package govector

func Intersection(p1, p2 Point2d, v1, v2 Vector2d) (bool, Point2d) {
	t := p2.Sub(p1).Cross(v2) / v1.Cross(v2)
	s := p2.Sub(p1).Cross(v1) / v1.Cross(v2)
	if t > 0 && t < 1 && s > 0 && s < 1 {
		return true, p1.Add(v1.Scale(t))
	}

	return false, Point2d{0, 0}
}

func RectRectIntersection(r1 AABB2d, r2 AABB2d) bool {
	return (r1.A.X < r2.B.X && r1.B.X > r2.A.X &&
		r1.A.Y < r2.B.Y && r1.B.Y > r2.A.Y)
}

func RectIntersection(r AABB2d, p Point2d, v Vector2d) (bool, bool, Point2d) {
	collision := false
	inside := false
	start_inside := PointInRect(p, r)
	end_inside := PointInRect(p.Add(v), r)
	if start_inside && end_inside {
		inside = true
		return collision, inside, p
	} else {
		wall_left, col1 := Intersection(p, r.A, v, Vector2d{X: 0, Y: r.B.Y - r.A.Y})
		if wall_left {
			return wall_left, inside, col1
		}
		wall_top, col2 := Intersection(p, r.A, v, Vector2d{X: r.B.X - r.A.X, Y: 0})
		if wall_top {
			return wall_top, inside, col2
		}
		wall_right, col3 := Intersection(p, r.B, v, Vector2d{X: 0, Y: -r.B.Y + r.A.Y})
		if wall_right {
			return wall_right, inside, col3
		}
		wall_bottom, col4 := Intersection(p, r.B, v, Vector2d{X: -r.B.X + r.A.X, Y: 0})
		if wall_bottom {
			return wall_bottom, inside, col4
		}

		return false, false, p
	}
}

func ProjectPolygon(axis Vector2d, p Polygon2d) (min float32, max float32) {
	min = axis.Dot(p.Points[0])
	max = min
	for _, point := range p.Points {
		d := axis.Dot(point)
		if d < min {
			min = d
		} else {
			if d > max {
				max = d
			}
		}
	}
	return min, max
}

func PolygonIntersection(r Polygon2d, p Point2d, v Vector2d) (bool, Point2d) {

	for point, _ := range r.Points {
		if point == len(r.Points) {
			break
		}

		edgePt, edgeVec := r.Edge(point)
		intersection, pt := Intersection(p, edgePt, v, edgeVec)
		if intersection {
			return intersection, pt
		}
	}

	return false, Point2d{}
}

func PolyPolyIntersection(p1 Polygon2d, v1 Vector2d, p2 Polygon2d, v2 Vector2d) bool {

	return false
}