package config

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

// LoadDotEnv reads KEY=VALUE pairs from path (default ".env") and applies
// them via os.Setenv, without overriding variables already set in the
// environment. Missing file is not an error — real env vars always win.
func LoadDotEnv(path string) error {
	if path == "" {
		path = ".env"
	}

	f, err := os.Open(path)
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return fmt.Errorf("open %s: %w", path, err)
	}
	defer f.Close()

	scanner := bufio.NewScanner(f)
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}

		key, value, ok := strings.Cut(line, "=")
		if !ok {
			continue
		}
		key = strings.TrimSpace(key)
		value = strings.Trim(strings.TrimSpace(value), `"'`)

		if _, exists := os.LookupEnv(key); !exists {
			os.Setenv(key, value)
		}
	}

	return scanner.Err()
}

func GetString(key, fallback string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return fallback
}

func GetInt(key string, fallback int) int {
	v := os.Getenv(key)
	if v == "" {
		return fallback
	}
	n, err := strconv.Atoi(v)
	if err != nil {
		return fallback
	}
	return n
}

func MustGetString(key string) (string, error) {
	v := os.Getenv(key)
	if v == "" {
		return "", fmt.Errorf("missing required environment variable: %s", key)
	}
	return v, nil
}