goseg/broadcast/broadcast.go

package broadcast

import (
	"encoding/json"
	"goseg/config"
	"goseg/structs"
	"log/slog"
	"os"
	"reflect"
	"sync"
	"fmt"

	"github.com/gorilla/websocket"
)

var (
	logger         = slog.New(slog.NewJSONHandler(os.Stdout, nil))
	clients        = make(map[*websocket.Conn]bool)
	broadcastState structs.AuthBroadcast
	mu             sync.RWMutex // synchronize access to broadcastState
)

func init(){
	// initialize broadcastState global var
	config := config.Conf()
	broadcast, err := bootstrapBroadcastState(config)
	if err != nil {
		errmsg := fmt.Sprintf("Unable to initialize broadcast: %v",err)
		panic(errmsg)
	}
	broadcastState = broadcast
}

// adds ws client
func RegisterClient(conn *websocket.Conn) {
	clients[conn] = true
	broadcastJson, err := GetStateJson()
	if err != nil {
		return
	}
	if err := conn.WriteMessage(websocket.TextMessage, broadcastJson); err != nil {
		fmt.Println("Error writing response:", err)
		return
	}
}

// remove ws client
func UnregisterClient(conn *websocket.Conn) {
	delete(clients, conn)
}

// take in config file and addt'l info to initialize broadcast
func bootstrapBroadcastState(config structs.SysConfig) (structs.AuthBroadcast, error) {
	var res structs.AuthBroadcast
	return res, nil
}

// update broadcastState with a map of items
func UpdateBroadcastState(values map[string]interface{}) error {
	mu.Lock()
	defer mu.Unlock()
	v := reflect.ValueOf(&broadcastState).Elem()
	for key, value := range values {
		// we are matching the map key with the broadcastState item
		field := v.FieldByName(key)
		if !field.IsValid() || !field.CanSet() {
			return fmt.Errorf("field %s does not exist or is not settable", key)
		}
		val := reflect.ValueOf(value)
		if field.Type() != val.Type() {
			return fmt.Errorf("type mismatch for field %s: expected %s, got %s", key, field.Type(), val.Type())
		}
		field.Set(val)
	}
	BroadcastToClients()
	return nil
}

// return broadcast state
func GetState() structs.AuthBroadcast {
	mu.Lock()
	defer mu.Unlock()
	return broadcastState
}

// return json string of current broadcast state
func GetStateJson() ([]byte, error) {
	mu.Lock()
	defer mu.Unlock()
	broadcastJson, err := json.Marshal(broadcastState)
	if err != nil {
		errmsg := fmt.Sprintf("Error marshalling response: %v", err)
		logger.Error(errmsg)
		return nil, err
	}
	return broadcastJson, nil
}

// broadcast the global state to all clients
func BroadcastToClients() error {
	broadcastJson, err := json.Marshal(broadcastState)
	if err != nil {
		logger.Error("Error marshalling response:", err)
		return err
	}
	for client := range clients {
		if err := client.WriteMessage(websocket.TextMessage, broadcastJson); err != nil {
			logger.Error("Error writing response:", err)
			return err
		}
	}
	return nil
}