unit Lab2_1;

interface

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

type
  TLabWork = class(TForm)
    btFindMaxArea: TButton;
    edCountTriangles: TEdit;
    ArrLength: TLabel;
    MainMenu: TMainMenu;
    Save: TMenuItem;
    Author: TMenuItem;
    OpenFile: TOpenDialog;
    Help: TMenuItem;
    SaveFile: TSaveDialog;
    PopupMenu: TPopupMenu;
    sgTriangles: TStringGrid;
    FileMenu: TMenuItem;
    SaveIntoFile: TMenuItem;
    InputfromFile: TMenuItem;
    edResult: TEdit;
    lbMaxArea: TLabel;
    procedure edCountTrianglesKeyPress(Sender: TObject; var Key: Char);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure AuthorClick(Sender: TObject);
    procedure InputfromFileClick(Sender: TObject);
    procedure HelpClick(Sender: TObject);
    procedure SaveIntoFileClick(Sender: TObject);
    procedure edCountTrianglesKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
    procedure OnChange(Sender: TObject);
    procedure sgTrianglesKeyPress(Sender: TObject; var Key: Char);
    procedure btFindMaxAreaClick(Sender: TObject);
    procedure FillHeadlines(Table: TStringGrid);
    procedure sgTrianglesKeyDown(Sender: TObject; var Key: Word;
      Shift: TShiftState);
    procedure CleanAllTriangles(Table: TStringGrid; edCountTriangles: TEdit);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  LabWork: TLabWork;

implementation

{$R *.dfm}


procedure TLabWork.FillHeadlines(Table: TStringGrid);
var
   i, Len: Integer;
begin
   Len := Table.RowCount - 1;
   with Table do
      for i := 0 to Len do
         Cells[0, i] := Format('[%d]', [i + 1]);
end;



function IsInValidInput(UserString: string; Key: char): Boolean;
const
   Digits = ['0'..'9', #8];
var
   i, Iteration: Integer;
   IsInvalidSymbol: boolean;
begin
   IsInvalidSymbol := False;
   if Key = '0' then
   begin
      Iteration := length(UserString);
      if Iteration <> 0 then
      begin
         IsInvalidSymbol := True;
         for i := 1 to Iteration do
            if UserString[i] <> '0' then
               IsInvalidSymbol := False;
      end
   end
   else
      if (Key = ',') and (length(UserString) <> 0) then
      begin
            Iteration := length(UserString);
            for i := 1 to Iteration do
               if UserString[i] = Key then
                  IsInvalidSymbol := True
      end
      else
         IsInvalidSymbol := (not (Key in Digits));
   Result := IsInvalidSymbol;
end;




procedure TLabWork.AuthorClick(Sender: TObject);
begin
   MessageBox(Handle, PChar('Author of this program is Vladislav Mironuk (851001)'), PChar('Author'), MB_ICONINFORMATION + MB_OK);
end;

procedure TLabWork.btFindMaxAreaClick(Sender: TObject);
const
   MaxSideIndex = 2;
var
   SideIndex, TriangleIndex,  CountOfTheTriangle: Integer;
   CurrentArea, p, MaxArea: Real;
   FSide, SSide, TSide: Real;
begin
   MaxArea := 0;
   CountOfTheTriangle := StrToInt(edCountTriangles.Text) - 1;
   with sgTriangles do
   begin
      for TriangleIndex := 0 to CountOfTheTriangle do
         for SideIndex := 1 to MaxSideIndex do
            if (Cells[SideIndex, TriangleIndex] = '') then
            begin
               btFindMaxArea.Enabled := False;
               if MessageBox(Handle, PChar('The triangle number ' + IntToStr(TriangleIndex + 1) +
                              ' contains incorrect ' + IntToStr(SideIndex) +
                              ' side ' + #13 + 'Do you want to open Help?'),
                            PChar('Error'), MB_ICONSTOP + MB_YESNO) = mrYES then
                  HelpClick(Sender);
               Exit;
            end;
      for TriangleIndex := 0 to CountOfTheTriangle do
      begin
         FSide := StrToFloat(Cells[1, TriangleIndex]);
         SSide := StrToFloat(Cells[2, TriangleIndex]);
         TSide := StrToFloat(Cells[3, TriangleIndex]);
         if (FSide >= SSide + TSide) or
            (SSide >= TSide + FSide) or
            (TSide >= FSide + SSide) then
         begin
            MessageBox(Handle, PChar('The triangle number ' + IntToStr(TriangleIndex + 1) + ' does not exist ' + #13 +
                       'Condition of existense triangle is '+ #13 + ' MaxSide < OtherSide + OtherSide'),
                        PChar('Error'), MB_ICONSTOP + MB_OK);
            Exit
         end
         else
         begin
            try
               p := (FSide + SSide + TSide) / 2;
               CurrentArea := Sqrt(p*((p-FSide)*(p-SSide)*(p-TSide)));
            except
               MessageBox(Handle, PChar('The triangle number '+ IntToStr(TriangleIndex + 1) +
                        ' contains too large sides'), PChar('Error'), MB_ICONSTOP + MB_YESNO);
               Exit
            end;
            if CurrentArea > MaxArea then
               MaxArea := CurrentArea;
         end;
      end;
   end;
   edResult.Visible := True;
   lbMaxArea.Visible := True;
   SaveIntoFile.Enabled := True;
   edResult.Text := Format('%.3f', [MaxArea]);
end;


procedure TLabWork.edCountTrianglesKeyDown(Sender: TObject; var Key: Word;
                                              Shift: TShiftState);
begin
   if Key = VK_Insert then
      Key := 0;
end;


procedure TLabWork.edCountTrianglesKeyPress(Sender: TObject; var Key: Char);
const
   Digits = ['0'..'9', #8];
var
   IsInvalidSymbol: Boolean;
begin
   if (length(edCountTriangles.Text) > 1) and (Key <> #8) and (Key <> #13) then
   begin
      MessageBox(Handle, PChar('Max count of the triangles is 99'),
               PChar('Error'), MB_ICONSTOP + MB_OK);
       IsInvalidSymbol := True;
   end
   else
      if (Key = '0') and (length(edCountTriangles.Text) = 0) then
         IsInvalidSymbol := True
      else
         IsInvalidSymbol := not (Key in Digits);
   if IsInvalidSymbol then
      Key := #0;
end;


procedure TLabWork.FormClose(Sender: TObject; var Action: TCloseAction);
begin
   if MessageBox(Handle, PChar('Are you sure?'), PChar('Exit?'), MB_ICONSTOP + MB_YESNO + MB_DEFBUTTON2) = mrNo then
      Action := TCloseAction.caNone;
end;


procedure TLabWork.OnChange(Sender: TObject);
const
   OneColHeigth = 27;
   MaxHeigth = 80;
   WidthWithScrolls = 190;
   WidthWithOutScrolls = 169;
   MaxRowsInOnePage = 3;
begin
   edResult.Visible := False;
   lbMaxArea.Visible := False;
   edResult.Clear;
   SaveIntoFile.Enabled := False;
   if (edCountTriangles.Text = '') or (edCountTriangles.Text = '1') then
   begin
      btFindMaxArea.Enabled := False;
      sgTriangles.Visible := False
   end
   else
   begin
      sgTriangles.RowCount := StrToInt(edCountTriangles.Text);
      if sgTriangles.RowCount > MaxRowsInOnePage then
      begin
         sgTriangles.Height := MaxHeigth;
         sgTriangles.ScrollBars := ssVertical;
         sgTriangles.Width := WidthWithScrolls
      end
      else
      begin
         sgTriangles.Height := ((StrToInt(edCountTriangles.Text)) * OneColHeigth);
         sgTriangles.ScrollBars := ssNone;
         sgTriangles.Width := WidthWithOutScrolls
      end;
      FillHeadlines(sgTriangles);
      sgTriangles.Visible := True;
   end;
end;

procedure TLabWork.HelpClick(Sender: TObject);
const
   RangeOfTheArray = '1 < Length < 100';
begin
    MessageBox(Handle, PChar('This program find max the area of the specified triangles' + #13 +
               'Sides of the triangles must be in range   Side < 99999 '),
               PChar('Help'), MB_ICONINFORMATION + MB_OK)
end;

procedure TLabWork.CleanAllTriangles(Table: TStringGrid; edCountTriangles: TEdit);
const
   MaxSideIndex = 3;
var
   TriangleIndex, CountOfTheTriangle, SideIndex: Integer;
begin
   CountOfTheTriangle := StrToInt(edCountTriangles.Text);
   edCountTriangles.Clear;
   with sgTriangles do
      for TriangleIndex := 0 to CountOfTheTriangle do
         for SideIndex := 1 to MaxSideIndex do
            Cells[SideIndex, TriangleIndex] := ''

end;

procedure TLabWork.InputfromFileClick(Sender: TObject);
const
   MaxSideIndex = 3;
var
   Input: TextFile;
   Element: Real;
   TriangleIndex, SideIndex, CountOfTheTriangles: Integer;
begin
   if OpenFile.Execute() then
   begin
      edResult.Clear;
      if edCountTriangles.Text <> '' then
         CleanAllTriangles(sgTriangles, edCountTriangles);
      try
         AssignFile(Input, OpenFile.FileName);
         Reset(Input);
      except
         MessageBox(Handle, PChar('Error open the file'), PChar('Error!'), MB_ICONERROR + MB_OK);
         Exit
      end;
      if EOF(Input) then
         MessageBox(Handle, PChar('Your file is empty'), PChar('Error!'), MB_ICONERROR + MB_OK)
      else
      begin
         CountOfTheTriangles := 0;
         while not EOF(Input) do
         begin
            inc(CountOfTheTriangles);
            Readln(Input);
         end;
         if (CountOfTheTriangles > 99) and (CountOfTheTriangles < 2) then
         begin
            if MessageBox(Handle, PChar('length of the array must be must be integers and belong to the set' + #13 +
                           'Do you want to read help?'), PChar('Error!'), MB_ICONERROR + MB_YESNO) = mrYES then
               HelpClick(Sender)
         end
         else
         begin
            edCountTriangles.Text := IntToStr(CountOfTheTriangles);
            Reset(Input);
            for TriangleIndex := 0 to CountOfTheTriangles do
            begin
               for SideIndex := 1 to MaxSideIndex do
                  try
                     Read(Input, Element);
                     sgTriangles.Cells[SideIndex, TriangleIndex] := FloatToStr(Element);
                  except
                     if MessageBox(Handle, PChar('The file does not contain suitable numbers' + #13 +
                             'Do you want to read help?'), PChar('Error!'), MB_ICONERROR + MB_YESNO) = mrYES then
                        HelpClick(Sender);
                     CloseFile(Input);
                     CleanAllTriangles(sgTriangles, edCountTriangles);
                     Exit;
                  end;
               Readln(Input);
            end;
            btFindMaxArea.Enabled := True;
         end;
      end;
      CloseFile(Input);
   end;
end;



procedure TLabWork.SaveIntoFileClick(Sender: TObject);
var
   Output: TextFile;
begin
   if SaveFile.Execute then
   begin
      AssignFile(Output, SaveFile.FileName);
      try
         Rewrite(Output);
         Write(Output, 'Max area is ', edResult.Text)
      except
         MessageBox(Handle, PChar('Critical error writing to file'), PChar('Error!'), MB_ICONERROR + MB_OK)
      end;
      CloseFile(Output);
   end;
end;


procedure TLabWork.sgTrianglesKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
    if Key = VK_Insert then
      Key := 0;
end;

procedure TLabWork.sgTrianglesKeyPress(Sender: TObject; var Key: Char);
const
   Row = 0;
   MaxElementLength = 5;
begin
   SaveIntoFile.Enabled := False;
   edResult.Visible := False;
   lbMaxArea.Visible := False;
   edResult.Clear;
   with sgTriangles do
   begin
      if (Length(Cells[Col, Row]) = MaxElementLength) and (Key <> #8) and (Key <> #9) then
      begin
         Key := #0;
         MessageBox(Handle, PChar('Max length of the side is 5'),
                  PChar('Error'), MB_ICONSTOP + MB_OK)
      end
      else
         if IsInValidInput(sgTriangles.Cells[sgTriangles.Col, Row], Key) then
            Key := #0;
      btFindMaxArea.Enabled := True;
   end;
end;
end.