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(define-module (src atom)
#:use-module (src mime-types)
#:use-module (src dates)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-19)
#:use-module (sxml simple)
#:use-module (ice-9 binary-ports)
#:use-module (rnrs bytevectors)
#:export (feed
append-feed-entry!
entry
person
media
render))
; ATOM Explanation: http://www.atomenabled.org/developers/syndication/
; ATOM Validator: https://validator.w3.org/feed/check.cgi
;; Entities
(define-record-type <feed>
(make-feed id title subtitle uri updated entries)
feed?
(id feed-id)
(title feed-title)
(subtitle feed-subtitle)
(uri feed-uri)
(updated feed-updated set-feed-updated!)
(entries feed-entries set-feed-entries!))
(define-record-type <entry>
(make-entry id title published updated authors summary content categories contributors media)
entry?
(id entry-id set-entry-id!)
(title entry-title)
(published entry-published)
(updated entry-updated)
(authors entry-authors)
(summary entry-summary)
(content entry-content)
(categories entry-categories)
(contributors entry-contributors)
(media entry-media))
(define-record-type <media>
(make-media title type length uri path)
media?
(title media-title)
(type media-type)
(length media-length)
(uri media-uri)
(path media-path))
(define-record-type <person>
(make-person name email uri)
person?
(name person-name)
(email person-email)
(uri person-uri))
(define zero-date (string/ISO->date "1970-01-01"))
(define (newest a b) (if (time>? (date->time-utc a) (date->time-utc b)) a b))
(define (find-newest dates) (reduce newest zero-date dates))
(define* (append-feed-entry! feed entry)
(let ((entries (feed-entries feed)))
(set-entry-id! entry (string-append
(feed-uri feed) "/"
(entry-id entry))) ;; TODO: is this enough
(set-feed-entries! feed (append entries (list entry))))
(set-feed-updated! feed (find-newest (map entry-updated
(feed-entries feed)))))
(define* (feed #:key (title "")
(subtitle "")
(uri "")
(entries '())
#:allow-other-keys)
(let* ((f (make-feed uri
title
subtitle
uri
(find-newest (map entry-updated entries))
'()))
(append-entry! (partial append-feed-entry! f)))
(for-each append-entry! entries)
f))
(define* (entry #:key (title "")
(id #f)
(published zero-date)
(updated zero-date)
(authors '())
(summary-html '())
(content-html '())
(categories '())
(contributors '())
(media '())
#:allow-other-keys)
(define (id-from-title title)
(string-map (lambda (c)
(if (char-set-contains? char-set:letter c) c #\-))
title))
(make-entry (or id (id-from-title title))
title
published
(find-newest (list published updated))
authors
summary-html
content-html
categories
contributors
media))
(define* (person name #:key (email "")
(uri "")
#:allow-other-keys)
(make-person name email uri))
(define* (media path #:key (title "")
(uri "")
#:allow-other-keys)
(define (type path)
(let* ((extension (car (last-pair (string-split path #\.))))
(type (assoc-ref mime-types extension)))
(if (string? type) type (throw "Unknown mime-type"))))
(let ((contents (call-with-input-file path get-bytevector-all #:binary #t)))
(make-media title
(type path)
(bytevector-length contents)
uri
path)))
;; Rendering
(define (render-person tag person)
`(,tag
(name ,(person-name person))
(uri ,(or (person-uri person) ""))
(email ,(or (person-email person) ""))))
(define (partial f . set)
(lambda (. args) (apply f (append set args))))
(define render-author (partial render-person 'author))
(define render-contributor (partial render-person 'contributor))
(define (render-media med)
`(link (@(rel enclosure)
(href ,(media-uri med))
(type ,(media-type med))
(title ,(media-title med))
(length ,(media-length med)))))
(define (render-category cat)
`(category (@(term ,cat))))
(define (render-entry ent)
`(entry
(id ,(entry-id ent))
(title ,(entry-title ent))
(published ,(date->string/RFC3339 (entry-published ent)))
(updated ,(date->string/RFC3339 (entry-updated ent)))
,@(map render-author (entry-authors ent))
(summary (@(type html)) ,(entry-summary ent))
(content (@(type html)) ,(entry-content ent))
,@(map render-category (entry-categories ent))
,@(map render-contributor (entry-contributors ent))
,@(map render-media (entry-media ent))))
(define (render-feed fe)
`(feed (@(xmlns "http://www.w3.org/2005/Atom"))
(id ,(feed-id fe))
(title ,(feed-title fe))
(link (@(href ,(feed-uri fe))
(rel "self")))
(updated ,(date->string/RFC3339 (feed-updated fe)))
(subtitle ,(feed-subtitle fe))
,@(map render-entry (feed-entries fe))))
(define* (render feed)
(display "<?xml version=\"1.0\" encoding=\"utf-8\"?>")
(sxml->xml (render-feed feed)))
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