feat: add database configuration

internal/config/config.go

@@ -10,8 +10,9 @@ import (
 
 // Config holds application configuration loaded from TOML
 type Config struct {
-	Server ServerConfig `toml:"server"`
-	MQTT   MQTTConfig   `toml:"mqtt"`
+	Server   ServerConfig   `toml:"server"`
+	MQTT     MQTTConfig     `toml:"mqtt"`
+	Database DatabaseConfig `toml:"database"`
 }
 
 type ServerConfig struct {
@@ -28,6 +29,14 @@ type MQTTConfig struct {
 	Topic    string `toml:"topic"`
 }
 
+type DatabaseConfig struct {
+	Host     string `toml:"host"`
+	Port     int    `toml:"port"`
+	User     string `toml:"user"`
+	Password string `toml:"password"`
+	Name     string `toml:"name"`
+}
+
 // Load loads configuration from the given path. If path is empty, it tries
 // to load ./config.toml or falls back to environment defaults.
 func Load(path string) (*Config, error) {
@@ -42,6 +51,12 @@ func Load(path string) (*Config, error) {
 			ClientID: "lambda-iot-core",
 			Topic:    "lambda/iot",
 		},
+		Database: DatabaseConfig{
+			Host: "localhost",
+			Port: 3306,
+			User: "root",
+			Name: "lambdaiot",
+		},
 	}
 
 	// try to load TOML if provided or present
@@ -90,5 +105,23 @@ func Load(path string) (*Config, error) {
 		cfg.MQTT.Topic = v
 	}
 
+	if v := os.Getenv("DB_HOST"); v != "" {
+		cfg.Database.Host = v
+	}
+	if v := os.Getenv("DB_PORT"); v != "" {
+		if p, err := strconv.Atoi(v); err == nil {
+			cfg.Database.Port = p
+		}
+	}
+	if v := os.Getenv("DB_USER"); v != "" {
+		cfg.Database.User = v
+	}
+	if v := os.Getenv("DB_PASSWORD"); v != "" {
+		cfg.Database.Password = v
+	}
+	if v := os.Getenv("DB_NAME"); v != "" {
+		cfg.Database.Name = v
+	}
+
 	return cfg, nil
 }