Add database driver and config module

Signed-off-by: Asai Neko <sugar@sne.moe>

config/config.go

@@ -1,5 +1,40 @@
 package config
 
-func Init() {
+import (
+	"log"
 
+	"github.com/spf13/viper"
+)
+
+func Init() {
+	// Read global config
+	viper.SetConfigFile("config.yaml")
+	viper.SetDefault("Server", serverDef)
+	viper.SetDefault("Database", databaseDef)
+	conf := &config{}
+	if err := viper.ReadInConfig(); err != nil {
+		log.Println("Can't read config, trying to modify!")
+		if err := viper.WriteConfig(); err != nil {
+			log.Fatal("[Config] Error writing config: ", err)
+		}
+	}
+	if err := viper.Unmarshal(conf); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func Get(key string) any {
+	viper.SetConfigFile("config.yaml")
+	if err := viper.ReadInConfig(); err != nil {
+		log.Fatal("[Config] Error reading config: ", err)
+	}
+	return viper.Get(key)
+}
+
+func Set(key string, value any) {
+	viper.SetConfigFile("config.yaml")
+	if err := viper.ReadInConfig(); err != nil {
+		log.Fatal("[Config] Error reading config: ", err)
+	}
+	viper.Set(key, value)
 }