#include <u.h>
#include <libc.h>
#include <draw.h>
#include <thread.h>
#include <mouse.h>

#include "submenu.h"

int gensubmenuhit(int but, Mousectl *mc, Submenu *menu, Point pos, int sub);

enum
{
	Margin = 4,		/* outside to text */
	Border = 2,		/* outside to selection boxes */
	Blackborder = 2,	/* width of outlining border */
	Vspacing = 2,		/* extra spacing between lines of text */
	Openspacing = 5,
	Closespacing = 8,
//	Maxunscroll = 25,	/* maximum #entries before scrolling turns on */
//	Nscroll = 20,		/* number entries in scrolling part */
//	Scrollwid = 14,		/* width of scroll bar */
//	Gap = 4,			/* between text and scroll bar */
};

#define Itemheight (font->height+Vspacing)

static	Image	*menutxt;
static	Image	*back;
static	Image	*high;
static	Image	*bord;
static	Image	*text;
static	Image	*htext;

static
void
menucolors(void)
{
	/* Main tone is greenish, with negative selection */
	back = allocimagemix(display, DPalegreen, DWhite);
	high = allocimage(display, Rect(0,0,1,1), screen->chan, 1, DDarkgreen);	/* dark green */
	bord = allocimage(display, Rect(0,0,1,1), screen->chan, 1, DMedgreen);	/* not as dark green */
	if(back==nil || high==nil || bord==nil)
		goto Error;
	text = display->black;
	htext = back;
	return;

    Error:
	freeimage(back);
	freeimage(high);
	freeimage(bord);
	back = display->white;
	high = display->black;
	bord = display->black;
	text = display->black;
	htext = display->white;
}

static Rectangle
menurect(Rectangle r, int i)
{
	if(i < 0)
		return Rect(0, 0, 0, 0);
	r.min.y += Itemheight*i;
	r.max.y = r.min.y+Itemheight;
	return insetrect(r, Border-Margin);
}

static void
paintitem(Image *m, Submenu *menu, Rectangle textr, int i, int highlight)
{
	char *item;
	Rectangle r;
	Point pt;

	if(i < 0)
		return;
	r = menurect(textr, i);
	item = menu->item[i].str;
	pt.x = (textr.min.x+textr.max.x-stringwidth(font, item))/2;
	pt.y = textr.min.y+i*Itemheight;
	draw(m, r, highlight? high : back, nil, pt);
	string(m, pt, highlight? htext : text, pt, font, item);

	if(menu->item[i].submenu){
		pt.x = textr.max.x - stringwidth(font, ">");
		string(m, pt, highlight? htext : text, pt, font, ">");
	}
}

static int
menusel(Rectangle r, Point p)
{
	if(!ptinrect(p, r))
		return -1;
	return (p.y-r.min.y)/Itemheight;
}

/* while mouse is over menu */
static int
menuscan(Image *m, Submenu *menu, int but, Mousectl *mc, Rectangle textr)
{
	int i, lasti, cmd;
	Submenu *sub;

	lasti = menusel(textr, mc->xy);
	paintitem(m, menu, textr, lasti, 1);
	readmouse(mc);
	while(mc->buttons & (1<<(but-1))){
		i = menusel(textr, mc->xy);
		if(i != lasti)
			paintitem(m, menu, textr, lasti, 0);
		if(i == -1)
			return -1;
		lasti = i;
		paintitem(m, menu, textr, lasti, 1);

		sub = menu->item[lasti].submenu;
		if(sub && mc->xy.x > textr.max.x-Openspacing){
			Point pt = Pt(textr.max.x + Margin,
				textr.min.y + Itemheight*lasti);
			cmd = gensubmenuhit(but, mc, sub, pt, 1);
//			print("subhit: %d\n", cmd);
			if(cmd >= 0){
				menu->lasthit = menu->item[i].cmd;
				return cmd;
			}
			/* redraw with current mouse state */
			continue;
		}

		readmouse(mc);
	}
	if(lasti == -1)
		return -1;
	menu->lasthit = menu->item[lasti].cmd;
	return menu->lasthit;
}

static void
menupaint(Image *m, Submenu *menu, Rectangle textr, int nitem)
{
	int i;

	draw(m, insetrect(textr, Border-Margin), back, nil, ZP);
	for(i = 0; i < nitem; i++)
		paintitem(m, menu, textr, i, 0);
}

static Point
clampscreen(Rectangle r)
{
	Point pt;

	pt = ZP;
	if(r.max.x>screen->r.max.x)
		pt.x = screen->r.max.x-r.max.x;
	if(r.max.y>screen->r.max.y)
		pt.y = screen->r.max.y-r.max.y;
	if(r.min.x<screen->r.min.x)
		pt.x = screen->r.min.x-r.min.x;
	if(r.min.y<screen->r.min.y)
		pt.y = screen->r.min.y-r.min.y;
	return pt;
}

int
gensubmenuhit(int but, Mousectl *mc, Submenu *menu, Point pos, int issub)
{
	int i, lasti, cmd;
	Menuitem *item;
	int hassub;
	int width, nitem;
	Rectangle r, textr, menur, closer;
	Point delta;

	if(back == nil)
		menucolors();

	hassub = 0;
	width = 0;
	lasti = 0;
	for(nitem = 0; item = &menu->item[nitem], item->str; nitem++){
		i = stringwidth(font, item->str);
		if(i > width)
			width = i;
		if(menu->lasthit == item->cmd)
			lasti = nitem;
		if(item->submenu)
			hassub = 1;
	}
	if(hassub)
		width += stringwidth(font, "   >");

	r = insetrect(Rect(0, 0, width, nitem*Itemheight), -Margin);
	if(issub){
		r = rectsubpt(r, Pt(-Margin, lasti*Itemheight));
		menur = rectaddpt(r, pos);
	}else{
		r = rectsubpt(r, Pt(width/2, lasti*Itemheight+Itemheight/2));
		menur = rectaddpt(r, mc->xy);
	}
	delta = clampscreen(menur);
	menur = rectaddpt(menur, delta);
	if(issub){
		// TODO: not sure about vertical spacing here
		closer = Rect(0, menur.min.y-2,
			menur.min.x-Closespacing, menur.max.y+2);
	}else{
		closer = Rect(0,0,0,0);
		if(delta.x || delta.y)
			moveto(mc, addpt(mc->xy, delta));
	}
	textr = insetrect(menur, Margin);

	Image *b, *backup;
	{
		b = screen;
		backup = allocimage(display, menur, screen->chan, 0, -1);
		draw(backup, menur, screen, nil, menur.min);
	}
	draw(b, menur, back, nil, ZP);
	border(b, menur, Blackborder, bord, ZP);
	menupaint(b, menu, textr, nitem);

	cmd = -1;
	while(mc->buttons & (1<<(but-1))){
		cmd = menuscan(b, menu, but, mc, textr);
//print("scan %d\n", cmd);
		if(cmd >= 0)
			break;
		if(ptinrect(mc->xy, closer))
			break;
	}
//print("menucmd: %d\n", cmd);

	if(backup){
		draw(screen, menur, backup, nil, menur.min);
		freeimage(backup);
	}
	flushimage(display, 1);

	return cmd;
}

int submenuhit(int but, Mousectl *mc, Submenu *menu)
{
	return gensubmenuhit(but, mc, menu, ZP, 0);
}