scripts/guile/fix-nationwide-statement.scm

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#!/usr/bin/env -S guile -e main -s
!#
;; Script for updating current account and credit card statements
;; downloaded from Nationwide, who use a date and currency format
;; that Gnucash does not support.
(use-modules (ice-9 getopt-long)
((srfi srfi-1) #:select (drop))
(dsv))
;; Date appears in Nationwide statements in the format
;; "10 Jan 2024", but this is not understood by Gnucash
;; so we convert it to YYYY-MM-DD format.
(define date-input-format "%d %b %Y")
(define date-output-format "%Y-%m-%d")
(define (format-date d)
(strftime date-output-format
(car (strptime date-input-format d))))
;; Characters we expect to see in a numeric amount field. The
;; Nationwide statements contain a non-ASCII currency character
;; that we want to delete.
(define currency-charset (string->char-set "0123456789.-"))
(define (format-amount s)
(string-filter currency-charset s))
;; Profiles for the different statemnets.
;; skip: the number of leading rows to skip
;; header: boolean indicating whether or not the first unskipped
;; row is a header
;; date-cols: list of columns containing dates
;; amount-cols: list columns containing amounts
(define profiles
'(("credit-card" . ((skip . 4)
(header . #t)
(date-cols . (0))
(amount-cols . (3 4))))
("current-account" . ((skip . 4)
(header . #t)
(date-cols . (0))
(amount-cols . (3 4 5))))))
;; Predicate for validating the profile option.
(define (valid-profile? p)
(if (assoc p profiles) #t #f))
;; Update a list by applying the given function to each of the
;; listed columns.
(define (update-list lst cols f)
(for-each (lambda (k)
(let ((v (list-ref lst k)))
(list-set! lst k (f v))))
cols))
;; Given a spec listing the date and amount columns, return a
;; function that will apply the corresponding formats to a row.
(define (process-row spec)
(let ((date-cols (assq-ref spec 'date-cols))
(amount-cols (assq-ref spec 'amount-cols)))
(lambda (row)
(when date-cols
(update-list row date-cols format-date))
(when amount-cols
(update-list row amount-cols format-amount)))))
;; Read a CSV from the given path.
(define (read-statement path)
(call-with-input-file path
(lambda (port)
(dsv->scm port #:format 'rfc4180))))
;; Write data to the given path in CSV format.
(define (write-statement data path)
(call-with-output-file path
(lambda (port)
(scm->dsv data port #:format 'rfc4180))))
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;; Apply the specified updates to data (a list of rows
;; read from the CSV). If a 'skip value is specified, drop
;; this many leading rows. If a 'header is present, only
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;; apply the updates to the succeeding rows, preserving
;; the header as-is.
(define (update-data spec data)
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(let* ((skip (assq-ref spec 'skip))
(data (if skip (drop data skip) data)))
(for-each (process-row spec) (if (assq-ref spec 'header) (cdr data) data))
data))
;; Apply the updates defined in `spec` to the statement read
;; from input-path and write the updated data to output-path.
(define (process-statement spec input-path output-path)
(let ((data (read-statement input-path)))
(write-statement (update-data spec data) output-path)))
;; Display a usage message and (optional) error message to STDERR
;; and exit. If an error message is given the exit code will be
;; non-zero.
(define* (usage #:optional errmsg)
(with-output-to-port (current-error-port)
(lambda ()
(when errmsg
(display "Error: ")
(display errmsg)
(newline))
(display "\
Usage: fix-credit-card-statement [options]
-h, --help Display this help.
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-i, --input=FILENAME Input file path. Required.
-o, --output=FILENAME Output file path. Required unless --overwrite is given.
-w, --overwrite Overwrite the input file with the updated data.
-p, --profile=PROFILE Profile name [credit-card|current-account].
")
(exit (if errmsg EXIT_FAILURE EXIT_SUCCESS)))))
;; Process command-line arguments and validate options.
;; If valid, run process-statement with the given options.
(define (main args)
(let* ((option-spec `((help (single-char #\h) (value #f))
(input (single-char #\i) (value #t))
(output (single-char #\o) (value #t))
(overwrite (single-char #\w) (value #f))
(profile (single-char #\p) (value #t) (predicate ,valid-profile?))))
(options (getopt-long args option-spec))
(help-wanted (option-ref options 'help #f))
(profile (option-ref options 'profile #f))
(input (option-ref options 'input #f))
(output (option-ref options 'output #f))
(overwrite (option-ref options 'overwrite #f)))
(cond
(help-wanted (usage))
((not profile) (usage "profile is required"))
((not input) (usage "input filename is required"))
((and overwrite output) (usage "output filename cannot be given with --overwrite"))
((not (or overwrite output)) (usage "output filename is required without --overwrite")))
(process-statement (assoc-ref profiles profile) input (or output input))))