/*
Alice aNicePasswrd a?m?g?a?z??f
Bob   aCoolPasswrd a???jxa?z??f

*/

#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>

typedef struct Users {
  char Id[12];
  char hashPW[32];
} User;

// Prototypes
User * user;
void passwordHasher(char *aPW, char *aHashedPw);
void E(char *in, char *out);
int passwordCompare(char *pw1, char *pw2);
void UserPrompts();
void filePopulate();
void passwdPadder(char *aString);
void usrNameValidity(char *userIdTrial);
void passwordChecker(char *apw);
void userCreation();
void fileRepop();   //writes to file after any changes
void PasswordCreation(int location);
static FILE *userFile;
static FILE *hashFile;


int main()
{
  user = malloc(sizeof(User) * 60);
  filePopulate(); // read and populate user array
  UserPrompts();  //Initial User Interaction
  printf("Goodbye");
}

void filePopulate()
{
  // Create and open the file, we need rw access since we may have to write to it
  userFile = fopen("users.txt","rw");
  hashFile = fopen("hash.txt","rw");
  int i = 0;

  // Go through the file and populate the array for userIDs
  while(fscanf(userFile, "%s", user[i].Id) != EOF)
    ++i;

  i = 0; // reset i for another use

  // Obviously in this case the hashPWs are ordered in the same order the userIDs are ordered
  while(fscanf(hashFile, "%s", user[i].hashPW) != EOF)
    ++i;
}


void UserPrompts()
{
  char enteredId[32];
  char enteredPw[12];
  char hashedPW[32];
  int n = 5;
  int attempts = 0;
  int size = 60;
  // Get user input
  printf("Input User ID: ");
  fgets(enteredId, 32, stdin);
  usrNameValidity(enteredId);

  // Clean out new input so it matches perfectly with what's in the array
  enteredId[strcspn(enteredId, "\r\n")] = '\0';
  //User = malloc(sizeof(User) * size); // Allows up to 60 users (fixed size)
  for (int i=0;i<size;i++)
  {
     if (strcmp(enteredId,user[i].Id) == 0) //strcmp(pw1,pw2) == 0 //
      {
	int location = i;
	printf("ID found\n");
	PasswordCreation(location);
      }
  }
	printf("INVALID, ID NOT FOUND! ");
	userCreation();

}
void PasswordCreation(int location)
{
  int n = 5;
  int i = location;
  int attempts = 0;
  int size = 60;
  char enteredId[32];
  char enteredPw [13];
  //char hashedPW[32];
  char ahashedPW[13];
  //while(attempts < n)
  //{
      printf("\n Enter password: ");
      fgets(enteredPw,13,stdin); // might need the same fix as above
      //passwordChecker(enteredPw);
      passwordHasher(enteredPw, ahashedPW);
      printf("%s", ahashedPW);
      printf("\n%s", user[i].hashPW);
      if (!(strcmp(ahashedPW, user[i].hashPW) == 0))
	{

	  printf("\nEnter New Password: ");
	  fgets(enteredPw,12,stdin);
	  passwordChecker(enteredPw);
	  passwordHasher(enteredPw, ahashedPW);
	  strcpy(user[i].hashPW, ahashedPW);
	  fileRepop();
	  printf("your password has been changed");
	  attempts = n;
	}
      attempts ++;
      //}

}

void userCreation()
{
  char enteredId[32];
  char enteredPw[12];

  hashFile = fopen("hash.txt","w");

  //Get input
  printf("\nCreate new ID: ");
  fgets(enteredId, 32, stdin);
  //fprintf(userFile, "\n%s", entered
  printf("\nCreate new password: ");
  fgets(enteredPw, 12, stdin);
  fprintf(userFile, "\n%s", enteredId);
  // enteredPW now goes through hash and hash is stored in hashpw file
  char *temp = malloc(sizeof(char *) * 12);
  passwordHasher(enteredPw, temp);
  fprintf(hashFile, "\n%s", temp);
  //UserPrompts();
}


void E(char *in, char *out)
{
  out[0]=(in[0]&0x80)^(((in[0]>>1)&0x7F)^((in[0])&0x7F));
  out[1]=((in[1]&0x80)^((in[0]<<7)&0x80))^(((in[1]>>1)&0x7F)^((in[1])&0x7F));
  out[2]=((in[2]&0x80)^((in[1]<<7)&0x80))^(((in[2]>>1)&0x7F)^((in[2])&0x7F));
  out[3]=((in[3]&0x80)^((in[2]<<7)&0x80))^(((in[3]>>1)&0x7F)^((in[3])&0x7F));
}

//Takes a string and returns a "E()"ed string
void passwordHasher(char *aPW, char *aHashedPw)
{
  char *hashedPw = malloc(sizeof(char) * 12);
  char *input = aPW;
  //blocks and their hashed space allocation
  char *b1 = malloc(4);
  char *b2 = malloc(4);
  char *b3 = malloc(4);
  char *h1 = malloc(4);
  char *h2 = malloc(4);
  char *h3 = malloc(4);

  //Uppercasing input
  //passwdPadder(input);

  for (int i= 0; i <strlen(input); i++)
    input[i] = toupper(input[i]);

  //defining contents of blocks
  strncpy(b1, input, 4);
  strncpy(b2, input+4, 4);
  strncpy(b3, input+8, 4);
  //defining end of string
  b1[4]='\0';
  b2[4]='\0';
  b3[4]='\0';
  //hashing(E()ing) each block using e
  E(b1, h1);
  h1[4]='\0';
  strcat(hashedPw, h1);
  E(b2, h2);
  h2[4]='\0';
  strcat(hashedPw, h2);
  E(b3, h3);
  h3[4]='\0';
  strcat(hashedPw, h3);
  strcpy(aHashedPw, hashedPw);
}

void passwdPadder(char *aString)
{
  int size = (int)strlen(aString);
  //pads passwords shorter than 12 characters with empty space chaaracter
  for (int i = size; i <12 ; i++)
    aString[i]=32;
}

void usrNameValidity(char *userIdTrial)
{
  char usr[32];
  strcpy(usr, userIdTrial);
  int idSize = (int)strlen(usr);

  if (idSize > 3 && idSize <33)
    return;
  else
    {
      printf("INVALID, ID NOT FOUND! \nCreate New ID: ");
      UserPrompts();

    }
}

//• Passwords must include upper and lower case letters and numbers only,
//i.e. no special characters
void passwordChecker(char * apw)
{
  char pw[12];
  //if value anything other than 0, it meants there is an invalid character in string
  int test = 0;
  strcpy(pw, apw);
  int size = (int)strlen(pw);
  if (size > 12)
    {
      printf("Password is too long, Try again\n");
      UserPrompts();
    }
  for (int i = 0; i <size; i++)
    {
      if ((pw[i] <48) || (pw[i] > 57 && pw[i] < 65) || (pw[i] > 90 && pw[i] < 96))
	test ++;
    }
  if (test != 0)
    {
      printf("invalid password, use only numbers and letters \n Any characters 12 will not count");
      UserPrompts();
    }
}

void fileRepop()
{
  userFile = fopen("users.txt","w+");
  hashFile = fopen("hash.txt","w+");
  for (int i = 0; i < 60; i++)
    fprintf(userFile, "%s\n", user[i].Id);

  for (int i = 0; i < 60; i++){
    fprintf(hashFile, "%s\n", user[i].hashPW);
  }
}