#!/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 the    #
# user # decision. This is why we keep with each node a record of the path  #
# from the root to the node, which we call *link*.                          #
# Layout of the tree:                                                       #
# Each node is a file <nodeName>.dep, which contains the names of the       #
# child nodes, one per line, except the first line is the *link*:           #
# the link is a series 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.           #
# 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="                                                                   "
declare -a exchange_triplet

# When we are backing up from a circular dependency, `exchange_triplet'
# shall contain (parent dependency_0 dependency_n)

#----------------------------#
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
    externals:  vars: BLFS_XML
		      DEP_LEVEL
    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 -a rootlink
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

{
# We use fd number 6 for input from DepFile, because we need 0 for user input
read -u6 -a rootlink
depth=${#rootlink[*]}
dep_level=$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[*]} "
# start of DepFile
echo -en "\nNode: $depth${spaceSTR:0:$depth}${RED}$DepFile${OFF}"

while read -u6 id_of_dep; do
# 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[*]} "} != ${srootlink} ]]; then # cir. dep
# First look for the other parent of this dependency.
# The parent has the same link without the last entry.
# We do not need otherlink anymore so just destroy the last element
      unset otherlink[${#otherlink[*]}-1]
      parent=$(grep ^"${otherlink[*]}"\$ -l *)
      parent=${parent%.dep}
      echo -en "\nCirc: $depth${spaceSTR:0:$depth}${BLUE}Circular dependency detected:${OFF}"
      echo -en "\nCirc: $depth${spaceSTR:0:$depth}${BOLD}${id_of_dep}${OFF} is a dependency \
of ${BOLD}${parent}${OFF}"
      echo -en "\nCirc: $depth${spaceSTR:0:$depth}${BOLD}${DepFile%.dep}${OFF} is a dependency \
of ${BOLD}${id_of_dep}${OFF}"
      echo -en "\nCirc: $depth${spaceSTR:0:$depth}${BOLD}${id_of_dep}${OFF} is a dependency \
of ${BOLD}${DepFile%.dep}${OFF}"
# we propose exchange always
      echo -en "\nCirc: $depth${spaceSTR:0:$depth}Do you want to build ${id_of_dep} first? yes/no (no):"
      read ANSWER
      if [ x$ANSWER = "xyes" ] ; then  # exchange:
# set triplet and return 1
        exchange_triplet=($parent $id_of_dep ${DepFile%.dep})
        return 1
      else # no exchange: prune and remove the line(s) from odep...
        lines_to_remove="$lines_to_remove $id_of_dep"
        sed -i "/$id_of_dep/d" ${DepFile/.dep/.odep}
      fi
    else # not circular: prune
      lines_to_remove="$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. 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 \
        -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" < ${id_of_dep}.odep \
                                    > ${id_of_dep}.dep # add the link
      generate_dependency_tree ${id_of_dep}.dep
# Test return value, in case we exchange dependencies
      case $? in
       0) # Normal return
         ;;
       1) # We are backing up to parent
         if [[ ${exchange_triplet} == ${DepFile%.dep} ]] # we are the parent
           then 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. let's just back up one step
# echo backing up to ${exchange_triplet} at ${DepFile%.dep}
           return 1
         fi
         ;;
      esac
    else # id_of_dep has no dependencies, just record the link in a file
         # and print
      echo "${rootlink[*]} $count" > ${id_of_dep}.dep
      echo -en "\nLeaf: $(($depth+1))${spaceSTR:0:$(($depth+1))}${CYAN}${id_of_dep}${OFF}"
    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 /^$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 ]' $file); do
#  echo f=$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 -a rootlink2

#echo file=$file
rootlink=($(head -n1 $file))
for f in $(grep '[^0-9 ]' $file); do
#  echo "    f"=$f
  if [ -f ${f}.dep ]; then
    rootlink2=($(head -n1 ${f}.dep))
    if [[ "${rootlink2[*]}" =~ "${rootlink[*]}" ]] ; then
      tree_erase ${f}.dep
    fi
  fi
done
rm -f $file
}