aiaa-notification-server/internal/config/config.go

package config

import (
	"fmt"
	"os"
	"strings"

	"github.com/spf13/viper"
)

type Config struct {
	Server    ServerConfig    `mapstructure:"server"`
	Database  DatabaseConfig  `mapstructure:"database"`
	Redis     RedisConfig     `mapstructure:"redis"`
	SMTP      SMTPConfig      `mapstructure:"smtp"`
	RateLimit RateLimitConfig `mapstructure:"rate_limit"`
	Logbull   LogbullConfig   `mapstructure:"logbull"`
}

type ServerConfig struct {
	Port     int    `mapstructure:"port"`
	AdminKey string `mapstructure:"admin_key"`
}

type DatabaseConfig struct {
	Host     string `mapstructure:"host"`
	Port     int    `mapstructure:"port"`
	User     string `mapstructure:"user"`
	Password string `mapstructure:"password"`
	Database string `mapstructure:"database"`
}

func (d DatabaseConfig) DSN() string {
	return fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=utf8mb4&parseTime=true&loc=Local",
		d.User, d.Password, d.Host, d.Port, d.Database)
}

type RedisConfig struct {
	Host     string `mapstructure:"host"`
	Port     int    `mapstructure:"port"`
	Password string `mapstructure:"password"`
	DB       int    `mapstructure:"db"`
}

func (r RedisConfig) Addr() string {
	return fmt.Sprintf("%s:%d", r.Host, r.Port)
}

type SMTPConfig struct {
	Host     string `mapstructure:"host"`
	Port     int    `mapstructure:"port"`
	User     string `mapstructure:"user"`
	Password string `mapstructure:"password"`
	From     string `mapstructure:"from"`
}

type RateLimitConfig struct {
	Default        int `mapstructure:"default"`
	DingTalkPerMin int `mapstructure:"dingtalk_per_min"` // per robot webhook; 0 => 18
}

type LogbullConfig struct {
	Host      string `mapstructure:"host"`
	ProjectID string `mapstructure:"project_id"`
	APIKey    string `mapstructure:"api_key"`
	LogLevel  string `mapstructure:"log_level"`
}

func Load(path string) (*Config, error) {
	v := viper.New()
	v.SetConfigFile(path)
	v.SetEnvPrefix("NOTIFY")
	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
	v.AutomaticEnv()

	if err := v.ReadInConfig(); err != nil {
		return nil, fmt.Errorf("read config: %w", err)
	}

	// Expand ${ENV_VAR} placeholders in config values
	for _, key := range v.AllKeys() {
		val := v.GetString(key)
		if strings.Contains(val, "${") {
			expanded := expandEnv(val)
			v.Set(key, expanded)
		}
	}

	var cfg Config
	if err := v.Unmarshal(&cfg); err != nil {
		return nil, fmt.Errorf("unmarshal config: %w", err)
	}
	return &cfg, nil
}

func expandEnv(s string) string {
	return os.Expand(s, func(key string) string {
		// support ${VAR:-default}
		if i := strings.Index(key, ":-"); i >= 0 {
			name := key[:i]
			def := key[i+2:]
			if v, ok := os.LookupEnv(name); ok {
				return v
			}
			return def
		}
		return os.Getenv(key)
	})
}