/**********************************************************************
 * prog1nurse.c
 * A program that allows only 5 nurses to sign in. Once logged on the
   program allows patient files to be created and nurses passwords to
   be changed.
 * December 2017
 **********************************************************************/

#include <stdio.h>
#include <unistd.h>
#include <string.h>

/* Function declarations */
void emptyBuffer(void);
void printLine(void);
int nurseLogin();
void createPatientFile
        (char *patientLastName, char *patientDay,
         char *patientMonth, char *patientYear,
         char *patientsFileName);
int mainMenu();
void decryptString(char decrypt[], char source[]);
void encryptString(char encrypt[], char source[]);
void addOtherPatient();
void changeStringToChar(char encrypt[], char source[], int change);
void alterPassword(int login);

int main()
{
    int choice;
    int nurse = -1;
    while(nurse == -1)
    {
        nurse = nurseLogin();
    }


    while(choice != 3)
    {
        choice = mainMenu();
        switch(choice)
        {
            case 1:
                addOtherPatient();
                break;
            case 2:
                alterPassword(nurse);
                break;
            case 3:
                printf("Make sure to visit soon!");
                break;
        }
    }

    return 0;
}

/* function that requires the user to enter valid username and
 password, which is then checked with files*/
int nurseLogin()
{
    FILE *filesPassword;
    int i;
    char nurseUsername[9];
    char nursePassword[9];
    char filesUsername[9];
    char filePassword[9];
    char encryptUser[9];
    char encryptPass[9];


    printf("=======================================================\n");
    printf("                 ACTION ON WEIGHT\n");
    printf("=======================================================\n");

    printf("\n                *// Nurse Login //*\n\n");
    printf("Please enter your Username: \n");
    scanf("%9[^\n]", nurseUsername);
    emptyBuffer();
    printf("Please enter your Password: \n");
    scanf("%9[^\n]", nursePassword);
    emptyBuffer();

    encryptString(nurseUsername, encryptUser);
    encryptString(nursePassword, encryptPass);

    filesPassword = fopen("passwords.txt", "r");

    while(0<fscanf(filesPassword, " %[^\t] %[^\n]", filesUsername,
                   filePassword))
    {

        printf("%s %s : %s %s", filesUsername, filePassword,
               encryptUser, encryptPass);
        if((strcmp(filesUsername, encryptUser) == 0)
           && (strcmp(filePassword, encryptPass) == 0))
        {
            fclose(filesPassword);
            return i;
        }
        ++i;
    }

    fclose(filesPassword);
    puts("\n|| The password or username you entered seems to be\n"
                 "incorrect, please try again ||\n");

    return -1;
}

/* Function that displays the main menu options to the user */
int mainMenu()
{
    int menuChoice;

    printLine();
    printf("\n              *// Nurse Main Menu //*\n\n");
    printLine();
    printf("\n1. Add a patient file\n");
    printf("2. Change password\n");
    printf("3. Exit\n");

    printf("\nPlease selection an option: ");

    while(((scanf(" %d", &menuChoice)) == 0) ||
          (menuChoice < 1) || (menuChoice > 3))
    {
        emptyBuffer();
        printf("Please select an appropiate number(1-3)! \n");
        printf("Re-enter number: ");
    }
    emptyBuffer();

    return menuChoice;
}

/* function that allows the user to enter a new patients details */

void addOtherPatient(void)
{
    FILE *patientDetails;
    char patientFileName[20];
    char patientsFirstName[20];
    char patientsSecondName[20];
    char patientsDateOfBirth[3][20];
    char patientsHeight[10];
    char patientsWaist[10];
    char patientsWeight[10];
    char patientsComment[500];

    printLine();
    printf("                 Add a patient to a file!\n");
    printLine();

    printf("Patients First Name: ");
    scanf("%[^\n]", &patientsFirstName);
    emptyBuffer();

    printf("Patients Second Name: ");
    scanf("%[^\n]", &patientsSecondName);
    emptyBuffer();

    printf("Patients DOB Day: ");
    scanf("%[^\n]", &patientsDateOfBirth[0]);
    emptyBuffer();

    printf("Patients DOB Month: ");
    scanf("%[^\n]", &patientsDateOfBirth[1]);
    emptyBuffer();

    printf("Patients DOB Year: ");
    scanf("%[^\n]", &patientsDateOfBirth[2]);
    emptyBuffer();

    printf("Patients Height: ");
    scanf("%[^\n]", &patientsHeight);
    emptyBuffer();

    printf("Patients Waist Measurement: ");
    scanf("%[^\n]", &patientsWaist);
    emptyBuffer();

    printf("Patients Weight: ");
    scanf("%[^\n]", &patientsWeight);
    emptyBuffer();

    printf("Extra Comments: ");
    scanf("%[^\n]", &patientsComment);
    emptyBuffer();

    /* Function to create the file name */
    createPatientFile(patientsSecondName, patientsDateOfBirth[0], patientsDateOfBirth[1],
                      patientsDateOfBirth[2], patientFileName);

    /*Encrypt information of the patients*/
    encryptString(patientsFirstName, patientsFirstName);
    encryptString(patientsSecondName, patientsSecondName);
    encryptString(patientsDateOfBirth[0], patientsDateOfBirth[0]);
    encryptString(patientsDateOfBirth[1], patientsDateOfBirth[1]);
    encryptString(patientsDateOfBirth[2], patientsDateOfBirth[2]);
    encryptString(patientsHeight, patientsHeight);
    encryptString(patientsWaist, patientsWaist);
    encryptString(patientsWeight, patientsWeight);
    encryptString(patientsComment, patientsComment);

    patientDetails = fopen(patientFileName, "w");

    fprintf(patientDetails, "%s\n", patientsFirstName);
    fprintf(patientDetails, "%s\n", patientsSecondName);

    fprintf(patientDetails, "%s/%s/%s\n", patientsDateOfBirth[0],
            patientsDateOfBirth[1], patientsDateOfBirth[2]);

    fprintf(patientDetails, "%s\n", patientsHeight);
    fprintf(patientDetails, "%s\n", patientsWaist);
    fprintf(patientDetails, "%s\n", patientsWeight);
    fprintf(patientDetails, "%s\n", patientsComment);

    fclose(patientDetails);

    printLine();
    puts("Patient successfully added!");
}

/* Function which creates a file name for patients based on their
  last name and their date of birth */

void createPatientFile(char *patientLastName, char *patientDay, char *patientMonth,
                       char *patientYear, char *patientsFileName)
{
    int i;
    char copyYearLastTwoDigits[3];

    strcpy(patientsFileName, "Patients/");

    strcat(patientsFileName, patientLastName);
    strcat(patientsFileName, patientDay);
    strcat(patientsFileName, patientMonth);

    memcpy(copyYearLastTwoDigits, &patientYear[2], 2);

    copyYearLastTwoDigits[2] = '\0';

    strcat(patientsFileName, copyYearLastTwoDigits);

    strcat(patientsFileName, ".aow");
}

/*A function which takes a string and transforms it's characters*/
void changeStringToChar(char encrypt[], char source[], int change)
{
    int length = strlen(encrypt);

    char toEncrypt[length+1];

    int i;
    int ch;

    for(i = 0; i < length; ++i)
    {
        ch = encrypt[i];

        if(ch >= '0' && ch <= '9')
        {
            ch += change;

            if(ch > '9')
                ch = '0' + (ch - '9') - 1;

            else if(ch < '0')
                ch = '9' + (ch - '0') + 1;
        }
        else if(ch >= 'A' && ch <= 'Z')
        {
            ch += change;

            if(ch > 'Z')
                ch = 'A' + (ch - 'Z') - 1;
            else if(ch < 'A')
                ch = 'Z' + (ch - 'A') + 1;
        }
        else if(ch >= 'a' && ch <= 'z')
        {
            ch += change;

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

            else if(ch < 'a')
                ch = 'z' + (ch - 'a') + 1;
        }
        toEncrypt[i] = ch;
    }
    toEncrypt[length] = '\0';

    strcpy(source, toEncrypt);

}
//A function for encryption which uses transform function
void encryptString(char encrypt[], char source[])
{
    changeStringToChar(encrypt, source, +7);
}

//A function for decryption which uses transform function
void decryptString(char decrypt[], char source[])
{
    changeStringToChar(decrypt, source, -7);
}

//A function which allows a nurse to change a password within
//a specified array location depending which nurse is logged in
void alterPassword(int login)
{
    FILE *passwordFileRead;
    FILE *passwordFileWrite;

    char newPassword[10];
    char reinforcePassword[10];

    printLine();
    printf("                Change your password!\n");
    printLine();

    printf("Please enter your new password:\n");
    scanf("%[^\n]", newPassword);
    emptyBuffer();

    if(strlen(newPassword) != 8)
    {
        printf("Password must be 8 characters long! \n");
        return;
    }
    printf("Please confirm your new password: \n");
    scanf("%[^\n]", reinforcePassword);
    emptyBuffer();

    /*function to compare two password strings to see if they
      match*/
    if(strcmp(newPassword, reinforcePassword) == 0)
    {
        char encryptedPassword[10];

        encryptString(reinforcePassword, encryptedPassword);

        char fileUsernames[5][10];
        char filePasswords[5][10];

        passwordFileRead = fopen("passwords.txt", "r");
        int i = 0;

        while(2==fscanf(passwordFileRead, " %[^\t] %[^\n]",
                        fileUsernames[i], filePasswords[i]))
        {
            i++;
        }

        fclose(passwordFileRead);

        passwordFileWrite = fopen("passwords.txt", "w");

        strcpy(filePasswords[login], encryptedPassword);

        for (i = 0; i < 5; ++i)
        {
            fprintf(passwordFileWrite, "%s\t%s\n", fileUsernames[i],
                    filePasswords[i]);
        }

        fclose(passwordFileWrite);

        printf("\nPassword successfully changed!\n");
        return;
    }
    else
    {
        puts("Your password did not match, please try again !");
        return;
    }
}
/*Function that asks user to press any key to continue */
void printLine(void)
{
    printf("-------------------------------------------------------\n");

}

/*Function to empty the buffer*/
void emptyBuffer(void)
{
    while(getchar() != '\n')
    {
        ;
    }
}