program TapeCtl;

{$MODE OBJFPC}

uses SysUtils;

type
    //Tape file path and reset state
    Tape = record
        Path: shortstring;
        Reset: boolean;
        Pos: integer;
    end;

var
    Reader, Punch: Tape; //States of the reader and punch
    State: file of Tape; //File storing the states of the reader and punch
    DoRead, DoPunch: integer; //Whether to (re)set the reader or the punch

begin

    //Check the arguments
    if ParamCount > 4 then begin
        writeln ('Usage: tapectl (-r tape) (-p tape)');
        halt (1);
    end
    else if ParamCount mod 2 <> 0 then begin
        writeln ('Usage: tapectl (-r tape) (-p tape)');
        halt (1);
    end;
    if ParamStr (1) = '-r' then begin
        DoRead := 2;
        DoPunch := 0;
        if ParamStr (3) = '-p' then begin
            DoPunch := 4;
        end;
    end
    else if ParamStr (1) = '-p' then begin
        DoRead := 0;
        DoPunch := 2;
        if ParamStr (3) = '-r' then DoRead := 4;
    end
    else begin
        writeln ('Usage: tapectl (-r tape) (-p tape)');
        halt (1);
    end;

    //Assign the state file
    assign (State, ExpandFileName ('~/.thingamajig/tapes'));

    //Read existing state if any
    if FileExists (ExpandFileName ('~/.thingamajig/tapes')) then begin
        try
            reset (State);
            read (State, Reader);
            read (State, Punch);
            close (State);
        except
        end;
    end
    //Or else assign a default state
    else begin
        Reader.Path := '';
        Reader.Reset := true;
        Reader.Pos := 0;
        Punch.Path := '';
        Punch.Reset := true;
        Punch.Pos := 0;
    end;

    //Get the files to be read from or punched to
    if DoRead <> 0 then begin
        Reader.Path := ExpandFileName (ParamStr (DoRead));
        Reader.Reset := true;
        Reader.Pos := 0;
    end;
    if DoPunch <> 0 then begin
        Punch.Path := ExpandFileName (ParamStr (DoPunch));
        Punch.Reset := true;
        Punch.Pos := 0;
    end;

    //Write the state
    try
        rewrite (State);
        write (State, Reader);
        write (State, Punch);
        close (State);
    except
        writeln ('Error: could not set the tape(s)');
    end;

end.