// Package registry is an interface for service discovery
package registry

import (
	"errors"

	"google.golang.org/grpc/resolver"
)

var (
	// Not found error when GetService is called
	ErrNotFound = errors.New("service not found")
	// Watcher stopped error when watcher is stopped
	ErrWatcherStopped = errors.New("watcher stopped")
)

// The registry provides an interface for service discovery
// and an abstraction over varying implementations
type Registry interface {
	ResolverBuilder() resolver.Builder
	Init(...Option) error
	Options() Options
	Register(*Service, ...RegisterOption) error
	Deregister(*Service, ...DeregisterOption) error
	GetService(string, ...GetOption) ([]*Service, error)
	ListServices(...ListOption) ([]*Service, error)
	Watch(...WatchOption) (Watcher, error)
	String() string
}

type Service struct {
	Name      string            `json:"name"`
	Version   string            `json:"version"`
	Metadata  map[string]string `json:"metadata"`
	Nodes     []*Node           `json:"nodes"`
}

type Node struct {
	Id       string            `json:"id"`
	Address  string            `json:"address"`
	Metadata map[string]string `json:"metadata"`
}

type Option func(*Options)

type RegisterOption func(*RegisterOptions)

type WatchOption func(*WatchOptions)

type DeregisterOption func(*DeregisterOptions)

type GetOption func(*GetOptions)

type ListOption func(*ListOptions)