#!/bin/bash
#
# $Id$
#

#---------------------------------------------------------------------------#
# This is a set of (recursive) functions for manipulating a dependency      #
# tree. Everything would be "simple" without circular dependencies. We      #
# would just have to build the tree using the packages.xml file, and to     #
# provide a function for browsing it. But we need to be able to detect      #
# circular dependencies and to possibly change the tree depending on        #
# priorities. This is why we keep with each node a record of the path       #
# from the root to the node, which we call *link* and a record of the       #
# successive priorities which we call *priolink*.                           #
#                                                                           #
# Layout of the tree:                                                       #
#                                                                           #
# A node of the tree is represented by a file <nodeName>.dep. We keep all   #
# those files in the same directory. The root node file is "root.dep".      #
# Files <nodeName>.dep have the following layout:                           #
#   - the first line is the link: the link is an array of numbers           #
#     (n1 n2 ... nN), describing the path from the root to <nodeName>: n1   #
#     is the position of the first node of the path in root.dep, n2 is the  #
#     position of the second node of the path in <node1>.dep and so on. The #
#     link is not needed for normal tree operations (building a subtree or  #
#     browsing the tree), but it allows to check whether a dependency is    #
#     circular, and to find its parent.                                     #
#   - the second line is an array of priorities (p1 p2 ... pN), giving the  #
#     priority (1=required, 2=recommended, 3=optional) of each dependency   #
#     in the link.                                                          #
#   - each subsequent line is of the form "p <depname>", where p is the     #
#     priority as above, and <depname> is the name of the dependency. The   #
#     position which is recorded in the link is the number of the line      #
#     minus 2.                                                              #
#                                                                           #
# Circular dependencies:                                                    #
#                                                                           #
# In case we find a cirdular dependency, it has the form :                  #
# parent->dependency_0->...->dependency_n->dependency_0                     #
# If we want to build dependency_n before dependency_0, no problem:         #
# we just prune the tree at dependency_n. If we want to build first         #
# dependency_0, we need to put dependency_n as a dependency of parent,      #
# then erase and rebuild the subtree from there. Now, we may have met       #
# another circular dependency in the subtree, and erasing the tree makes    #
# us forget the decision which was made. So, after first generating the     #
# list of dependencies from packages.xml, we keep the generated list in     #
# a file <nodeName>.odep, which we modify according to the decision which   #
# was made.                                                                 #
#---------------------------------------------------------------------------#

# Global variables:
# A string of spaces for indenting:
declare -a spaceSTR="                                                                   "
# When we are backing up from a circular dependency, `exchange_triplet'
# shall contain (parent dependency_0 dependency_n):
declare -a exchange_triplet

#----------------------------#
generate_dependency_tree() { #
#----------------------------#
: <<inline_doc
    function:   Create a subtree of the dependency tree
                (recursive function)
    input vars: $1 : file with a list of targets (child nodes)
		     the first line of the file is the link
                $2 : priority (1=req, 2=rec, 3=opt)
    externals:  vars:  DEP_LEVEL   contains 1 if we want to build the
                                   tree only for required dependencies,
                                   2 if we want also recommended ones,
                                   and 3 if we want optional ones too.
                       MAIL_SERVER contains the name of the MTA we want to use.
                files: ../xsl/dependencies.xsl: stylesheet for creating the
                                               .dep files
                       ../packages.xml:         File containing packages id
                                                and dependencies
    returns:    0 if the tree has been successfully created
                1 if we are backing up to the parent of a circular dep
    modifies:   vars: exchange_triplet contains the triplet when return is 1
    output:     files: for each <pkg> with dependencies in $1,
                       a file <pkg>.dep and its dependencies
    on error:   nothing
    on success: nothing
inline_doc

local DepFile=$1
local priority=$2
local -a rootlink
local -a priolink
local -a otherlink
local -i depth
local -i count=0
local id_of_dep
local parent
local lines_to_remove=
local srootlink
local dep_level
local priostring
local dpriostring
local i

{
# We use fd number 6 for input from DepFile, because we need 0 for user input
read -u6 -a rootlink
depth=${#rootlink[*]}
read -u6 -a priolink
dep_level=$DEP_LEVEL
# For now, process optional deps only for the root packages.
if (( $DEP_LEVEL > 2 )) && (( $depth > 1 )); then dep_level=2; fi
srootlink="${rootlink[*]} "
case $priority in
    1) priostring=required ;;
    2) priostring=recommended ;;
    3) priostring=optional ;;
    4) priostring=external ;;
esac
# start of DepFile
echo -en "\nNode: $depth${spaceSTR:0:$depth}${RED}$DepFile${OFF} $priostring"

while read -u6 prio_of_dep id_of_dep; do
case $prio_of_dep in
    1) dpriostring=required ;;
    2) dpriostring=recommended ;;
    3) dpriostring=optional ;;
    4) dpriostring=external ;;
esac
# count entries in file
  (( count++ ))
# Has this entry already been seen?
  if [ -f ${id_of_dep}.dep ]; then # found ${id_of_dep}.dep already in tree
    otherlink=($(head -n 1 ${id_of_dep}.dep))
    if [ -z "${otherlink[*]}" ] 
      then echo otherlink empty for $id_of_dep.dep
      echo This should not happen, but happens to happen...
      exit 1
    fi
# Do not use "${rootlink[*]}" =~ "${otherlink[*]}": case rootlink=(1 11)
# and otherlink=(1 1)
    if [[ ${srootlink#"${otherlink[*]} "} != ${srootlink} ]]; then # cir. dep
      echo -en "\nCirc: $((depth+1))${spaceSTR:0:$((depth+1))}${YELLOW}${id_of_dep}${OFF} $dpriostring"
# First look for the other parent of this dependency.
# The parent has the same link without the last entry.
# We do not need otherlink anymore so just destroy the last element
      unset otherlink[-1]
      parent=$(grep ^"${otherlink[*]}"\$ -l *)
      parent=${parent%.dep}
# Find lowest priority in branch from parent to DepFile:
      p2=0
      for (( i=${#otherlink[*]}; i < $depth ; i++ )) ; do
        if (( ${priolink[i]} > $p2 )); then p2=${priolink[i]}; fi
      done
      if (( $prio_of_dep >= $p2 )); then # prune
        lines_to_remove="$lines_to_remove $id_of_dep"
        sed -i "/$id_of_dep/d" ${DepFile/.dep/.odep}
      else #backup with prio priority
        exchange_triplet=($parent $id_of_dep ${DepFile%.dep})
        return $priority
      fi
    else # not circular: prune tree (but not .odep, since it may happen that
         # the tree is destroyed and rebuilt in another order)
      lines_to_remove="$lines_to_remove $id_of_dep"
    fi # circular or not
    continue # this dependency has already been seen, and the associated
             # subtree computed. We are done
  fi # Has this entry already been seen?
# So, this entry has not already been seen.
# If this is an external dep, just display it and go to next dep:
  if [ "$prio_of_dep" -eq 4 ]; then
    echo "${rootlink[*]} $count" > ${id_of_dep}.dep
    echo -en "\nLeaf: $(($depth+1))${spaceSTR:0:$(($depth+1))}${CYAN}${id_of_dep}${OFF} $dpriostring"
    continue
  fi
# Otherwise, let's build the corresponding
# subtree. Since decisions about circular deps can lead us to start again
# dependencies, we restart until the flag is false.
  flag=true
  while [ $flag = true ]; do
    flag=false
    if [ ! -f "${id_of_dep}.odep" ]; then
      xsltproc --stringparam dependencies ${dep_level} \
        --stringparam idofdep $id_of_dep \
        --stringparam MTA $MAIL_SERVER   \
        -o ${id_of_dep}.odep \
        ../xsl/dependencies.xsl ../packages.xml
    fi

# Use -s, because it may happen that after removing lines, .odep exists
# but is empty.
    if [[ -s ${id_of_dep}.odep ]]; then # this dependency has dependencies
      sed "1i${rootlink[*]} $count\\
${priolink[*]} $prio_of_dep" < ${id_of_dep}.odep \
                             > ${id_of_dep}.dep # add link and priolink
      generate_dependency_tree ${id_of_dep}.dep $prio_of_dep
# Test return value, in case we exchange dependencies
      p2=$?
      case $p2 in
       0) # Normal return
         ;;
       [123]) # We are backing up to parent
         if [[ ${exchange_triplet} == ${DepFile%.dep} ]] ; then
# We are the parent!
# First, we have to find the parent of our new direct dep, and remove
# the new direct dep from the parent.odep:
           otherlink=($(head -n1 ${exchange_triplet[2]}.dep))
           unset otherlink[-1]
           parent=$(grep -l ^"${otherlink[*]}"\$ *.dep)
           sed -i /[[:digit:]]\ ${exchange_triplet[2]}\$/d ${parent/.dep/.odep}
           tree_erase ${id_of_dep}.dep
# We want that our direct dep be ${exchange_triplet[2]} and that id_of_dep
# be pulled in as an indirect dep, so exchange.
# Just doing a sed -i "s@${id_of_dep}@${exchange_triplet[2]}@" $DepFile
# is not good if $DepFile contains several times the same line
# so first find the first line and then sed
           lineno=$(sed -n /${id_of_dep}/= $DepFile | head -n1)
           sed -i "${lineno}s@${id_of_dep}@${exchange_triplet[2]}@" $DepFile
# Do the same for the odep file:
           local OdepFile=${DepFile/.dep/.odep}
           lineno=$(sed -n /${id_of_dep}/= $OdepFile | head -n1)
           sed -i "${lineno}s@${id_of_dep}@${exchange_triplet[2]}@" $OdepFile
           id_of_dep=${exchange_triplet[2]}
           flag=true # we have to regenerate the tree for the new dependency
         else
# We are not the parent. If our priority is greater than p2
# we have to change the triplet and return priority, else return current p2.
# echo (DEBUG) backing up to ${exchange_triplet} at ${DepFile%.dep}
           if (( $priority > $p2 )); then
             exchange_triplet[2]=${DepFile%.dep}
             return $priority
           else
             return $p2
           fi
         fi
         ;;
      esac
    else # id_of_dep has no dependencies, just record the link in a file
         # and print
      echo "${rootlink[*]} $count" > ${id_of_dep}.dep
      echo -en "\nLeaf: $(($depth+1))${spaceSTR:0:$(($depth+1))}${CYAN}${id_of_dep}${OFF} $dpriostring"
    fi
  done
done
echo -en "\n End: $depth${spaceSTR:0:$depth}${GREEN}$DepFile${OFF}"
} 6<$DepFile
# It may happen that a file is created with several times
# the same line. Normally, all those lines but one
# would be flagged to be removed (or all of them if
# the dependency appeared before). A simple sed /$line/d
# destroys all the lines. We should instead remove
# only one for each appearance of it in lines_to_remove.
# so first get the position of last line and then delete
# that line
for line in $lines_to_remove
  do lineno=$(sed -n /^[[:digit:]]\ $line\$/= $DepFile | tail -n1)
  sed -i ${lineno}d $DepFile
done
return 0
}

#---------------#
tree_browse() { #
#---------------#
local file=$1
local f

#echo file=$file
for f in $(grep '[^0-9 ]' $file | sed 's/.* //'); do
#  echo f=$f
  if grep -q '[^0-9 ]' ${f}.dep ; then
    tree_browse ${f}.dep
  fi
  echo $f
done
}

#--------------#
tree_erase() { #
#--------------#
local file=$1
local f
local -a rootlink
local rootlink2

#echo file=$file
rootlink=($(head -n1 $file))
for f in $(grep '[^0-9 ]' $file | sed 's/.* //'); do
#  echo "    f"=$f
  if [ -f ${f}.dep ]; then
    rootlink2="$(head -n1 ${f}.dep) "
# See comment above about srootlink
    if [[ "${rootlink2#"${rootlink[*]} " != ${rootlink2} ]] ; then
      tree_erase ${f}.dep
    fi
  fi
done
rm -f $file
}