package e2ee

import "fmt"

// Manager holds the process-wide selected E2EE backend (or none, if E2EE
// is disabled), reachable from both the xmpp and telegram packages without
// either importing the other's e2ee-specific glue.
type Manager struct {
	backend Backend
}

// NewManager selects a backend by name from the registry. An empty name
// means E2EE is disabled: the returned Manager's Backend() always reports
// ok=false, and every call site is expected to treat that as "behave
// exactly as if this feature didn't exist".
func NewManager(name string) (*Manager, error) {
	if name == "" {
		return &Manager{}, nil
	}
	b, ok := Get(name)
	if !ok {
		return nil, fmt.Errorf("e2ee: unknown backend %q (forgot to import its package for its init() side effect?)", name)
	}
	return &Manager{backend: b}, nil
}

// Backend returns the selected backend. ok is false if m is nil or no
// backend was selected (E2EE disabled) - callers should treat a nil
// Manager the same as one built via NewManager("").
func (m *Manager) Backend() (backend Backend, ok bool) {
	if m == nil || m.backend == nil {
		return nil, false
	}
	return m.backend, true
}