/**
 * \file line-snapper.cpp
 * \brief LineSnapper class.
 *
 * Authors:
 *   Diederik van Lierop <mail@diedenrezi.nl>
 *   And others...
 * 
 * Copyright (C) 1999-2007 Authors
 *
 * Released under GNU GPL, read the file 'COPYING' for more information
 */

#include "libnr/nr-values.h"
#include "libnr/nr-point-fns.h"
#include <2geom/geom.h>
#include "line-snapper.h"
#include "snapped-line.h"
#include <gtk/gtk.h>

Inkscape::LineSnapper::LineSnapper(SPNamedView const *nv, NR::Coord const d) : Snapper(nv, d)
{

}

void Inkscape::LineSnapper::_doFreeSnap(SnappedConstraints &sc,
                                                    Inkscape::Snapper::PointType const &t,
                                                    NR::Point const &p,
                                                    bool const &f,
                                                    std::vector<NR::Point> &points_to_snap,
                                                    std::list<SPItem const *> const &it) const
{
    Inkscape::SnappedPoint s = SnappedPoint(p, NR_HUGE);

    /* Get the lines that we will try to snap to */
    const LineList lines = _getSnapLines(p);

    // std::cout << "snap point " << p << " to: " << std::endl;

    for (LineList::const_iterator i = lines.begin(); i != lines.end(); i++) {
        NR::Point const p1 = i->second; // point at guide/grid line
        NR::Point const p2 = p1 + NR::rot90(i->first); // 2nd point at guide/grid line
        
        // std::cout << "  line through " << i->second << " with normal " << i->first;
        
        g_assert(i->first != NR::Point(0,0)); // otherwise we'll have div. by zero because NR::L2(d2) = 0
        
        // p_proj = projection of p on the grid/guide line running from p1 to p2
        // p_proj = p1 + u (p2 - p1)
        // calculate u according to "Minimum Distance between a Point and a Line"
        // see http://local.wasp.uwa.edu.au/~pbourke/geometry/pointline/        
        NR::Point const d1(p-p1); // delta 1
        NR::Point const d2(p2-p1); // delta 1
        double const u = (d1[NR::X] * d2[NR::X] + d1[NR::Y] * d2[NR::Y]) / (NR::L2(d2) * NR::L2(d2));
        
        NR::Point const p_proj(p1 + u*(p2-p1));
        NR::Coord const dist = NR::L2(p_proj - p);
        //Store any line that's within snapping range
        if (dist < getDistance()) {
            _addSnappedLine(sc, p_proj, dist, i->first, i->second);
            // std::cout << " -> distance = " << dist; 
        }     
        // std::cout << std::endl;
    }    
}

void Inkscape::LineSnapper::_doConstrainedSnap(SnappedConstraints &sc,
                                               Inkscape::Snapper::PointType const &/*t*/,
                                               NR::Point const &p,
                                               bool const &/*f*/,
                                               std::vector<NR::Point> &/*points_to_snap*/,
                                               ConstraintLine const &c,
                                               std::list<SPItem const *> const &/*it*/) const

{
    Inkscape::SnappedPoint s = SnappedPoint(p, NR_HUGE);

    /* Get the lines that we will try to snap to */
    const LineList lines = _getSnapLines(p);

    for (LineList::const_iterator i = lines.begin(); i != lines.end(); i++) {

        /* Normal to the line we're trying to snap along */
        NR::Point const n(NR::rot90(NR::unit_vector(c.getDirection())));

        NR::Point const point_on_line = c.hasPoint() ? c.getPoint() : p;

        /* Constant term of the line we're trying to snap along */
        NR::Coord const q0 = dot(n, point_on_line);
        /* Constant term of the grid or guide line */
        NR::Coord const q1 = dot(i->first, i->second);        

        /* Try to intersect this line with the target line */
        Geom::Point t_2geom(NR_HUGE, NR_HUGE);
        Geom::IntersectorKind const k = Geom::line_intersection(n.to_2geom(), q0, i->first.to_2geom(), q1, t_2geom);
        NR::Point t(t_2geom);

        if (k == Geom::intersects) {
            const NR::Coord dist = L2(t - p);
            //Store any line that's within snapping range
            if (dist < getDistance()) {
				_addSnappedLine(sc, t, dist, c.getDirection(), t);
            }
        }
    }
}

/*
  Local Variables:
  mode:c++
  c-file-style:"stroustrup"
  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
  indent-tabs-mode:nil
  fill-column:99
  End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :