package main

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"crypto/sha512"
	"encoding/base64"
	"errors"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"strings"
)

const (
	UserFile = "loop_users"
)

var (
	EnvironmentVariables = map[string]string{
		"LOOP_URL":  "localhost:6006",
		"LOOP_SALT": "whatyoutalkingaboutwillus",
		"LOOP_DATA": ".",
	}
)

func ConfigureEnvironment() {
	for key, value := range EnvironmentVariables {
		env := os.Getenv(key)
		if env == "" && value != "" {
			os.Setenv(key, value)
		}
	}
}

func main() {
	log.Print("Configuring environment...")
	ConfigureEnvironment()

	//http.HandleFunc("/", DefaultHandler)

	log.Fatal(http.ListenAndServe(address(), nil))
}

// General stuff

type Account struct {
	Username   string `json:username`
	Passphrase string `json:passphrase`
}

func address() string {
	return os.Getenv("LOOP_URL")
}

// Security stuff

func encodeBase64(data []byte) string {
	return base64.StdEncoding.EncodeToString(data)
}
func decodeBase64(data []byte) []byte {
	b, _ := base64.StdEncoding.DecodeString(string(data))
	return b
}
func salt() string {
	return os.Getenv("LOOP_SALT")
}
func getSizedKey(key string) string {
	// Get the correct key length
	l := len(key)
	if l < 16 {
		for i := 0; i < 16-l; i++ {
			key += "."
		}
	} else if l < 24 {
		for i := 0; i < 24-l; i++ {
			key += "."
		}
	} else if l < 32 {
		for i := 0; i < 32-l; i++ {
			key += "."
		}
	} else {
		key = key[:32]
	}

	return key
}
func encrypt(text, passphrase string) ([]byte, error) {
	key := []byte(getSizedKey(passphrase))
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}
	cipherText := make([]byte, aes.BlockSize+len(text))
	iv := cipherText[:aes.BlockSize]
	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
		return nil, err
	}
	encrypter := cipher.NewCFBEncrypter(block, iv)
	encrypter.XORKeyStream(cipherText[aes.BlockSize:], []byte(text))
	return cipherText, nil
}
func decrypt(text []byte, passphrase string) ([]byte, error) {
	key := []byte(getSizedKey(passphrase))
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}
	if len(text) < aes.BlockSize {
		return nil, errors.New("Cipher text too short")
	}
	iv := text[:aes.BlockSize]
	data := text[aes.BlockSize:]
	decrypter := cipher.NewCFBDecrypter(block, iv)
	decrypter.XORKeyStream(data, data)
	return data, nil
}
func hash(username, passphrase, salt string) []byte {
	clearText := fmt.Sprintf(
		"%s%s-%s",
		salt,
		strings.ToLower(username),
		strings.ToLower(passphrase))

	sha := sha512.New()
	sha.Write([]byte(clearText))
	return sha.Sum(nil)
}
func generatePassphrase(username, passphrase string) string {
	return encodeBase64(hash(username, passphrase, salt()))
}