#!/bin/sh
# Extract manpages from C source files.

# Copyright (C) 2006 Marc Vertes

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
# 02111-1307, USA.

# release 1.7.1

man() {
	cat << \EOT
NAME
  src2man - extract man pages from source files.
SYNOPSIS
  src2man [-n][-d date][-v volume][-r release] [srcfile ...]
DESCRIPTION
  src2man scans source file srcfile. Only C source files are supported
  for now. Comments blocks starting by "/** num", where num is a section
  number, are converted into a man file, using txt2man(1).

  The first line of the comment block must contain the name of the
  manpage, usually the function name, followed by a "-" and a short
  description. The following lines are the "DESCRIPTION" section
  content, except if they are in upper case, in which case they define
  a new section.

  If the next line after a comment block is empty, Then no "SYNOPSIS"
  section will be generated. Otherwise, src2man will look in the following
  source lines for a function prototype or a type definion (struct,
  union, typedef, ...) matching the manpage name, and include it in a
  "SYNOPSIS" section. This avoids to duplicate the type or function
  prototype in the comment block.

  The best place for code documentation is in the source file, where
  the body is implemented, not the header file which only contains
  the prototype. src2man automatically searches for the presence of a
  prototype in the corresponding header file, and if found, will print a
  "#include" statement in the synopsis.

OPTIONS
  -d date	Set the date of the man pages. Defaults to current date.
  -n		No man page is created. The name of the manpages that would
  		be created are printed.
  -v volume	Specify the name of the volume to be printed in center header
  		of generated manpages.
  -r release	Specify the project name and release number for the generated
		manpage.
ENVIRONMENT
  SOURCE_DATE_EPOCH  Unix timestamp that is used for date in header instead
                     of current date.
EXAMPLE
  The following example displays C code and comments to generate a manpage
  foobar.3:

     /** 3
      * foobar - a sample dummy function
      * This line is now the first of the description section.
      * Note that function parameters parm1 and parm2 are highlighted
      * in the generated man page.
      */
     int foobar(char *parm1, int parm2)
     {
     	...
	return 0;
     }

SEE ALSO
  txt2man(1), bookman(1).
AUTHOR
  Marc Vertes <mvertes@free.fr>
EOT
}

nogen=0
release=unknown
while getopts :d:hnr:v: opt
do
	case $opt in
	(d) date="$OPTARG";;
	(n) nogen=1;;
	(v) volume="$OPTARG";;
	(r) release="$OPTARG";;
	(*) man; exit;;
	esac
done
shift $(($OPTIND - 1))

# Compatibility wrapper for BSD/GNU date, for parsing dates
if date -j >/dev/null 2>&1; then
  pdate() { date -u -j -f '@%s' "$@"; }
else
  pdate() { date -u -d "$@"; }
fi

if [ -n "$SOURCE_DATE_EPOCH" ]; then
  date=$(LC_ALL=C pdate "@$SOURCE_DATE_EPOCH" +'%d %B %Y')
fi
date=${date:-$(LC_ALL=C date -u +'%d %B %Y')}

#
# Extract manpages from source files. Man page content is enclosed in
# commment blocks starting by "/** sectnum"
#
awk -v release="$release" -v volume="$volume" -v nogen=$nogen '
$1 == "/**" && $2 ~ /^[0-9]/ {
	sect = $2
	getline
	sub(/^ *\* */, "  ")
	title = $1
	line1_after_comment = 0
	in_struct = 0
	name = $0
	inc = FILENAME
	sub(/.[cS]$/, ".h", inc)
	found = ""
	grep_cmd = "test -f " inc " && grep -wq " title "  " inc " \
		   2>/dev/null && echo ok || echo nok"
	grep_cmd | getline found
	# description section extraction.
	in_synop = 0
	synop = ""
	while (getline) {
		if ($0 ~ / *\*\//) { # end of comment block
			sub(/ *\*\//, "")
			line1_after_comment = 1
			break
		}
		sub(/^ \* /, "")
		sub(/^ \*/, "")
		if ($1 ~ /^[A-Z ]+$/ && $1 != "SYNOPSIS")
			in_synop = 0
		if ($1 == "SYNOPSIS") {
			in_synop = 1
			continue
		}
		if ($1 == "DESCRIPTION")
			continue
		if (in_synop)
			synop = synop (synop ? "\n" : "") $0
		else
			desc = desc (desc ? "\n" : "") $0
	}
	# function prototype or struct extraction for synopsis.
	if (! synop) {
		while (getline) {
			if (line1_after_comment) {
				line1_after_comment = 0
				if (NF == 0) 
					break
				split(name, tname)
			}
			if ((!in_struct && $1 == "struct" && $2 == tname[1]) ||
			    (!in_struct && $2 == "struct" && $3 == tname[1])) {
			    	in_struct = 1
				synop = synop (synop ? "\n" : "") $0
				continue
			}
			synop = synop (synop ? "\n" : "") $0
			if (in_struct) {
				if ($0 ~ " *" tname[1] "[; ][*]*") break
				continue
			}
			if ($0 !~ /\)$/) {
				getline
				synop = synop " " $0
			}
			if ($0 ~/\)[ \t{};]*$/) {
				sub(/{[^}]}/, "", synop)
				sub(/[ \t]*$/, "", synop)
				if (found == "ok")
					synop = "#include \"" inc "\"\n" synop
				if (synop !~ /;$/)
					synop = synop ";"
				break
			}
		}
	}
	print title "." sect > "/dev/stdout"
	if (nogen) {
		name = synop = desc = sect = ""
		next
	}
	print "NAME\n" name (synop ? "\nSYNOPSIS\n  " synop : "") \
	      "\nDESCRIPTION\n" desc "\nFILE\n  " FILENAME | \
	      "{ echo '\''.\\\" Extracted by src2man from " FILENAME "'\''; \
	      txt2man -d \"$date\" -v \"" volume "\" -r " release \
	      " -s " sect " -t " title "; } >" title "." sect
	name = synop = desc = sect = ""
}
' $*