#!/bin/bash
set -a
USAGE='go to the wiki web you want to process, run it by
    wiki-list-tree [options] topics...
it will output all the topics sons of the listed topics.
Options:
  -t outputs the file names (.txt appended)
  -i ignore errors and print the results anyways in case of errors
  -s ignore errors only if none happens in topics to be outputted (sons)
  -_ allow underscores in wiki topic names
  -as) alphabetical sort (default) topics are printed in alphabetical sort,
       and appear only once
  -ts) topological sort, they are sorted from top to bottom, appear once
  -is) indented sort, tree-like, but topics may appear many times
'

pext=''
topicnamechars='a-zA-Z0-9'
ignore_errors=false
subset=false
type=alphabetical
while test -z "${1##-*}" -a -n "$1";do case $1 in
  -t) pext='.txt';;
  -i) ignore_errors=true;;
  -_) topicnamechars="_$topicnamechars";;
  -s) subset=true;;
  -ts) type=topological;;
  -as) type=alphabetical;;
  -is) type=indented;;
  *) echo "$USAGE"; exit;;
  esac;shift
done  

if test -z "$*"; then echo "$USAGE"; exit;fi
# the list of topics with errors
in_err=
# the list of roots of the to-be-printed hierarchy
topics=
# cache are lines of space seprarated topics and ancestors till WebHome
cache=/tmp/wiki-list-tree.$$
echo "WebHome " >$cache

# error still continues to perform all checks, but nothing will be printed
# $topic MUST contain the topic name
ERROR () { in_err="$in_err $topic"; echo "ERROR: $*" >&2; }

for i in "$@"; do
  topic="${i%.txt}"; file="$topic.txt"
  if test ! -e "$file"; then ERROR "topic $topic not found"; exit 1; fi
  topics="$topics $topic"
done

find_ancestry () { # $1=file
  local file parent ancestry topic tname wname
  file="$1"
  topic="${file%.txt}"
  parent=`grep '^%META:TOPICPARENT{name="[^"]*"}%[\r\t ]*$' "$file"`
  parent="${parent%\"*}"; parent="${parent#*\"}"
  parent="${parent:=WebHome}"
  case "$topic" in *[^$topicnamechars]*) ERROR "Illegal topic name $topic";; esac
  case "$parent" in *[^.$topicnamechars]*) ERROR "Illegal parent name $parent for topic $topic";; esac
  case "$parent" in 
    *.*) tname=${parent#*.}; wname=${parent%.*}
	 local details
	 if test -e ../$wname/$tname.txt; then 
	   details="which exists"
	 else details="which do not exist"
	 fi
	 if test -e $tname.txt; then details="$details, but local topic exists"
	 else details="$details, and local topic do not exist"
	 fi
	 ERROR "non-local parent $parent for $topic
    $details";;
  esac
  if test "$topic" = "$parent" -a "$topic" != WebHome; then 
    ERROR "topic has himself as parent: $parent"
  fi
  if test -n "$in_err"; then return; fi
  if test ! -e "$parent.txt"; then 
    ERROR "parent $parent of topic  $topic not found"
  fi
  if test "$parent" = WebHome; then # one-level deep
    ancestry="WebHome "
  fi
  if test -z "$ancestry"; then
    ancestry=`grep "^$parent " $cache`
    if test -z "$ancestry"; then # recurse to complete parent ancestry
      find_ancestry $parent.txt
    fi
    ancestry=`grep "^$parent " $cache`
    if test -z "$ancestry"; then # arg.... something broken
      ERROR "hierarchy broken for $parent parent of $topic"
    fi
  fi
  if ! grep -q "^$topic " $cache; then # not yet, add it
    echo "$topic $ancestry" >>$cache
  fi
}

process_web () {
  while read file; do find_ancestry "${file#./}"; done
  topics="${topics# }"; in_err="${in_err# }"
  if test -z "$in_err" -o $ignore_errors = true; then 
    print_results
  elif test -z "$in_err" -o $subset = true; then 
    in_err_subset=`egrep "${topics// /|}" $cache  \
      | sed -e 's/ .*//' | egrep "${in_err// |}"`
    if test -z "$in_err_subset"; then
      print_results
    fi
  fi
  #mv $cache /tmp/wiki-list-tree.cache  # DEBUG
  rm -f $cache
}

print_results () {
  if test $type = topological; then
    egrep " (${topics// /|})( |$)" $cache  | sed -e 's/\([^ ]* [^ ]*\) .*/\1/'\
     | tsort | tac
  elif test $type = indented; then
    for topic in $topics; do
      print_level "" $topic
    done
  else
    egrep "( |^)(${topics// /|})( |$)" $cache  | sed -e 's/ .*//' \
     | sort | uniq | sed -e "s/$/$pext/"
  fi
}

print_level () {
  local topic parent
  echo "$1$2"
  egrep "^[^ ]* $2( |$)" $cache | while read topic parent; do 
    print_level "$1  " $topic
  done
}

find . -type f -name '[A-Z]*.txt' | process_web