Shell Programming and Scripting

# Input file
AAA,OAA,0313
AAB,OAB,0314

# Ref file1
NAA,123
NAB,456

# Ref file2
0313,123
081A,456
0314,789

AAA,OAA,0313,123,NAA
AAB,OAB,0314,456,NAB

FILE1=reffile1
FILE2=reffile2
FILE3=inputfile
awk -F"," -v "file1=$FILE1" -v "file2=$FILE2" '
FILENAME == file1 {
        f1[$2] = $0
        next
}
FILENAME == file2 {
        f2[$1] = $2
        next
}
{
        if ( $NF in f2 ) {
                if ( f2[$NF] in f1 ) {   ## I'm not sure why $NF works here and $2 does not, but I seem to get the output I want..
                        print $0","f2[$NF]","f1[$1]  # This line does not produce the relevant output from the f1 array (I want field 1 to print)
                }
        }
}' $FILE1 $FILE2 $FILE3

FILENAME==file1 { f1[$2]=$1;next}
FILENAME==file2 { f2[$1]=$2;next}
$NF in f2 && f2[$NF] in f1 { $0=$0 OFS f2[$NF] OFS f1[f2[$NF]]}
1

$NF in f2 && f2[$NF] in f1 { $0=$0 OFS f2[$NF] OFS f1[f2[$NF]]}
1