almost complete telegram user verification

When signing up, the user is given a pin code which they send to a
telegram bot. This provides user verification, but more importantly
allows the bot to message the user, as the Telegram API requires the
user to interact with the bot before it can do the opposite.

The bot should recognize the correct language, but a /lang command is
also provided to change it.

The verification process is pretty much functional but ui is still
broken, and it isn't properly integrated yet.

api.go

@@ -549,7 +549,7 @@ func (app *appContext) EnableDisableUsers(gc *gin.Context) {
 	}
 	if len(addresses) != 0 {
 		go func(reason string, addresses []string) {
-			var msg *Email
+			var msg *Message
 			var err error
 			if req.Enabled {
 				msg, err = app.email.constructEnabled(reason, app, false)
@@ -1580,7 +1580,7 @@ func (app *appContext) GetCustomEmailTemplate(gc *gin.Context) {
 	id := gc.Param("id")
 	var content string
 	var err error
-	var msg *Email
+	var msg *Message
 	var variables []string
 	var conditionals []string
 	var values map[string]interface{}
@@ -1874,6 +1874,36 @@ func (app *appContext) ServeLang(gc *gin.Context) {
 	respondBool(400, false, gc)
 }
 
+// @Summary Returns true/false on whether or not a telegram PIN was verified.
+// @Produce json
+// @Success 200 {object} boolResponse
+// @Success 401 {object} boolResponse
+// @Param pin path string true "PIN code to check"
+// @Param invCode path string true "invite Code"
+// @Router /invite/{invCode}/telegram/verified/{pin} [get]
+// @tags Other
+func (app *appContext) TelegramVerified(gc *gin.Context) {
+	code := gc.Param("invCode")
+	if _, ok := app.storage.invites[code]; !ok {
+		respondBool(401, false, gc)
+		return
+	}
+	pin := gc.Param("pin")
+	tokenIndex := -1
+	for i, v := range app.telegram.verifiedTokens {
+		if v == pin {
+			tokenIndex = i
+			break
+		}
+	}
+	if tokenIndex != -1 {
+		length := len(app.telegram.verifiedTokens)
+		app.telegram.verifiedTokens[length-1], app.telegram.verifiedTokens[tokenIndex] = app.telegram.verifiedTokens[tokenIndex], app.telegram.verifiedTokens[length-1]
+		app.telegram.verifiedTokens = app.telegram.verifiedTokens[:length-1]
+	}
+	respondBool(200, tokenIndex != -1, gc)
+}
+
 // @Summary Restarts the program. No response means success.
 // @Router /restart [post]
 // @tags Other