// Package env provides .env file loading and typed lookups using only the
// standard library.
package env

import (
	"bufio"
	"os"
	"strings"
)

// Load reads KEY=VALUE pairs from the given file into the process
// environment. Existing environment variables win over file values. A
// missing file is not an error, so .env stays optional.
func Load(path string) error {
	f, err := os.Open(path)
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return 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(strings.TrimPrefix(key, "export "))
		value = strings.TrimSpace(value)
		if len(value) >= 2 {
			if (value[0] == '"' && value[len(value)-1] == '"') ||
				(value[0] == '\'' && value[len(value)-1] == '\'') {
				value = value[1 : len(value)-1]
			}
		}
		if _, exists := os.LookupEnv(key); !exists {
			os.Setenv(key, value)
		}
	}
	return scanner.Err()
}

// Get returns the environment variable or a default.
func Get(key, fallback string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return fallback
}