/*
 * This file contains routines used to support the "set jitter" option.
 * This plot mode was inspired by the appearance of "beeswarm" plots produced
 * by R, but I do not know to what extent the algorithms used are the same.
 */
/*[
 * Copyright Ethan A Merritt 2015
 *
 * Gnuplot license:
 *
 * Permission to use, copy, and distribute this software and its
 * documentation for any purpose with or without fee is hereby granted,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.
 *
 * Permission to modify the software is granted, but not the right to
 * distribute the complete modified source code.  Modifications are to
 * be distributed as patches to the released version.  Permission to
 * distribute binaries produced by compiling modified sources is granted,
 * provided you
 *   1. distribute the corresponding source modifications from the
 *    released version in the form of a patch file along with the binaries,
 *   2. add special version identification to distinguish your version
 *    in addition to the base release version number,
 *   3. provide your name and address as the primary contact for the
 *    support of your modified version, and
 *   4. retain our contact information in regard to use of the base
 *    software.
 * Permission to distribute the released version of the source code along
 * with corresponding source modifications in the form of a patch file is
 * granted with same provisions 2 through 4 for binary distributions.
 *
 * This software is provided "as is" without express or implied warranty
 * to the extent permitted by applicable law.
 *
 * Alternative license:
 *
 * As an alternative to distributing code in this file under the gnuplot license,
 * you may instead comply with the terms below. In this case, redistribution and
 * use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.  Redistributions in binary
 * form must reproduce the above copyright notice, this list of conditions and
 * the following disclaimer in the documentation and/or other materials provided
 * with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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]*/

#include "jitter.h"

t_jitter jitter = {{first_axes, first_axes, first_axes, 0.0, 0.0, 0.0}, 0.0, 0.0, JITTER_DEFAULT};

static int compare_xypoints(SORTFUNC_ARGS arg1, SORTFUNC_ARGS arg2);

static int
compare_xypoints(SORTFUNC_ARGS arg1, SORTFUNC_ARGS arg2)
{
    struct coordinate const *p1 = arg1;
    struct coordinate const *p2 = arg2;

    /* Primary sort is on x */
    /* FIXME: I'd like to treat x coords within jitter.x as equal, */
    /*        but the coordinate system mismatch makes this hard.  */
    if (p1->x > p2->x)
	return (1);
    if (p1->x < p2->x)
	return (-1);

    if (p1->y > p2->y)
	return (1);
    if (p1->y < p2->y)
	return (-1);
    return (0);
}

/*
 * "set jitter overlap  spread "
 * displaces overlapping points in a point plot.
 * The jittering algorithm is inspired by the beeswarm plot variant in R.
 */
static double
jdist(coordinate *pi, coordinate *pj)
{
    int delx = map_x(pi->x) - map_x(pj->x);
    int dely = map_y(pi->y) - map_y(pj->y);
    return sqrt( delx*delx + dely*dely );
}

void
jitter_points(struct curve_points *plot)
{
    int i, j;
    double xjit, ygap;
    struct position yoverlap;

    /* The "x" and "xscale" stored in jitter are really along y */
    yoverlap.x = 0;
    yoverlap.y = jitter.overlap.x;
    yoverlap.scaley = jitter.overlap.scalex;
    map_position_r(&yoverlap, &xjit, &ygap, "jitter");

    /* Clear data slots where we will later store the jitter offsets.
     * Store variable color temporarily in z so it is not lost by sorting.
     */
    for (i = 0; i < plot->p_count; i++) {
	if (plot->varcolor)
	    plot->points[i].z = plot->varcolor[i];
	plot->points[i].CRD_XJITTER = 0.0;
	plot->points[i].CRD_YJITTER = 0.0;
    }

    /* Sort points */
    qsort(plot->points, plot->p_count, sizeof(struct coordinate), compare_xypoints);

    /* For each point, check whether subsequent points would overlap it. */
    /* If so, displace them in a fixed pattern */
    i = 0;
    while (i < plot->p_count - 1) {
	for (j = 1; i+j < plot->p_count; j++) {
	    if (jdist(&plot->points[i], &plot->points[i+j]) >= ygap)
		break;

	    /* Displace point purely on x */
	    xjit  = (j+1)/2 * jitter.spread * plot->lp_properties.p_size;
	    if (jitter.limit > 0)
		while (xjit > jitter.limit)
			xjit -= jitter.limit;
	    if ((j & 01) != 0)
		    xjit = -xjit;
	    plot->points[i+j].CRD_XJITTER = xjit;

	    if (jitter.style == JITTER_SQUARE)
		plot->points[i+j].CRD_YJITTER = plot->points[i].y - plot->points[i+j].y;

	    /* Displace points on y instead of x */
	    if (jitter.style == JITTER_ON_Y) {
		plot->points[i+j].CRD_YJITTER = xjit;
		plot->points[i+j].CRD_XJITTER = 0;
	    }

	}
	i += j;
    }

    /* Copy variable colors back to where the plotting code expects to find them */
    if (plot->varcolor) {
	for (i = 0; i < plot->p_count; i++)
	    plot->varcolor[i] = plot->points[i].z;
    }

}

/* process 'set jitter' command */
void
set_jitter()
{
    c_token++;
    /* Default overlap criterion 1 character (usually on y) */
    jitter.overlap.scalex = character;
    jitter.overlap.x = 1;
    jitter.spread = 1.0;
    jitter.limit = 0.0;
    jitter.style = JITTER_DEFAULT;
    if (END_OF_COMMAND)
	return;

    while (!END_OF_COMMAND) {
	if (almost_equals(c_token, "over$lap")) {
	    c_token++;
	    get_position_default(&jitter.overlap, character, TRUE, 2);
	} else if (equals(c_token, "spread")) {
	    c_token++;
	    jitter.spread = real_expression();
	    if (jitter.spread