package config

import (
	"log"
	"reflect"
	"fmt"

	"github.com/spf13/viper"
)

type Config struct {
	Hostname 		string `mapstructure:"HOSTNAME"`
	Port     		string `mapstructure:"PORT"`

	DatabaseUrl 	string `mapstructure:"DATABASE_URL"`
	RedisUrl 		string `mapstructure:"REDIS_URL"`
	MinioUrl 		string `mapstructure:"MINIO_URL"`

	JwtAlgorithm 	string `mapstructure:"JWT_ALGORITHM"`
	JwtSecret 		string `mapstructure:"JWT_SECRET"`
	JwtIssuer 		string `mapstructure:"JWT_ISSUER"`
	JwtAudience 	string `mapstructure:"JWT_AUDIENCE"`
	JwtExpAccess 	string `mapstructure:"JWT_EXP_ACCESS"`
	JwtExpRefresh 	string `mapstructure:"JWT_EXP_REFRESH"`

	Environment 	string `mapstructure:"ENVIRONMENT"`
}

var config *Config

func LoadConfig() error {

	// Load .env file
	if err := viper.ReadInConfig(); err != nil {
		log.Printf("Error reading config file, proceeding with environment variables. %s", err)
	}

	// Set default parameters
	viper.SetDefault("HOSTNAME", "localhost")
	viper.SetDefault("PORT", "8080")
	viper.SetDefault("DATABASE_URL", "mydb")
	viper.SetDefault("REDIS_URL", "myredis")
	viper.SetDefault("MINIO_URL", "myminio")
	viper.SetDefault("JWT_ALGORITHM", "HS256")
	viper.SetDefault("JWT_SECRET", "default_jwt_secret_please_change") // TODO: remove and randomly generate
	viper.SetDefault("JWT_EXP_ACCESS", "5m")
	viper.SetDefault("JWT_EXP_REFRESH", "1w")
	viper.SetDefault("JWT_AUDIENCE", "easywish")
	viper.SetDefault("JWT_ISSUER", "easywish")
	
	viper.SetDefault("ENVIRONMENT", "production")

	// Set the file name and type for Viper
	viper.SetConfigName(".env") // name of config file (without extension)
	viper.SetConfigType("env")   // REQUIRED if the config file does not have the extension
	viper.AddConfigPath(".")     // optionally look for config in the working directory

	// Unmarshal the configuration into the Config struct
	if err := viper.Unmarshal(&config); err != nil {
		log.Fatalf("Unable to decode into struct, %v", err)
	}

	// Perform validation
	if err := validateConfig(); err != nil {
		return err
	}

	return nil
}

func validateConfig() error {
	v := reflect.ValueOf(*config)
	t := v.Type()

	for i := range v.NumField() {
		field := v.Field(i)
		fieldType := t.Field(i)

		// Check if the field is a string and is empty
		if field.Kind() == reflect.String && field.String() == "" {
			return fmt.Errorf("Missing required configuration: %s", fieldType.Name)
		}
	}

	return nil
}

func GetConfig() *Config {
	return config
}