#include "shape.h"

shape::shape(const coordsys& sys):drawable(sys),center_angle(0),
   filled(false),fill_color(red) {
}

void shape::set_filled(bool b) {
   filled = b;
}

void shape::set_center_angle(double a) {
   center_angle = a;
}

void shape::set_fill_color(const color& c) {
   fill_color = c;
}

bool shape::inside(const coordinate& o, const canvas& C) {
    // true if o is in C
    if (round(o.x()) >= C.width()  ||
        o.x() < 0           ||
        round(o.y()) >= C.height() ||
        o.y() < 0) {
        return false;
    }
    return true;
}

bool shape::intersects(const coordinate& p1, const coordinate& p2,
    const canvas& C, coordinate& o) {
    // the equation of the line
    // 
    //      dy               dy
    //     ---- x +  p1.y - ---- p1.x  = y
    //      dx               dx
    //
    // where dy = p2.y - p1.y, dx = p2.y - p2.x 
    //
    // special case when p2.x == p1.x, ie dx = 0
    //

    if (p2.x() == p1.x()) {
       if (p2.x() >= 0 && p2.x() < C.width()) {
          o = coordinate(p2.x(),C.height()/2);
          return true;
       } else {
          return false;
       }
    }


    double dy = p2.y() - p1.y(),
           dx = p2.x() - p1.x();

    double a = dy/dx, b = p1.y() - (p1.x()*dy)/dx;

    coordinate o1;
    bool o1_set=false;

    // does it intersect x = 0
    if (b>=0 && b< (double)C.height()) {
       o1_set = true;
       o1 = coordinate(0,b);
    }

    // does it intersect x = C.width() - 1?
    double y = (double)(C.width()-1)*a + b; 

    if (y>=0 && y < (double)C.height()) {
       if (!o1_set) {
          o1_set=true;
          o1 = coordinate(C.width()-1,y);
       } else {
          o = coordinate((o1.x()+C.width() - 1)/2,(o1.y()+y)/2);
          return true;
       }
    } 

    // does it intersect y = C.height()-1 ?
    double x = ((double)C.height() - 1  - b)/a;
 
    if (x>=0 && x < (double)C.width()) {
       if (!o1_set) {
          o1_set=true;
          o1 = coordinate(x,C.height()-1);
       } else {
          o = coordinate((o1.x()+x)/2,(o1.y()+C.height()-1)/2);
          return true;
       }
    }

    // does it intersect y = 0
    x = -b/a;

    if (!o1_set) return false;

    if (x>=0 && x < (double)C.width()) {
       o = coordinate((o1.x()+x)/2,o1.y()/2);
       return true;
    }
   
    return false;
}

coordinate shape::find_in(const coordinate& o1, const coordinate& o2,
       const canvas& C) {

    // assumptions o1 in, o2 in or out
    //
    //                 |  o2 if o2 in
    // eval f(o1,o2) = |
    //                 |  f(o1,(o1+o2)/2)

    // this procedure only takes a logarithmic number of steps,
    // and in practice is very fast

    if (inside(o2,C)) return o2;
    
    return find_in(o1, coordinate((o1.x()+o2.x())/2,(o1.y()+o2.y())/2),C);
}