policyclient

type Client interface {
	// GetString returns a string policy setting with the specified key,
	// or defaultValue (and a nil error) if it does not exist.
	GetString(key pkey.Key, defaultValue string) (string, error)

	// GetStringArray returns a string array policy setting with the specified key,
	// or defaultValue (and a nil error) if it does not exist.
	GetStringArray(key pkey.Key, defaultValue []string) ([]string, error)

	// GetBoolean returns a boolean policy setting with the specified key,
	// or defaultValue (and a nil error) if it does not exist.
	GetBoolean(key pkey.Key, defaultValue bool) (bool, error)

	// GetUint64 returns a numeric policy setting with the specified key,
	// or defaultValue (and a nil error) if it does not exist.
	GetUint64(key pkey.Key, defaultValue uint64) (uint64, error)

	// GetDuration loads a policy from the registry that can be managed by an
	// enterprise policy management system and describes a duration for some
	// action. The registry value should be a string that time.ParseDuration
	// understands. If the registry value is "" or can not be processed,
	// defaultValue (and a nil error) is returned instead.
	GetDuration(key pkey.Key, defaultValue time.Duration) (time.Duration, error)

	// GetPreferenceOption loads a policy from the registry that can be
	// managed by an enterprise policy management system and allows administrative
	// overrides of users' choices in a way that we do not want tailcontrol to have
	// the authority to set. It describes user-decides/always/never options, where
	// "always" and "never" remove the user's ability to make a selection. If not
	// present or set to a different value, defaultValue (and a nil error) is returned.
	GetPreferenceOption(key pkey.Key, defaultValue ptype.PreferenceOption) (ptype.PreferenceOption, error)

	// GetVisibility returns whether a UI element should be visible based on
	// the system's configuration.
	// If unconfigured, implementations should return [ptype.VisibleByPolicy]
	// and a nil error.
	GetVisibility(key pkey.Key) (ptype.Visibility, error)

	// SetDebugLoggingEnabled enables or disables debug logging for the policy client.
	SetDebugLoggingEnabled(enabled bool)

	// HasAnyOf returns whether at least one of the specified policy settings is
	// configured, or an error if no keys are provided or the check fails.
	HasAnyOf(keys ...pkey.Key) (bool, error)

	// RegisterChangeCallback registers a callback function that will be called
	// whenever a policy change is detected. It returns a function to unregister
	// the callback and an error if the registration fails.
	RegisterChangeCallback(cb func(PolicyChange)) (unregister func(), err error)
}

type NoPolicyClient struct{}

type PolicyChange interface {
	// HasChanged reports whether the policy setting identified by the given key
	// has changed.
	HasChanged(pkey.Key) bool

	// HasChangedAnyOf reports whether any of the provided policy settings
	// changed in this change.
	HasChangedAnyOf(keys ...pkey.Key) bool
}