a (macOS-targed) bash script to combine multiple named imports from a single library into one statement

combine-imports.sh

#!/bin/bash

# In this script, the library I maintain for work, "@casecommons/cbp-undercase"
# is used. I'll abstract it out in a future version of this so that the syntax
# is more like "combine-imports.sh [file] [library name]

imports=$(cat $1 | grep '@casecommons/cbp-undercase' | wc -l)
if [[ $imports -le 1 ]]; then
  # next line commented out for scripted use
  # echo "$1: no imports to combine."
  exit 0
fi

cat $1 | perl -pe "
  # concatenate multiline imports
  s/,\n/, /g if /(^import|^ {2}[^:}. )']+,$)/;
  s/{\n/{/g if /^import/;
" | \
perl -0777 -pe '
  # if there are any combined imports that dont end in a 
  # comma before the closing bracket, inline those, too
  s/\n} from/} from/g;
' | \
perl -0777 -pe '
  # if there are named imports whose "from" is on a newline, fix that
  s/}\n *from/} from/g;
' | \
perl -pe '
  # remove errant spaces inside imports
  s/, +/, /g if /^import/;
  s/{ +/{ /g if /^import/;
  s/, *}/ }/g if /^import/;
' | \
perl -0777 -pe '
  # get rid of blank lines between imports
  s/\n\nim/\nim/g if /^import/
' | \
# have to add a blank line to the end of the file in case there is none, 
# otherwise "tail -r" causes problems
sed -e '$a\' | \
# add "##" marker after the last import
tail -r | awk '!p && /^import/{print "##"; p=1} 1' | tail -r | \
perl -ne '
  # find range between the first import and the "##" marker
  $between = /^import/ .. /^##/;
  # push each of those lines to a buffer if it starts with "import"
  push @buff, $_ if $between && /^import/;
  # sort imports and print them
  print sort splice(@buff) if $between =~ /E/;
  # print everything else
  print unless $between
' | \
perl -pe "
  # chop off the end of the import and replace it with a comma
  s/ ?} from '\@casecommons\/cbp-undercase'/,/g;
" | \
perl -pe '
  # chop of the start of the import and pad the beginning and end of lines with "##"
  s/^import { (.*),$/##\1##/g;
' | \
perl -0777 -pe '
  # replace ##\n## between imported elements with comma; now all imports for this
  # library are on a single line, bounded by ## at the ^ and $
  s/##\n##/, /g;
' | \
perl -pe "
  # replace remaining ## with the front and back of the import
  s/^##/import { /g;
  s/##$/ } from '\@casecommons\/cbp-undercase'/g;
" | \
perl -pe '
  # clean up any errant double commas
  s/,+/,/g;
  # clean up any errant double spaces in import statements
  s/ +/ /g if /^import/;
' | \
perl -pe "
  # insert newlines back into combined import and indent elements 2 - n
  s/, /,\n  /g if /^import/;
  # insert a comma and a newline after last element of import
  s/ }/,\n}/g if /cbp-undercase'$/;
" | \
perl -pe '
  # move the first element of the import to a new line and indent
  s/{ /{\n  /g if (/^import/ && /,$/);
' | \
perl -pe "
  # add a newline back after the combined import
  s/(\@casecommons\/cbp-undercase')$/\1\n/g;
"