/*
  C code for a GUI VT100 terminal Emulator
  Originally developed for the Mac in June 1996 by
  Orion Sky Lawlor.  Released into the public domain
  by the author in 1997.

  This is just a hunk of a larger Macintosh program.
	API calls are Mac OS (version 2.1 and greater) API calls.
  Substantially comment-free.  Developed as throwaway code.

key: Procedure(params);  <- MacOS API call (capital first letter)
       procedure(params);  <- my procedures (lowercase first letter).
*/
typedef struct winData {
	Rect frame;
	Boolean frontmost;
	long sig;
	Boolean terminal;
		short charWidth,lineHeight;
		short pos,line;//x,y
		short maxPos,maxLine;//maximum x,y
		Rect hiliteR;
		short scrollStart,scrollEnd;
		char inVT52Y,savedPos,savedLine,savedAttrib;
		char reverseScreen,relative,wraparound,ANSI,attrib;
		char inEsc;//number of characters in
		char escSeq[14];//escape sequence.
		short inRef,outRef;
		char *tab;
} winData;

//External procedure:
void send(winData *o,char sendThis); //Send one character to the remote machine

//Entry points:
void termInit(winData *o);//fill out a terminal record
void termChar(WindowPtr win,char c);//Process a recieved character
void termClick(winData *o,Point where);//handle a mouse click in the VT window

//Private routines
Rect getPos(winData *o,short pos,short line);
void checkPos(winData *o,short *pos,short *line);
void termReset(winData *o);
void termLF(winData *o);
void termEsc(winData *o);

void termInit(winData *o)
{
	o->terminal=true;
	o->tab=(char *)NewPtr(256);
	termReset(o);
}

#define abs(x) ((x<0)?(-x):x)
void termClick(winData *o,Point where)
{
	short x=where.h/o->charWidth,y=where.v/o->lineHeight;
	short dirx=o->pos-x,diry=o->line-y;
	short numx=abs(dirx),numy=abs(diry);
	for (numy;numy>0;numy--)
	{
		send(o,0x1B);
		if (diry>0)
			//move up
			send(o,'A');
		else //move down
			send(o,'B');
	}
	for (numx;numx>0;numx--)
	{
		send(o,0x1B);
		if (dirx>0)
			//move left
			send(o,'D');
		else //move right
			send(o,'C');
	}
}
void termReset(winData *o)
{
	short i;
	for (i=0;i<256;i++) 
		o->tab[i]=0;
	for (i=0;i<(256/4);i++) 
		o->tab[i<<2]=1;
	TextFont(4);
	TextSize(9);
	o->charWidth=CharWidth(' ');
	o->lineHeight=12;
	o->pos=o->line=0;
	o->hiliteR=getPos(o,o->pos,o->line);
	o->reverseScreen=o->relative=o->wraparound=o->ANSI=o->attrib=0;
	o->scrollStart=0;
	o->scrollEnd=1000;
	o->inVT52Y=o->inEsc=0;//number of characters in
	//	char escSequence[7];//escape sequence.
}
void termLF(winData *o)
{
	if (o->line>=o->maxLine)
	{
		Rect r=o->frame;
		r.top=o->scrollStart*o->lineHeight;
		r.bottom=o->scrollEnd*o->lineHeight;
		if (r.bottom>o->frame.bottom)
			r.bottom=o->frame.bottom;
		o->line=o->maxLine;
		RgnHandle scrollRgn=NewRgn();
		ScrollRect(&o->frame,0,-o->lineHeight,scrollRgn);
		DisposeRgn(scrollRgn);
	}
}
Boolean isAlpha(char c);
Boolean isAlpha(char c) 
	{return ((c<='z')&&(c>='a'))||((c<='Z')&&(c>='A'));}
Boolean isNum(char c);
Boolean isNum(char c)
	{return (c<='9')&&(c>='0');}
short num(char *c);
short num(char *c) 
{
	short i=0,out=0;
	for (i=0;isNum(c[i]);i++)
	{
		out*=10;
		out+=c[i]-'0';
	}
	return out;
}
short num2(char *c);
short num2(char *c) 
{
	short i=0;
	while (c[i]!=';') i++;
	i++;
	return num(&c[i]);
}
char toUpper(char c);
char toUpper(char c)
{
	if ((c<='z')&&(c>='a'))
		return c-'a'+'A';
	return c;
}
void termEsc(winData *o)
{
	Rect r;
	short i;
	short oldInEsc=o->inEsc;
	char c=o->escSeq[oldInEsc-2];
	o->inEsc=0;
	char first=o->escSeq[0];
	if ((first=='=')||(first=='>')||(first=='1')||(first=='2')) 
		{}//don't care about enter/exit keypad, or graphics anything.
	else if (first=='<')
		o->ANSI=1;//enter ANSI mode...
	else if (first=='7') //save Cursor position+attribs:
		{o->savedPos=o->pos;o->savedLine=o->line;o->savedAttrib=o->attrib;}
	else if (first=='8') //restore Cursor position+attribs:
		{o->pos=o->savedPos;o->line=o->savedLine;o->attrib=o->savedAttrib;}
	else if ((first=='#')&&(oldInEsc==3))
		{}//ignore double/single height codes
	else if (((first=='(')||(first==')'))&&(oldInEsc==3))
		{}//ignore alternate character set selection.
	else if (isAlpha(c))
	{//might be the end... find out.
		if (first=='[')
		{
			char val;
			switch(c)
			{
				case 'A':o->line-=num(&o->escSeq[1]);break;
				case 'B':o->line+=num(&o->escSeq[1]);break;
				case 'C':o->pos+=num(&o->escSeq[1]);break;
				case 'c'://What are you?
					send(o,0x1b);send(o,'[');send(o,'?');send(o,'1');send(o,';');
					send(o,'2');//I'm a base terminal (noOptions), with advanced video
					send(o,'c');
					break;
				case 'D':o->pos-=num(&o->escSeq[1]);break;
				case 'H': case 'f':
					if (o->relative)
					{
						o->line+=num(&o->escSeq[1])-1;
						o->pos+=num2(&o->escSeq[1])-1;
					} else {
						o->line=num(&o->escSeq[1])-1;
						o->pos=num2(&o->escSeq[1])-1;
					}
					break;
				case 'h':case 'l'://sets or clears a value:
					val=(c=='h');
					if (o->escSeq[1]=='?')
					{
						switch(o->escSeq[2])
						{
							case '2':o->ANSI&=val;//turn ANSI off only.
							case '5':o->reverseScreen=val;break;//inverse video on/off
							case '6':o->relative=val;break;//relative moves on/off
							case '7':o->wraparound=val;break;//edge screen wrap on/off
						}
					}
					break;
				case 'g': 
					if (o->escSeq[1]!='3')
						o->tab[o->pos]=0;//clear one tab
					else
						for (i=0;i<256;i++)
							o->tab[i]=0;//clear all tabs
					break;
				case 'J':
					r=o->frame;
					if (o->escSeq[1]!='2')
						{r.top=o->hiliteR.bottom;}
					EraseRect(&r);
					break;
				case 'K':
					r=o->hiliteR;
					r.right=o->frame.right;
					if (o->escSeq[1]=='2')
						{r.left=0;}
					else if (o->escSeq[1]=='1')
						{r.left=0;r.right=o->hiliteR.right;}
					EraseRect(&r);
					break;
				case 'm':
					if (o->escSeq[1]=='1')
						o->attrib|=bold;
					else if (o->escSeq[1]=='4')
						o->attrib|=underline;
					else if (o->escSeq[1]=='7'||o->escSeq[1]=='5')
						o->attrib|=outline;
					else if (o->escSeq[1]=='m')
						o->attrib=0;
					else
						o->attrib=bold|outline;
					break;
				case 'n'://report:
					send(o,0x1B);
					send(o,'[');
					switch(o->escSeq[1])
					{
						case '6'://cursor position report
							send(o,o->line+'0');send(o,';');send(o,o->pos+'0');send(o,'R');
							break;
						case '5'://are you OK?
							send(o,'c');//yes.
							break;
					}
					break;
				case 'L': case 'M': case 'P':
					SysBeep(20);
					//edit commands: insert one line if [L, insert n lines for [nL.
					//delete [M one char from cursor position, delete [nM n lines down.
					//delete [P one char from cursor position,[nP delete n characters.
					//don't care yet.
					break;
				case 'p':
					termReset(o);
					break;
				case 'q': break;//Set cursor LED's:don't care.
				case 'r'://scrolling region select:
					o->scrollStart=num(&o->escSeq[1])-1;
					o->scrollEnd=num2(&o->escSeq[1]);
					break;
				default: interrupt();
			}
		} else {
			switch(c)
			{
				case 'A': o->line--; break;
				case 'B': o->line++; break;
				case 'C': o->pos++; break;
				case 'c': termReset(o);break;//reset terminal
				case 'D': 
					if (o->ANSI)
					{
						o->line++;
						termLF(o);
					}
					else
						o->pos--; 
					break;
				case 'E': o->pos=0;o->line++;termLF(o);break;
				case 'F': break;//enter special graphics set (don't care)
				case 'G': break;//enter ASCII character set (don't care)
				case 'H': 
					if (!o->ANSI)
						o->line=o->pos=0;
					else
						o->tab[o->pos]=1;
					break;
				case 'I': o->line--; break;
				case 'J':
					r=o->frame;r.bottom=o->hiliteR.bottom;
					EraseRect(&r);break;
				case 'K':
					r=o->hiliteR;r.right=o->frame.right;
					EraseRect(&r);break;
				case 'M': o->line--;break;
				case 'Y': o->inVT52Y=2;break;
				case 'Z': send(o,0x1B);send(o,'/');send(o,'Z');break;
				default: interrupt();
			}
		}
	} else o->inEsc=oldInEsc;//otherwise, keep listening.
}
void termChar(const WindowPtr win, char c)
{
	register winData *o=obj(win);
	if (o->inVT52Y)
	{
		if (o->inVT52Y==2)
		{
			o->inVT52Y--;
			o->line=c-'0';
		} else if (o->inVT52Y==1)
		{
			o->inVT52Y--;
			o->pos=c-'0';
		}
	}
	else if (o->inEsc!=0)
	{//escape sequence:
		if (o->inEsc-1>13) 
			o->inEsc=0;
		o->escSeq[o->inEsc-1]=c;
		o->inEsc++;
		termEsc(o);
	} 
	else if (c==0x1B)//escape
		o->inEsc=1;
	else if (c==0x09)//tab
	{//find next tab stop
		short i;
		for (i=o->pos;!o->tab[i];i++)
			o->pos=i;
	}
	else if ((c==0x03)||(c==0x0A))//newline or LF
	{
		o->line++;
		termLF(o);
	}
	else if (c==0x0d)//CR
		o->pos=0;
	else if ((c==0x08)||(c==0x10))//backspace or delete
	{
		o->pos--;
		checkPos(o,&o->pos,&o->line);
		o->hiliteR=getPos(o,o->pos,o->line);
		EraseRect(&o->hiliteR);
	}
	else
	{
		short x=o->pos*o->charWidth,y=o->line*o->lineHeight;
		o->hiliteR.right=o->hiliteR.left=x;o->hiliteR.bottom=o->hiliteR.top=y;
		o->hiliteR.right+=o->charWidth;o->hiliteR.bottom+=o->lineHeight;
		y+=o->lineHeight;
		EraseRect(&o->hiliteR);
		MoveTo(x,y-3);
		DrawChar(c);
		if (o->attrib&bold)
		{
			MoveTo(x+1,y-3);
			DrawChar(c);
		}
		if (o->attrib&underline)
		{
			MoveTo(x,y-3);
			LineTo(x+o->charWidth,y-3);
		}
		if (o->attrib&outline)
			InvertRect(&o->hiliteR);
		++o->pos;
		if (o->wraparound)
			if (o->pos>=o->maxPos) 
			{
				o->line++;
				o->pos=0;
				termLF(o);
			}
	}
	checkPos(o,&o->pos,&o->line);
	o->hiliteR=getPos(o,o->pos,o->line);
}