prepare user system

util/idManager.go

@@ -0,0 +1,41 @@
+package util
+
+import (
+	"context"
+	"crypto/rand"
+	"io"
+
+	"github.com/SowinskiBraeden/DeviceBookingAPI/databases"
+	"go.uber.org/zap"
+
+	"go.mongodb.org/mongo-driver/bson"
+)
+
+var table = [...]byte{'1', '2', '3', '4', '5', '6', '7', '8', '9', '0'}
+
+func ValidateID(id string, DB databases.UserDatabase) bool { // true: valid id, false: id already in use
+
+	dbResp, err := DB.Find(context.TODO(), bson.M{})
+	if err != nil {
+		zap.S().With(err).Error("failed to get users")
+		return false
+	}
+
+	// If len == 0 then ID is not in use
+	if len(dbResp) == 0 {
+		return true
+	}
+	return false
+}
+
+func GenerateID(length int) string {
+	b := make([]byte, length)
+	n, err := io.ReadAtLeast(rand.Reader, b, length)
+	if n != length {
+		panic(err)
+	}
+	for i := 0; i < len(b); i++ {
+		b[i] = table[int(b[i])%len(table)]
+	}
+	return string(b)
+}