#lang pollen/mode racket/base
; SPDX-License-Identifier: BlueOak-1.0.0
; This file is licensed under the Blue Oak Model License 1.0.0.
;; Builds an HTML page containing the keyword index for all ◊index entries in
;; the articles, by pulling them out of the SQLite cache DB.
(require racket/match
racket/list
racket/file
racket/string
db/base
net/uri-codec
pollen/template)
(require "cache.rkt"
"dust.rkt"
"snippets-html.rkt")
(provide main)
;; Terminology (because these things get confusing fast)
;;
;; Index HEADING: A word or phrase that appears in the index
;; Index SUBHEADING: A Heading that appears under another Heading
;; Index LINK: The connection between a particular Article and a Heading.
;; In the Index, represented by a URL+fragment back into the Article.
;; In the Article, represented by a URL+fragment to the Heading in the Index.
;; Index ENTRY: A Heading, a unique ID, a list of Links, and a list of Subheading-entries
;; Index RECORD: A simple vector representing a Link the way it is fetched from the SQLite
;; cache: #("heading" "subheading" NUMBER "/absolute-path.html#id_fragment" "Article Title")
(struct entry (heading ; String
id ; String
links ; List
subentries) #:transparent) ; List of entry structs
;; Get the first letter of an entry’s heading
(define (first-letter e)
(char-upcase (first (string->list (entry-heading e)))))
;; Format the ID for back-linking to a particular entry on the keyword index page
(define (format-entry-id head subhead)
(define maybe-sub
(cond [(non-empty-string? subhead) (string-append "!" subhead)]
[else ""]))
(uri-encode (string-downcase (string-append head maybe-sub))))
;; Convert a Record into a txexpr representing a link to the original article
(define (make-link rec)
(match-define (vector _ _ num link-url article-title) rec)
`(a [[href ,link-url]
[title ,article-title]]
,(number->string num)))
;; See if a Record belongs under an entry's heading or under an entry's subheading.
;; For subheadings, only checks the first one! This is because we rely on the records
;; being pre-alphabetized as they are fetched from the SQLite cache, and being
;; processed in order.
(define (test-match e record)
(match-define (vector record-head record-subhead _ _ _) record)
(define heading-match?
(string-ci=? (entry-heading e) record-head))
(define subheading-match?
(and heading-match?
(not (null? (entry-subentries e)))
(non-empty-string? record-subhead)
(string-ci=? (entry-heading (first (entry-subentries e))) record-subhead)))
(cond [(and heading-match? subheading-match?) 'existing-subhead]
[(and heading-match?
(non-empty-string? record-subhead)) 'new-subhead]
[heading-match? 'heading]
[else 'not-a-match]))
;; Add a record’s link to the front of an entry’s list of links
(define (add-entry-link e rec)
(define existing-links (entry-links e))
(struct-copy entry e [links (cons (make-link rec) existing-links)]))
;; Add a record’s link to the first subheading given in an entry.
(define (add-to-first-subentry e record)
(match-define (entry _ _ _ (cons last-sub rest-subs)) e)
(define updated-sub (add-entry-link last-sub record))
(struct-copy entry e [subentries (cons updated-sub rest-subs)]))
;; Add a record's link to a new subheading in an entry
(define (add-new-subentry e record)
(match-define (vector head subhead _ _ _) record)
(define subhead-id (format-entry-id head subhead))
(define new-sub (entry subhead subhead-id (list (make-link record)) '()))
(struct-copy entry e [subentries (list new-sub)]))
;; Make a new entry from a record, placing its link in either the main entry
;; or in a new sub-entry.
(define (new-entry record)
(match-define (vector head subhead _ _ _) record)
(define e (entry head (format-entry-id head "") '() '()))
(cond [(non-empty-string? subhead) (add-new-subentry e record)]
[else (add-entry-link e record)]))
;; Get the index entries from the SQLite cache, return them as a list of vectors (Records!)
(define (fetch-entries)
(define q
◊string-append{
SELECT entry, subentry, a.rowid, "◊web-root" || k.page || "#" || html_anchor AS href, title_plain
FROM index_entries k INNER JOIN articles a
ON a.page = k.page
ORDER BY entry COLLATE NOCASE ASC, subentry COLLATE NOCASE ASC;})
(query-rows cache-conn q))
;; Convert a list of vectors from the cache DB into a list of the form:
;; ((FIRST-LETTER (entries ...)) ...)
;; The method relies on the records being pre-sorted by the SQL query.
(define (group-entries records)
(define collated
(for/fold ([entries (list (new-entry (first records)))]
#:result (reverse entries))
([row (in-list (rest records))])
(match-define (cons last-entry rest-entries) entries)
(case (test-match last-entry row)
[(existing-subhead) (cons (add-to-first-subentry last-entry row) rest-entries)]
[(new-subhead) (cons (add-new-subentry last-entry row) rest-entries)]
[(heading) (cons (add-entry-link last-entry row) rest-entries)]
[else (cons (new-entry row) entries)])))
(for/list ([letter-group (in-list (group-by first-letter collated))])
(list (first-letter (first letter-group)) letter-group)))
;; Convert an entry into a list item, recursively adding subentries
(define (entry->txexpr e)
(match-define (entry head id links subentries) e)
(define sub-txs
(cond [(null? subentries) ""]
[else `(ul ,@(map entry->txexpr subentries))]))
`(li [[id ,id]] ,head nbsp ,@(add-between links ", ") ,sub-txs))
;; Return the complete HTML for the keyword index. Each letter group begins with a heading for the
;; letter, followed by a definition list for its entries.
(define (html$-index grouped-entries)
(define groups
(for/list ([letter-group (in-list grouped-entries)])
(match-define (list letter-char entries) letter-group)
`(section (h2 ,(list->string (list letter-char)))
(ul ,@(map entry->txexpr entries)))))
(apply string-append (map ->html groups)))
;; Build the complete HTML page
(define (html$-keywordindex-page the-index)
◊string-append{
<!DOCTYPE html>
<html lang="en">
◊html$-page-head{The Local Yarn: Keyword Index}
◊html$-page-body-open[]
<div id="keywordindex">
◊the-index
</div>
◊html$-page-body-close[]
</html>})
(define (main)
(displayln "Writing keyword-index.html…")
(display-to-file (html$-keywordindex-page (html$-index (group-entries (fetch-entries))))
"keyword-index.html"
#:mode 'text
#:exists 'replace))
