#include "solvespace.h"

bool Constraint::HasLabel(void) {
    switch(type) {
        case PT_PT_DISTANCE:
            return true;

        default:
            return false;
    }
}

void Constraint::LineDrawOrGetDistance(Vector a, Vector b) {
    if(dogd.drawing) {
        glBegin(GL_LINE_STRIP);
            glxVertex3v(a);
            glxVertex3v(b);
        glEnd();
    } else {
        Point2d ap = SS.GW.ProjectPoint(a);
        Point2d bp = SS.GW.ProjectPoint(b);

        double d = dogd.mp.DistanceToLine(ap, bp.Minus(ap), true);
        dogd.dmin = min(dogd.dmin, d);
    }
}

void Constraint::DrawOrGetDistance(Vector *labelPos) {
    if(!SS.GW.showConstraints) return;

    // Unit vectors that describe our current view of the scene.
    Vector gr = SS.GW.projRight;
    Vector gu = SS.GW.projUp;
    Vector gn = gr.Cross(gu);

    glxColor(1, 0.3, 1);
    switch(type) {
        case PT_PT_DISTANCE: {
            Vector ap = SS.GetEntity(ptA)->PointGetCoords();
            Vector bp = SS.GetEntity(ptB)->PointGetCoords();

            Vector ref = ((ap.Plus(bp)).ScaledBy(0.5)).Plus(disp.offset);
            if(labelPos) *labelPos = ref;

            Vector ab   = ap.Minus(bp);
            Vector ar   = ap.Minus(ref);
            // Normal to a plan containing the line and the label origin.
            Vector n    = ab.Cross(ar);
            Vector out  = ab.Cross(n).WithMagnitude(1);
            out = out.ScaledBy(-out.Dot(ar));

            LineDrawOrGetDistance(ap, ap.Plus(out));
            LineDrawOrGetDistance(bp, bp.Plus(out));

            if(dogd.drawing) {
                glPushMatrix();
                    glxTranslatev(ref);
                    glxOntoCsys(gr, gu);
                    glxWriteText(exprA->Print());
                glPopMatrix();
            } else {
                Point2d o = SS.GW.ProjectPoint(ref);
                dogd.dmin = min(dogd.dmin, o.DistanceTo(dogd.mp) - 10);
            }

            break;
        }

        case POINTS_COINCIDENT: {
            if(!dogd.drawing) {
                for(int i = 0; i < 2; i++) {
                    Vector p = SS.GetEntity(i == 0 ? ptA : ptB)->
                                                            PointGetCoords();
                    Point2d pp = SS.GW.ProjectPoint(p);
                    // The point is selected within a radius of 7, from the
                    // same center; so if the point is visible, then this
                    // constraint cannot be selected. But that's okay.
                    dogd.dmin = min(dogd.dmin, pp.DistanceTo(dogd.mp) - 3);
                }
                break;
            }

            for(int a = 0; a < 2; a++) {
                Vector r = SS.GW.projRight.ScaledBy((a+1)/SS.GW.scale);
                Vector d = SS.GW.projUp.ScaledBy((2-a)/SS.GW.scale);
                for(int i = 0; i < 2; i++) {
                    Vector p = SS.GetEntity(i == 0 ? ptA : ptB)->
                                                            PointGetCoords();
                    glxColor(0.4, 0, 0.4);
                    glBegin(GL_QUADS);
                        glxVertex3v(p.Plus (r).Plus (d));
                        glxVertex3v(p.Plus (r).Minus(d));
                        glxVertex3v(p.Minus(r).Minus(d));
                        glxVertex3v(p.Minus(r).Plus (d));
                    glEnd();
                }

            }
            break;
        }

        case PT_IN_PLANE: {
            double s = 5;
            Vector r = SS.GW.projRight.ScaledBy(s/SS.GW.scale);
            Vector d = SS.GW.projUp.ScaledBy(s/SS.GW.scale);
            Vector p = SS.GetEntity(ptA)->PointGetCoords();
            LineDrawOrGetDistance(p.Plus (r).Plus (d), p.Plus (r).Minus(d));
            LineDrawOrGetDistance(p.Plus (r).Minus(d), p.Minus(r).Minus(d));
            LineDrawOrGetDistance(p.Minus(r).Minus(d), p.Minus(r).Plus (d));
            LineDrawOrGetDistance(p.Minus(r).Plus (d), p.Plus (r).Plus (d));
            break;
        }

        case EQUAL_LENGTH_LINES: {
            for(int i = 0; i < 2; i++) {
                Entity *e = SS.GetEntity(i == 0 ? entityA : entityB);
                Vector a = SS.GetEntity(e->assoc[0])->PointGetCoords();
                Vector b = SS.GetEntity(e->assoc[1])->PointGetCoords();
                Vector m = (a.ScaledBy(1.0/3)).Plus(b.ScaledBy(2.0/3));
                Vector ab = a.Minus(b);
                Vector n = (gn.Cross(ab)).WithMagnitude(10/SS.GW.scale);
                
                LineDrawOrGetDistance(m.Minus(n), m.Plus(n));
            }
            break;
        }

        default: oops();
    }
}

void Constraint::Draw(void) {
    dogd.drawing = true;
    DrawOrGetDistance(NULL);
}

double Constraint::GetDistance(Point2d mp) {
    dogd.drawing = false;
    dogd.mp = mp;
    dogd.dmin = 1e12;

    DrawOrGetDistance(NULL);
    
    return dogd.dmin;
}

Vector Constraint::GetLabelPos(void) {
    dogd.drawing = false;
    dogd.mp.x = 0; dogd.mp.y = 0;
    dogd.dmin = 1e12;

    Vector p;
    DrawOrGetDistance(&p);
    return p;
}