/**********************************************************************
 * 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>
#include <unistd.h>



/*Function prototypes*/
void displayTitle(char *title);
void equalsLine(void);
void waitForKey(void);
void emptyBuffer(void);
int nurseLogin();
int mainMenu();
void addOtherPatient();
void alterPassword(int nurse);
void createPatientFile(char *patientLastName, char *patientDay,
                       char *patientMonth, char *patientYear,
                       char *patientsFileName);
void decryptString(char dest[], char source[]);
void encryptString(char dest[], char source[]);
void changeString(char encrypted[], char source[], int change);
char toLower(char any);

int main()
{
    int choice;
    int nurse = -1;

    /*Show the nurseLogin and get the nurse login*/
    while(nurse == -1)
    {
        nurse = nurseLogin();
    }

    /*Iterated switch selection used for calling a function using
    maineMenu function return value*/
    while(choice != 3)
    {   /*Display mainu menu screen and get choice made by the user*/
        choice = mainMenu();
        switch(choice)
        {
            case 1:
                /*Call addOtherPatient function*/
                addOtherPatient();
                break;
            case 2:
                /*Call alterPassword function*/
                alterPassword(nurse);
                break;
            case 3:
                /*Clear the contents and display a closing message*/
                printf("See you soon!");
                break;
        }
    }

    return 0;
}
/*A function which prompts for a user login and password, if the user
inputs matches the contents within a file the loop will end*/
int nurseLogin()
{
    FILE *filesPassword;
    int i;
    int nurse;
    char nurseUsername[9];
    char nursePassword[9];
    char filesUsername[9];
    char filePassword[9];

    /*Displaying the header*/
    displayTitle("\t\t      || LOGIN ||");

    puts("Enter your username and password:\n");

    /*Receiving user string inputs*/
    printf("Username: ");
    scanf("%9[^\n]", nurseUsername);
    emptyBuffer();
    printf("Password: ");
    scanf("%9[^\n]", nursePassword);
    emptyBuffer();

    /*Declare variables for encrypted username and password*/
    char encryptedNurseUsername[9];
    char encryptedNursePassword[9];

    /*Use encryptString to encrypt username and password*/
    encryptString(nurseUsername, encryptedNurseUsername);
    encryptString(nursePassword, encryptedNursePassword);


    /*Opening file for reading purposes*/
    filesPassword = fopen("passwords.txt", "r");

    /*Scanning for username and password within a file*/
    while(0<fscanf(filesPassword, " %[^\t] %[^\n]", filesUsername,
                   filePassword))
    {

        /*Comparing user input strings with file strings*/
        if((strcmp(filesUsername, encryptedNurseUsername) == 0)
           && (strcmp(filePassword, encryptedNursePassword) == 0))
        {
            /*Closing the file*/
            fclose(filesPassword);
            /*Returning a nurse address*/
            return i;
        }
        /*Adding one to i*/
        ++i;
    }
    /*Closing the file*/
    fclose(filesPassword);

    puts("\n!! Wrong username or password, please try again !!\n");
    waitForKey();

    return -1;
}
/*Main menu function which displays main menu contents including
a header and returns user's input*/
int mainMenu()
{
    int choice;
    /*Displaying menu list choices*/
    displayTitle("\t\t    || NURSE MENU ||");
    puts("1) Add a patient");
    puts("2) Change password");
    puts("3) Exit");

    printf(">>> ");

    /*If the input is less than 1 or higher than 3 then
    display an error message*/
    while(((scanf(" %d", &choice)) == 0) ||
          (choice < 1) || (choice > 3))
    {
        emptyBuffer();
        puts("!! Please make a valid choice !!");
        printf(">>> ");
    }
    emptyBuffer();

    return choice;
}

void addOtherPatient(void)
{
    /*Declaring variables for iteriation and patient details, using
    2d array to store date of birth*/
    FILE *patientDetails;
    char patientFileName[265];
    char patientsFirstName[256];
    char patientsLastName[256];
    char patientsDateOfBirth[3][256];
    char patientsHeight[256];
    char patientsWaist[256];
    char patientsWeight[256];
    char patientsComment[512];


    /*Displaying the header*/
    displayTitle("\t\t   || ADD A PATIENT ||");

    /*Storing non-encryped patient details into [0]*/
    printf("First Name: ");
    scanf("%[^\n]", &patientsFirstName);
    emptyBuffer();

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

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

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

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

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

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

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

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

    /*Creating file name using the createPatientFile function*/
    createPatientFile(patientsLastName, patientsDateOfBirth[0], patientsDateOfBirth[1],
                      patientsDateOfBirth[2], patientFileName);

    /*Encrypting patient's details*/
    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);

    /*Opening the file for writing purposes*/
    patientDetails = fopen(patientFileName, "w");

    /*Writing user to a file*/
    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);

    /*Closing the file*/
    fclose(patientDetails);

    equalsLine();
    puts("Patient has been added!");
    /*Display continue message using waitForKey function*/
    waitForKey();
}

/*Function that takes patient's last name and DOB input and returns
a file name for the patient*/
void createPatientFile(char *patientLastName, char *patientDay, char *patientMonth,
                       char *patientYear, char *patientsFileName)
{
    int i;
    char copyYearLastTwoDigits[3];

    strcpy(patientsFileName, "Patients/");

    /*Adding last name, day and month to a file name*/
    strcat(patientsFileName, patientLastName);
    strcat(patientsFileName, patientDay);
    strcat(patientsFileName, patientMonth);

    /*Copy two last characters from the patient year of birth and store
    it to the variable*/
    memcpy(copyYearLastTwoDigits, &patientYear[2], 2);

    /*Adding \0 to the variable to make it a string*/
    copyYearLastTwoDigits[2] = '\0';

    /*Adding last two DOB digits to the file name*/
    strcat(patientsFileName, copyYearLastTwoDigits);
    /*Add the .aow extension to the file name*/
    strcat(patientsFileName, ".aow");

    /*Iterating trough a file name*/
    for(i = 0; patientsFileName[i]; ++i)
    {
        /*Changing file first character to lowercase*/
        patientsFileName[i] = toLower(patientsFileName[i]);
    }

}
/*A function which takes a string and transforms it's characters*/
void changeString(char encrypted[], char source[], int change)
{
    /*storing length of the string to encrypt*/
    int strLen = strlen(source);

    int i;
    int ch;

    /*Iterate trough the string*/
    for(i = 0; i < strLen; ++i)
    {
        /*Assign one character of the string to
        the character variable*/
        ch = source[i];

        /*If the character is between a and z*/
        if(ch >= 'a' && ch <= 'z')
        {
            /*Add change(7) to the character*/
            ch += change;

            /*If character is out of the range of z*/
            if(ch > 'z')
            {
                /*Get the difference between the character a and z,
                subtract 1 and add it to the a value*/
                ch = 'a' + (ch - 'z') - 1;
            }
                /*If the character is out of the range of a*/
            else if(ch < 'a')
            {
                /*Get the difference between the character z and a,
                add 1 and add it to the z value*/
                ch = 'z' + (ch - 'a') + 1;
            }
        }
            /*If the character is between A and Z*/
        else if(ch >= 'A' && ch <= 'Z')
        {
            /*Add change(7) to the character*/
            ch += change;

            /*If character is out of the range of Z*/
            if(ch > 'Z')
            {
                /*Get the difference between the character A and Z,
                subtract 1 and add it to the A value*/
                ch = 'A' + (ch - 'Z') - 1;
            }
                /*If the character is out of the range of A*/
            else if(ch < 'A')
            {
                /*Get the difference between the character Z and A,
                add 1 and add it to the Z value*/
                ch = 'Z' + (ch - 'A') + 1;
            }
        }
            /*If the character is between 0 and 9*/
        else if(ch >= '0' && ch <= '9')
        {
            //Add change(7) to the character
            ch += change;

            /*If character is out of the range of 9*/
            if(ch > '9')
            {
                /*Get the difference between the character 0 and 9,
                subtract 1 and add it to the 9 value*/
                ch = '0' + (ch - '9') - 1;
            }
                /*If character is out of the range of 0*/
            else if(ch < '0')
            {
                /*Get the difference between the character 9 and 0,
                add 1 and add it to the 0 value*/
                ch = '9' + (ch - '0') + 1;
            }
        }
        /*Store the encrypted character in the encrypted array*/
        encrypted[i] = ch;
    }
    /*Add \0 to the encrypted array to make it a string*/
    encrypted[strLen] = '\0';

}
/*A function for encryption which uses transform function*/
void encryptString(char dest[], char source[])
{
    /*Transforming character and moving it forwards by seven places*/
    changeString(dest, source, +7);
}
/*A function for decryption which uses transform function*/
void decryptString(char dest[], char source[])
{
    /*Transforming character and moving it backwards by seven places*/
    changeString(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];

    /*Displaying the header*/
    displayTitle("\t\t  || CHANGE PASSWORD ||");

    puts("Enter your new password:");
    printf(">>> ");
    /*Receiving user first password input*/
    scanf("%[^\n]", newPassword);
    emptyBuffer();
    /*If password string is not equal to 8 characters then display
    an an appropiate error*/
    if(strlen(newPassword) != 8)
    {
        puts("!! Password MUST be 8 characters long !!");
        waitForKey();
        return;
    }
    puts("Confirm your new password:");
    printf(">>> ");

    /*Receiving user second password input*/
    scanf("%[^\n]", reinforcePassword);
    emptyBuffer();

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

        /*Encrypting the new password*/
        encryptString(reinforcePassword, encryptedPassword);

        char allPasswords[5][10];
        char allUsernames[5][10];

        /*Opening file for reading purposes*/
        passwordFileRead = fopen("passwords.txt", "r");
        int i = 0;

        /*Read all usernames and passwords*/
        while(2==fscanf(passwordFileRead, " %[^\t] %[^\n]",
                        allUsernames[i], allPasswords[i]))
        {
            i++;
        }

        /*Closing the file*/
        fclose(passwordFileRead);
        /*Opening the file for writing purposes*/
        passwordFileWrite = fopen("passwords.txt", "w");
        /*Overwriting an old password with a new password string*/
        strcpy(allPasswords[nurse], encryptedPassword);

        for (i = 0; i < 5; ++i)
        {
            /*Writing new strings to a file*/
            fprintf(passwordFileWrite, "%s\t%s\n", allUsernames[i],
                    allPasswords[i]);
        }
        /*Closing the file*/
        fclose(passwordFileWrite);

        equalsLine();
        puts("Password has been changed!");
        waitForKey();
        return;
    }
    else
    {
        puts("!! Your password did not match, please try again !!");
        waitForKey();
        return;
    }
}
/*Function that display the header*/
void displayTitle(char *header)
{
    puts("*********************************************************");
    printf("\t\t    ACTION ON WEIGHT\n");
    puts("*********************************************************");
    equalsLine();
    printf(header);
    printf("\n");
    equalsLine();
    printf("\n");
}
/*Function that displays some ending text and waits for user
to press any key*/
void waitForKey(void)
{
    puts("=========================================================");
    printf("Press the Enter Key to Continue...\n");
    puts("=========================================================");
    getchar();

}
/*Function which displays a line*/
void equalsLine(void)
{
    puts("=========================================================");
}
/*Function that emptys the buffer*/
void emptyBuffer(void)
{
    while(getchar() != '\n')
    {
        ;
    }
}
char toLower(char any)
{
    return tolower(any);
}