// Package embeddednats starts an in-process NATS server with JetStream enabled.
//
// This lets the whole unibus stack run with `go run` without installing or
// managing a separate NATS deployment. In production, point clients at an
// external NATS via the --nats-url flag instead of using this.
package embeddednats

import (
	"fmt"
	"time"

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

// Start launches an embedded nats-server with JetStream enabled, listening on
// the given port and persisting JetStream state under storeDir. It blocks until
// the server is ready to accept connections (up to 5s) and returns the running
// server. The caller is responsible for calling Shutdown on it.
func Start(storeDir string, port int) (*server.Server, error) {
	opts := &server.Options{
		JetStream:  true,
		StoreDir:   storeDir,
		Port:       port,
		DontListen: false,
		// Keep the embedded server quiet by default; the host app logs the URLs.
		NoLog:  true,
		NoSigs: true,
	}

	ns, err := server.NewServer(opts)
	if err != nil {
		return nil, fmt.Errorf("embeddednats: new server: %w", err)
	}

	go ns.Start()

	if !ns.ReadyForConnections(5 * time.Second) {
		ns.Shutdown()
		return nil, fmt.Errorf("embeddednats: server not ready for connections within 5s")
	}

	return ns, nil
}

// ClientURL returns a NATS connection URL for the running embedded server.
func ClientURL(ns *server.Server) string {
	return ns.ClientURL()
}