, interrupt, context );

	port8_init( &vga->misc_port, 0x3C2 );
	port8_init( &vga->crtc_index_port, 0x3D4 );
	port8_init( &vga->crtc_data_port, 0x3D5 );
	port8_init( &vga->sequencer_index_port, 0x3C4 );
	port8_init( &vga->sequencer_data_port, 0x3C5 );
	port8_init( &vga->graphics_controller_index_port, 0x3CE );
	port8_init( &vga->graphics_controller_data_port, 0x3CF );
	port8_init( &vga->attribute_controller_index_port, 0x3C0 );
	port8_init( &vga->attribute_controller_read_port, 0x3C1 );
	port8_init( &vga->attribute_controller_write_port, 0x3C0 );
	port8_init( &vga->attribute_controller_reset_port, 0x3DA );

	((driver_t *)vga)->vtable = (driver_vtable_t *)&vga_vtable;
}

void vga_activate( void *obj )
{
	puts( "Activating driver for generic VGA video card.." );
}

void vga_deactivate( void *obj )
{
	puts( "Dectivating driver for generic VGA video card.." );
}

void vga_deinit( void *obj )
{
	vga_t *vga = (vga_t *)obj;
	
	if( vga->zbuffer != NULL ) {
		free( vga->zbuffer );
		vga->zbuffer = NULL;
	}
}

void vga_print_info( void *obj )
{
	puts( "Generic VGA video driver" );
}

static void write_registers( vga_t *vga, uint8_t *regs )
{
	// misc
	port8_write( &vga->misc_port, *( regs++ ) );

	// seq (5)
	for( uint8_t i = 0; i < 5; i++ ) {
		port8_write( &vga->sequencer_index_port, i );
		port8_write( &vga->sequencer_data_port, *( regs++ ) );
	}

	// unlock CRTC register (and make sure mode data doesn't lock it again by accident) 
	port8_write( &vga->crtc_index_port, 0x03 );
	port8_write( &vga->crtc_data_port, port8_read( &vga->crtc_data_port ) | 0x80 );
	port8_write( &vga->crtc_index_port, 0x11 );
	port8_write( &vga->crtc_data_port, port8_read( &vga->crtc_data_port ) & ~0x80 );
	regs[0x3] |= 0x80;
	regs[0x11] &= ~0x80;

	// crtc (25)
	for( uint8_t i = 0; i < 25; i++ ) {
		port8_write( &vga->crtc_index_port, i );
		port8_write( &vga->crtc_data_port, *( regs++ ) );
	}

	// gc (9)
	for( uint8_t i = 0; i < 9; i++ ) {
		port8_write( &vga->graphics_controller_index_port, i );
		port8_write( &vga->graphics_controller_data_port, *( regs++ ) );
	}

	// ac (21)
	for( uint8_t i = 0; i < 21; i++ ) {
		(void)port8_read( &vga->attribute_controller_reset_port );
		port8_write( &vga->attribute_controller_index_port, i );
		port8_write( &vga->attribute_controller_write_port, *( regs++ ) );
	}

	// lock 16-color palette and unblank display
	(void)port8_read( &vga->attribute_controller_reset_port );
	port8_write( &vga->attribute_controller_index_port, 0x20 );
}

vga_mode_t vga_make_mode( const vga_mode_type_t mode_type, const int x, const int y, const int color_depth )
{
	vga_mode_t mode;

	mode.mode_type = mode_type;
	mode.x = x;
	mode.y = y;
	mode.color_depth = color_depth;

	return mode;
}
	
// from http://files.osdev.org/mirrors/geezer/osd/graphics/modes.c
static vga_mode_t modes[] = {
	{ VGA_MODE_TYPE_TEXT, 640, 480, 4,
		{ 
		/* MISC */
			0x67,
		/* SEQ */
			0x03, 0x00, 0x03, 0x00, 0x02,
		/* CRTC */
			0x5F, 0x4F, 0x50, 0x82, 0x55, 0x81, 0xBF, 0x1F,
			0x00, 0x4F, 0x0D, 0x0E, 0x00, 0x00, 0x00, 0x50,
			0x9C, 0x0E, 0x8F, 0x28, 0x1F, 0x96, 0xB9, 0xA3,
			0xFF,
		/* GC */
			0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x0E, 0x00,
			0xFF,
		/* AC */
			0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x14, 0x07,
			0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F,
			0x0C, 0x00, 0x0F, 0x08, 0x00
		},
		NULL
	},
	{ VGA_MODE_TYPE_GRAPHICS, 320, 200, 8,
		{
		/* MISC */
			0x63,
		/* SEQ */
			0x03, 0x01, 0x0F, 0x00, 0x0E,
		/* CRTC */
			0x5F, 0x4F, 0x50, 0x82, 0x54, 0x80, 0xBF, 0x1F,
			0x00, 0x41, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x9C, 0x0E, 0x8F, 0x28, 0x40, 0x96, 0xB9, 0xA3,
			0xFF,
		/* GC */
			0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x05, 0x0F,
			0xFF,
		/* AC */
			0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
			0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
			0x41, 0x00, 0x0F, 0x00, 0x00
		},
		NULL
	},
	{ VGA_MODE_TYPE_GRAPHICS, 640, 480, 4,
		{
		/* MISC */
			0xE3,
		/* SEQ */
			0x03, 0x01, 0x08, 0x00, 0x06,
		/* CRTC */
			0x5F, 0x4F, 0x50, 0x82, 0x54, 0x80, 0x0B, 0x3E,
			0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0xEA, 0x0C, 0xDF, 0x28, 0x00, 0xE7, 0x04, 0xE3,
			0xFF,
		/* GC */
			0x00, 0x00, 0x00, 0x00, 0x03, 0x00, 0x05, 0x0F,
			0xFF,
		/* AC */
			0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x14, 0x07,
			0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F,
			0x01, 0x00, 0x0F, 0x00, 0x00
		},
		NULL
	}
};

bool vga_supports_mode( const vga_mode_t mode )
{
	for( int i = 0; modes[i].x != 0; i++ ) {
		if( 	mode.mode_type == modes[i].mode_type &&
			mode.x == modes[i].x &&
			mode.y == modes[i].y &&
			mode.color_depth == modes[i].color_depth ) {
			return true;
		}
	}

	return false;
}

static int get_matching_mode_idx( const vga_mode_t mode )
{
	for( int i = 0; modes[i].x != 0; i++ ) {
		if( 	mode.mode_type == modes[i].mode_type &&
			mode.x == modes[i].x &&
			mode.y == modes[i].y &&
			mode.color_depth == modes[i].color_depth ) {
			return i;
		}
	}

	return -1;
}

static uint8_t *get_frame_buffer_segment( vga_t *vga )
{
	port8_write( &vga->graphics_controller_index_port, 0x06 );
	uint8_t segment_no = ( port8_read( &vga->graphics_controller_data_port ) >> 2 ) & 0x03;
	uint8_t *segment = 0x0;

	switch( segment_no  ) {
		case 0: // A0000h - BFFFFh
			segment = (uint8_t *)0xA0000;
			break;

		case 1: // A0000h - AFFFFh
			segment = (uint8_t *)0xA0000;
			break;

		case 2: // B0000h - B7FFFh
			segment = (uint8_t *)0xB0000;
			break;

		case 3: // B8000h - BFFFFh
			segment = (uint8_t *)0xB8000;
			break;
	}

#ifdef DEBUG
	printf( "segment: %d 0x%X\n", segment_no, segment );
#endif

	return segment;
}

static size_t get_frame_buffer_segment_size( vga_t *vga )
{
	port8_write( &vga->graphics_controller_index_port, 0x06 );
	uint8_t segment_no = ( port8_read( &vga->graphics_controller_data_port ) >> 2 ) & 0x03;
	size_t segment_size = 0;

	switch( segment_no  ) {
		case 0: // 128k
			segment_size = 128 * 1024;
			break;

		case 1: // 64k
			segment_size = 64 * 1024;
			break;

		case 2: // 32k
		case 3:
			segment_size = 32 * 1024;
			break;
	}

#ifdef DEBUG
	printf( "segment size: %d 0x%X\n", segment_no, segment_size );
#endif

	return segment_size;
}

bool vga_set_mode( vga_t *vga, const vga_mode_t mode )
{
	// do not allow unknown timings!
	if( !vga_supports_mode( mode ) ) {
		return false;
	}

	vga_mode_t matching_mode = modes[get_matching_mode_idx( mode )];

	write_registers( vga, matching_mode.regs );

	vga->mode = mode;
	vga->mode.segment = get_frame_buffer_segment( vga );
	vga->mode.segment_size = get_frame_buffer_segment_size( vga );

	vga_use_z_buffer( vga, false );

	return true;
}


vga_color_t vga_make_RGB( int R, int G, int B )
{
	vga_color_t c;

	c.R = R;
	c.G = G;
	c.B = B;

	return c;
}

const vga_color_t VGA_COLOR_BLACK 	= { 0x00, 0x00, 0x00 };
const vga_color_t VGA_COLOR_BLUE 	= { 0x00, 0x00, 0xAA };
const vga_color_t VGA_COLOR_GREEN 	= { 0x00, 0xAA, 0x00 };
const vga_color_t VGA_COLOR_CYAN 	= { 0x00, 0xAA, 0xAA };
const vga_color_t VGA_COLOR_RED 	= { 0xAA, 0x00, 0x00 };
const vga_color_t VGA_COLOR_MAGENTA 	= { 0xAA, 0x00, 0xAA };
const vga_color_t VGA_COLOR_BROWN 	= { 0xAA, 0x55, 0x00 };
const vga_color_t VGA_COLOR_LIGHT_GREY 	= { 0xAA, 0xAA, 0xAA };
const vga_color_t VGA_COLOR_WHITE 	= { 0xFF, 0xFF, 0xFF };

static bool is_same( const vga_color_t c1, const vga_color_t c2 )
{
	return c1.R == c2.R && c1.G == c2.G && c1.B == c2.B;
}

static uint8_t get_color_index( const vga_color_t c )
{
	if( is_same( c, VGA_COLOR_BLACK ) ) return 0x00;
	if( is_same( c, VGA_COLOR_BLUE ) ) return 0x01;
	if( is_same( c, VGA_COLOR_GREEN ) ) return 0x02;
	if( is_same( c, VGA_COLOR_CYAN ) ) return 0x03;
	if( is_same( c, VGA_COLOR_RED ) ) return 0x04;
	if( is_same( c, VGA_COLOR_MAGENTA ) ) return 0x05;
	if( is_same( c, VGA_COLOR_BROWN ) ) return 0x06;
	if( is_same( c, VGA_COLOR_LIGHT_GREY ) ) return 0x07;
	if( is_same( c, VGA_COLOR_WHITE ) ) return 0x3F;
	return 0x00;
}

static bool params_ok( vga_t *vga, const int x, const int y )
{
	if( x < 0 || x > vga->mode.x || y < 0 || y > vga->mode.y ) {
		return false;
	}

	return true;
}

void vga_set_pixel( vga_t *vga, const int x, const int y, const vga_color_t color )
{
	if( !params_ok( vga, x, y ) ) {
		kernel_panic( "Pixel coordinates are out of bounds: (%d, %d), resolution is only (%d, %d)",
			x, y, vga->mode.x, vga->mode.y );
	}

	uint8_t color_idx = get_color_index( color );

	uint8_t *addr = vga->base_addr + vga->mode.x * y + x;

	*addr = color_idx;
}	

void vga_draw_rectangle( vga_t *vga, const int x, const int y, const int w, const int h, const vga_color_t color )
{
	if( !params_ok( vga, x, y ) ) {
		kernel_panic( "Rectangle start coordinates are out of bounds: (%d, %d), resolution is only (%d, %d)",
			x, y, vga->mode.x, vga->mode.y );
	}

	if( !params_ok( vga, x + w, y + h ) ) {
		kernel_panic( "Rectangle end coordinates are out of bounds: (%d, %d), resolution is only (%d, %d)",
			x + w, y + h, vga->mode.x, vga->mode.y );
	}

	uint8_t color_idx = get_color_index( color );

	for( int yy = y; yy < y + h; yy++ ) {
		uint8_t *addr = vga->base_addr + vga->mode.x * yy + x;
		memset( addr, color_idx, w );
	}
}

void vga_clear_screen( vga_t *vga, const vga_color_t color )
{
	memset( vga->base_addr, get_color_index( color ),
		vga->mode.x * vga->mode.y );
}

void vga_draw_char( vga_t *vga, const unsigned char c, const int x, const int y, const vga_color_t background, const vga_color_t foreground )
{

//const struct bitmap_font font = {

/*        .Width = 8, .Height = 16,
        .Chars = 2899,
        .Widths = __font_widths__,
        .Index = __font_index__,
        .Bitmap = __vga_font_bitmap__,
*/
	// assuming font width is 8
	int mask[8] = { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80 };

	// for now, the 34 entry, character height is 16, assuming A-Z
	const unsigned char *bmap = &vga_font.Bitmap[(c-32)*16];

	uint8_t fg_color_idx = get_color_index( foreground );
	uint8_t bg_color_idx = get_color_index( background );
	// should be dynamic and vga_font.Width
	uint8_t data[8];

	for( int yy = 0; yy < vga_font.Height; yy++ ) {
		memset( data, bg_color_idx, sizeof( data ) );
		for( int xx = 0; xx < vga_font.Width; xx++ ) {
			if( bmap[yy] & mask[xx] ) {
				data[vga_font.Width-1-xx] = fg_color_idx;
			}
		}
		uint8_t *addr = vga->base_addr + vga->mode.x * ( y + yy ) + x;
		memcpy( addr, data, vga_font.Width );
	}
}

void vga_wait_for_retrace( vga_t *vga )
{
	while( port8_read( &vga->attribute_controller_reset_port ) & 0x08 );
	while( !( port8_read( &vga->attribute_controller_reset_port ) & 0x08 ) );
}

void vga_use_z_buffer( vga_t *vga, bool use )
{
	if( vga->use_z_buffer == use ) {
		return;
	}
	
	vga->use_z_buffer = use;

	if( vga->use_z_buffer ) {
		vga->zbuffer = (uint8_t *)malloc( vga->mode.segment_size );
		vga->base_addr = &vga->zbuffer[0];
	} else {
		if( vga->zbuffer != NULL ) {
			free( vga->zbuffer );
			vga->zbuffer = NULL;
		}
		vga->base_addr = vga->mode.segment;
	}
}

void vga_refresh( vga_t *vga )
{
	if( vga->use_z_buffer ) {
		vga_wait_for_retrace( vga );
		memcpy( vga->mode.segment, vga->zbuffer, vga->mode.segment_size );
	}
}