// 
// http://en.wikipedia.org/wiki/VT52
// http://vt100.net/docs/vt520-rm/
//

#include "vt52.h"
#include "kernel/kmalloc.h"

#define VT52_WIDTH 80
#define VT52_HEIGHT 25


#define VT52_ESC_1 0x1b  //ESC
#define VT52_ESC_2 0x5b  //[

#define VT52_UP 'A'
#define VT52_DOWN 'B'
#define VT52_RIGHT 'C'
#define VT52_LEFT 'D'
#define VT52_GRAPH_ON 'F'
#define VT52_GRAPH_OFF 'G'
#define VT52_HOME 'H'
#define VT52_REV_FEED 'I'
#define VT52_ERASE_SCR 'J'
#define VT52_ERASE_LINE 'K'
#define VT52_KEYPAD_ON '='
#define VT52_KEYPAD_OFF '>'

#define VT52_EXIT '<'

#define VT52_ENTER_AUTOPRINT '^'
#define VT52_EXIT_AUTOPRINT '_'

#define VT52_PRINT_LINE 'W'
#define VT52_ENTER_PRINT 'W'
#define VT52_EXIT_PRINT 'X'
#define VT52_PRINT ']'
#define VT52_JUMP 'Y' // followed by LINE COL (subtr -32 from val)
#define VT52_IDENTIFY 'Z'
#define VT52_IDENTIFY_TO_HOST "/Z"

static uint32_t index(vt52_tty *tty, uint32_t x, uint32_t y)
{
    return tty->width*y+x;
}

static void clear(vt52_tty *tty)
{
    for(int x=0;x<tty->width;x++)
	for(int y=0;y<tty->height;y++)
	{
	    tty->data[index(tty,x,y)]=' ';
	    tty->screen->put_char(' ',0xf,x,y);
	}
}

vt52_tty vt52_init(term_out *screen,term_in *input)
{
    vt52_tty tty;

    tty.data=kballoc(1);
    tty.screen=screen;
    tty.input=input;

    tty.x=0;
    tty.y=0;

    tty.width=VT52_WIDTH;
    tty.height=VT52_HEIGHT;

    clear(&tty);

    return tty;
}


static void set_char(vt52_tty *tty, uint32_t x, uint32_t y, uint32_t c)
{
    tty->data[index(tty,x,y)]=c;
}

static uint8_t escaping=0;

void vt52_kb(vt52_tty *tty, uint8_t c)
{
    vt52_put(tty,c);
    tty->input->put_char(c);
}
// send one ASCII character to the terminal
bool vt52_put(vt52_tty *tty, uint8_t c)
{   
    if(c==VT52_ESC_1){escaping=1;return;}
    if(c==VT52_ESC_2){if(escaping==1)escaping=2;return;}

    if(escaping==3){tty->x=c-32; escaping++;return;} //TODO: check for overflow?
    if(escaping==4){tty->y=c-32; escaping=0;return;}

    if(escaping==2) // two last characters are escape seq: ^[
    {
	if(c==VT52_JUMP)escaping++;

	else
	{
	    switch('c')
	    {
		case VT52_UP:
		    if(tty->y>0)tty->y--;
		break;

		case VT52_DOWN:
		    if(tty->y+1<tty->height)tty->y++;
		break;

		case VT52_LEFT:
		    if(tty->x+1<tty->width)tty->x++;
		break;

		case VT52_RIGHT:
		    if(tty->x>0)tty->x--;
		break;

		case VT52_HOME:
		    tty->x=tty->y=0;
		break;

		case VT52_REV_FEED:

		break;

		case VT52_ERASE_SCR:
		    for(uint32_t y=tty->y+1;y<tty->height;y++)
		    {
			for(uint32_t x=0;x<tty->width-1;x++)
			{
			    uint32_t c=tty->data[index(tty,x,y+1)];
			    tty->data[index(tty,x,y)] = c;
			    tty->screen->put_char(c,0xf,x,y);
			}
		    }
		case VT52_ERASE_LINE:

		    for(uint32_t x=tty->x;x<tty->width-1;x++)
		    {
			uint32_t c=tty->data[index(tty,x,tty->y)];
			tty->data[index(tty,x,tty->y)] = c;
			tty->screen->put_char(c,0xf,x,tty->y);
		    }

		break;

	    }

	    escaping=0;
	}

	return;

    }

    if(c!='\n')
    {
        tty->data[index(tty,tty->x,tty->y)]=c;
	tty->screen->put_char(c,0xf,tty->x,tty->y);
    }
    else
    {
	tty->y++;
	tty->x=0;
    }

    tty->x++;

    if(tty->x>=tty->width)
    {
	tty->x=0;
	tty->y++;
    }

    //autoscroll
    if(tty->y>=tty->height)
    {
	tty->y--;
	for(uint32_t y=0;y<tty->height;y++)
	{
	    for(uint32_t x=0;x<tty->width-1;x++)
	    {
		uint32_t c=tty->data[index(tty,x,y+1)];
		tty->data[index(tty,x,y)] = c;
		tty->screen->put_char(c,0xf,x,y);
	    }
	}
    }

    tty->screen->update_cursor(tty->x,tty->y);
    return true;
}