AWK: dynamically change FS or RS - regex

Question

I cannot seem to get the trick to interchange the FS/RS variables dynamically, so that I get the following results from the input:
Input_file
header 1
header 2
{
something should not be removed
}
50
(
auto1
{
type good;
remove not useful;
}
auto2
{
type good;
keep useful;
}
auto3
{
type moderate;
remove not useful;
}
)
Output_file
header 1
header 2
{
something that should not be removed
}
50
(
auto1//good
{
type good;//good
}
auto2//good
{
type good;//good
keep useful;
}
auto3//moderate
{
type moderate;//moderate
}
)
The key things are:
There's no change is happening when the code-block {...} is not preceded by a autoX (X can be 1,2,3 etc.).
The changes should happen when autoX is followed by a codeblock {...}.
the value inside the codeblock & autoX is modified with the addition of \\good or //moderate, which needs to be read from the {...} itself.
the whole line should be removed from {...}, if it contains the phrase remove.
HINT: It might be something that can use regex and the idea explained here, with this particular example.
For now, I only have been able to meet the last requirement, with the following code:
awk ' {$1=="{"; FS=="}";} {$1!="}"; gsub("remove",""); print NR"\t\t"$0}' Input_file
Thanks in advance, for your skill & time, to tackle this problem with awk.

Answer 1

Here is my attempt to solve this problem:
awk '
FNR==NR{
if($0~/auto[0-9]+/){
found1=1
val=$0
next
}
if(found1 && $0 ~ /{/){
found2=1
next
}
if(found1 && found2 && $0 ~ /type/){
sub(/;/,"",$NF)
a[val]=$NF
next
}
if($0 ~ /}/){
found1=found2=val=""
}
next
}
found3 && /not useful/{
next
}
/}/{
found3=val1=""
}
found3 && /type/{
sub($NF,$NF"//"a[val1])
}
/auto[0-9]+/ && $0 in a{
print $0"//"a[$0]
found3=1
val1=$0
next
}
1
' Input_file Input_file
Explanation: Adding detailed explanation for above code here.
awk ' ##Starting awk program from here.
FNR==NR{ ##FNR==NR will be TRUE when first time Input_file is being read.
if($0~/auto[0-9]+/){ ##Check condition if a line is having auto string followed by digits then do following.
found1=1 ##Setting found1 to 1 which makes sure that the line with auto is FOUND to later logic.
val=$0 ##Storing current line value to variable val here.
next ##next will skip all further statements from here.
}
if(found1 && $0 ~ /{/){ ##Checking condition if found1 is SET and line has { in it then do following.
found2=1 ##Setting found2 value as 1 which tells program further that after auto { is also found now.
next ##next will skip all further statements from here.
}
if(found1 && found2 && $0 ~ /type/){ ##Checking condition if found1 and found2 are ET AND line has type in it then do following.
sub(/;/,"",$NF) ##Substituting semi colon in last field with NULL.
a[val]=$NF ##creating array a with variable var and its value is last column of current line.
next ##next will skip all further statements from here.
}
if($0 ~ /}/){ ##Checking if line has } in it then do following, which basically means previous block is getting closed here.
found1=found2=val="" ##Nullify all variables value found1, found2 and val here.
}
next ##next will skip all further statements from here.
}
/}/{ ##Statements from here will be executed when 2nd time Input_file is being read, checking if line has } here.
found3=val1="" ##Nullifying found3 and val1 variables here.
}
found3 && /type/{ ##Checking if found3 is SET and line has type keyword in it then do following.
sub($NF,$NF"//"a[val1]) ##Substituting last field value with last field and array a value with index val1 here.
}
/auto[0-9]+/ && $0 in a{ ##Searching string auto with digits and checking if current line is present in array a then do following.
print $0"//"a[$0] ##Printing current line // and value of array a with index $0.
found3=1 ##Setting found3 value to 1 here.
val1=$0 ##Setting current line value to val1 here.
next ##next will skip all further statements from here.
}
1 ##1 will print all edited/non0-edited lines here.
' Input_file Input_file ##Mentioning Input_file names here.

Answer 2

You can use two newlines as record separator and process each record which may contain one
autoX
{
...
...
}
block.
awk '
BEGIN{
RS="\n\n" # set record separator RS to two newlines
a["good"]; a["moderate"] # create array a with indices "good" and "moderate"
}
{
sub(/\n[ \t]+remove[^;]+;/, "") # remove line containing "remove xxx;"
for (i in a){ # loop array indices "good" and "moderate"
if (index($0, i)){ # if value exists in record
sub(i";", i";//"i) # add "//good" to "good;" or "//moderate" to "moderate;"
match($0, /(auto[0-9]+)/) # get pos. RSTART and length RLENGTH of "autoX"
if (RSTART){ # RSTART > 0 ?
# set prefix including "autox", "//value" and suffix
$0=substr($0, 1, RSTART+RLENGTH-1) "//"i substr($0, RSTART+RLENGTH)
}
break # stop looping (we already replaced "autoX")
}
}
printf "%s", (FNR==1 ? "" : RS)$0 # print modified line prefixed by RS if not the first line
}
' Input_file