package config

import (
	"log"
	"log/slog"
	"os"
	"strings"

	"github.com/joho/godotenv"
)

// Config holds our application's configuration.
type Config struct {
	TelegramBotAPIKey string
	DBPath            string
	LogLevel          slog.Level
}

// LoadEnv loads environment variables from a .env file (if available).
func LoadEnv() {
	if err := godotenv.Load(); err != nil {
		log.Println("Warning: .env file not found. Using system environment variables.")
	}
}

// GetConfig loads and validates configuration from the environment.
func GetConfig() Config {
	// Load .env file first.
	LoadEnv()

	// Create a config struct.
	cfg := Config{}

	// Telegram bot's API key must not be empty.
	telegramBotAPIKey := os.Getenv("TELEGRAM_BOT_API_KEY")
	if telegramBotAPIKey == "" {
		panic("TELEGRAM_BOT_API_KEY is required!")
	}
	cfg.TelegramBotAPIKey = telegramBotAPIKey

	// Read DATABASE_FILE and default to badger.db
	dbPath := os.Getenv("DATABASE_FILE")
	if dbPath == "" {
		dbPath = "badger.db"
	}
	cfg.DBPath = dbPath

	// Read LOG_LEVEL and default to info if not set
	logLevel := os.Getenv("LOG_LEVEL")
	if logLevel == "" {
		logLevel = "info"
	}
	switch strings.ToLower(logLevel) {
	case "debug":
		cfg.LogLevel = slog.LevelDebug
	case "info":
		cfg.LogLevel = slog.LevelInfo
	case "warn":
		cfg.LogLevel = slog.LevelWarn
	case "error":
		cfg.LogLevel = slog.LevelError
	default:
		panic("invalid log level! value must be in debug, info, warn, or error!")
	}

	return cfg
}