--*****************************************************************************
--
--    Program MORE displays one or more files (or piped input) a page at a time.
--
--    Invocation:
--
--        more  -<num_lines>  <input_file(s)>
--
--    where
--
--        <num_lines>
--            is the number of lines to display for each page.
--        <input_file(s)>
--            are the input files to read.  MORE currently doesn't work in
--            a pipeline.
--
--*****************************************************************************

with TEXT_IO ;  use TEXT_IO ;
-- package INTEGER_IO is new INTEGER_IO(INTEGER) ;
-- with INTEGER_IO ;  use INTEGER_IO ;
with IIO ;  use IIO ;
with TTY ;  use TTY ;

with ALEX ;  use ALEX ;
with BOPT ;  use BOPT ;



procedure MORE is

    CRLF : constant STRING := ascii.CR & ascii.LF ;
    OPTION : character ;
    OPTARG : STRING (1..64) ;
    END_OF_OPTIONS : boolean ;
    FILE_NAME : STRING (1..64) ;
    LAST : integer ;
    NUM_LINES : integer := 15 ;
    NO_FILES_DISPLAYED : boolean := TRUE ;


    procedure DISPLAY_FILE (FILE_NAME: in STRING ; NUM_LINES: INTEGER) is

        BUFFER : STRING (1..256) ;
        C : character ;
        INPUT_FILE : text_io.FILE_TYPE ;
        LENGTH : integer ;
        NUM_LINES_NOW : integer := NUM_LINES ;

    begin

        if (EQUAL (FILE_NAME, "")) then
            INPUT_FILE := STANDARD_INPUT ;
        else
            text_io.open (INPUT_FILE, text_io.IN_FILE, TRIM(FILE_NAME)) ;
            tty.put (CRLF & "Input file = " & TRIM(FILE_NAME) & CRLF & CRLF) ;
        end if ;

        loop

            for I in 1 .. NUM_LINES_NOW loop
                exit when end_of_file (INPUT_FILE) ;
                text_io.get_line (INPUT_FILE, BUFFER, LENGTH) ;
                tty.put (BUFFER(1..LENGTH) & CRLF) ;
            end loop ;

            exit when end_of_file (INPUT_FILE) ;

            C := tty.get (No_Echo => TRUE, Direct => FALSE, Clear => TRUE) ;
            exit when (C = 'q') or (C = 'Q') ;
            if (C = ascii.CR) then
                NUM_LINES_NOW := 1 ;
            else
                NUM_LINES_NOW := NUM_LINES ;
            end if ;

        end loop ;

    exception

        when NAME_ERROR =>
            tty.put ("File not found: " & TRIM(FILE_NAME) & CRLF) ;

    end DISPLAY_FILE ;


-- Main Program

begin

    loop
        GETOPT ("9", OPTION, OPTARG, END_OF_OPTIONS) ;
        exit when END_OF_OPTIONS ;
        case OPTION is
        when '-' =>
            iio.get (OPTARG, NUM_LINES, LAST) ;
        when ' ' =>
            DISPLAY_FILE (OPTARG, NUM_LINES) ;
            NO_FILES_DISPLAYED := FALSE ;
        when others =>
            tty.put ("Bad option = " & TRIM(OPTARG) & CRLF) ;
        end case ;
    end loop ;

    if (NO_FILES_DISPLAYED) then
        DISPLAY_FILE ("", NUM_LINES) ;
    end if ;

end MORE ;