package dotenv

import (
	"bytes"
	"io"
	"os"
)

//
// copied from https://github.com/joho/godotenv/blob/main/godotenv.go
//

// Read all env (with same file loading semantics as Load) but return values as
// a map rather than automatically writing values into env
func Read(filenames ...string) (envMap map[string]string, err error) {
	filenames = filenamesOrDefault(filenames)
	envMap = make(map[string]string)

	for _, filename := range filenames {
		individualEnvMap, individualErr := readFile(filename)

		if individualErr != nil {
			err = individualErr
			return // return early on a spazout
		}

		for key, value := range individualEnvMap {
			envMap[key] = value
		}
	}

	return
}

func filenamesOrDefault(filenames []string) []string {
	if len(filenames) == 0 {
		return []string{".env"}
	}
	return filenames
}

func readFile(filename string) (envMap map[string]string, err error) {
	file, err := os.Open(filename)
	if err != nil {
		return
	}
	defer file.Close()

	return parse(file)
}

// parse reads an env file from io.Reader, returning a map of keys and values.
func parse(r io.Reader) (map[string]string, error) {
	var buf bytes.Buffer
	_, err := io.Copy(&buf, r)
	if err != nil {
		return nil, err
	}

	return unmarshal(buf.Bytes())
}

// unmarshal parses env file from byte slice of chars, returning a map of keys and values.
func unmarshal(src []byte) (map[string]string, error) {
	out := make(map[string]string)
	err := parseBytes(src, out)

	return out, err
}