package config

import (
	"fmt"
	"os"
	"strconv"
	"strings"
	"time"
)

const defaultEnvPrefix = "GO_OMNI_"

// LoadFromEnv loads application settings from GO_OMNI_* variables. The
// database settings remain owned by database.ConfigFromEnv.
func LoadFromEnv(prefix string) (Config, error) {
	prefix = strings.TrimSpace(prefix)
	if prefix == "" {
		prefix = defaultEnvPrefix
	}
	cfg := Default()
	cfg.Address = envString(prefix+"HTTP_ADDR", cfg.Address)
	cfg.RequestIDHeader = envString(prefix+"REQUEST_ID_HEADER", cfg.RequestIDHeader)
	cfg.Log.Level = envString(prefix+"LOG_LEVEL", cfg.Log.Level)
	cfg.Log.Format = envString(prefix+"LOG_FORMAT", cfg.Log.Format)
	cfg.Log.Output = envString(prefix+"LOG_OUTPUT", cfg.Log.Output)
	cfg.Log.File = envString(prefix+"LOG_FILE", cfg.Log.File)
	cfg.Log.Service = envString(prefix+"SERVICE", cfg.Log.Service)
	cfg.Log.Environment = envString(prefix+"ENVIRONMENT", cfg.Log.Environment)

	var err error
	if cfg.EnableLogger, err = envBool(prefix+"ENABLE_LOGGER", cfg.EnableLogger); err != nil {
		return Config{}, err
	}
	if cfg.Log.AddSource, err = envBool(prefix+"LOG_ADD_SOURCE", cfg.Log.AddSource); err != nil {
		return Config{}, err
	}
	if value := strings.TrimSpace(os.Getenv(prefix + "SHUTDOWN_TIMEOUT")); value != "" {
		cfg.ShutdownTimeout, err = time.ParseDuration(value)
		if err != nil {
			return Config{}, fmt.Errorf("%sSHUTDOWN_TIMEOUT must be a duration: %w", prefix, err)
		}
	}
	if err := cfg.Validate(); err != nil {
		return Config{}, err
	}
	return cfg, nil
}

func envString(key, fallback string) string {
	if value := strings.TrimSpace(os.Getenv(key)); value != "" {
		return value
	}
	return fallback
}

func envBool(key string, fallback bool) (bool, error) {
	value := strings.TrimSpace(os.Getenv(key))
	if value == "" {
		return fallback, nil
	}
	parsed, err := strconv.ParseBool(value)
	if err != nil {
		return false, fmt.Errorf("%s must be a boolean: %w", key, err)
	}
	return parsed, nil
}