Added plugins folder location in config for the server.

Created get and ser plugin files.
Created server function to load plugins.
Moved Makefile inside server folder to build and run server.

server/main.go

@@ -5,22 +5,35 @@ import (
 	"crypto/tls"
 	"fmt"
 	"io"
+	"io/ioutil"
+	"log"
 	"net"
 	"net/http"
+	"path"
+	"plugin"
+	"strings"
 	"sync"
 
 	"github.com/kelvinmwinuka/memstore/serialization"
 	"github.com/kelvinmwinuka/memstore/utils"
 )
 
+type Plugin interface {
+	Name() string
+	Command() string
+	Description() string
+	HandleCommand(tokens []string, server interface{}) error
+}
+
 type Data struct {
 	mu   sync.Mutex
 	data map[string]interface{}
 }
 
 type Server struct {
-	config utils.Config
-	data   Data
+	config  utils.Config
+	data    Data
+	plugins []Plugin
 }
 
 func (server *Server) handleConnection(conn net.Conn) {
@@ -116,11 +129,69 @@ func (server *Server) StartHTTP() {
 	}
 }
 
+func (server *Server) LoadPlugins() {
+	conf := server.config
+
+	// Load plugins
+	pluginDirs, err := ioutil.ReadDir(conf.Plugins)
+
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	for _, file := range pluginDirs {
+		if file.IsDir() {
+			switch file.Name() {
+			case "commands":
+				files, err := ioutil.ReadDir(path.Join(conf.Plugins, "commands"))
+
+				if err != nil {
+					log.Fatal(err)
+				}
+
+				for _, file := range files {
+					if !strings.HasSuffix(file.Name(), ".so") {
+						// Skip files that are not .so
+						continue
+					}
+					p, err := plugin.Open(path.Join(conf.Plugins, "commands", file.Name()))
+					if err != nil {
+						log.Fatal(err)
+					}
+
+					pluginSymbol, err := p.Lookup("Plugin")
+					if err != nil {
+						fmt.Printf("unexpected plugin symbol in plugin %s\n", file.Name())
+						continue
+					}
+
+					plugin, ok := pluginSymbol.(Plugin)
+					if !ok {
+						fmt.Printf("invalid plugin signature in plugin %s \n", file.Name())
+						continue
+					}
+
+					// Check if a plugin that handles the same command already exists
+					for _, loadedPlugin := range server.plugins {
+						if loadedPlugin.Command() == plugin.Command() {
+							fmt.Printf("plugin that handles %s command already exists. Please handle a different command.", plugin.Command())
+						}
+					}
+
+					server.plugins = append(server.plugins, plugin)
+				}
+			}
+		}
+	}
+}
+
 func (server *Server) Start() {
 	server.data.data = make(map[string]interface{})
 
 	conf := server.config
 
+	server.LoadPlugins()
+
 	if conf.TLS && (len(conf.Key) <= 0 || len(conf.Cert) <= 0) {
 		fmt.Println("Must provide key and certificate file paths for TLS mode.")
 		return
@@ -134,10 +205,9 @@ func (server *Server) Start() {
 }
 
 func main() {
-	conf := utils.GetConfig()
-
 	server := Server{
-		config: conf,
+		config:  utils.GetConfig(),
+		plugins: []Plugin{},
 	}
 
 	server.Start()