// Package leaf starts an in-process nats-server and optional hub leaf.
package leaf

import (
	"errors"
	"net/url"
	"time"

	natsserver "github.com/nats-io/nats-server/v2/server"
	nats "github.com/nats-io/nats.go"
)

// Node is an in-process broker plus client.
type Node struct {
	ns *natsserver.Server
	nc *nats.Conn
}

// Start binds 127.0.0.1:0 and optionally leaf-connects to hub.
func Start(hub string) (*Node, error) {
	opts := &natsserver.Options{Host: "127.0.0.1", Port: -1}
	if hub != "" {
		u, err := url.Parse(hub)
		if err != nil {
			return nil, err
		}
		opts.LeafNode.Remotes = []*natsserver.RemoteLeafOpts{{URLs: []*url.URL{u}}}
	}
	ns, err := natsserver.NewServer(opts)
	if err != nil {
		return nil, err
	}
	go ns.Start()
	if !ns.ReadyForConnections(5 * time.Second) {
		return nil, errors.New("nats not ready")
	}
	nc, err := nats.Connect(ns.ClientURL())
	if err != nil {
		ns.Shutdown()
		return nil, err
	}
	n := &Node{ns: ns, nc: nc}
	if _, err := n.nc.Subscribe("verae.sm.send", func(msg *nats.Msg) {
		if msg.Reply != "" {
			_ = n.nc.Publish(msg.Reply, []byte(`{"accepted":true}`))
		}
	}); err != nil {
		n.Shutdown()
		return nil, err
	}
	return n, nil
}

// Addr is the in-process client URL.
func (n *Node) Addr() string { return n.ns.ClientURL() }

// Shutdown stops client and server.
func (n *Node) Shutdown() error {
	if n.nc != nil {
		n.nc.Close()
	}
	if n.ns != nil {
		n.ns.Shutdown()
	}
	return nil
}