#include<stdio.h>
#include<stdlib.h>
#include<string.h>
char menu(void);
char action(char option);
void encypt();
void decrypt();



char menu(void){
  char option;
  printf("Pick whether you would like to enycrypt a text or decrypt a text.\n");
  printf("1 - encrypt\n");
  printf("2 - decrypt\n");
  printf("x - end");
  scanf(" %c", &option);
  return option;
}
char action(char option){
switch(option){
  case '1':
  encypt();
  case '2':
  decrypt();
}
}


void encrypt(){
  char message_1[100], ch,message_2[100];
    int i, key;

    printf("Enter a message to encrypt: ");
    fgets(message_1,100,stdin);
    printf("Enter key: ");
    scanf("%d", &key);

    for(i = 0; message_1[i] != '\0'; ++i){
        ch = message_1[i];

        if(ch >= 'a' && ch <= 'z'){
            ch = ch + key;

            if(ch > 'z'){
                ch = ch - 'z' + 'a' - 1;
            }

            message_1[i] = ch;
        }
        else if(ch >= 'A' && ch <= 'Z'){
            ch = ch + key;

            if(ch > 'Z'){
                ch = ch - 'Z' + 'A' - 1;
            }

            message_1[i] = ch;
        }
    }

   printf("Encrypted message: %s", message_1);
}
void decrypt(){
  char ch,message_2[100];
    int i, key;
  printf("Enter a message to decrypt: \n");
    fgets(message_2,100,stdin);


    for(i = 0; message_2[i] != '\0'; ++i){
        ch = message_2[i];

        if(ch >= 'a' && ch <= 'z'){
            ch = ch - key;

            if(ch < 'a'){
                ch = ch + 'z' - 'a' + 1;
            }

            message_2[i] = ch;
        }
        else if(ch >= 'A' && ch <= 'Z'){
            ch = ch - key;

            if(ch < 'A'){
                ch = ch + 'Z' - 'A' + 1;
            }

            message_2[i] = ch;
        }
    }
    printf("Enter key: ");
    scanf("%d", &key);
    printf("Decrypted message: %s", message_2);

}
int main(){
    char option;
    printf("Encryption and decription program\n");
    printf("-------------------------------------\n");

    do{
      while(option != 'x'){
      if(option == '1'){
        do(encypt());
      }else{
        do(decrypt());
      }
    }
    }

    return 0;
}