#include <u.h>
#include <libc.h>
#include <thread.h>
#include <draw.h>
#include <memdraw.h>
#include <geometry.h>
#include "libobj/obj.h"
#include "graphics.h"
#include "internal.h"

Rectangle UR = {0,0,1,1};
//Procpool *turbodrawingpool;

static Vertexattr *
sparams_getuniform(Shaderparams *sp, char *id)
{
	USED(sp, id);
	return nil;
}

static Vertexattr *
sparams_getattr(Shaderparams *sp, char *id)
{
	return getvattr(sp->v, id);
}

static void
sparams_setattr(Shaderparams *sp, char *id, int type, void *val)
{
	addvattr(sp->v, id, type, val);
}

static void
sparams_toraster(Shaderparams *sp, char *rname, void *v)
{
	Framebuf *fb;
	Raster *r;
	ulong c;

	/* keep the user away from the color buffer */
	if(rname == nil || v == nil)
		return;

	fb = sp->su->fb;
	r = fb->fetchraster(fb, rname);
	if(r == nil)
		return;

	switch(r->chan){
	case COLOR32:
		c = col2ul(*(Color*)v);
		rasterput(r, sp->p, &c);
		break;
	case FLOAT32:
		rasterput(r, sp->p, v);
		break;
	}
}

static void
pixel(Raster *fb, Point p, Color c, int blend)
{
	Color dc;

	if(blend){
		dc = srgb2linear(ul2col(getpixel(fb, p)));
		c = lerp3(dc, c, c.a);	/* SoverD */
//		c = addpt3(mulpt3(dc, 1), mulpt3(c, 1-c.a));
//		c = subpt3(Vec3(1,1,1), subpt3(dc, c));
//		c = subpt3(addpt3(dc, c), Vec3(1,1,1));
	}
	putpixel(fb, p, col2ul(linear2srgb(c)));
}

static int
isvisible(Point3 p)
{
	if(p.x < -p.w || p.x > p.w ||
	   p.y < -p.w || p.y > p.w ||
	   p.z < -p.w || p.z > p.w)
		return 0;
	return 1;
}

static int
isfacingback(Primitive *p)
{
	double sa;	/* signed area */

	sa = p->v[0].p.x * p->v[1].p.y - p->v[0].p.y * p->v[1].p.x +
	     p->v[1].p.x * p->v[2].p.y - p->v[1].p.y * p->v[2].p.x +
	     p->v[2].p.x * p->v[0].p.y - p->v[2].p.y * p->v[0].p.x;
	return sa <= 0;
}

static void
pushtoAbuf(Framebuf *fb, Point p, Color c, float z)
{
	Abuf *buf;
	Astk *stk;
	int i;

	buf = &fb->abuf;
	stk = &buf->stk[p.y*Dx(fb->r) + p.x];
	stk->items = erealloc(stk->items, ++stk->size*sizeof(*stk->items));
	memset(&stk->items[stk->size-1], 0, sizeof(*stk->items));

	for(i = 0; i < stk->size; i++)
		if(z > stk->items[i].z)
			break;

	if(i < stk->size){
		memmove(&stk->items[i+1], &stk->items[i], (stk->size-1 - i)*sizeof(*stk->items));
		stk->items[i] = (Fragment){c, z};
	}else
		stk->items[stk->size-1] = (Fragment){c, z};

	if(!stk->active){
		stk->active++;
		stk->p = p;
		qlock(buf);
		buf->act = erealloc(buf->act, ++buf->nact*sizeof(*buf->act));
		buf->act[buf->nact-1] = stk;
		qunlock(buf);
	}
}

static void
squashAbuf(Framebuf *fb, int blend)
{
	Abuf *buf;
	Astk *stk;
	Raster *cr, *zr;
	int i, j;

	buf = &fb->abuf;
	cr = fb->rasters;
	zr = cr->next;
	for(i = 0; i < buf->nact; i++){
		stk = buf->act[i];
		j = stk->size;
		while(j--)
			pixel(cr, stk->p, stk->items[j].c, blend);
		/* write to the depth buffer as well */
		putdepth(zr, stk->p, stk->items[0].z);
	}
}

static Point3
_barycoords(Triangle2 t, Point2 p)
{
	Point2 p0p1 = subpt2(t.p1, t.p0);
	Point2 p0p2 = subpt2(t.p2, t.p0);
	Point2 pp0  = subpt2(t.p0, p);

	Point3 v = crossvec3(Vec3(p0p2.x, p0p1.x, pp0.x), Vec3(p0p2.y, p0p1.y, pp0.y));

	/* handle degenerate triangles—i.e. the ones where every point lies on the same line */
	if(fabs(v.z) < 1e-5)
		return Pt3(-1,-1,-1,1);
	return Pt3(1 - (v.x + v.y)/v.z, v.y/v.z, v.x/v.z, 1);
}

static void
rasterize(Rastertask *task)
{
	SUparams *params;
	Raster *cr, *zr;
	Primitive *prim;
	Vertex v;
	Shaderparams fsp;
	Triangle2 t;
	Point p, dp, Δp, p0, p1;
	Point3 bc;
	Color c;
	double dplen, perc;
	float z, pcz;
	int steep = 0, Δe, e, Δy;

	params = task->params;
	prim = &task->p;
	memset(&fsp, 0, sizeof fsp);
	memset(&v, 0, sizeof v);
	fsp.su = params;
	fsp.v = &v;
	fsp.getuniform = sparams_getuniform;
	fsp.getattr = sparams_getattr;
	fsp.setattr = nil;
	fsp.toraster = sparams_toraster;

	cr = params->fb->rasters;
	zr = cr->next;

	switch(prim->type){
	case PPoint:
		p = Pt(prim->v[0].p.x, prim->v[0].p.y);

		z = fclamp(prim->v[0].p.z, 0, 1);
		if(params->camera->enabledepth && z <= getdepth(zr, p))
			break;

		fsp.v = &prim->v[0];
		fsp.p = p;
		c = params->fshader(&fsp);
		if(c.a == 0)			/* discard non-colors */
			break;
		if(params->camera->enabledepth)
			putdepth(zr, p, z);
		if(params->camera->enableAbuff)
			pushtoAbuf(params->fb, p, c, z);
		else
			pixel(cr, p, c, params->camera->enableblend);
		delvattrs(fsp.v);
		break;
	case PLine:
		p0 = Pt(prim->v[0].p.x, prim->v[0].p.y);
		p1 = Pt(prim->v[1].p.x, prim->v[1].p.y);
		/* clip it against our wr */
		if(rectclipline(task->wr, &p0, &p1, &prim->v[0], &prim->v[1]) < 0)
			break;

		/* transpose the points */
		if(abs(p0.x-p1.x) < abs(p0.y-p1.y)){
			steep = 1;
			SWAP(int, &p0.x, &p0.y);
			SWAP(int, &p1.x, &p1.y);
		}

		/* make them left-to-right */
		if(p0.x > p1.x){
			SWAP(Point, &p0, &p1);
			SWAP(Vertex, &prim->v[0], &prim->v[1]);
		}

		dp = subpt(p1, p0);
		Δe = 2*abs(dp.y);
		e = 0;
		Δy = p1.y > p0.y? 1: -1;

		for(p = p0; p.x <= p1.x; p.x++){
			Δp = subpt(p, p0);
			dplen = hypot(dp.x, dp.y);
			perc = dplen == 0? 0: hypot(Δp.x, Δp.y)/dplen;

			if(steep) SWAP(int, &p.x, &p.y);

			z = flerp(prim->v[0].p.z, prim->v[1].p.z, perc);
			/* TODO get rid of the bounds check and make sure the clipping doesn't overflow */
			if(params->camera->enabledepth &&
			   !ptinrect(p, params->fb->r) || z <= getdepth(zr, p))
				goto discard;

			/* interpolate z⁻¹ and get actual z */
			pcz = flerp(prim->v[0].p.w, prim->v[1].p.w, perc);
			pcz = 1.0/(pcz < 1e-5? 1e-5: pcz);

			/* perspective-correct attribute interpolation  */
			perc *= prim->v[0].p.w * pcz;
			lerpvertex(fsp.v, &prim->v[0], &prim->v[1], perc);

			fsp.p = p;
			c = params->fshader(&fsp);
			if(c.a == 0)			/* discard non-colors */
				goto discard;
			if(params->camera->enabledepth)
				putdepth(zr, p, z);
			if(params->camera->enableAbuff)
				pushtoAbuf(params->fb, p, c, z);
			else
				pixel(cr, p, c, params->camera->enableblend);
discard:
			if(steep) SWAP(int, &p.x, &p.y);

			e += Δe;
			if(e > dp.x){
				p.y += Δy;
				e -= 2*dp.x;
			}
		}
		delvattrs(fsp.v);
		break;
	case PTriangle:
		t.p0 = Pt2(prim->v[0].p.x, prim->v[0].p.y, 1);
		t.p1 = Pt2(prim->v[1].p.x, prim->v[1].p.y, 1);
		t.p2 = Pt2(prim->v[2].p.x, prim->v[2].p.y, 1);

		for(p.y = task->wr.min.y; p.y < task->wr.max.y; p.y++)
		for(p.x = task->wr.min.x; p.x < task->wr.max.x; p.x++){
			bc = _barycoords(t, Pt2(p.x+0.5,p.y+0.5,1));
			if(bc.x < 0 || bc.y < 0 || bc.z < 0)
				continue;

			z = fberp(prim->v[0].p.z, prim->v[1].p.z, prim->v[2].p.z, bc);
			if(params->camera->enabledepth && z <= getdepth(zr, p))
				continue;

			/* interpolate z⁻¹ and get actual z */
			pcz = fberp(prim->v[0].p.w, prim->v[1].p.w, prim->v[2].p.w, bc);
			pcz = 1.0/(pcz < 1e-5? 1e-5: pcz);

			/* perspective-correct attribute interpolation  */
			bc = modulapt3(bc, Vec3(prim->v[0].p.w*pcz,
						prim->v[1].p.w*pcz,
						prim->v[2].p.w*pcz));
			berpvertex(fsp.v, &prim->v[0], &prim->v[1], &prim->v[2], bc);

			fsp.p = p;
			c = params->fshader(&fsp);
			if(c.a == 0)			/* discard non-colors */
				continue;
			if(params->camera->enabledepth)
				putdepth(zr, p, z);
			if(params->camera->enableAbuff)
				pushtoAbuf(params->fb, p, c, z);
			else
				pixel(cr, p, c, params->camera->enableblend);
		}
		delvattrs(fsp.v);
		break;
	default: sysfatal("alien primitive detected");
	}
}

static void
rasterizer(void *arg)
{
	Rasterparam *rp;
	Rastertask *task;
	SUparams *params;
	Renderjob *job;
	uvlong t0;
	int i;

	rp = arg;
	threadsetname("rasterizer %d", rp->id);

	while((task = recvp(rp->taskc)) != nil){
		t0 = nanosec();

		params = task->params;
		job = params->job;
		if(job->rctl->doprof && job->times.Rn[rp->id].t0 == 0)
			job->times.Rn[rp->id].t0 = t0;

		/* end of job */
		if(params->entity == nil){
			if(decref(job) < 1){
				if(job->camera->enableAbuff)
					squashAbuf(job->fb, job->camera->enableblend);
				if(job->rctl->doprof)
					job->times.Rn[rp->id].t1 = nanosec();
				nbsend(job->donec, nil);
				free(params);
			}else if(job->rctl->doprof)
				job->times.Rn[rp->id].t1 = nanosec();
			free(task);
			continue;
		}

		rasterize(task);

		for(i = 0; i < task->p.type+1; i++)
			delvattrs(&task->p.v[i]);
		free(params);
		free(task);
	}
}

static void
tiler(void *arg)
{
	Tilerparam *tp;
	SUparams *params, *newparams;
	Rastertask *task;
	Shaderparams vsp;
	Primitive *ep, *cp, *p;		/* primitives to raster */
	Rectangle *wr, bbox;
	Channel **taskchans;
	ulong Δy, nproc;
	int i, np;
	uvlong t0;

	tp = arg;
	threadsetname("tiler %d", tp->id);

	cp = emalloc(sizeof(*cp)*16);
	taskchans = tp->taskchans;
	nproc = tp->nproc;
	wr = emalloc(nproc*sizeof(Rectangle));

	memset(&vsp, 0, sizeof vsp);
	vsp.getuniform = sparams_getuniform;
	vsp.getattr = sparams_getattr;
	vsp.setattr = sparams_setattr;
	vsp.toraster = nil;

	while((params = recvp(tp->paramsc)) != nil){
		t0 = nanosec();
		if(params->job->rctl->doprof &&
		   params->job->times.Tn[tp->id].t0 == 0)
			params->job->times.Tn[tp->id].t0 = t0;

		/* end of job */
		if(params->entity == nil){
			if(params->job->rctl->doprof)
				params->job->times.Tn[tp->id].t1 = nanosec();
			if(decref(params->job) < 1){
				params->job->ref = nproc;
				for(i = 0; i < nproc; i++){
					task = emalloc(sizeof *task);
					memset(task, 0, sizeof *task);
					task->params = params;
					sendp(taskchans[i], task);
				}
			}
			continue;
		}
		vsp.su = params;

		wr[0] = params->fb->r;
		Δy = Dy(wr[0])/nproc;
		wr[0].max.y = wr[0].min.y + Δy;
		for(i = 1; i < nproc; i++)
			wr[i] = rectaddpt(wr[i-1], Pt(0,Δy));
		if(wr[nproc-1].max.y < params->fb->r.max.y)
			wr[nproc-1].max.y = params->fb->r.max.y;

		for(ep = params->eb; ep != params->ee; ep++){
			np = 1;	/* start with one. after clipping it might change */

			p = ep;
			switch(p->type){
			case PPoint:
				p->v[0].mtl = p->mtl;
				p->v[0].attrs = nil;
				p->v[0].nattrs = 0;

				vsp.v = &p->v[0];
				vsp.idx = 0;
				p->v[0].p = params->vshader(&vsp);

				if(!isvisible(p->v[0].p))
					break;

				p->v[0].p = clip2ndc(p->v[0].p);
				p->v[0].p = ndc2viewport(params->fb, p->v[0].p);

				bbox.min.x = p->v[0].p.x;
				bbox.min.y = p->v[0].p.y;
				bbox.max.x = p->v[0].p.x+1;
				bbox.max.y = p->v[0].p.y+1;

				for(i = 0; i < nproc; i++)
					if(rectXrect(bbox, wr[i])){
						newparams = emalloc(sizeof *newparams);
						*newparams = *params;
						task = emalloc(sizeof *task);
						task->params = newparams;
						task->p = *p;
						task->p.v[0] = dupvertex(&p->v[0]);
						sendp(taskchans[i], task);
						break;
					}
				delvattrs(&p->v[0]);
				break;
			case PLine:
				for(i = 0; i < 2; i++){
					p->v[i].mtl = p->mtl;
					p->v[i].attrs = nil;
					p->v[i].nattrs = 0;

					vsp.v = &p->v[i];
					vsp.idx = i;
					p->v[i].p = params->vshader(&vsp);
				}

				if(!isvisible(p->v[0].p) || !isvisible(p->v[1].p)){
					np = clipprimitive(p, cp);
					p = cp;
				}

				if(np < 1)
					break;

				p->v[0].p = clip2ndc(p->v[0].p);
				p->v[1].p = clip2ndc(p->v[1].p);
				p->v[0].p = ndc2viewport(params->fb, p->v[0].p);
				p->v[1].p = ndc2viewport(params->fb, p->v[1].p);

				bbox.min.x = min(p->v[0].p.x, p->v[1].p.x);
				bbox.min.y = min(p->v[0].p.y, p->v[1].p.y);
				bbox.max.x = max(p->v[0].p.x, p->v[1].p.x)+1;
				bbox.max.y = max(p->v[0].p.y, p->v[1].p.y)+1;

				for(i = 0; i < nproc; i++)
					if(rectXrect(bbox, wr[i])){
						newparams = emalloc(sizeof *newparams);
						*newparams = *params;
						task = emalloc(sizeof *task);
						task->params = newparams;
						task->wr = wr[i];
						task->p = *p;
						task->p.v[0] = dupvertex(&p->v[0]);
						task->p.v[1] = dupvertex(&p->v[1]);
						sendp(taskchans[i], task);
					}
				delvattrs(&p->v[0]);
				delvattrs(&p->v[1]);
				break;
			case PTriangle:
				for(i = 0; i < 3; i++){
					p->v[i].mtl = p->mtl;
					p->v[i].attrs = nil;
					p->v[i].nattrs = 0;
					p->v[i].tangent = p->tangent;

					vsp.v = &p->v[i];
					vsp.idx = i;
					p->v[i].p = params->vshader(&vsp);
				}

				if(!isvisible(p->v[0].p) || !isvisible(p->v[1].p) || !isvisible(p->v[2].p)){
					np = clipprimitive(p, cp);
					p = cp;
				}

				for(; np--; p++){
					p->v[0].p = clip2ndc(p->v[0].p);
					p->v[1].p = clip2ndc(p->v[1].p);
					p->v[2].p = clip2ndc(p->v[2].p);

					/* culling */
					switch(params->camera->cullmode){
					case CullFront: if(!isfacingback(p)) goto skiptri; break;
					case CullBack: if(isfacingback(p)) goto skiptri; break;
					}

					p->v[0].p = ndc2viewport(params->fb, p->v[0].p);
					p->v[1].p = ndc2viewport(params->fb, p->v[1].p);
					p->v[2].p = ndc2viewport(params->fb, p->v[2].p);

					bbox.min.x = min(min(p->v[0].p.x, p->v[1].p.x), p->v[2].p.x);
					bbox.min.y = min(min(p->v[0].p.y, p->v[1].p.y), p->v[2].p.y);
					bbox.max.x = max(max(p->v[0].p.x, p->v[1].p.x), p->v[2].p.x)+1;
					bbox.max.y = max(max(p->v[0].p.y, p->v[1].p.y), p->v[2].p.y)+1;

					for(i = 0; i < nproc; i++)
						if(rectXrect(bbox, wr[i])){
							newparams = emalloc(sizeof *newparams);
							*newparams = *params;
							task = emalloc(sizeof *task);
							task->params = newparams;
							task->wr = bbox;
							rectclip(&task->wr, wr[i]);
							task->p = *p;
							task->p.v[0] = dupvertex(&p->v[0]);
							task->p.v[1] = dupvertex(&p->v[1]);
							task->p.v[2] = dupvertex(&p->v[2]);
							sendp(taskchans[i], task);
						}
skiptri:
					delvattrs(&p->v[0]);
					delvattrs(&p->v[1]);
					delvattrs(&p->v[2]);
				}
				break;
			default: sysfatal("alien primitive detected");
			}
		}
		free(params);
	}
}

static void
entityproc(void *arg)
{
	Entityparam *ep;
	Channel *paramsin, **paramsout, **taskchans;
	Tilerparam *tp;
	Rasterparam *rp;
	SUparams *params, *newparams;
	Primitive *eb, *ee;
	ulong stride, nprims, nproc, nworkers;
	int i;
	uvlong t0;

	threadsetname("entityproc");

	ep = arg;
	paramsin = ep->paramsc;

	nproc = ep->rctl->nprocs;
	if(nproc > 2)
		nproc /= 2;

	paramsout = emalloc(nproc*sizeof(*paramsout));
	taskchans = emalloc(nproc*sizeof(*taskchans));
	for(i = 0; i < nproc; i++){
		paramsout[i] = chancreate(sizeof(SUparams*), 256);
		tp = emalloc(sizeof *tp);
		tp->id = i;
		tp->paramsc = paramsout[i];
		tp->taskchans = taskchans;
		tp->nproc = nproc;
		proccreate(tiler, tp, mainstacksize);
	}
	for(i = 0; i < nproc; i++){
		rp = emalloc(sizeof *rp);
		rp->id = i;
		rp->taskc = taskchans[i] = chancreate(sizeof(Rastertask*), 512);
		proccreate(rasterizer, rp, mainstacksize);
	}

	while((params = recvp(paramsin)) != nil){
		t0 = nanosec();
		if(params->job->rctl->doprof && params->job->times.E.t0 == 0)
			params->job->times.E.t0 = t0;

		/* prof: initialize timing slots for the next stages */
		if(params->job->rctl->doprof && params->job->times.Tn == nil){
			assert(params->job->times.Rn == nil);
			params->job->times.Tn = emalloc(nproc*sizeof(Rendertime));
			params->job->times.Rn = emalloc(nproc*sizeof(Rendertime));
			memset(params->job->times.Tn, 0, nproc*sizeof(Rendertime));
			memset(params->job->times.Rn, 0, nproc*sizeof(Rendertime));
		}

		/* end of job */
		if(params->entity == nil){
			params->job->ref = nproc;
			for(i = 0; i < nproc; i++)
				sendp(paramsout[i], params);
			if(params->job->rctl->doprof)
				params->job->times.E.t1 = nanosec();
			continue;
		}

		eb = params->entity->mdl->prims;
		nprims = params->entity->mdl->nprims;
		ee = eb + nprims;

		if(nprims <= nproc){
			nworkers = nprims;
			stride = 1;
		}else{
			nworkers = nproc;
			stride = nprims/nproc;
		}

		for(i = 0; i < nworkers; i++){
			newparams = emalloc(sizeof *newparams);
			*newparams = *params;
			newparams->eb = eb + i*stride;
			newparams->ee = i == nworkers-1? ee: newparams->eb + stride;
			sendp(paramsout[i], newparams);
		}
		free(params);
	}
}

static void
renderer(void *arg)
{
	Renderer *rctl;
	Renderjob *job;
	Scene *sc;
	Entity *ent;
	SUparams *params;
	Entityparam *ep;
	uvlong time, lastid;

	threadsetname("renderer");

	rctl = arg;
	lastid = 0;

	ep = emalloc(sizeof *ep);
	ep->rctl = rctl;
	ep->paramsc = chancreate(sizeof(SUparams*), 256);
	proccreate(entityproc, ep, mainstacksize);

	while((job = recvp(rctl->jobq)) != nil){
		time = nanosec();
		if(job->rctl->doprof) job->times.R.t0 = time;
		job->id = lastid++;
		sc = job->scene;
		if(sc->nents < 1){
			nbsend(job->donec, nil);
			continue;
		}

		/* initialize the A-buffer */
		if(job->camera->enableAbuff && job->fb->abuf.stk == nil){
			job->fb->abuf.stk = emalloc(Dx(job->fb->r)*Dy(job->fb->r)*sizeof(Astk));
			memset(job->fb->abuf.stk, 0, Dx(job->fb->r)*Dy(job->fb->r)*sizeof(Astk));
		}

		for(ent = sc->ents.next; ent != &sc->ents; ent = ent->next){
			params = emalloc(sizeof *params);
			memset(params, 0, sizeof *params);
			params->fb = job->fb;
			params->job = job;
			params->camera = job->camera;
			params->entity = ent;
			params->uni_time = time;
			params->vshader = job->shaders->vshader;
			params->fshader = job->shaders->fshader;
			sendp(ep->paramsc, params);
		}
		/* mark end of job */
		params = emalloc(sizeof *params);
		memset(params, 0, sizeof *params);
		params->job = job;
		sendp(ep->paramsc, params);

		if(job->rctl->doprof) job->times.R.t1 = nanosec();
	}
}

Renderer *
initgraphics(void)
{
	Renderer *r;
	char *nprocs;
	ulong nproc;

	nprocs = getenv("NPROC");
	if(nprocs == nil || (nproc = strtoul(nprocs, nil, 10)) < 2)
		nproc = 1;
	free(nprocs);

//	turbodrawingpool = mkprocpool(nproc);

	r = emalloc(sizeof *r);
	memset(r, 0, sizeof *r);
	r->jobq = chancreate(sizeof(Renderjob*), 8);
	r->nprocs = nproc;
	proccreate(renderer, r, mainstacksize);
	return r;
}