unit Unit_DeleteUser;

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
  TfrmDeleteUser = class(TForm)
    lbledtAccount: TLabeledEdit;
    MemoAccount: TMemo;
    btnEnter: TButton;
    btnExit: TButton;
    btnDelete: TButton;
    CoBoxAccount: TComboBox;
    procedure btnExitClick(Sender: TObject);
    procedure btnEnterClick(Sender: TObject);
    procedure CoBoxAccountChange(Sender: TObject);
    procedure btnDeleteClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  frmDeleteUser: TfrmDeleteUser;

implementation
 uses
 Unit_Login;
{$R *.dfm}
var
TeacherID, StudentID : Boolean;
Count,StudentMatch: Integer;  //Variables used for students
StudentExists,TeacherExists: Boolean;
StudentUser, StudentPassword : TStrings;
TeacherUser, TeacherPassword : Tstrings;
TeacherMatch : Integer;
procedure TfrmDeleteUser.btnDeleteClick(Sender: TObject);
Var
N,Counter: Integer;
begin
 if CoboxAccount.Text = 'Student Account' then
  begin
   //Uses the variables from the login form
   StudentUser.Delete(StudentMatch);  //String list for StudentNumbers
   StudentPassword.Delete(StudentMatch);//String list for Student's passwords
   AssignFile(frmLogin.StudentNumberFile, 'StudentNumber.Dat');
   ReWrite(frmLogin.StudentNumberFile);
   AssignFile(frmLogin.PasswordFile, 'Password.Dat');
   ReWrite(frmLogin.PasswordFile);
   {The count is reduced to ensure the stringlists do not go out of bounds}
    for N := 0 to Count - 2 do
     begin
        //The following two lines copy the cotent of the stringlist into the main array
        frmLogin.Student_Number[N].StudentNumber := StudentUser[N];
        frmLogin.Student_Password[N].StudentPassword := StudentPassword[N];
        //This writes back all the accounts into the array which now does not include the deleted one
        Write(frmLogin.StudentNumberFile,frmLogin.Student_Number[N]);
        Write(frmLogin.PasswordFile,frmLogin.Student_Password[N]);
     end;
    CloseFile(frmLogin.StudentNumberFile);
    CloseFile(frmLogin.PasswordFile);
    Showmessage('Student account has been deleted');
  end;

if CoboxAccount.Text = 'Teacher Account' then
 begin
   TeacherUser.Delete(TeacherMatch);
   TeacherPassword.Delete(TeacherMatch);
   AssignFile(frmLogin.TeacherUsernameFile, 'TeacherUser.Dat');
   ReWrite(frmLogin.TeacherUsernameFile);
   AssignFile(frmLogin.TeacherPasswordFile, 'TeacherPassword.Dat');
   ReWrite(frmLogin.TeacherPasswordFile);
   for N := 0 to Count - 2 do
    begin
     frmLogin.Teacher_Username[N].TeacherUsername := TeacherUser[N];
     frmLogin.Teacher_Password[N].TeacherPassword := TeacherPassword[N];
     Write(frmLogin.TeacherUsernameFile, frmLogin.Teacher_Username[N]);
     Write(frmLogin.TeacherPasswordFile, frmLogin.Teacher_Password[N]);
    end;
    Showmessage('Teacher account has been deleted');
 end;
end;

procedure TfrmDeleteUser.btnEnterClick(Sender: TObject);
begin
if CoboxAccount.Text = 'Student Account' then
   begin
    //Uses the public variables from the login form
    AssignFile(frmLogin.StudentNumberFile, 'StudentNumber.Dat');
    Reset(frmLogin.StudentNumberFile);
    AssignFile(frmLogin.PasswordFile, 'Password.Dat');
    Reset(frmLogin.PasswordFile);
    Count := 0;
    {StudentUser and StudentPassword are Stringlist}
    StudentUser := TStringList.Create;
    StudentPassword := TStringList.Create;
    StudentExists := False;
    //Reads all the studentnumber and passwords in the file
    while not eof (frmLogin.StudentNumberFile) and not eof (frmLogin.PasswordFile) do
     begin
       Read(frmLogin.StudentNumberFile,frmLogin.Student_Number[Count]);
       Read(frmLogin.PasswordFile,frmLogin.Student_Password[Count]);
       //The contents of the array are coppied into both stringlists
       StudentUser.Add(frmLogin.Student_Number[Count].StudentNumber);
       StudentPassword.Add(frmLogin.Student_Password[Count].StudentPassword);
       //The if statement checks if the student numbers matches any in the array
       if frmLogin.Student_Number[Count].StudentNumber = lbledtAccount.Text then
        begin
          StudentMatch := Count;
          //Clears the memo of any text
          MemoAccount.Clear;
          //Adds the account credentials of the account searched for
          MemoAccount.Lines.Add('Student Number : '+ frmLogin.Student_Number[Count].StudentNumber +
          ' Password : '+frmLogin.Student_Password[Count].StudentPassword);
          StudentExists := True;
        end;
        Count := Count + 1;
     end;
    CloseFile(frmLogin.StudentNumberFile);
    CloseFile(FrmLogin.PasswordFile);
     if StudentExists = False then
     begin
       Showmessage('Student Account does not exists');
     end;
   end;
 if CoboxAccount.Text = 'Teacher Account' then
  begin
    AssignFile(frmLogin.TeacherUsernameFile, 'TeacherUser.Dat');
    Reset(frmLogin.TeacherUsernameFile);
    AssignFile(frmLogin.TeacherPasswordFile, 'TeacherPassword.Dat');
    Reset(frmLogin.TeacherPasswordFile);
    Count := 0;
    TeacherUser := TStringList.Create;
    TeacherPassword := TStringList.Create;
    TeacherExists := False;
    while not eof (frmLogin.TeacherUsernameFile) and not eof (frmLogin.TeacherPasswordFile) do
     begin
       Read(frmLogin.TeacherUsernameFile,frmLogin.Teacher_Username[Count]);
       Read(frmLogin.TeacherPasswordFile,frmLogin.Teacher_Password[Count]);
       TeacherUser.Add(frmLogin.Teacher_Username[Count].TeacherUsername);
       TeacherPassword.Add(frmLogin.Teacher_Password[Count].TeacherPassword);
       if frmLogin.Teacher_Username[Count].TeacherUsername = lbledtAccount.Text  then
        begin
          TeacherMatch := Count;
          MemoAccount.Clear;
          MemoAccount.Lines.Add('Username : '+frmLogin.Teacher_Username[Count].TeacherUsername
          +' Password: ' + frmLogin.Teacher_Password[Count].TeacherPassword);
          TeacherExists := True;
        end;
        Count := Count + 1;
     end;
      if TeacherExists = False then
       begin
         Showmessage('This Teacher account does not exist');
       end;
  end;



end;

procedure TfrmDeleteUser.btnExitClick(Sender: TObject);
begin
  Close;
end;

procedure TfrmDeleteUser.CoBoxAccountChange(Sender: TObject);
begin
  //If the User selects the teader acount in the combobox the edit label will change to teacher ID
  if CoboxAccount.Text = 'Teacher Account' then
   begin
    lbledtAccount.EditLabel.Caption := 'Teacher ID';
    //The two following boolean variables tells the system which acconts needs to be deleted.
    TeacherID := True;
    StudentID := False;
   end;
  //If the User selects the Student acount in the combobox the edit label will change to student ID
  if CoboxAccount.Text = 'Student Account'  then
   begin
     //The two following boolean variables tells the system which acconts needs to be deleted.
     lbledtAccount.EditLabel.Caption := 'Student ID';
     TeacherID := False;
     StudentID := True;
   end;
end;

end.