package gg

//import "fmt"

// The type represents mathematical equation of line and line itself.
type Line struct {
	K, C, X Float
	Vertical bool
}

// Returns the line itself. Made to implement the Liner interface.
func (l Line) Line() Line {
	return l
}

func (l Line) ContainsPoint(p Point) bool {
	buf := Line{0, p.Y, 0, false}
	pc, ok := l.crossesLine(buf)
	if !ok {
		return false
	}
	
	//Println("points:", l, p, pc)
	return Neq(pc.X, p.X) && Neq(pc.Y, p.Y)
}

func (l1 Line) crossesLine(l2 Line) (Point, bool) {
	var x, y Float
	if LinersParallel(l1, l2) {
		return Point{}, false
	}

	switch {
	case l1.Vertical :
		x = l1.X
		y = l2.K*x + l2.C
		//Println("l1-vert:", x, y)
	case l2.Vertical :
		x = l2.X
		y = l1.K*x + l1.C
		//Println("l2-vert:", x, y)
	default:
		x = (l1.C - l2.C) / (l2.K - l1.K)
		y = l1.K*x + l1.C
	}

	//Println("in:", x, y)
	return Point{x, y}, true
}