package host

import (
	"github.com/carlosframework/platform/internal/hostbox"
	"github.com/carlosframework/platform/internal/park"
)

// The signed roster supplies both the engine name and the fleet home.
// An empty local placement binds an alias only when those names agree.
func claimRegionBinding(roster, code, fleetHome string) (engine, home string, err error) {
	engine = park.PlacementRegion(roster)
	placement := park.PlacementRegion(code)
	if roster == "" || engine == "" || placement == "" || (code != "" && engine != placement) {
		return "", "", hostbox.ErrChanged
	}
	if code == "" && fleetHome != "" {
		if roster != fleetHome {
			return "", "", hostbox.ErrChanged
		}
		home = engine
	}
	return engine, home, nil
}