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;; Copyright 2022, Jaidyn Levesque <jadedctrl@posteo.at>
;; This program is free software: you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation, either version 3 of
;; the License, or (at your option) any later version.
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with this program. If not, see <https://www.gnu.org/licenses/>.
;; Module for misc. helper functions used by both feedsnake & feedsnake-unix
(module feedsnake-helpers
(alist-car-ref date->utc-date current-date-utc)
(import scheme
(chicken base)
;; Just car's the value of alist-ref (if it exists)
(define (alist-car-ref key alist)
(let ([value (alist-ref key alist)])
(if value
(car value)
;; Convert a date of arbitrary timezone to UTC
(define (date->utc-date date)
(time-utc->date (date->time-utc date)))
;; The current date, with UTC (-0; Z) timezone
(define (current-date-utc)
(date->utc-date (current-date)))
) ;; feedsnake-helper module
;; The main feedsnake module; parses atom feeds into alists and strings
(module feedsnake
(updated-feed-string read-feed filter-entries write-entry update-feed-file
write-entry-to-file write-entries-to-file all-entries entry->string
*maildir-template* *mbox-template*)
(import scheme
(chicken base) (chicken condition) (chicken io) (chicken file)
(chicken process-context) (chicken pathname) (chicken port)
srfi-1 srfi-13 srfi-19 srfi-69
atom rss)
(define *maildir-template*
"From: ~{{~A ||||from-name}}"
"To: ~{{~A ||You||TO_NAME||USER}}"
"Subject: ~{{~A||Unnamed post||title}}\n"
"Date: ~{{~A||||updated-rfc228||published-rfc228}}\n"
"~{{*** ~{~a~^ ~}~%||||urls}}\n"
(multifile-output? #t)))
(define *mbox-template*
`((entry-template ,(string-append
"From FEEDSNAKE ~{{~A||||updated-mbox||published-mbox}}\n"
(car (alist-ref 'entry-template *maildir-template*))
(multifile-output? #f)))
(define *default-template*
(append *maildir-template*
'((output-dir "./"))))
(define *default-values*
'((output-dir "./")))
(define *default-multifile-values*
'((filename-template "~{{~A||||updated||published}}.~{{~A||you||USER}}@~{{~A||localhost|HOSTNAME}}")
(multifile-output? #t)))
(define *default-singlefile-values*
'((filename-template "feed.out")
(multifile-output? #f)))
;; Read the given port into a feedsnake-feed (alist), no matter the format! c:<
(define (read-feed in-port)
(let (;;[rss (rss:read in-port)]
[atom (read-atom-feed in-port)])
(if atom
(atom-doc->feedsnake-feed atom)
;; Construct a filter function for feeds, given the script's arguments
(define (filter-entries feed filter)
(let ([entry-date (lambda (entry) (car (alist-ref 'updated entry)))]
[unfiltered (if feed
(alist-car-ref 'entries feed)
[entries '()])
(if unfiltered
(lambda (entry)
(if (apply filter (list entry))
(set! entries
(append entries (list entry)))))
;; Returns either the updated string of a feed (in comparison to old string),
;; or #f if literally nothing's changed
(define (updated-feed-string url old-string)
(let* ([new-string (fetch-http-string url)]
[updated? (not (string=? old-string new-string))])
(if updated?
(define (entry->string entry template)
(append entry
(entry-templating-parameters entry template))))
;; Returns an alist of string replacements/parameters for a given entry
;; For use with named-format
(define (entry-templating-parameters entry template)
(entry-url-templating-parameters entry)
(entry-author-templating-parameters entry)
(entry-date-templating-parameters entry)))
;; URL-related named-format templating parameters for given entry
(define (entry-url-templating-parameters entry)
(let ([urls (alist-car-ref 'urls entry)])
`((url ,(cond
[(list? urls) (car urls)]
[(string? urls) urls])))))
;; Author-related named-format templating parameters for given entry
(define (entry-author-templating-parameters entry)
(let* ([authors (alist-car-ref 'authors entry)]
[author (if authors (car authors) (alist-car-ref 'feed-title entry))])
`((author ,author))))
;; Date-related named-format templating parameters for given entry
(define (entry-date-templating-parameters entry)
(let* ([updated (or (alist-car-ref 'updated entry) (alist-car-ref 'published entry))]
[published (or (alist-car-ref 'published entry) updated)])
`((updated-rfc228 ,(if updated (date->rfc228-string updated)))
(published-rfc228 ,(if published (date->rfc228-string published)))
(updated-mbox ,(if updated (date->mbox-string updated)))
(published-mbox ,(if published (date->mbox-string published))))))
;; Writes a given feed entry to the out-port, as per the feedsnake-unix-format template alist
(define (write-entry entry template-alist out-port)
(let ([env-variables
(map (lambda (pair)
(list (string->symbol (car pair))
(cdr pair)))
(entry->string (append env-variables entry)
(alist-car-ref 'entry-template template-alist))
;; Write an entry to the given file (directory for multifile; normal file otherwise)
(define (write-entry-to-file entry template-alist out-path)
(let* ([template (if (alist-car-ref 'multifile-output? template-alist)
(append template-alist *default-multifile-values* *default-values*)
(append template-alist *default-singlefile-values* *default-values*))]
[file-mode (if (alist-car-ref 'multifile-output? template) #:text #:append)])
(entry-output-path entry template out-path)
(lambda (out-port)
(write-entry entry template out-port))
;; Writes all entries in a list to an out-path (mere convenience function)
(define (write-entries-to-file entries template-alist out-path)
(map (lambda (entry)
(write-entry-to-file entry template-alist out-path))
;; Decides the correct output path for an entry, given the template's filename rules etc.
(define (entry-output-path entry template-alist base-out-path)
(let ([multifile? (alist-car-ref 'multifile-output? template-alist)])
(if multifile?
(multifile-entry-path entry template-alist base-out-path)
(singlefile-entry-path entry template-alist base-out-path))))
;; Output path for entry with a single-file template
(define (singlefile-entry-path entry template-alist base-out-path)
(if (directory-exists? base-out-path)
'exn 'location 'file
'message (string-append base-out-path " shouldn't be a directory.")))
;; Output path for an entry w multifile template
(define (multifile-entry-path entry template-alist base-out-path)
(let* ([file-leaf (named-format (alist-car-ref 'filename-template template-alist) entry)]
[new-out-path (string-append base-out-path "/" "new")])
(if (and (create-directory base-out-path)
(create-directory new-out-path)
(create-directory (string-append base-out-path "/" "cur"))
(create-directory (string-append base-out-path "/" "tmp")))
(string-append new-out-path "/" file-leaf ":2,")
'exn 'location 'file
'message (string-append base-out-path " either isn't accessible or isn't a directory."))))))
;; Switch the cached version of the feed with a newer version, if available.
;; If the feed-path doesn't exist, then the feed will be downloaded fresh.
(define (update-feed-file feed-path feed-url)
(let* ([old-string (if (file-exists? feed-path)
(call-with-input-file feed-path
(lambda (in-port)
(read-string #f in-port)))
[new-string (updated-feed-string
(if new-string
(call-with-output-file feed-path
(lambda (out-port)
(write-string new-string #f out-port)))
;; List of all entries of the feed
(define (all-entries feed)
(alist-car-ref 'entries feed))
;; Atom parsing
;; ————————————————————————————————————————
;; Parse an atom feed into a feedsnake-friendly alist
(define (atom-doc->feedsnake-feed atom)
`((title ,(last (feed-title atom)))
(url ,(atom-feed-preferred-url atom))
(authors ,(map author-name (feed-authors atom)))
(updated ,(feed-updated atom))
(entry-updated ,(atom-feed-latest-entry-date atom))
(entries ,(map
(lambda (entry)
(atom-entry->feedsnake-entry entry atom))
(feed-entries atom)))))
;; Parse an atom entry into a feedsnake entry :>
(define (atom-entry->feedsnake-entry entry atom)
(let ([published (rfc339-string->date (entry-published entry))]
[updated (rfc339-string->date (entry-updated entry))]
[feed-authors (map author-name (feed-authors atom))]
[entry-authors (map author-name (entry-authors entry))])
`((title ,(last (entry-title entry)))
(updated ,(or updated published))
(published ,(or published updated))
(summary ,(last (or (entry-summary entry)
(entry-content entry))))
(urls ,(map (lambda (link) (atom-link->string link atom))
(entry-links entry)))
(authors ,(if (null? entry-authors) feed-authors entry-authors))
(feed-title ,(last (feed-title atom))))))
;; The preferred/given URL for an atom feed
(define (atom-feed-preferred-url atom)
(lambda (link)
(string=? (link-relation link) "self"))
(feed-links atom))))
;; Get an atom feed's latest date for an entry's updating/publishing
(define (atom-feed-latest-entry-date atom)
(let ([entry-date
(lambda (entry)
(or (rfc339-string->date (entry-updated entry))
(rfc339-string->date (entry-published entry))))])
(lambda (a b)
(if (date>=? a b) a b))
(map entry-date (feed-entries atom)))))
;; Convert an atom-link into a proper, valid url
(define (atom-link->string link atom)
(if (string-contains (link-uri link) "://")
(link-uri link)
(string-append (pathname-directory (atom-feed-preferred-url atom))
(link-uri link))))
;; Misc. functions
;; ————————————————————————————————————————
;; Download a file over HTTP to the given port.
(define (fetch-http url out-port)
url #f
(lambda (in-port) (copy-port in-port out-port))))
;; Download a feed (AKA fetch over HTTP to a string)
(define (fetch-http-string url)
(lambda (out) (fetch-http url out))))
) ;; feedsnake module
;; The UNIX-style frontend for feedsnake
(module feedsnake-unix
(main main)
(import scheme
(chicken base) (chicken condition) (chicken file) (chicken file posix)
(chicken io) (chicken port) (chicken process-context)
(chicken process-context posix)
srfi-1 srfi-19
feedsnake feedsnake-helpers
(define *help-msg*
"usage: feedsnake [-hnuU] [-s|S] [-o|d] FILE...\n"
" feedsnake [-hn] [-c] [-s] [-o|d] URL...\n"
" feedsnake [-h] [-s] [-o|d]\n\n"
"Feedsnake is a program for converting Atom feeds into mbox/maildir files.\n"
"Any Atom feeds passed as input will be output in mbox or maildir format.\n\n"
"If a FILE value is '-' or not provided, feedsnake will read a feed over standard\n"
"input. --since-last and similar arguments have no impact on these feeds.\n\n"
"If you want to subscribe to feeds with Feedsnake, you'll probably do something\n"
"like so:\n"
" feedsnake --cache ~/feeds/hacker_news.xml \\\n"
" --output ~/feeds/hacker_news.mbox \\\n"
" https://news.ycombinator.com/rss\n\n"
"Then, to update your subscription, just run:\n"
" feedsnake --update --since-last \\\n"
" --output ~/feeds/hacker_news.mbox \\\n"
" ~/feeds/hacker_news.xml\n\n"
"For updating all feeds:\n"
" feedsnake --update --since-last ~/feeds/*.xml > ~/feeds/all.mbox\n\n"
"The FILE given as input can be any Atom/RSS file. If you'd like to update\n"
"the FILE (with --update or --update-since), then it must have the\n"
"'user.xdg.origin.url' extended attribute set as the feed URL. You can create\n"
"such a file as in the above example, by passing a URL with a --cache file set.\n\n"))
(define *opts*
"Print a usage message"
(single-char #\h))
"Output directory, used for maildir output"
(single-char #\d)
(value (required DIR)))
"Output file, used for mbox output. Default is stdout ('-')."
(single-char #\o)
(value (required FILE)))
"The cache file used if a URL is passed as argument."
(single-char #\c)
(value (required FILE)))
"Update a feed FILE by downloading its newest version to the same path."
(single-char #\u))
"Alias for --update and --since-last. This is probably the option you want."
(single-char #\U))
"Output entries after the given date, in YYYY-MM-DD hh:mm:ss format."
(single-char #\s)
(value (required DATETIME)))
"Output entries dating from the last saved parsing of the file."
(single-char #\S))
"Output entries dating from the last update of the file.")
"Don't save parse/update time of this operation, to avoid influencing --since-*."
(single-char #\n))))
;; Prints cli usage to stderr.
(define (help)
(write-string *help-msg* #f (open-output-file* fileno/stderr))
(write-string (usage *opts*) #f (open-output-file* fileno/stderr)))
;; Wrap around the main function, so that the user isn't scared off by exceptions
(define-syntax exception-condom
(syntax-rules ()
((exception-condom expr)
(handle-exceptions exn
(string-append (get-condition-property exn 'exn 'message)
" ("
;; (symbol->string (get-condition-property exn 'exn 'location))
#f (open-output-file* fileno/stderr))
(exit 2))
;; Just ignore whatever exceptions the expression throws our way
(define-syntax ignore-errors
(syntax-rules ()
((ignore-errors expr)
(handle-exceptions exn #f expr))))
;; The `main` procedure that should be called to run feedsnake-unix for use as script.
(define (main)
(let* ([args (getopt-long (command-line-arguments) *opts*)]
[free-args (alist-ref '@ args)])
(if (alist-ref 'help args)
(map (lambda (feed-pair)
(process-feed args feed-pair))
(get-feeds free-args args))))))
;; Turn the scripts free-args into parsed Feedsnake feed alists
(define (get-feeds free-args args)
(let ([feed-paths
(if (eq? (length free-args) 0)
(map (lambda (path) (get-feed path args))
;; Turn a given feed-path (free-arg) into a parsed Feedsnake feed, if possible
(define (get-feed feed-path args)
([uri (ignore-errors (absolute-uri feed-path))]
[out-path (cond
[(and uri (alist-ref 'cache args))
(alist-ref 'cache args)]
[uri "-"]
[#t feed-path])]
[(string=? feed-path "-")
(call-with-input-string (read-string)
[(and uri (not (string=? "-" out-path)))
(update-feed-file out-path (uri->string uri))
(ignore-errors (call-with-input-file out-path read-feed)))]
(call-with-input-string (updated-feed-string (uri->string uri) "")
(ignore-errors (call-with-input-file out-path read-feed))])])
;; Set the origin URL, if newly-created cache file
(if (and uri (not (string=? "-" out-path)))
(set-xattr out-path "user.xdg.origin.url" (uri->string uri)))
(list out-path feed)))
;; Process a parsed feed, given arguments passed to the script
(define (process-feed args feed-pair)
(let* ([feed (last feed-pair)]
[feed-path (first feed-pair)]
[update? (or (alist-ref 'update args) (alist-ref 'update-since args))])
;; Update the feed
(if update?
(update-feed-file feed-path
(get-xattr feed-path "user.xdg.origin.url"))
(set! feed (call-with-input-file feed-path read-feed))))
;; Print all entries to stdout
(output-entries args `(,feed-path ,feed))
;; Change file's update-date
(if (and update?
(not (alist-ref 'no-save-date args)))
(set-xattr feed-path "user.feedsnake.updated"
(date->rfc339-string (current-date-utc))))
;; Save the file's parsing date
(if (and (file-exists? feed-path)
(not (alist-ref 'no-save-date args)))
(set-xattr feed-path "user.feedsnake.parsed"
(date->rfc339-string (current-date-utc))))))
;; Output the appropriate entrise of the given feed, using script's args
(define (output-entries args feed-pair)
(let* ([feed (last feed-pair)]
[output-dir (alist-ref 'outdir args)]
[output (or (alist-ref 'output args) output-dir)]
[template (if output-dir *maildir-template* *mbox-template*)]
[filter (entry-filter feed-pair args)]
[entries (filter-entries feed filter)])
[(not entries)
(write-entries-to-file entries template output)]
[(not output)
(map (lambda (entry)
(write-entry entry template
(open-output-file* fileno/stdout)))
;; Construct a filter function for feeds, given the script's arguments
(define (entry-filter feed-pair args)
(let* ([since-string (alist-ref 'since args)]
[since (if since-string
(date->utc-date (string->date since-string "~Y-~m-~d ~H:~M:~S"))
[entry-date (lambda (entry)
(or (alist-car-ref 'updated entry)
(alist-car-ref 'published entry)))]
[last-parse-string (or (ignore-errors
(get-xattr (first feed-pair) "user.feedsnake.parsed"))
[last-parse (rfc339-string->date last-parse-string)]
[last-update-string (or (ignore-errors
(get-xattr (first feed-pair) "user.feedsnake.updated"))
[last-update (rfc339-string->date last-update-string)])
(lambda (entry)
(cond [since
(date>=? (entry-date entry) since)]
[(or (alist-ref 'since-last args) (alist-ref 'update-since args))
(date>=? (entry-date entry) (or last-parse last-update))]
[(alist-ref 'since-update args)
(date>=? (entry-date entry) last-update)]
;; Supposed config root of the user (as per XDG, or simple ~/.config)
(define (config-directory)
(or (get-environment-variable "XDG_CONFIG_HOME")
(string-append (sixth (user-information (current-user-id))) "/.config")))
;; Path of the feedsnake config directory
(define (feedsnake-directory)
(create-directory (string-append (config-directory) "/feedsnake") #t))
;; Path of the feeds directory
(define (feeds-directory)
(create-directory (string-append (feedsnake-directory) "/feeds") #t))
;; Lists all configured feeds (files in feed directory)
(define (feed-files)
(map (lambda (relative-path)
(string-append (feeds-directory) "/" relative-path))
(directory (feeds-directory))))
) ;; feedsnake-unix module