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

void RequestLines(Pad*);

static Image *scrtemp;
static Image *scrback;

void ScrollTemps( void ){
	int h;

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

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

	dprint(1, "scrollbar( %R, from.%d, to.%d, lo.0, hi.%d )", r, from, to, hi);
	ScrollTemps();
	r.max.y -= muldiv(hi-to, rh, h);
	r.min.y += muldiv(from-lo, rh, h);
	dprint(0, "r = %R", r);
	dprint(-1, "scrollbar()");
	return r;
}

Rectangle ScrollPos( Rectangle r, long lo, long hi, long tot ){
	Rectangle q;
	int h;

	dprint(1, "ScrollPos(%R, lo.%d, hi.%d, tot.%d)", r, lo, hi, tot);
	q = r;
	if( tot == 0 ) return q;
	h = q.max.y-q.min.y;
	if( tot > 1024L*1024L )
		tot>>=10, lo>>=10, hi>>=10;
	if( lo > 0 )
		q.min.y += h*lo/tot;
	if( hi < tot-1 )
		q.max.y -= h*(tot-hi-1)/tot;
	if( q.max.y < q.min.y+2 ){
		if( q.min.y+2 <= r.max.y )
			q.max.y = q.min.y+2;
		else
			q.min.y = q.max.y-2;
	}
	dprint(-1, "ScrollPos() => %R", q);
	return q;
}

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

	dprint(1, "PaintScroll(p.%s)", p? p->name: "<null>");
	dprint(0, "tot == %d", tot);
	ScrollTemps();
	r1 = p->scroll;
	r2 = scrollbar( r1, p->lo, p->hi, 0, tot );
	if( !eqrect( r2, p->bar ) ){
		p->bar = r2;
		draw( screen, r1, padcols[BACK], nil, ZP );
		draw( screen, r2, padcols[BORD], nil, r2.min );
	}
	dprint(-1, "PaintScroll(...)");
}

void Doscroll( Pad *p, int but ){
	Rectangle r, s;
	int lo, delta;
	Line *l, *lsent = &p->sentinel;
	int x, dy, y, y0, y1, y2, yscale;
	int x0 = p->scroll.min.x;
	int x1 = p->scroll.max.x;
	int lines = ScrollTotal(p);

	if( but!=2 ) return;

	dprint(1, "Doscroll()");
	y0 = p->scroll.min.y;
	yscale = p->scroll.max.y - y0;
	s = insetrect(p->scroll, 1);
	x = (s.min.x+s.max.x)/2;
	delta = p->hi - p->lo + 1;
	r = scrollbar( p->scroll, p->lo, p->hi+1, 0, lines+1 );
	y = r.min.y;
	draw(scrback, Rect(0,0,Dx(p->scroll),Dy(p->scroll)), screen, nil, p->scroll.min);
	while(button(but)){
		if( ptinrect(mousep->xy, p->scroll) ) {
			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(y != y1){
				Rectangle clr, set;
				dy = y - y0;
				lo = muldiv(dy, lines, yscale) - (delta >> 1);
				if (lo < 0)
					lo = 0;
				else if ((lo + delta) > lines)
					lo = lines - delta;
				s = scrollbar(p->scroll, lo, lo+delta, 0, lines+1);
				if (s.min.y-r.min.y > 0) {	/* down */
					clr = Rect(x0, r.min.y, x1, s.min.y);
					set = Rect(x0, r.max.y, x1, s.max.y);
				} else {			/* up */
					clr = Rect(x0, s.max.y, x1, r.max.y);
					set = Rect(x0, s.min.y, x1, r.min.y);
				}
				draw(screen, clr, padcols[BACK], nil, ZPoint);
				draw(screen, set, padcols[BORD], nil, ZPoint);
				r = s;
				y = r.min.y;
			}
		}
jnap:
		waitMOUSE();
	}
	if( ptinrect(mousep->xy,p->scroll) ){
		Scrolly = mousep->xy.y;
		Paint(p);
		Scrolly = 0;
		RequestLines(p);
		dprint(-1, "Doscroll()");
		return;
	}
	draw(screen, p->scroll, scrback, nil, ZPoint);
	dprint(-1, "Doscroll()");
}