#include <u.h>
#include <libc.h>
#include <draw.h>
#include <thread.h>
#include <mouse.h>
#include <keyboard.h>
#include "univ.h"

void RequestLines(Pad*);

static Image *scrtemp;
static Image *scrback;

void scrltemp( void ){
	int h;

	if( scrtemp )
		return;
#define	BIG 3
	h = BIG*Dy( screen->r );
	scrtemp = allocimage( display, Rect(0, 0, 32, h), screen->chan, 0, 0 );
	scrback = allocimage( display, Rect(0, 0, 32, h), screen->chan, 0, 0 );
	if( scrtemp==0 || scrback==0 )
		panic( "scrltemp" );
}

long ScrollTotal( Pad *p ){		/* should be in ClipPaint ?? */
	long lines;
	Line *l, *lsent=&p->sentinel;

	if( lsent->key )
		lines = lsent->key;
	else
		for( lines=0, l=lsent->down; l!=lsent ; l=l->down )
			lines++;
	return (p->nlines=lines);
}

void Mark( Pad *p, Rectangle r ){
	if(rectclip(&r, p->scroll))
		draw(screen, r, padcols[BORD], nil, ZPoint);
}

void Unmark( Pad *p, Rectangle r ){
	if(rectclip(&r, p->scroll))
		draw(screen, r, padcols[BACK], nil, Pt(0, r.min.y-p->scroll.min.y));
}

Rectangle scrollbar( Rectangle r, int from, int to, int lo, int hi ){
	int rh = Dy(r), h = hi-lo;

	scrltemp();
	r.max.y -= muldiv(hi-to,rh,h);
	r.min.y += muldiv(from-lo,rh,h);
	return r;
}

void PaintScroll( Pad *p ){
	long tot = ScrollTotal( p );
	Rectangle r1, r2;

	scrltemp();
	if( !tot ) return;
	r1 = p->scroll;
	r2 = scrollbar( r1, p->lo, p->hi, 0, tot );
	if( !eqrect( r2, p->lastsr ) ){
		p->lastsr = r2;
		draw( screen, r1, padcols[BACK], nil, ZP );
		draw( screen, r2, padcols[BORD], nil, r2.min );
	}
}

void Doscroll( Pad *p, int but ){
	int lines, delta;
	int x, dy, y, y0, y1, y2, yscale;
	Rectangle r, s;

	if( but!=2 ) return;

	y0 = p->scroll.min.y;
	yscale = p->scroll.max.y - y0;
	s = insetrect(p->scroll, 1);
	x = (s.min.x+s.max.x)/2;
	lines = ScrollTotal(p);
	delta = p->hi - p->lo + 1;
	r = scrollbar( p->scroll, p->lo, p->hi, 0, lines );
	y = mousep->xy.y;
	draw(scrback, Rect(0,0,Dx(p->scroll),Dy(p->scroll)), screen, nil, p->scroll.min);
	while(button(but)){
		y1 = y;
		y2 = mousep->xy.y;
		if(y2 < p->scroll.min.y)
			y2 = p->scroll.min.y;
		if(y2 >= p->scroll.max.y)
			y2 = p->scroll.max.y;
		y = y2;
		if(y > p->scroll.max.y-2)
			y = p->scroll.max.y-2;
		if(!eqpt(mousep->xy, Pt(x, y))){		/* from acme */
			moveto(mousectl, Pt(x, y));
			readmouse(mousectl);
		}
		if(y != y1){
			dy = y - y1;
			Unmark(p, r);
			r = rectaddpt(r, Pt(0,dy));
			Mark(p, r);
		}
		waitMOUSE();
	}
	if( ptinrect(mousep->xy, p->scroll) ){
		Scrolly = mousep->xy.y;
		Paint(p);
		Scrolly = 0;
		RequestLines(p);
		return;
	}
	draw(screen, p->scroll, scrback, nil, ZPoint);
}