move again

Lab04/content/part1/encrypt/main.go

@@ -0,0 +1,95 @@
+package main
+
+import (
+	"flag"
+	"io/ioutil"
+	"log"
+	"os"
+	"regexp"
+	"strings"
+	"unicode"
+)
+
+const lettersInTheAlphabet = 26
+const startUpperCase = 65
+const endUpperCase = startUpperCase + lettersInTheAlphabet
+const startLowerCase = 97
+const endLowerCase = startLowerCase + lettersInTheAlphabet
+
+type keyLetter struct {
+	upperCase string
+	position  int32
+}
+
+func parseArguments() (string, string) {
+	var inputKey string
+	var inputFile string
+	flag.StringVar(&inputKey, "k", "", "Specify key word.")
+	flag.StringVar(&inputFile, "f", "", "Specify file to encrypt.")
+	flag.Parse()
+	return inputKey, inputFile
+}
+
+func readFile(relativePath string) string {
+	content, err := ioutil.ReadFile(relativePath)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	return string(content)
+}
+
+func writeFile(relativePath string, message string) {
+	file, err := os.Create(relativePath)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	defer file.Close()
+	file.WriteString(message)
+}
+
+func validateKeyWord(inputKey string) string {
+	reg, err := regexp.Compile("[^a-zA-Z]+")
+	if err != nil {
+		log.Fatalln(err)
+	}
+	processedString := reg.ReplaceAllString(inputKey, "")
+	return strings.ToUpper(processedString)
+}
+
+func initKeyWord(key string) []keyLetter {
+	var keyWord []keyLetter
+	for _, letter := range key {
+		keyWord = append(keyWord, keyLetter{
+			upperCase: string(letter),
+			position:  letter - 'A',
+		})
+	}
+	return keyWord
+}
+
+func encryptMessage(keyWord []keyLetter, message string) string {
+	encrypted := ""
+	index := 0
+	for _, letter := range message {
+		if !unicode.IsLetter(letter) {
+			encrypted += string(letter)
+		} else {
+			keyWordIndex := index % len(keyWord)
+			newLetter := letter + keyWord[keyWordIndex].position
+			if (unicode.IsLower(letter) && newLetter >= endLowerCase) ||
+				(unicode.IsUpper(letter) && newLetter >= endUpperCase) {
+				newLetter -= lettersInTheAlphabet
+			}
+			encrypted += string(newLetter)
+			index += 1
+		}
+	}
+	return encrypted
+}
+
+func main() {
+	inputKey, inputFile := parseArguments()
+	message := readFile(inputFile)
+	keyWord := initKeyWord(validateKeyWord(inputKey))
+	writeFile("output.txt", encryptMessage(keyWord, message))
+}