#include "geometry.h"
#include <math.h>
#include <stdlib.h>
#include <gtk/gtk.h>


int vertexOnLine(const Vertex *v, const LINE *l) {
  if(l->v1.getX() == l->v2.getX() && l->v1.getY() == l->v2.getY()) {
    if(l->v1.getX() == v->getX() && l->v1.getY() == v->getY()) return 1;
    else return 0;
  }
  
  if(l->v1.getX() == l->v2.getX()) {
    if(l->v1.getX() != v->getX()) return 0;
    else if(v->getY() >= MIN(l->v1.getY(), l->v2.getY()) && v->getY() <= MAX(l->v1.getY(), l->v2.getY())) return 1;
    else return 1;
  }
  
  if(l->v1.getY() == l->v2.getY()) {
    if(l->v1.getY() != v->getY()) return 0;
    else if(v->getX() >= MIN(l->v1.getX(), l->v2.getX()) && v->getX() <= MAX(l->v1.getX(), l->v2.getX())) return 1;
    else return 1;
  }
  if((v->getX()-l->v1.getX())/(l->v2.getX()-l->v1.getX()) - (v->getY()-l->v1.getY())/(l->v2.getY()-l->v1.getY()) == 0) return 1;
  else return 0;
}

int vertexInRect(const Vertex *v, const RECTANGLE *rect) {
  int ret = EDGE_NONE;
  
  if(v->getX() < rect->x) ret |= EDGE_LEFT;
  else if(v->getX() >= rect->x+rect->width) ret |= EDGE_RIGHT;
  
  if(v->getY() < rect->y) ret |= EDGE_TOP;
  else if(v->getY() >= rect->y+rect->height) ret |= EDGE_BOTTOM;
  
  return ret;
}


int lineRectIntersection(const LINE *l, const RECTANGLE *rect, int edge, Vertex *v) {
  const double minX = rect->x, maxX = rect->x+rect->width;
  const double minY = rect->y, maxY = rect->y+rect->height;
  const LINE top = {Vertex(minX, minY), Vertex(maxX, minY)};
  const LINE bottom = {Vertex(minX, maxY), Vertex(maxX, maxY)};
  const LINE left = {Vertex(minX, minY), Vertex(minX, maxY)};
  const LINE right = {Vertex(maxX, minY), Vertex(maxX, maxY)};
  
  if((edge & EDGE_TOP) && (lineIntersection(&top, l, v) == INTERSECTION_SEGMENT_SEGMENT))
    return EDGE_TOP;
  if((edge & EDGE_BOTTOM) && (lineIntersection(&bottom, l, v) == INTERSECTION_SEGMENT_SEGMENT))
    return EDGE_BOTTOM;
  if((edge & EDGE_LEFT) && (lineIntersection(&left, l, v) == INTERSECTION_SEGMENT_SEGMENT))
    return EDGE_LEFT;
  if((edge & EDGE_RIGHT) && (lineIntersection(&right, l, v) == INTERSECTION_SEGMENT_SEGMENT))
    return EDGE_RIGHT;
  
  v->setLocation(0, 0);
  
  return EDGE_NONE;
}

int lineRectIntersections(const LINE *line, const RECTANGLE *rect, int edge, Vertex *v1, Vertex *v2) {
  int ret = EDGE_NONE;
  
  ret |= lineRectIntersection(line, rect, edge, v1);
  ret |= lineRectIntersection(line, rect, EDGE_ALL^edge, v2);
  
  return ret;
}


static void edgeVertex(Vertex *v, int edge, const RECTANGLE *rect) {
  if(edge == EDGE_NONE)
    edge = vertexInRect(v, rect);
  
  if(edge & EDGE_LEFT) v->setX(rect->x);
  else if(edge & EDGE_RIGHT) v->setX(rect->x+rect->width);
  
  if(edge & EDGE_TOP) v->setY(rect->y);
  else if(edge & EDGE_BOTTOM) v->setY(rect->y+rect->height);
}

static int simplifyVertex(Vertex *v, const Vertex *to, const RECTANGLE *rect) {
  LINE l = {*v, *to};
  int edge, edge2;
  
  
  edge = vertexInRect(v, rect);
  if(edge == EDGE_NONE) return EDGE_NONE;
  
  edge2 = lineRectIntersection(&l, rect, edge, v);
  if(edge2 != EDGE_NONE) return edge2;
  
  edgeVertex(v, edge, rect);
  return edge;
}



static void addSimplifiedLine(const Vertex *v1, const Vertex *v2, const RECTANGLE *rect, int last, Polygon *out) {
  const LINE d1 = {Vertex(rect->x, rect->y), Vertex(rect->x+rect->width, rect->y+rect->height)};
  const LINE d2 = {Vertex(rect->x, rect->y+rect->height), Vertex(rect->x+rect->width, rect->y)};
  
  LINE l = {*v1, *v2};
  Vertex v, vi;
  int edge1, edge2;
  
  
  v = *v1;
  if((edge1 = simplifyVertex(&v, v2, rect)) != EDGE_NONE)
    out->push_back(v);
  
  v = *v2;
  edge2 = simplifyVertex(&v, v1, rect);
  
  if(edge1 != EDGE_NONE && edge2 != EDGE_NONE && !(edge1 & edge2)) {
    if(lineIntersection(&l, &d1, &vi) == INTERSECTION_SEGMENT_LINE) {
      edgeVertex(&vi, 0, rect);
      out->push_back(vi);
    }
    else if(lineIntersection(&l, &d2, &vi) == INTERSECTION_SEGMENT_LINE) {
      edgeVertex(&vi, 0, rect);
      out->push_back(vi);
    }
  }
  
  if(!last)
    out->push_back(v);
}

void simplifyPolygon(const Polygon *in, const RECTANGLE *rect, Polygon *out) {
  Vertex v;
  
  if(in->empty()) return;
  else if(in->size() == 1) {
    out->push_back(in->front());
    return;
  }
  
  v = in->front();
  simplifyVertex(&v, &in->back(), rect);
  out->push_back(v);
  
  for(Polygon::const_iterator it = in->begin(); it != in->end(); it++) {
    Polygon::const_iterator it2 = it+1;
    if(it2 == in->end()) it2 = in->begin();
    
    addSimplifiedLine(&*it, &*it2, rect, (it2 == in->begin()), out);
  }
}