package ensure

// What we need here is a way to define resources one would like to have.
// Each resource must be checked if it needs to be handled or if it already
// exists.
// The question is, who should do that? Is it the responsibility of the user
// to make sure that resources exist or should it be done "magically"?
type (
	// Enforced checks if state is already enforced in the environment. When it
	// is, it must return true.
	Enforced func() bool

	// State represents a wanted state that should be pushed to the environment.
	Ensurer interface {
		// Ensure will modify the environment so that it represents the wanted
		// state.
		Ensure() error
	}

	checkEnsurer struct {
		Is    Enforced
		State Ensurer
	}
)

// WithCheck creates an Ensurer instance that runs is before Ensure.
func WithCheck(is Enforced, en Ensurer) Ensurer {
	return &checkEnsurer{
		Is:    is,
		State: en,
	}
}

func (c *checkEnsurer) Ensure() error {
	if !c.Is() {
		return c.State.Ensure()
	}
	return nil
}