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#------------------------------------------------------------------------------

sub decimal_sub {
  my ($x, $y) = @_;
  # would prefer an actual decimal-arithmetic subtract here
  my $decimals = max (count_decimals($x), count_decimals($y));
  return sprintf ('%.*f', $decimals, $x - $y);
}

#------------------------------------------------------------------------------

sub count_decimals {
  my ($str) = @_;
  my $pos = index ($str, '.');
  if ($pos >= 0) {
    return length($str) - $pos - 1;
  } else {
    return 0;
  }
}

#------------------------------------------------------------------------------

# Return min or max of the arguments, ignoring any undefs.
# If no args (no undefs that is) then return undef.
# List::Util min() and max() return undef for no args, but they want all args
# to be numeric.
#
sub min_maybe {
  return min (grep {defined} @_);
}
sub max_maybe {
  return max (grep {defined} @_);
}

#------------------------------------------------------------------------------

# App::Chart::datafilename ($filename)
# App::Chart::datafilename ($dir,...,$dir, $filename)
#
# Return an absolute path like /usr/share/perl5/App/Chart/$filename,
# wherever App/Chart/$filename is found in @INC.  $dir arguments specify a
# subdirectory like App/Chart/$dir1/$dir2/$filename.  All args and the
# return are in filesystem charset bytes.
#
# Module::Find and Module::Util have similar @INC searches, but only for .pm
# files it seems.
#
sub datafilename {
  foreach my $inc (@INC) {
    my $filename = File::Spec->catfile ($inc, 'App', 'Chart', @_);
    if (-e $filename) { return $filename; }
  }
  require File::Basename;
  return File::Spec->catfile (File::Basename::dirname($INC{'App/Chart.pm'}),
                              'Chart', @_);
}

# return true if range ($alo,$ahi) overlaps range ($blo,$bhi)
# each endpoint is taken as inclusive, so say (1,4) and (4,7) do overlap
#
sub overlap_inclusive_p {
  my ($alo, $ahi, $blo, $bhi) = @_;
  return ! ($ahi < $blo || $alo > $bhi);
}

1;
__END__

=head1 NAME

App::Chart -- various shared Chart things

=head1 SYMBOL FUNCTIONS

=over 4

=cut

=item C<< %App::Chart::option >>

Various program options.

=over 4

=item C<verbose> (default false)

Print more things (mainly during downloads).  This is the C<--verbose>
command line option.

=item C<d_fmt> (default from C<langinfo()>)

C<strftime> format string for a date.  Non-ASCII can be included as Perl
wide-chars.

The default is from C<langinfo(D_FMT)> if the L<I18N::Langinfo> and
L<I18N::Langinfo::Wide> modules are available.  Otherwise the default is
C<%Y-%m-%d> which gives an ISO style YYYY-MM-DD.

=item C<wd_fmt> (default C<%a> and C<d_fmt>)

C<strftime> format string for a weekday name and date.

=item C<http_get_cost> (default 3000)

Byte cost reckoned for each separate HTTP request.  This is used when
choosing between an individual download per symbol or a whole-day download
of everything at the exchange.

If your connection is badly lagged you could increase this to prefer the
single big file.  If you want to minimize downloaded bytes then reduce this
to roughly HTTP per-request overhead (packet and headers each way), which
might be a few hundred bytes.

=back

=item C<< App::Chart::symbol_sans_suffix ($symbol) >>

Return C<$symbol> without its suffix.  Eg.