1 files changed, 103 insertions, 0 deletions
diff --git a/lib/PublicInbox/LeiHelp.pm b/lib/PublicInbox/LeiHelp.pm
new file mode 100644
index 00000000..fa0e7866
--- /dev/null
+++ b/lib/PublicInbox/LeiHelp.pm
@@ -0,0 +1,103 @@
+# Copyright (C) 2020-2021 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+
+# -h/--help support for lei
+package PublicInbox::LeiHelp;
+use strict;
+use v5.10.1;
+use Text::Wrap qw(wrap);
+
+my %NOHELP = map { $_ => 1 } qw(mfolder);
+
+sub call {
+        my ($self, $errmsg, $CMD, $OPTDESC) = @_;
+        my $cmd = $self->{cmd} // 'COMMAND';
+        my @info = @{$CMD->{$cmd} // [ '...', '...' ]};
+        my @top = ($cmd, shift(@info) // ());
+        my $cmd_desc = shift(@info);
+        $cmd_desc = $cmd_desc->($self) if ref($cmd_desc) eq 'CODE';
+        $cmd_desc =~ s/default: /default:\xa0/;
+        my @opt_desc;
+        my $lpad = 2;
+        for my $sw (grep { !ref } @info) { # ("prio=s", "z", $GLP_PASS)
+                my $desc = $OPTDESC->{"$sw\t$cmd"} // $OPTDESC->{$sw} // next;
+                my $arg_vals = '';
+                ($arg_vals, $desc) = @$desc if ref($desc) eq 'ARRAY';
+
+                # lower-case is a keyword (e.g. `content', `oid'),
+                # ALL_CAPS is a string description (e.g. `PATH')
+                if ($desc !~ /default/ && $arg_vals =~ /\b([a-z]+)[,\|]/) {
+                        $desc .= " (default:\xa0`$1')";
+                } else {
+                        $desc =~ s/default: /default:\xa0/;
+                }
+                my (@vals, @s, @l);
+                my $x = $sw;
+                if ($x =~ s/!\z//) { # solve! => --no-solve
+                        $x =~ s/(\A|\|)/$1no-/g
+                } elsif ($x =~ s/\+\z//) { # verbose|v+
+                } elsif ($x =~ s/:.+//) { # optional args: $x = "mid:s"
+                        @vals = (' [', undef, ']');
+                } elsif ($x =~ s/=.+//) { # required arg: $x = "type=s"
+                        @vals = (' ', undef);
+                } # else: no args $x = 'threads|t'
+
+                # we support underscore options from public-inbox-* commands;
+                # but they've never been documented and will likely go away.
+                # $x = help|h
+                for (grep { !/_/ && !$NOHELP{$_} } split(/\|/, $x)) {
+                        length($_) > 1 ? push(@l, "--$_") : push(@s, "-$_");
+                }
+                if (!scalar(@vals)) { # no args 'threads|t'
+                } elsif ($arg_vals =~ s/\A([A-Z_=]+)\b//) { # "NAME"
+                        $vals[1] = $1;
+                } else {
+                        $vals[1] = uc(substr($l[0], 2)); # "--type" => "TYPE"
+                }
+                if ($arg_vals =~ /([,\|])/) {
+                        my $sep = $1;
+                        my @allow = split(/\Q$sep\E/, $arg_vals);
+                        my $must = $sep eq '|' ? 'Must' : 'Can';
+                        @allow = map { length $_ ? "`$_'" : () } @allow;
+                        my $last = pop @allow;
+                        $desc .= "\n$must be one of: " .
+                                join(', ', @allow) . " or $last";
+                }
+                my $lhs = join(', ', @s, @l) . join('', @vals);
+                if ($x =~ /\|\z/) { # "stdin|" or "clear|"
+                        $lhs =~ s/\A--/- , --/;
+                } else {
+                        $lhs =~ s/\A--/    --/; # pad if no short options
+                }
+                $lpad = length($lhs) if length($lhs) > $lpad;
+                push @opt_desc, $lhs, $desc;
+        }
+        my $msg = $errmsg ? "E: $errmsg\n" : '';
+        $msg .= <<EOF;
+usage: lei @top
+$cmd_desc
+
+EOF
+        $lpad += 2;
+        local $Text::Wrap::columns = 78 - $lpad;
+        # local $Text::Wrap::break = ; # don't break on nbsp (\xa0)
+        my $padding = ' ' x ($lpad + 2);
+        while (my ($lhs, $rhs) = splice(@opt_desc, 0, 2)) {
+                $msg .= '  '.pack("A$lpad", $lhs);
+                $rhs = wrap('', '', $rhs);
+                $rhs =~ s/\n/\n$padding/sg; # LHS pad continuation lines
+                $msg .= $rhs;
+                $msg .= "\n";
+        }
+        my $fd = $errmsg ? 2 : 1;
+        $self->start_pager if -t $self->{$fd};
+        $msg =~ s/\xa0/ /gs; # convert NBSP to SP
+        print { $self->{$fd} } $msg;
+        $self->x_it($errmsg ? (1 << 8) : 0); # stderr => failure
+        undef;
+}
+
+# the "lei help" command
+sub lei_help { $_[0]->_help }
+
+1;