program z2_3;

{$APPTYPE CONSOLE}

uses
    System.SysUtils;

const
    NumOfRows = 30;
    NumOfCols = 10;

type
    TMarks = array [1 .. 30] of array [1 .. 10] of Integer;
    TExcellents = array [1 .. 30] of Boolean;

procedure OpenInputFile(var InputFile: Text);
var
    IsCorrect: Boolean;
    InputPath: string;
begin
    IsCorrect := False;
    repeat
        Writeln('Enter path to the file:');
        Readln(InputPath);
        if FileExists(InputPath) then
        begin
            AssignFile(InputFile, InputPath);
            try
                Reset(InputFile);
                if not EOF(InputFile) then
                    IsCorrect := True
                else
                    Writeln('Empty file provided.');
            except
                on E: EInOutError do
                    Writeln('This file can''t be opened.');
            end;
        end
        else
            Writeln('File with such name doesn''t exist.');
    until IsCorrect;
end;

procedure GetMenu(var Character: Char);
var
    IsCorrect: Boolean;
    Buffer: string;
const
    AllowedChars = ['y', 'Y', 'n', 'N'];
begin
    IsCorrect := False;
    repeat
        try
            Readln(Buffer);
            if (Length(Buffer) = 1) and (Buffer[1] in AllowedChars) then
            begin
                Character := Buffer[1];
                IsCorrect := True;
            end
            else
                Writeln('Invalid input!');
        except
            on EInOutError do
                Writeln('Invalid input!');
        end;
    until IsCorrect;
end;

function RewriteFile(var OutputFile: Text;
    const OutputPath, Prompt: string): Boolean;
var
    Menu: Char;
const
    ErrorMessage = 'File access denied. Please try another file.';
    Yes = ['y', 'Y'];
begin
    RewriteFile := False;
    Writeln(Prompt);
    GetMenu(Menu);
    if Menu in Yes then
    begin
        AssignFile(OutputFile, OutputPath);
        try
            Rewrite(OutputFile);
            RewriteFile := True;
        except
            on E: EInOutError do
                Writeln(ErrorMessage);
        end;
    end;
end;

procedure OpenOutputFile(var OutputFile: Text);
var
    IsCorrect: Boolean;
    OutputPath: string;
const
    OverwritePrompt = 'File with such name exists. Overwrite? (Y-yes, N-no)';
    NewFilePrompt =
        'File with such name doesn''t exist. Create new file? (Y-yes, N-no)';
begin
    IsCorrect := False;
    repeat
        Writeln('Enter path to the file:');
        Readln(OutputPath);
        if FileExists(OutputPath) then
            IsCorrect := RewriteFile(OutputFile, OutputPath, OverwritePrompt)
        else
            IsCorrect := RewriteFile(OutputFile, OutputPath, NewFilePrompt);
    until IsCorrect;
end;

function GetMarks(var InputFile: Text; var Marks: TMarks): Boolean;
var
    i, j: Byte;
    IsCorrect: Boolean;
const
    MinMark = 0;
    MaxMark = 10;
begin
    IsCorrect := True;
    i := 1;
    while (not EOF(InputFile)) and IsCorrect do
    begin
        if i > NumOfRows then
        begin
            Writeln('Too many rows.');
            IsCorrect := False;
        end
        else
        begin
            j := 1;
            while (not EOLN(InputFile)) and IsCorrect do
            begin
                try
                    if j > NumOfCols then
                    begin
                        Writeln('Too many marks in row ', i, '.');
                        IsCorrect := False;
                    end
                    else
                    begin
                    ///////////////////
                        Read(InputFile, Marks[i, j]);
                        if ((Marks[i, j] < MinMark) or (Marks[i, j] > MaxMark))
                        then
                        begin
                            Writeln('Invalid number in row ', i, ' col ', j,
                                '! Mark must be an integer from ', MinMark,
                                ' to ', MaxMark, ' inclusive.');
                            IsCorrect := False;
                        end;

                        Inc(j);
                    end;
                except
                    on EInOutError do
                    begin
                        Writeln('Invalid input! Mark must be an integer from ',
                            MinMark, ' to ', MaxMark, ' inclusive in row ', i,
                            ' col ', j, '.');
                        IsCorrect := False;
                    end;
                end;
            end;
            if (j < NumOfCols) and IsCorrect then
            begin
                Writeln('Not enough marks in row ', i, '.');
                IsCorrect := False;
            end;
            Readln(InputFile);
            Inc(i);
        end;
    end;
    if (i < NumOfRows) and IsCorrect then
    begin
        Writeln('Not enough rows in file.');
        IsCorrect := False;
    end;
    GetMarks := IsCorrect;
end;

procedure FindExcellents(var Excellents: TExcellents; var Marks: TMarks);
var
    i, j: Integer;
const
    MinPositiveMark = 8;
begin
    for i := 1 to NumOfRows do
    begin
        Excellents[i] := True;
        for j := 1 to NumOfCols do
            if (Marks[i, j] < MinPositiveMark) and (Excellents[i]) then
                Excellents[i] := False;
    end;
end;

procedure PrintMarks(const Marks: TMarks; var OutputFile: Text);
var
    i, j: Integer;
const
    HorizontalDelimiter =
        '----------------------------------------------------------------';
begin
    for i := 1 to NumOfRows do
    begin
        Writeln(OutputFile, HorizontalDelimiter);
        Write(OutputFile, '| Student ', i:2, ' |');
        for j := 1 to NumOfCols do
            Write(OutputFile, ' ', Marks[i, j]:2, ' |');
        Writeln(OutputFile);
    end;
    Writeln(OutputFile, HorizontalDelimiter);
end;

procedure PrintExcellents(const Excellents: TExcellents; var OutputFile: Text);
var
    i: Integer;
begin
    Write(OutputFile, #10#13'Numbers of excellent students:');
    for i := 1 to NumOfRows do
        if Excellents[i] then
            Write(OutputFile, ' ', i:2, ' ');
    Writeln(OutputFile);
end;

procedure PrintData(var OutputFile: Text; const Marks: TMarks;
    const Excellents: TExcellents);
begin
    PrintMarks(Marks, OutputFile);
    PrintExcellents(Excellents, OutputFile);
end;

procedure Main;
var
    InputFile, OutputFile: Text;
    Marks: TMarks;
    Excellents: TExcellents;
    IsCorrect: Boolean;
begin
    Writeln('This program prints marks and finds underperforming students.');
    OpenInputFile(InputFile);
    IsCorrect := GetMarks(InputFile, Marks);
    CloseFile(InputFile);
    if IsCorrect then
    begin
        FindExcellents(Excellents, Marks);
        PrintData(Output, Marks, Excellents);
        OpenOutputFile(OutputFile);
        PrintData(OutputFile, Marks, Excellents);
        Writeln('Data was written to file.');
        CloseFile(OutputFile);
    end;
    Readln;
end;

begin
    Main;

end.