#!/usr/bin/env perl
#***************************************************************************
#                                  _   _ ____  _
#  Project                     ___| | | |  _ \| |
#                             / __| | | | |_) | |
#                            | (__| |_| |  _ <| |___
#                             \___|\___/|_| \_\_____|
#
# Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
#
# This software is licensed as described in the file COPYING, which
# you should have received as part of this distribution. The terms
# are also available at https://curl.se/docs/copyright.html.
#
# You may opt to use, copy, modify, merge, publish, distribute and/or sell
# copies of the Software, and permit persons to whom the Software is
# furnished to do so, under the terms of the COPYING file.
#
# This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
# KIND, either express or implied.
#
# SPDX-License-Identifier: curl
#
###########################################################################

=begin comment

Converts a curldown file to nroff (man page).

=end comment
=cut

use strict;
use warnings;

my $cd2nroff = "0.1"; # to keep check
my $dir;
my $extension;
my $keepfilename;

while(@ARGV) {
    if($ARGV[0] eq "-d") {
        shift @ARGV;
        $dir = shift @ARGV;
    }
    elsif($ARGV[0] eq "-e") {
        shift @ARGV;
        $extension = shift @ARGV;
    }
    elsif($ARGV[0] eq "-k") {
        shift @ARGV;
        $keepfilename = 1;
    }
    elsif($ARGV[0] eq "-h") {
        print <<HELP
Usage: cd2nroff [options] [file.md]

-d <dir> Write the output to the file name from the meta-data in the
         specified directory, instead of writing to stdout
-e <ext> If -d is used, this option can provide an added "extension", arbitrary
         text really, to append to the file name.
-h       This help text,
-v       Show version then exit
HELP
            ;
        exit 0;
    }
    elsif($ARGV[0] eq "-v") {
        print "cd2nroff version $cd2nroff\n";
        exit 0;
    }
    else {
        last;
    }
}

use POSIX qw(strftime);
my @ts;
if (defined($ENV{SOURCE_DATE_EPOCH})) {
    @ts = gmtime($ENV{SOURCE_DATE_EPOCH});
} else {
    @ts = localtime;
}
my $date = strftime "%Y-%m-%d", @ts;

sub outseealso {
    my (@sa) = @_;
    my $comma = 0;
    my @o;
    push @o, ".SH SEE ALSO\n";
    for my $s (sort @sa) {
        push @o, sprintf "%s.BR $s", $comma ? ",\n": "";
        $comma = 1;
    }
    push @o, "\n";
    return @o;
}

sub outprotocols {
    my (@p) = @_;
    my $comma = 0;
    my @o;
    push @o, ".SH PROTOCOLS\n";

    if($p[0] eq "TLS") {
        push @o, "All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.";
    }
    else {
        my @s = sort @p;
        for my $e (sort @s) {
            push @o, sprintf "%s$e",
                $comma ? (($e eq $s[-1]) ? " and " : ", "): "";
            $comma = 1;
        }
    }
    push @o, "\n";
    return @o;
}

sub outtls {
    my (@t) = @_;
    my $comma = 0;
    my @o;
    if($t[0] eq "All") {
        push @o, "\nAll TLS backends support this option.";
    }
    else {
        push @o, "\nThis option works only with the following TLS backends:\n";
        my @s = sort @t;
        for my $e (@s) {
            push @o, sprintf "%s$e",
                $comma ? (($e eq $s[-1]) ? " and " : ", "): "";
            $comma = 1;
        }
    }
    push @o, "\n";
    return @o;
}

my %knownprotos = (
    'DICT' => 1,
    'FILE' => 1,
    'FTP' => 1,
    'FTPS' => 1,
    'GOPHER' => 1,
    'GOPHERS' => 1,
    'HTTP' => 1,
    'HTTPS' => 1,
    'IMAP' => 1,
    'IMAPS' => 1,
    'LDAP' => 1,
    'LDAPS' => 1,
    'MQTT' => 1,
    'POP3' => 1,
    'POP3S' => 1,
    'RTMP' => 1,
    'RTMPS' => 1,
    'RTSP' => 1,
    'SCP' => 1,
    'SFTP' => 1,
    'SMB' => 1,
    'SMBS' => 1,
    'SMTP' => 1,
    'SMTPS' => 1,
    'TELNET' => 1,
    'TFTP' => 1,
    'WS' => 1,
    'WSS' => 1,
    'TLS' => 1,
    'TCP' => 1,
    'All' => 1
    );

my %knowntls = (
    'BearSSL' => 1,
    'GnuTLS' => 1,
    'mbedTLS' => 1,
    'OpenSSL' => 1,
    'rustls' => 1,
    'Schannel' => 1,
    'Secure Transport' => 1,
    'wolfSSL' => 1,
    'All' => 1,
    );

sub single {
    my @seealso;
    my @proto;
    my @tls;
    my $d;
    my ($f)=@_;
    my $copyright;
    my $errors = 0;
    my $fh;
    my $line;
    my $list;
    my $tlslist;
    my $section;
    my $source;
    my $spdx;
    my $start = 0;
    my $title;

    if(defined($f)) {
        if(!open($fh, "<:crlf", "$f")) {
            print STDERR "cd2nroff failed to open '$f' for reading: $!\n";
            return 1;
        }
    }
    else {
        $f = "STDIN";
        $fh = \*STDIN;
        binmode($fh, ":crlf");
    }
    while(<$fh>) {
        $line++;
        if(!$start) {
            if(/^---/) {
                # header starts here
                $start = 1;
            }
            next;
        }
        if(/^Title: *(.*)/i) {
            $title=$1;
        }
        elsif(/^Section: *(.*)/i) {
            $section=$1;
        }
        elsif(/^Source: *(.*)/i) {
            $source=$1;
        }
        elsif(/^See-also: +(.*)/i) {
            $list = 1; # 1 for see-also
            push @seealso, $1;
        }
        elsif(/^See-also: */i) {
            if($seealso[0]) {
                print STDERR "$f:$line:1:ERROR: bad See-Also, needs list\n";
                return 2;
            }
            $list = 1; # 1 for see-also
        }
        elsif(/^Protocol:/i) {
            $list = 2; # 2 for protocol
        }
        elsif(/^TLS-backend:/i) {
            $list = 3; # 3 for TLS backend
        }
        elsif(/^ +- (.*)/i) {
            # the only lists we support are see-also and protocol
            if($list == 1) {
                push @seealso, $1;
            }
            elsif($list == 2) {
                push @proto, $1;
            }
            elsif($list == 3) {
                push @tls, $1;
            }
            else {
                print STDERR "$f:$line:1:ERROR: list item without owner?\n";
                return 2;
            }
        }
        # REUSE-IgnoreStart
        elsif(/^C: (.*)/i) {
            $copyright=$1;
        }
        elsif(/^SPDX-License-Identifier: (.*)/i) {
            $spdx=$1;
        }
        # REUSE-IgnoreEnd
        elsif(/^---/) {
            # end of the header section
            if(!$title) {
                print STDERR "ERROR: no 'Title:' in $f\n";
                return 1;
            }
            if(!$section) {
                print STDERR "ERROR: no 'Section:' in $f\n";
                return 2;
            }
            if(!$seealso[0]) {
                print STDERR "$f:$line:1:ERROR: no 'See-also:' present\n";
                return 2;
            }
            if(!$copyright) {
                print STDERR "$f:$line:1:ERROR: no 'C:' field present\n";
                return 2;
            }
            if(!$spdx) {
                print STDERR "$f:$line:1:ERROR: no 'SPDX-License-Identifier:' field present\n";
                return 2;
            }
            if($section == 3) {
                if(!$proto[0]) {
                    printf STDERR "$f:$line:1:ERROR: missing Protocol:\n";
                    exit 2;
                }
                my $tls = 0;
                for my $p (@proto) {
                    if($p eq "TLS") {
                        $tls = 1;
                    }
                    if(!$knownprotos{$p}) {
                        printf STDERR "$f:$line:1:ERROR: invalid protocol used: $p:\n";
                        exit 2;
                    }
                }
                # This is for TLS, require TLS-backend:
                if($tls) {
                    if(!$tls[0]) {
                        printf STDERR "$f:$line:1:ERROR: missing TLS-backend:\n";
                        exit 2;
                    }
                    for my $t (@tls) {
                        if(!$knowntls{$t}) {
                            printf STDERR "$f:$line:1:ERROR: invalid TLS backend: $t:\n";
                            exit 2;
                        }
                    }
                }
            }
            last;
        }
        else {
            chomp;
            print STDERR "WARN: unrecognized line in $f, ignoring:\n:'$_';"
        }
    }

    if(!$start) {
        print STDERR "$f:$line:1:ERROR: no header present\n";
        return 2;
    }

    my @desc;
    my $quote = 0;
    my $blankline = 0;
    my $header = 0;

    # cut off the leading path from the file name, if any
    $f =~ s/^(.*[\\\/])//;

    push @desc, ".\\\" generated by cd2nroff $cd2nroff from $f\n";
    push @desc, ".TH $title $section \"$date\" $source\n";
    while(<$fh>) {
        $line++;

        $d = $_;

        if($quote) {
            if($quote == 4) {
                # remove the indentation
                if($d =~ /^    (.*)/) {
                    push @desc, "$1\n";
                    next;
                }
                else {
                    # end of quote
                    $quote = 0;
                    push @desc, ".fi\n";
                    next;
                }
            }
            if(/^~~~/) {
                # end of quote
                $quote = 0;
                push @desc, ".fi\n";
                next;
            }
            # convert single backslahes to doubles
            $d =~ s/\\/\\\\/g;
            # lines starting with a period needs it escaped
            $d =~ s/^\./\\&./;
            push @desc, $d;
            next;
        }

        # remove single line HTML comments
        $d =~ s/<!--.*?-->//g;

        # **bold**
        $d =~ s/\*\*(\S.*?)\*\*/\\fB$1\\fP/g;
        # *italics*
        $d =~ s/\*(\S.*?)\*/\\fI$1\\fP/g;

        if($d =~ /[^\\][\<\>]/) {
            print STDERR "$f:$line:1:WARN: un-escaped < or > used\n";
        }
        # convert backslash-'<' or '> to just the second character
        $d =~ s/\\([<>])/$1/g;

        # mentions of curl symbols with man pages use italics by default
        $d =~ s/((lib|)curl([^ ]*\(3\)))/\\fI$1\\fP/gi;

        # backticked becomes italics
        $d =~ s/\`(.*?)\`/\\fI$1\\fP/g;

        if(/^## (.*)/) {
            my $word = $1;
            # if there are enclosing quotes, remove them first
            $word =~ s/[\"\'\`](.*)[\"\'\`]\z/$1/;

            # enclose in double quotes if there is a space present
            if($word =~ / /) {
                push @desc, ".IP \"$word\"\n";
            }
            else {
                push @desc, ".IP $word\n";
            }
            $header = 1;
        }
        elsif(/^##/) {
            # end of IP sequence
            push @desc, ".PP\n";
            $header = 1;
        }
        elsif(/^# (.*)/) {
            my $word = $1;
            # if there are enclosing quotes, remove them first
            $word =~ s/[\"\'](.*)[\"\']\z/$1/;

            if($word eq "PROTOCOLS") {
                print STDERR "$f:$line:1:WARN: PROTOCOLS section in source file\n";
            }
            elsif($word eq "EXAMPLE") {
                # insert the generated PROTOCOLS section before EXAMPLE
                push @desc, outprotocols(@proto);

                if($proto[0] eq "TLS") {
                    push @desc, outtls(@tls);
                }
            }
            push @desc, ".SH $word\n";
            $header = 1;
        }
        elsif(/^~~~c/) {
            # start of a code section, not indented
            $quote = 1;
            push @desc, "\n" if($blankline && !$header);
            $header = 0;
            push @desc, ".nf\n";
        }
        elsif(/^~~~/) {
            # start of a quote section; not code, not indented
            $quote = 1;
            push @desc, "\n" if($blankline && !$header);
            $header = 0;
            push @desc, ".nf\n";
        }
        elsif(/^    (.*)/) {
            # quoted, indented by 4 space
            $quote = 4;
            push @desc, "\n" if($blankline && !$header);
            $header = 0;
            push @desc, ".nf\n$1\n";
        }
        elsif(/^[ \t]*\n/) {
            # count and ignore blank lines
            $blankline++;
        }
        else {
            # don't output newlines if this is the first content after a
            # header
            push @desc, "\n" if($blankline && !$header);
            $blankline = 0;
            $header = 0;

            # quote minuses in the output
            $d =~ s/([^\\])-/$1\\-/g;
            # replace single quotes
            $d =~ s/\'/\\(aq/g;
            # handle double quotes first on the line
            $d =~ s/^(\s*)\"/$1\\&\"/;

            # lines starting with a period needs it escaped
            $d =~ s/^\./\\&./;

            if($d =~ /^(.*)  /) {
                printf STDERR "$f:$line:%d:ERROR: 2 spaces detected\n",
                    length($1);
                $errors++;
            }
            if($d =~ /^[ \t]*\n/) {
                # replaced away all contents
                $blankline= 1;
            }
            else {
                push @desc, $d;
            }
        }
    }
    if($fh != \*STDIN) {
        close($fh);
    }
    push @desc, outseealso(@seealso);
    if($dir) {
        if($keepfilename) {
            $title = $f;
            $title =~ s/\.[^.]*$//;
        }
        my $outfile = "$dir/$title.$section";
        if(defined($extension)) {
            $outfile .= $extension;
        }
        if(!open(O, ">", $outfile)) {
            print STDERR "Failed to open $outfile : $!\n";
            return 1;
        }
        print O @desc;
        close(O);
    }
    else {
        print @desc;
    }
    return $errors;
}

if(@ARGV) {
    for my $f (@ARGV) {
        my $r = single($f);
        if($r) {
            exit $r;
        }
    }
}
else {
    exit single();
}