/**********************************************************************
 * nurseprogram.c                                                     *
 * A program with intergrated login system that let's a nurse write   *
 * patient details to a file and has an option to change password.    *
 * Written details are then encrypted to a file.                      *
 * Candidate NO: 181452                                               *
 * December 2017                                                      *
 **********************************************************************/

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


/* Function declarations */

void emptyBuffer(void);
int nurseLogin();
void createPatientFile
        (char *patientLastName, char *patientDay,
         char *patientMonth, char *patientYear,
         char *patientsFileName);
void displayTitle(char *title);
int mainMenu();
void waitForKey(void);
void decryptString(char dest[], char source[]);
void encryptString(char dest[], char source[]);
void addOtherPatient();
void changeStringToChar(char *encrypted, char *source, int change);
void alterPassword(int);

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("Dont forget 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];


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

    //encryptString(nurseUsername, nurseUsername);
    //encryptString(nursePassword, nursePassword);

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

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


        if((strcmp(filesUsername, nurseUsername) == 0)
           && (strcmp(filePassword, nursePassword) == 0))
        {
            fclose(filesPassword);
            return i;
        }
        ++i;
    }

    fclose(filesPassword);
    puts("\n You entered the wrong username or password, please try "
                 "again!\n");
    waitForKey();

    return -1;
}

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

    displayTitle("                // NURSE MENU //");
    printf("1. Add a patient file\n");
    printf("2. Change password\n");
    printf("3. Exit\n");

    printf("Enter Appropriate Number: ");

    while(((scanf(" %d", &menuChoice)) == 0) ||
          (menuChoice < 1) || (menuChoice > 3))
    {
        emptyBuffer();
        printf("Please enter a valid 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 patientsLastName[20];
    char patientsDateOfBirth[3][20];
    char patientsHeight[10];
    char patientsWaist[10];
    char patientsWeight[10];
    char patientsComment[500];

    displayTitle("                // ADD A PATIENT //");

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

    printf("Patients Last Name: ");
    scanf("%[^\n]", &patientsLastName);
    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 in cm: ");
    scanf("%[^\n]", &patientsHeight);
    emptyBuffer();

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

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

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

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

    /*Encrypt information of the patients*/
    encryptString(patientsFirstName, patientsFirstName);
    encryptString(patientsLastName, patientsLastName);
    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", patientsLastName);

    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);

    printf("-------------------------------------------------------\n");
    puts("Patient successfully added!");
    /*Display continue message using waitForKey function*/
    waitForKey();
}

/* 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 *encrypted, char *source, int change)
{
    int strLen = strlen(source);

    int i;
    int ch;

    for(i = 0; i < strLen; ++i)
    {
        ch = source[i];

        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;
            }
        }

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

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

            else if(ch < '0')
            {
                ch = '9' + (ch - '0') + 1;
            }
        }
        encrypted[i] = ch;
    }
    encrypted[strLen] = '\0';

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

/*A function for decryption which uses transform function*/
void decryptString(char dest[], char source[])
{
    changeStringToChar(dest, 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 nurse)
{
    FILE *passwordFileRead;
    FILE *passwordFileWrite;

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

    displayTitle("                // CHANGE PASSWORD //");

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

    if(strlen(newPassword) != 8)
    {
        printf("Your new password MUST be 8 characters long ! \n");
        waitForKey();
        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 allPasswords[5][10];
        char allUsernames[5][10];

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

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

        fclose(passwordFileRead);

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

        strcpy(allPasswords[nurse], encryptedPassword);

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

        fclose(passwordFileWrite);

        printf("Password has been changed!\n");
        printf("---------------------------------------------------\n");
        waitForKey();
        return;
    }
    else
    {
        puts("Your password did not match, please try again !");
        waitForKey();
        return;
    }
}
/*Function that display the program header*/
void displayTitle(char *header)
{
    printf
            ("=========================================================\n");
    printf("                 ACTION ON WEIGHT\n");
    printf("========================================================\n");
    printf(header);
    printf("\n");
}

/*Function that displays some ending text and waits for user
to press any key*/
void waitForKey(void)
{
    printf
            ("*********************************************************"
                     "*\n");
    printf("Press any key in order to continue...\n");
    printf
            ("*********************************************************"
                     "*\n");
    getchar();

}

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