package instancectl

import "context"

func (u ClaimUnits) StopInvocation(ctx context.Context, host, invocation string) error {
	if u.BoundUnit == "" && u.BoundHost == "" {
		return u.Stop(ctx, host)
	}
	unit, group, err := u.Placement(host)
	if err != nil || invocation == "" || u.Systemctl == nil {
		return ErrClaimUnit
	}
	state, err := u.show(ctx, unit, "ActiveState", "InvocationID", "ControlGroup")
	if err != nil {
		return err
	}
	if state["InvocationID"] != invocation || state["ControlGroup"] != "/"+group {
		return ErrClaimUnitBusy
	}
	if err := u.Stop(ctx, host); err != nil {
		return err
	}
	state, err = u.show(ctx, unit, "InvocationID", "ControlGroup")
	if err != nil {
		return err
	}
	// systemctl stops by name. A replacement between the check and stop
	// makes the result uncertain; never issue a successful stop receipt.
	if state["InvocationID"] != "" && state["InvocationID"] != invocation || state["ControlGroup"] != "" && state["ControlGroup"] != "/"+group {
		return ErrClaimUnitBusy
	}
	return nil
}