/*
  This file is part of the Astrometry.net suite.
  Copyright 2011, 2012 Dustin Lang.

  The Astrometry.net suite is free software; you can redistribute
  it and/or modify it under the terms of the GNU General Public License
  as published by the Free Software Foundation, version 2.

  The Astrometry.net suite is distributed in the hope that it will be
  useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with the Astrometry.net suite ; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
*/

double MANGLE(lanczos_resample_unw_sep)(double px, double py,
										const number* img,
										int W, int H, void* token) {
	lanczos_args_t* args = token;
	int order = args->order;
	int support = order;
	double weight;
	double sum;
	int x0,x1,y0,y1;
	const number* imgrow;
	int weighted = args->weighted;

	// pre-compute Lanczos kernel weights
	double KY[12];
	double KX[12];

	x0 = MAX(0,   (int)floor(px - support));
	y0 = MAX(0,   (int)floor(py - support));
	x1 = MIN(W-1, (int) ceil(px + support));
	y1 = MIN(H-1, (int) ceil(py + support));

	int nx,ny,dx,dy;
	nx = 1+x1-x0;
	ny = 1+y1-y0;
	assert(nx < 12);
	assert(ny < 12);

	for (dy=0; dy<ny; dy++)
		KY[dy] = lanczos(py - (y0+dy), order);
	for (dx=0; dx<nx; dx++)
		KX[dx] = lanczos(px - (x0+dx), order);

	weight = 0.0;
	sum = 0.0;
	for (dy=0; dy<ny; dy++) {
		double Ky;
		double xweight;
		double xsum;
		Ky = KY[dy];
		if (Ky == 0)
			continue;
		imgrow = img + (dy+y0)*W + x0;
		xweight = 0.0;
		xsum = 0.0;
		for (dx=0; dx<nx; dx++) {
			double K;
			number pix;
			K = KX[dx];
			if (K == 0)
				continue;
			pix = imgrow[dx];
			if (isnan(pix))
				continue;
			if (weighted)
				xweight += K;
			xsum += K * pix;
		}
		if (weighted && xweight == 0.0)
			continue;
		if (weighted) {
			/*
			 weight += Ky;
			 sum += Ky * (xsum / xweight);
			 */
			weight += Ky * xweight;
		}
		sum += Ky * xsum;
	}
	if (weighted)
		return sum / weight;
	else
		return sum;
}

double MANGLE(lanczos_resample)(double px, double py,
								const number* img, const number* weightimg,
								int W, int H,
								double* out_wt,
								void* token) {
	lanczos_args_t* args = token;
	int order = args->order;
	int support = order;

	double weight;
	double sum;
	int x0,x1,y0,y1;
	int ix,iy;

	x0 = MAX(0, (int)floor(px - support));
	y0 = MAX(0, (int)floor(py - support));
	x1 = MIN(W-1, (int) ceil(px + support));
	y1 = MIN(H-1, (int) ceil(py + support));
	weight = 0.0;
	sum = 0.0;

	for (iy=y0; iy<=y1; iy++) {
		for (ix=x0; ix<=x1; ix++) {
			double K;
			number pix;
			number wt;
			double d;
			d = hypot(px - ix, py - iy);
			K = lanczos(d, order);
			if (K == 0)
				continue;
			if (weightimg) {
				wt = weightimg[iy*W + ix];
				if (wt == 0.0)
					continue;
			} else
				wt = 1.0;
			pix = img[iy*W + ix];
			if (isnan(pix))
				// out-of-bounds pixel
				continue;
			/*
			 if (!isfinite(pix)) {
			 logverb("Pixel value: %g\n", pix);
			 continue;
			 }
			 */
			weight += K * wt;
			sum += K * wt * pix;
		}
	}

	if (out_wt)
		*out_wt = weight;
	return sum;
}

double MANGLE(nearest_resample)(double px, double py,
								const number* img, const number* weightimg,
								int W, int H,
								double* out_wt,
								void* token) {
	int ix = round(px);
	int iy = round(py);
	double wt;

	if (ix < 0 || ix >= W || iy < 0 || iy >= H) {
		if (out_wt)
			*out_wt = 0.0;
		return 0.0;
	}

	if (weightimg)
		wt = weightimg[iy * W + ix];
	else
		wt = 1.0;

	if (out_wt)
		*out_wt = wt;

	return img[iy*W + ix] * wt;
}

