feedsnake/feedsnake.scm
2022-11-12 22:14:08 -06:00

231 lines
6.7 KiB
Scheme

;;
;; 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
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; 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/>.
;;
(load "date-strings.scm")
(load "named-format.scm")
(module feedsnake
(updated-feed-string read-feed entries-since entry->string)
(import scheme
(chicken base) (chicken condition) (chicken io) (chicken port)
srfi-1 srfi-19 srfi-69
date-strings
http-client
named-format
atom rss)
;; 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)
#f)))
;; A list of entries updated since the given date
(define (entries-since feed date-utc)
(let ([entry-date (lambda (entry) (car (alist-ref 'updated entry)))]
[since-entries '()])
(map
(lambda (entry)
(if (date>=? (entry-date entry) date-utc)
(set! since-entries
(append since-entries (list entry)))))
(car (alist-ref 'entries feed)))
since-entries))
;; 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-feed-string url)]
[updated? (not (eq? (hash old-string) (hash new-string)))])
(if updated?
new-string
#f)))
;; Download a feed (AKA fetch over HTTP to a string)
(define (fetch-feed-string url)
(call-with-output-string
(lambda (out) (fetch-http url out))))
(define (entry->string entry template)
(named-format
template
(entry-string-templating-parameters entry template)))
;; Returns an alist of string replacements/parameters for a given entry
;; For use with named-format
(define (entry-string-templating-parameters entry template)
(let* ([alist-car
(lambda (key alist)
(let ([value (alist-ref key alist)])
(if value
(car value))))]
[updated (or (alist-car 'updated entry) (alist-car 'published entry))]
[published (or (alist-car 'published entry) updated)]
[urls (alist-car 'url entry)])
`((title ,(alist-car 'title entry))
(updated ,(if updated (date->rfc228-string updated)))
(published ,(if published (date->rfc228-string published)))
(summary ,(alist-car 'summary entry))
(url ,(cond
[(list? urls) (car urls)]
[(string? urls) urls]))
(urls ,(cond
[(list? urls) urls]
[(string? urls) (list urls)])))))
;; Parse an atom feed into a feedsnake-friendly alist
(define (atom-doc->feedsnake-feed atom)
`((title ,(last (feed-title atom)))
(updated ,(feed-updated atom))
(entry-updated ,(atom-feed-latest-entry-date atom))
(entries ,(map atom-entry->feedsnake-entry (feed-entries atom)))))
;; Parse an atom entry into a feedsnake entry :>
(define (atom-entry->feedsnake-entry entry)
(let ([published (rfc339-string->date (entry-published entry))]
[updated (rfc339-string->date (entry-updated entry))])
`((title ,(last (entry-title entry)))
(updated ,(or updated published))
(published ,(or published updated))
(summary ,(last (entry-summary entry)))
(url ,(map link-uri (entry-links entry))))))
;; 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))))])
(reduce
(lambda (a b)
(if (date>=? a b) a b))
#f
(map entry-date (feed-entries atom)))))
;; Download a file over HTTP to the given port.
(define (fetch-http url out-port)
(call-with-input-request
url #f
(lambda (in-port) (copy-port in-port out-port))))
) ;; feedsnake module
;; The UNIX-style frontend for feedsnake
(module feedsnake-unix
(update-feed-file latest-entries feed-files)
(import scheme
(chicken base) (chicken condition) (chicken file) (chicken io)
(chicken process-context) (chicken process-context posix)
srfi-1 srfi-19
date-strings
feedsnake
xattr)
;; Switch the cached version of the feed with a newer version, if available
(define (update-feed-file feed-path)
(let* ([old-string (call-with-input-file feed-path
(lambda (in-port) (read-string #f in-port)))]
[new-string (updated-feed-string
(get-xattr feed-path "user.xdg.origin.url")
old-string)])
(if new-string
(call-with-output-file feed-path
(lambda (out) (write-string new-string #f out))))
new-string))
;; List of entries updated/published since last feed parsing
(define (latest-entries feed-path)
(let* ([feed (call-with-input-file feed-path read-feed)]
[xattr-last-update (get-xattr feed-path "user.feedsnake.parsed")]
[last-update (if xattr-last-update
(rfc339-string->date xattr-last-update)
(date->utc-date (make-date 0 0 0 0 01 01 1971)))])
(set-xattr feed-path "user.feedsnake.parsed"
(date->rfc339-string (current-date-utc)))
(entries-since feed last-update)))
;; List of all entries of the feed
(define (all-entries feed-path)
(let ([feed (call-with-input-file feed-path read-feed)])
(car (alist-ref 'entries feed))))
;; The user's presumed config root.
(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))))
;; 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-unix module
(define *retpoŝto*
"Subject: ~{{~A||Unnamed post||title}}
From:~{{ ~A ||||from-name}}<~{{~A||feedsnake@localhost||from-address}}>
To:~{{ ~A ||You||to-name}}<~{{~A||you@localhost||to-address}}>
Date: ~{{~A||||updated}}
~{{~{~a~^, ~}~%~%***~%||||urls}}
~{{~A||||summary}}")