#lang racket/base
; SPDX-License-Identifier: BlueOak-1.0.0
; This file is licensed under the Blue Oak Model License 1.0.0.
;; Generates an Atom feed from the SQLite cache
(require txexpr
deta
racket/match
racket/file
racket/date
racket/string
racket/sequence
"dust.rkt"
"cache.rkt")
(provide main)
(define feed-author default-authorname)
(define feed-author-email "joel@jdueck.net")
(define feed-title "The Local Yarn (Beta)")
(define feed-site-url "https://thelocalyarn.com")
(define feed-item-limit 50)
(define (as-cdata string)
(cdata #f #f (format "<![CDATA[~a]]>" string))) ; cdata from xml package via txexpr
(define (email-encode str)
(map char->integer (string->list str)))
;; Atom feeds require dates to be in RFC 3339 format
;; Our published/updated dates only give year-month-day. No need to bother about time zones or DST.
;; So, arbitrarily, everything happens at a quarter of noon UTC.
(define (ymd->rfc3339 datestr)
(format "~aT11:45:00Z" datestr))
;; For the feed "updated" value, we do want a complete timestamp.
(define (current-rfc3339)
;; #f argument to seconds->date forces a UTC timestamp
(define now (seconds->date (* 0.001 (current-inexact-milliseconds)) #f))
(define timestamp
(parameterize [(date-display-format 'iso-8601)]
(date->string now #t)))
(string-append timestamp "Z"))
;; Get the data out of the SQLite cache as vectors
(define (fetch-rows)
(sequence->list
(in-entities (cache-conn)
(articles+notes 'content #:series #f #:limit feed-item-limit))))
(define (listing->rss-item lst)
(match-define (listing _ path title author published updated html) lst)
(define entry-url (string-append feed-site-url web-root path))
(define updated-ts (if (non-empty-string? updated) updated published))
`(entry (author (name ,author))
(published ,(ymd->rfc3339 published))
(updated ,(ymd->rfc3339 updated-ts))
(title ,title)
(link [[rel "alternate"] [href ,entry-url]])
(id ,entry-url)
(summary [[type "html"]]
,(as-cdata html))))
(define (rss-feed)
(define feed-xpr
`(feed [[xml:lang "en-us"] [xmlns "http://www.w3.org/2005/Atom"]]
(title ,feed-title)
(link [[rel "self"] [href ,(string-append feed-site-url web-root "feed.xml")]])
(generator [[uri "http://pollenpub.com/"]] "Pollen")
(id ,(string-append feed-site-url web-root))
(updated ,(current-rfc3339))
(author
(name ,feed-author)
(email ,@(email-encode feed-author-email)))
,@(map listing->rss-item (fetch-rows))))
(string-append "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
(xexpr->string feed-xpr)))
(define (main)
(display-to-file (rss-feed) "feed.xml" #:mode 'text #:exists 'replace))
