Add plugin API (#48)

6 files changed, 107 insertions, 3 deletions

diff --git a/client_conn.go b/client_conn.go
index 29db611..4898518 100644
--- a/client_conn.go
+++ b/client_conn.go
@@ -553,7 +553,49 @@ func handleClt(cc *clientConn) {
 				cc.log("-->", "no server")
 				break
 			}
-			cc.server().SendCmd(cmd)
+
+			var handled bool
+			if strings.HasPrefix(cmd.Msg, conf().CmdPrefix) {
+				substrs := strings.Split(cmd.Msg, " ")
+				cmdName := strings.Replace(substrs[0], conf().CmdPrefix, "", 1)
+
+				var args []string
+				if len(substrs) > 1 {
+					args = substrs[1:]
+				}
+
+				cc.log("-->", append([]string{"cmd", cmdName}, args...))
+
+				pluginsMu.RLock()
+				for _, p := range plugins {
+					sym, err := p.Lookup("HandleChatCmd")
+					if err != nil {
+						cc.log("-->", err)
+						continue
+					}
+
+					if handler, ok := sym.(func(string, []string) bool); ok {
+						if handler(cmdName, args) {
+							handled = true
+							break
+						}
+					}
+				}
+				pluginsMu.RUnlock()
+
+				if !handled {
+					cc.SendCmd(&mt.ToCltChatMsg{
+						Type:      mt.SysMsg,
+						Text:      "Command not found.",
+						Timestamp: time.Now().Unix(),
+					})
+					handled = true
+				}
+			}
+
+			if !handled {
+				cc.server().SendCmd(cmd)
+			}
 		case *mt.ToSrvDeletedBlks:
 			if cc.server() == nil {
 				cc.log("-->", "no server")
diff --git a/config.go b/config.go
index 89249b6..2cd4efe 100644
--- a/config.go
+++ b/config.go
@@ -14,6 +14,7 @@ const maxPlayerNameLen = 20
 const playerNameChars = "^[a-zA-Z0-9-_]+$"
 const bytesPerMediaBunch = 5000
 
+const defaultCmdPrefix = ">"
 const defaultSendInterval = 0.09
 const defaultUserLimit = 10
 const defaultAuthBackend = "sqlite3"
@@ -23,6 +24,8 @@ var config Config
 var configMu sync.RWMutex
 
 type Config struct {
+	NoPlugins     bool
+	CmdPrefix     string
 	RequirePasswd bool
 	SendInterval  float32
 	UserLimit     int
@@ -56,6 +59,7 @@ func loadConfig() error {
 
 	oldConf := config
 
+	config.CmdPrefix = defaultCmdPrefix
 	config.SendInterval = defaultSendInterval
 	config.UserLimit = defaultUserLimit
 	config.AuthBackend = defaultAuthBackend
diff --git a/doc/config.md b/doc/config.md
index 39164ed..47ef4a6 100644
--- a/doc/config.md
+++ b/doc/config.md
@@ -5,6 +5,13 @@ The file name is `config.json`.
 ## Format
 The configuration file contains JSON data. The fields are as follows.
 
+> `NoPlugins`
+```
+Type: bool
+Default: false
+Description: Plugins are not loaded if this is true.
+```
+
 > `RequirePasswd`
 ```
 Type: bool
diff --git a/log.go b/log.go
index 0b44ffb..f4e25be 100644
--- a/log.go
+++ b/log.go
@@ -22,13 +22,13 @@ func (lw *LogWriter) Write(p []byte) (n int, err error) {
 func init() {
 	executable, err := os.Executable()
 	if err != nil {
-		log.Fatal(err)
+		log.Fatal("{←|⇶} ", err)
 	}
 
 	path := filepath.Dir(executable) + "/latest.log"
 	f, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0666)
 	if err != nil {
-		log.Fatal(err)
+		log.Fatal("{←|⇶} ", err)
 	}
 
 	go func() {
diff --git a/main.go b/main.go
index 5c73ed2..c18b387 100644
--- a/main.go
+++ b/main.go
@@ -17,6 +17,12 @@ func main() {
 		log.Fatal("{←|⇶} ", err)
 	}
 
+	if !conf().NoPlugins {
+		if err := loadPlugins(); err != nil {
+			log.Fatal("{←|⇶} ", err)
+		}
+	}
+
 	var err error
 	switch conf().AuthBackend {
 	case "sqlite3":
diff --git a/plugin.go b/plugin.go
new file mode 100644
index 0000000..d4e3d27
--- /dev/null
+++ b/plugin.go
@@ -0,0 +1,45 @@
+package main
+
+import (
+	"log"
+	"os"
+	"path/filepath"
+	"plugin"
+	"sync"
+)
+
+var plugins []*plugin.Plugin
+var pluginsMu sync.RWMutex
+
+func loadPlugins() error {
+	executable, err := os.Executable()
+	if err != nil {
+		return err
+	}
+
+	path := filepath.Dir(executable) + "/plugins"
+	os.Mkdir(path, 0777)
+
+	dir, err := os.ReadDir(path)
+	if err != nil {
+		return err
+	}
+
+	pluginsMu.Lock()
+	defer pluginsMu.Unlock()
+
+	plugins = []*plugin.Plugin{}
+
+	for _, file := range dir {
+		p, err := plugin.Open(path + "/" + file.Name())
+		if err != nil {
+			log.Print("{←|⇶} ", err)
+			continue
+		}
+
+		plugins = append(plugins, p)
+	}
+
+	log.Print("{←|⇶} load plugins")
+	return nil
+}