% MINERVA (c) IF Computer  1996,97
% http://www.ifcomputer.com/MINERVA   mailto:support@ifcomputer.com

% standalone application 
main([Source|_]) :- 
	write('MINERVA Crawl Application started..'),nl, flush_output,
	urlGet(Source).

% open the URL, then read it, then write to standard output
urlGet(Source) :-
	write('Trying to open Url '),write(Source),nl, flush_output,
	catch(
		open(Source, read, InputStream, [url,buffered,text]),
		AnyError,
		sorry(open(Source),AnyError)
		),
	readAndWrite(InputStream),
	!.
urlGet(_Source).

readAndWrite(InputStream) :-
	write('Url opened..'),nl, flush_output,
	readLines(InputStream,Lines),
	write('Reading done..'),nl,flush_output,
	current_output(OutputStream),
	writeLines(OutputStream,Lines),
	write('Writing done.. Done!'),nl,
	flush_output,!.

% if the url does not exist or is not accessible, e,g, network down
% ** no catch/3 found for: error(existence_error(source_sink,'http://www.ifcomputer.com/MINERVA'),[])

sorry(Goal,SomeError) :-
        write('Oooops: '),writeq(Goal),nl,
        write('   caused: '), write(SomeError),nl,
	fail.


readLines(Stream,Lines) :-
	get_line(Stream, Line), !,
	Lines = [Line|Rest],
	readLines(Stream, Rest).
readLines(_, []).

writeLines(_Stream,[]).
writeLines(Stream,[Line|Lines]) :- 
	write(Stream,Line),nl,flush_output(Stream),
	writeLines(Stream,Lines).