Aligning postings to a specific column number in an hledger journal - bash

Question

This is a follow-up question to Right justify amounts in hledger journal text file
hledger is a plaintext accounting CLI program that can output all the postings of a transaction aligned amongst themselves, but not align the entire journal to a specific column number (see Add option to print with normalized output width · Issue #1045 · simonmichael/hledger)
# Test journal
; To test right-alignment of amounts
* Transactions
2018-01-01 #Payee | Internet
expenses:communication:internet 123.00 EUR
assets:cash:eur
2018-01-01 #Landlady | Rent
expenses:housing:rent 321.00 EUR
expenses:fees 2.50 EUR ; Bank fee
assets:bank:eur -323.50 EUR
2016/01/01 Unit prices
Expense:Foo 56 # $6.00 ; a comment after a space
Cash $-336 ; a comment after two spaces
2022-01-01 Time
skill 10000h
time -10000h
weird ; weird comment on posting without amount
2018-01-01 #Some things in life | Are free
; With and without comment
expenses:misc:stuff 0 ; A comment
expenses:misc:things 0
assets:cash:eur
Output should be
# Test journal
; To test right-alignment of amounts
* Transactions
2018-01-01 #Payee | Internet
expenses:communication:internet 123.00 EUR
assets:cash:eur
2018-01-01 #Landlady | Rent
expenses:housing:rent 321.00 EUR
expenses:fees 2.50 EUR ; Bank fee
assets:bank:eur -323.50 EUR
2016/01/01 Unit prices
Expense:Foo 56 # $6.00 ; a comment after a space
Cash $-336 ; a comment after two spaces
2022-01-01 Time
skill 10000h
time -10000h
weird ; weird comment on posting without amount
2018-01-01 #Some things in life | Are free
; With and without comment
expenses:misc:stuff 0 ; A comment
expenses:misc:things 0
assets:cash:eur
So the spaces have to stretch between the accounts (indented entries to the left) and the amounts (the text to the right)
Sounds like a job for awk, printf, something like that.

Answer 1

The solution is adapted from Ed Morton's answer to the initial question. The regexp is made more flexible, to cover more of the edge cases possible in a journal file.
Here is how to align right up to column 53.
align-journal.awk
match($0,/^( {2,4}[^ ]+) +([^;]+\y)?( *;.*)?/,a) {
$0 = sprintf("%-39s %12s%s", a[1], a[2], a[3])
}
{ print }
Running this AWK script on test.journal...
awk -f align-journal.awk test.journal
...produces the desired output. awk -f align-journal.awk test.journal > neat.journal to redirect it to a neat.journal file.
Explanations
The regular expression goes something like this: at the start of a line, in the first capture group match 2 to 4 spaces followed by 1 or more of any character that isn't space. Then 2 or more spaces, not captured. This is the space that's supposed to stretch to provide alignment / justification. Then second capture group, this is the amount of the posting, which can have many forms. Match whatever character isn't a ; (semicolons are how comments start in hledger journals) 1 or more times up to a word boundary. Do this if such a pattern exists. Then the third and final capture group, for the posting comment, if it exists: 0 or more spaces followed by a ;, followed by anything till the end of the line.
The idea is not to try to match the form of the amount field, so the script will manage to align it correctly whatever it is.
a is the variable name for what will hold the capturing groups.
The stretching of the spaces in the middle is done by the sprintf() function, using printf statements for fancier printing. The format string %-39s %12%s is chosen to align up to column 53, so last character of text should be on col. 52, and also to ensure a space is kept between the two fields even if the first is longer than 40 chars. That's why 39 and 12 add up to 51 instead of 53.
The script was tested with gawk 5.0.0.