From 1b1945779d520e29f6e8f550fb55b937da31e774 Mon Sep 17 00:00:00 2001
From: Florian Hoss <mail@florianhoss.de>
Date: Mon, 30 May 2022 12:50:59 +0200
Subject: [PATCH] encrypting works

---
 Lab04/code/part01-encrypt/main.go | 72 ++++++++++++++++++++++++++++++-
 1 file changed, 71 insertions(+), 1 deletion(-)

diff --git a/Lab04/code/part01-encrypt/main.go b/Lab04/code/part01-encrypt/main.go
index f3ae387..04f162b 100644
--- a/Lab04/code/part01-encrypt/main.go
+++ b/Lab04/code/part01-encrypt/main.go
@@ -1,7 +1,77 @@
 package main
 
 import (
+	"fmt"
+	"log"
+	"regexp"
+	"strings"
+	"unicode"
 )
 
-func main() {
+const lettersInTheAlphabet = 26
+const startUpperCase = 65
+const endUpperCase = 65 + lettersInTheAlphabet
+const startLowerCase = 97
+const endLowerCase = 97 + lettersInTheAlphabet
+
+var key string
+
+type keyLetter struct {
+	upperCase string
+	position  int32
+}
+
+func getKeyWord() {
+	var input string
+	fmt.Println("Please enter a key word:")
+	_, err := fmt.Scanln(&input)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	reg, err := regexp.Compile("[^a-zA-Z]+")
+	if err != nil {
+		log.Fatalln(err)
+	}
+	processedString := reg.ReplaceAllString(input, "")
+	key = strings.ToUpper(processedString)
+}
+
+func initKeyWord() []keyLetter {
+	var keyWord []keyLetter
+	for _, letter := range key {
+		keyWord = append(keyWord, keyLetter{
+			upperCase: string(letter),
+			position:  letter - 'A',
+		})
+	}
+	fmt.Println(keyWord)
+	return keyWord
+}
+
+func encryptMessage(keyWord []keyLetter, message string) string {
+	encrypted := ""
+	index := 0
+	for _, letter := range message {
+		if letter == 32 {
+			encrypted += " "
+		} 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() {
+	message := "Make It Happen"
+	fmt.Println(message)
+	getKeyWord()
+	keyWord := initKeyWord()
+	fmt.Println(encryptMessage(keyWord, message))
 }