unit Unit_Login;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ExtCtrls;

type
  TfrmLogin = class(TForm)
    lbledtUsername: TLabeledEdit;
    lbledtPassword: TLabeledEdit;
    btnEnter: TButton;
    Exit: TButton;
    procedure btnEnterClick(Sender: TObject);
    procedure ExitClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    Type
    TPassword = record    //creating a record for the file to store passwords.
    StudentPassword : string[20];
    end;

    Type
    TStudentNumber = record
    StudentNumber : String[6];
    end;

    Type
    TTeacherUser = record
    TeacherUsername : String[25];
    end;

    Type
    TTeacherPassword = record
    TeacherPassword : String[25];
    end;

    var
    //Variables for Student accounts
    PasswordFile : File of Tpassword;    // This will be the file whch stores the usernames
    StudentNumberFile : File of TStudentNumber;
    Student_Password : array [0..1000] of TPassword;       //An array used to store multiple Passwords
    Student_Number : array [0..1000] of TStudentNumber;
    //Variabels for teacher account
    TeacherUsernameFile : File of TTeacherUser;
    TeacherPasswordFile : File of TTeacherPassword;
    Teacher_Username : array [0..1000] of TTeacherUser;
    Teacher_Password : array [0..1000] of TTeacherPassword ;
    FinalStudent,FinalTeacher : Integer;
  end;

var
  frmLogin: TfrmLogin;

implementation
uses
 Unit_AddLogin,UnitStudent_menu,Unit_TeacherMenu;  //Allows access to the form add login and studnet menu
{$R *.dfm}

var
Path : String;

procedure TfrmLogin.btnEnterClick(Sender: TObject);
var
count,counter,I,Temp_num : integer;  //Variables for Student account
N,Current,Counts : Integer;   //Variables for Teacher accounts
StudentCorrect,TeacherCorrect : Boolean;
begin

   //Reads the username and password file for students
   AssignFile(PasswordFile ,Path +'Password.dat');   //assigns exsiting file to Passwordfile
   reset(PasswordFile );             //opens the file
   AssignFile(StudentNumberFile ,Path +'StudentNumber.dat');   //assigns exsiting file to StudentNumberFile
   reset(StudentNumberFile );
   count := 0;    //intialises count

   while not  eof (StudentNumberFile) and not Eof (passwordfile) do
   {This will repeat the code below untill the end of file is reached}
    begin
      Read(Passwordfile,Student_Password[count]);  //reads the password from Passwordfile
      Read(StudentNumberFile,Student_Number[count]);
      if ((lbledtusername.Text = Student_Number[count].StudentNumber)  and
      (lbledtPassword.Text = Student_Password[count].StudentPassword)) then
       begin
        Showmessage('Login Successful');
        frmStudentmenu.Show;   //if the login credentials is correct it shows the student menu
       end;
       count := count + 1;
    end;
    CloseFile(Passwordfile);  //Closes file which contains passwords
    CloseFile(StudentNumberFile);
   {Code to output incorrect login}
    I := 0;
   for counter  := 0 to count do
    begin
      I := I + 1;
      if (lbledtusername.Text = Student_Number[I].StudentNumber) and
       (lbledtPassword.Text = Student_Password[I].StudentPassword)  then
       begin
        Temp_num:= I;
       end;
      end;

      StudentCorrect := True;
      if ((lbledtusername.Text <> Student_Number[temp_num].StudentNumber)) then
          begin
            StudentCorrect := False;
          end;

   //Read from the teacher's Username and Password file
     AssignFile(TeacherPasswordFile ,Path +'TeacherPassword.dat');   //assigns exsiting file to Passwordfile
     reset(TeacherPasswordFile);             //opens the file
     AssignFile(TeacherUserNameFile ,Path +'TeacherUser.dat');   //assigns exsiting file to StudentNumberFile
     reset(TeacherUserNameFile);
     counts := 0;    //intialises count
     while not  eof (TeacherUserNameFile) and not Eof (TeacherPasswordFile) do
   {This will repeat the code below untill the end of file is reached}
    begin
      Read(TeacherPasswordfile,Teacher_Password[counts]);  //reads the password from Passwordfile
      Read(TeacherUsernameFile,Teacher_Username[counts]);
      if ((lbledtusername.Text = Teacher_Username[counts].TeacherUsername)  and
      (lbledtPassword.Text = Teacher_Password[counts].TeacherPassword)) then
       begin
        Showmessage('Login Successful');
        frmTeachermenu.Show;   //if the login credentials is correct it shows the student menu
       end;
       counts := counts + 1;
    end;
    CloseFile(TeacherPasswordfile);  //Closes file which contains passwords
    CloseFile(TeacherUserNameFile);

       N := 0;
   for counter  := 0 to counts do
    {This checks to see if the account credntials match the ones stored in the system }
    begin
      if (lbledtusername.Text = Teacher_Username[N].TeacherUsername) and
       (lbledtPassword.Text = Teacher_Password[N].TeacherPassword)  then
       begin
        Current:= N;
       end;
       N := N + 1;
      end;

      TeacherCorrect := True;
      if ((lbledtusername.Text <> Teacher_Username[N].TeacherUsername)) then
          begin
            TeacherCorrect := False;
          end;

   //This checks that the user enters either teacher or student login
  if  ((StudentCorrect = False) or (TeacherCorrect = False) and
      (lbledtPassword.Text <> Student_Password[temp_num].StudentPassword)) and ((lbledtusername.Text <>
        Teacher_Username[Current].TeacherUsername)
        or (lbledtPassword.Text <> Teacher_Password[Current].TeacherPassword))
        or (lbledtPassword.Text = '') or
       (lbledtUsername.Text = '')then
         begin
          Showmessage('Incorrect Login');
         end
end;

procedure TfrmLogin.ExitClick(Sender: TObject);
begin
  close;
end;

procedure TfrmLogin.FormCreate(Sender: TObject);
var
count : integer;
begin
  Count := Count + 1;
  if Count = 1 then
   begin
    Path := GetCurrentDir;
    Count := 2;
   end;
end;
end.