#
# A version of join not requiring the files to be sorted 
#
if [ "$1" = "" ] || [ "$1" = "-?" ] || [ "$1" = "--help" ]
then
  echo "Usage: join.unsorted [OPTION]... FILE1 FILE2"
  echo "For each pair of input lines with identical join fields, write a line to"
  echo "standard output.  The default join field is the first, delimited"
  echo "by whitespace.  When FILE1 or FILE2 (not both) is -, read standard input."
  echo ""
  echo "  -a FILENUM        print unpairable lines coming from file FILENUM, where"
  echo "                      FILENUM is 1 or 2, corresponding to FILE1 or FILE2"
  echo "  -e EMPTY          replace missing input fields with EMPTY"
  echo "  -i, --ignore-case ignore differences in case when comparing fields"
  echo "  -j FIELD          equivalent to ""-1 FIELD -2 FIELD"""
  echo "  -o FORMAT         obey FORMAT while constructing output line"
  echo "  -t CHAR           use CHAR as input and output field separator"
  echo "  -v FILENUM        like -a FILENUM, but suppress joined output lines"
  echo "  -1 FIELD          join on this FIELD of file 1"
  echo "  -2 FIELD          join on this FIELD of file 2"
  echo "      --help     display this help and exit"
  echo "      --version  output version information and exit"
  echo ""
  echo "Unless -t CHAR is given, leading blanks separate fields and are ignored,"
  echo "else fields are separated by CHAR.  Any FIELD is a field number counted"
  echo "from 1.  FORMAT is one or more comma or blank separated specifications,"
  echo "each being FILENUM.FIELD or 0.  Default FORMAT outputs the join field,"
  echo "the remaining fields from FILE1, the remaining fields from FILE2, all"
  echo "separated by CHAR."
  echo ""
  exit
fi

AWK=gawk

AOPTION=0
EMPTY=""
FIELD1=1
FIELD2=1
FIELDSEP=" "
IGNORECASE=0
VOPTION=0

switch=1
while [ $switch = 1 ]
do case "$1" in
  -a) AOPTION=$2; shift 2 ;;
  -1) FIELD1=$2; shift 2 ;;
  -2) FIELD2=$2; shift 2 ;;
  -i) IGNORECASE=$2; shift 2 ;;
  -j) FIELD1=$2; FIELD2=$2; shift 2 ;;
  -t) FIELDSEP=$2; shift 2 ;;
  -v) VOPTION=$2; shift 2 ;;
  -*) echo "Flag not recognised: $1" ; shift ;;
  *) switch=0 ;;
  esac
done

if ! [ -f $1 ] || ! [ -f $2 ]
then
  echo "join.unsorted: too few non-option arguments"
  exit
fi

FIL1=$1
FIL2=$2

if [ $AOPTION = 0 ] || [ $AOPTION = 1 ]
then
  $AWK -v aoption=$AOPTION -v empty=$EMPTY -v field1=$FIELD1 -v field2=$FIELD2 \
       -v voption=$VOPTION -v fil2=$FIL2 -v fieldsep=$FIELDSEP '
  BEGIN { if (length(fieldsep)>0) {
            FS=fieldsep
            OFS=fieldsep
          }
          while(getline < fil2) {
            idx=$(field2)
            $(field2)=""
            lin[idx]=$0
          }
  }
        { idx=$(field1)
          $(field1)=""
          if (idx in lin) {
            print idx, $0, lin[idx]
            delete lin[idx]
          }else if (aoption==1) {
            print idx, $0, empty
          }
  }' $FIL1
else
  $AWK -v aoption=$AOPTION -v field1=$FIELD1 -v field2=$FIELD2 \
       -v voption=$VOPTION -v fil1=$FIL1 -v fieldsep=$FIELDSEP '
  BEGIN { FS=fieldsep
          OFS=fieldsep
          while(getline < fil1) {
            idx=$(field1)
            $(field1)=""
            lin[idx]=$0
          }
  }
        { idx=$(field2)
          $(field2)=""
          if (idx in lin) {
            print idx, lin[idx], $0
            delete lin[idx]
          }else if (aoption==2) {
            print idx, empty, $0
          }
  }' $FIL2
fi