package resolver

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

const (
	// static:///maudit
	StaticScheme = "static"
)

var (
	addrsStore = map[string][]string{}
)

func SetAddr(serviceName string, addrs []string) {
	addrsStore[serviceName] = addrs
}

// Following is an example name resolver. It includes a
// ResolverBuilder(https://godoc.org/google.golang.org/grpc/resolver#Builder)
// and a Resolver(https://godoc.org/google.golang.org/grpc/resolver#Resolver).
//
// A ResolverBuilder is registered for a scheme (in this example, "example" is
// the scheme). When a ClientConn is created for this scheme, the
// ResolverBuilder will be picked to build a Resolver. Note that a new Resolver
// is built for each ClientConn. The Resolver will watch the updates for the
// target, and send updates to the ClientConn.

// exampleResolverBuilder is a
// ResolverBuilder(https://godoc.org/google.golang.org/grpc/resolver#Builder).
type exampleResolverBuilder struct{}

func (*exampleResolverBuilder) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (resolver.Resolver, error) {
	r := &exampleResolver{
		target:     target,
		cc:         cc,
		addrsStore: addrsStore,
	}
	r.start()
	return r, nil
}
func (*exampleResolverBuilder) Scheme() string { return StaticScheme }

// exampleResolver is a
// Resolver(https://godoc.org/google.golang.org/grpc/resolver#Resolver).
type exampleResolver struct {
	target     resolver.Target
	cc         resolver.ClientConn
	addrsStore map[string][]string
}

func (r *exampleResolver) start() {
	addrStrs := r.addrsStore[r.target.Endpoint]
	addrs := make([]resolver.Address, len(addrStrs))

	for i, s := range addrStrs {
		addrs[i] = resolver.Address{Addr: s}
	}

	r.cc.UpdateState(resolver.State{Addresses: addrs})
}
func (e *exampleResolver) ResolveNow(o resolver.ResolveNowOptions) {
	e.start()
}
func (*exampleResolver) Close() {}

func init() {
	// Register the example ResolverBuilder. This is usually done in a package's
	// init() function.
	resolver.Register(&exampleResolverBuilder{})
}