package artist

import "image/color"

// Chiseled is a pattern that has a highlight section and a shadow section.
type Chiseled struct {
	Highlight Pattern
	Shadow    Pattern
}

// AtWhen satisfies the Pattern interface.
func (chiseled Chiseled) AtWhen (x, y, width, height int) (c color.RGBA) {
	var highlighted bool
	// FIXME: this doesn't work quite right, the
	// slope of the line is somewhat off.
	bottomCorner :=
		float64(x) < float64(y) *
		(float64(width) / float64(height))
	if bottomCorner {
		highlighted = float64(x) < float64(height) - float64(y)
	} else {
		highlighted = float64(width) - float64(x) > float64(y)
	}

	if highlighted {
		return chiseled.Highlight.AtWhen(x, y, width, height)
	} else {
		return chiseled.Shadow.AtWhen(x, y, width, height)
	}
}