package dotenv

import (

	"bytes"

	"fmt"

	"sort"

	"strings"

	"github.com/subosito/gotenv"

)

const keyDelimiter = "_"

// Codec implements the encoding.Encoder and encoding.Decoder interfaces for encoding data containing environment variables

// (commonly called as dotenv format).

type Codec struct{}

func (Codec) Encode(v map[string]interface{}) ([]byte, error) {

	flattened := map[string]interface{}{}

	flattened = flattenAndMergeMap(flattened, v, "", keyDelimiter)

	keys := make([]string, 0, len(flattened))

	for key := range flattened {

		keys = append(keys, key)

	}

	sort.Strings(keys)

	var buf bytes.Buffer

	for _, key := range keys {

		_, err := buf.WriteString(fmt.Sprintf("%v=%v\n", strings.ToUpper(key), flattened[key]))

		if err != nil {

			return nil, err

		}

	}

	return buf.Bytes(), nil

}

func (Codec) Decode(b []byte, v map[string]interface{}) error {

	var buf bytes.Buffer

	_, err := buf.Write(b)

	if err != nil {

		return err

	}

	env, err := gotenv.StrictParse(&buf)

	if err != nil {

		return err

	}

	for key, value := range env {

		v[key] = value

	}

	return nil

}