#!/bin/sh
[ -n "$BASH" ] || exec bash -p $0 $@

# Script to process man pages output by doxygen.
# We need to use bash for its associative array facility.
# (`bash -p` prevents import of functions from the environment).
# Args: none or 2 being man7 page name & relative path of source with \mainpage

declare -A renamed_page
done_synopsis=false

main(){
  set -e
  # make_man7 has no dependencies or dependants so kick it off now
  [ $# -ne 2 ] || make_man7 $@ &
  pushd man/man3 >/dev/null; rm -f _*
  count_real_pages
  rename_real_pages
  # Nothing depends on make_symlinks so background it
  make_symlinks &
  post_process $@
  wait
}

count_real_pages(){
  page_count=0
  #
  # Count "real" man pages (i.e. not generated by MAN_LINKS)
  # MAN_LINKS pages are 1-liners starting .so
  # Method: list files in descending order of size,
  # looking for the first 1-liner
  #
  for i in $(ls -S)
  do head -n1 $i | grep -E -q '^\.so' && break
    page_count=$(($page_count + 1))
  done
  first_link=$(($page_count + 1))
}

rename_real_pages(){
  for i in $(ls -S | head -n$page_count)
  do
    j=$(ed -s $i <<////
/Functions/+1;.#
/^\\.RI/;.#
.,.s/^.*\\\\fB//
.,.s/\\\\.*//
.,.w /dev/stdout
Q
////
).3
    mv -f $i $j
    renamed_page[$i]=$j
  done
}

make_symlinks(){
  for j in $(ls -S | tail -n+$first_link)
  do ln -sf ${renamed_page[$(cat $j | cut -f2 -d/)]} $j
  done
}

post_process(){
  #
  # DIAGNOSTIC / DEVELOPMENT CODE
  # set -x and restrict processing to keep_me: un-comment to activate
  # Change keep_me as required
  #
  #keep_me=nfq_icmp_get_hdr.3
  #do_diagnostics

  # Record doxygen version
  i=$(doxygen --version)
  doxymajor=$(echo $i|cut -f1 -d.)
  doxyminor=$(echo $i|cut -f2 -d.)

  # Decide if we need to fix rendering of verbatim "\n"
  [ $doxymajor -eq 1 -a $doxyminor -lt 9 ] &&
    fix_newlines=true || fix_newlines=false

  # Decide if we need to fix double-to-single-quote conversion
  [ $doxymajor -eq 1 -a $doxyminor -ge 9 -a $doxyminor -lt 13 ] &&
    fix_quotes = true || fix_quotes=false

  # Work through the "real" man pages
  for target in $(ls -S | head -n$page_count)
  do grep -Eq "^\\.SH \"Function Documentation" $target || continue

    {
      del_bogus_synopsis
      $done_synopsis || del_modules
      fix_name_line
      move_synopsis
      del_empty_det_desc
      del_def_at_lines
      fix_double_blanks
      [ $# -ne 2 ] || insert_see_also $@

      # Work around doxygen bugs (doxygen version-specific)

      # Best effort: \" becomes \'
      #              Only do lines with some kind of printf,
      #              since other single quotes might be OK as-is.
      $fix_quotes && sed -i '/printf/s/'\''/"/g' $target

      # Fix rendering of verbatim "\n" (in code snippets)
      $fix_newlines && sed -i 's/\\n/\\\\n/' $target
    }&

  done

}

make_man7(){
  target=$(grep -Ew INPUT doxygen.cfg | rev | cut -f1 -d' ' | rev)/$2
  mypath=$(dirname $0)

  # Build up temporary source in temp.c
  # (doxygen only makes man pages from .c files).
  ed -s $target << ////
1,/\\\\mainpage/d
0i
/**
 * \\defgroup $1 $1 overview
.
/\\*\\//+1,\$d
a

/**
 * @{
 *
 * $1 - DELETE_ME
 */
int $1(void)
{
	return 0;
}
/**
 * @}
 */
.
wq temp.c
////

  # Create temporary doxygen config in doxytmp
  grep -Ew PROJECT_NUMBER doxygen.cfg >doxytmp
  cat >>doxytmp <<////
PROJECT_NAME = $1
ABBREVIATE_BRIEF =
FULL_PATH_NAMES = NO
TAB_SIZE = 8
OPTIMIZE_OUTPUT_FOR_C = YES
EXAMPLE_PATTERNS =
ALPHABETICAL_INDEX = NO
SEARCHENGINE = NO
GENERATE_LATEX = NO
INPUT = temp.c
GENERATE_HTML = NO
GENERATE_MAN = YES
MAN_EXTENSION = .7
////

  doxygen doxytmp >/dev/null

  # Remove SYNOPSIS line if there is one
  target=man/man7/$1.7
  mygrep "SH SYNOPSIS" $target
  [ $linnum -eq 0 ] || delete_lines $linnum $((linnum+1))

  # doxygen 1.8.9.1 and possibly newer run the first para into NAME
  # (i.e. in this unusual group). There won't be a SYNOPSIS when this happens
  if grep -Eq "overview$1" $target; then
    echo "Re-running doxygen $(doxygen --version)"
    ed -s temp.c << ////
2a
 * \\manonly
.PP
.SH "Detailed Description"
.PP
\\endmanonly
.
wq
////
    doxygen doxytmp >/dev/null
  fi

  rm temp.c doxytmp
}

# Insert top-level "See also" of man7 page in man3 page
insert_see_also(){
  mygrep "Detailed Description" $target
  [ $linnum -ne 0 ] || mygrep "Function Documentation" $target
  [ $linnum -ne 0 ] || { echo "NO HEADER IN $target" >&2; return; }
  ed -s $target <<////
${linnum}i
.SH "See also"
\\fB${1}\\fP(7)
.
wq
////
}

fix_double_blanks(){
  linnum=1
  #
  # Older versions of man display a blank line on encountering "\fB\fP";
  # newer versions of man do not.
  # doxygen emits "\fB\fP" on seeing "\par" on a line by itself.
  # "\par" gives us double-spacing in the web doc, which we want, but double-
  # spacing looks odd in a man page so remove "\fB\fP".
  #
  while [ $linnum -ne 0 ]
  do mygrep \\\\fB\\\\fP $target
    [ $linnum -eq 0 ] || delete_lines $linnum $linnum
  done
}

del_def_at_lines(){
  linnum=1
  while [ $linnum -ne 0 ]
  do mygrep '^Definition at line (\\fB)?[[:digit:]]*(\\fP)? of file' $target
    [ $linnum -eq 0 ] || delete_lines $(($linnum - 1)) $linnum
  done
}

# Only invoked if you un-comment the 2 diagnostic / development lines above
do_diagnostics(){
  mv $keep_me xxx
  rm *.3
  mv xxx $keep_me
  page_count=1
  set -x
}

del_empty_det_desc(){
  mygrep "^\\.SH \"Function Documentation" $target
  i=$linnum
  mygrep "^\\.SH \"Detailed Description" $target
  [ $linnum -ne 0  ] || return 0
  [ $(($i - $linnum)) -eq 3 ] || return 0
  # A 1-line Detailed Description is also 3 lines long,
  # but the 3rd line is not empty
  i=$(($i -1))
  [ $(tail -n+$i $target | head -n1 | wc -c) -le 2 ] || return 0
  delete_lines $linnum $i
}

move_synopsis(){
  mygrep "SH SYNOPSIS" $target
  [ $linnum -ne 0  ] || return 0
  i=$linnum
  # If this is a doxygen-created synopsis, leave it.
  # (We haven't inserted our own one in the source yet)
  mygrep "^\\.SS \"Functions" $target
  [ $i -gt $linnum ] || return 0

  ed -s $target <<////
/^\\.SS \"Functions\"/;.d
.ka
/^\\.SH SYNOPSIS/;/^[[:space:]]*\$/-1m'a-1
/\"Function Documentation\"/-1;.d
wq
////
}

fix_name_line(){
  all_funcs=""

  # Search a shortened version of the page in case there are .RI lines later
  mygrep "^\\.SH \"Function Documentation" $target
  head -n$linnum $target >../$target.tmp

  while :
  do foundline=$(grep -En "^\\.RI" ../$target.tmp 2>/dev/null | head -n1)
    [ "$foundline" ] || break
    linnum=$(echo $foundline | cut -f1 -d:)
    # Discard this entry (and all previous lines)
    ed -s ../$target.tmp <<////
1,${linnum}d
wq
////

    func=$(echo $foundline | cut -f2 -d\\ | cut -c3-)
    [ -z "$all_funcs" ] && all_funcs=$func ||\
      all_funcs="$all_funcs, $func"
  done
  # For now, assume name is at line 5
  desc=$(head -n5 $target | tail -n1 | cut -f3- -d" ")
  ed -s $target <<////
5c
$all_funcs \\- $desc
.
wq
////
  rm ../$target.tmp
}

# Prior to doxygen 1.8.20 there was a "Modules" entry which became part of the
# "bogus" synopsis. Doxygen 1.11.0 replaces "Modules" with "Topics" still as
# part of the "bogus" synopsis and so cleaned up by del_bogus_synopsis().
del_modules(){
  grep -Eq "^\\.SS \"Modules" $target || return 0
  ed -s $target <<////
/^\\.SS \"Modules/,/^\\.SS \"Functions/-1d
wq
////
}

del_bogus_synopsis(){
  [ $(grep -E 'SH SYNOPSIS' $target | wc -l) -eq 2 ] || return 0
  #
  # doxygen 1.8.20 inserts its own SYNOPSIS line but there is no mention
  # in the documentation or git log what to do with it.
  # So get rid of it
  #
  ed -s $target <<////
/SH SYNOPSIS/,/^\\.SS \"Functions/-1d
wq
////
  done_synopsis=true
}

# Delete lines $1 through $2 from $target
delete_lines(){
  ed -s $target <<////
$1,$2d
wq
////
}

mygrep(){
  linnum=$(grep -En "$1" $2 2>/dev/null | head -n1 | cut -f1 -d:)
  [ $linnum ] || linnum=0
}

main $@