presence

type Clock interface {
	// Now returns the current clock time.
	Now() time.Time
}

type Connections interface {
	// ForModel will return the connections just for the specified model UUID.
	ForModel(model string) Connections

	// ForServer will return just the connections for agents connected to the specified
	// server. The server is a stringified machine tag for the API server.
	ForServer(server string) Connections

	// ForAgent returns the connections for the specified agent in the model.
	// The agent is the stringified machine or unit tag.
	ForAgent(agent string) Connections

	// Count returns the number of connections.
	Count() int

	// Models returns all the model UUIDs that have connections.
	Models() []string

	// Servers returns all the API servers that have connections in this
	// collection.
	Servers() []string

	// Agents returns all the stringified agent tags that have connections
	// in this collection.
	Agents() []string

	// For a given non controller agent, return the Status for that agent.
	AgentStatus(agent string) (Status, error)

	// Values returns the connection information for this collection.
	Values() []Value
}

type Recorder interface {
	// Disable clears the entries and marks the recorder as disabled. Note
	// that all agents will have a recorder, but they are only enabled for
	// API server agents.
	Disable()

	// Enable marks the recorder as enabled.
	Enable()

	// IsEnabled returns whether or not the recorder is enabled.
	IsEnabled() bool

	// Connect adds an entry for the specified agent.
	// The server and agent strings are the stringified machine and unit tags.
	// The model is the UUID for the model.
	Connect(server, model, agent string, id uint64, controllerAgent bool, userData string)

	// Disconnect removes the entry for the specified connection id.
	Disconnect(server string, id uint64)

	// Activity updates the last seen timestamp for the connection specified.
	Activity(server string, id uint64)

	// ServerDown marks all connections on the specified server as unknown.
	ServerDown(server string)

	// UpdateServer replaces all known connections for the specified server
	// with the connections specified. If any of the connections are not for
	// the specified server, an error is returned.
	UpdateServer(server string, connections []Value) error

	// Connections returns all connections info that the recorder has.
	Connections() Connections
}

type Status int

type Value struct {
	// Model is the model UUID.
	Model string

	// Server is the stringified machine tag of the API server.
	Server string

	// Agent is the stringified machine, unit, or application tag of the agent.
	Agent string

	// ControllerAgent is true if the agent is in the controller model.
	ControllerAgent bool

	// ConnectionID is the unique identifier given by the API server.
	ConnectionID uint64

	// Status is either Missing or Alive.
	Status Status

	// UserData is the user data provided with the Login API call.
	UserData string

	// LastSeen is the timestamp when the connection was added using
	// Connect, or the last time Activity was called.
	LastSeen time.Time
}