#lang scribble/manual

@; Copyright (c) 2019 Joel Dueck
@;
@; Copying and distribution of this file, with or without modification,
@; are permitted in any medium without royalty provided the copyright
@; notice and this notice are preserved.  This file is offered as-is,
@; without any warranty.

@(require "scribble-helpers.rkt")

@(require (for-label "../pollen.rkt"
                     "../dust.rkt"
                     "../crystalize.rkt"
                     racket/base
                     racket/contract
                     racket/string
                     txexpr
                     pollen/template
                     pollen/pagetree
                     sugar/coerce))

@title{@filepath{crystalize.rkt}}

@defmodule["crystalize.rkt" #:packages ()]

“Crystalizing” is an extra layer in between docs and templates that destructures the doc and stores
it in various pieces in a SQLite cache. Individual articles save chunks of rendered HTML to the
cache when their individual pages are rendered. The SQLite cache is then referenced by any page that
collects multiple articles and notes together. This is much faster than fetching docs and metas
through Pollen’s cache and re-converting them to HTML.

@defproc[(spell-of-summoning!) void?]

Initializes the SQLite database cache file. This involves creating the file
(@filepath{vitreous.sqlite}) if it does not exist, and running queries to create tables in the
database if they do not exist.

This function is called automatically in @filepath{pollen.rkt} whenever HTML is the target output.

@defproc[(crystalize-article! [pagenode pagenode?] [doc txexpr?]) non-empty-string?]

Returns a string containing the HTML of @racket[_doc]. @margin-note{This is one function that breaks
my convention of using a prefix of @tt{html$-} for functions that return strings of HTML.}
Privately, it does a lot of other work. The article is saved to the SQLite cache. If the article
specifies a @racket['series] meta, information about that series is fetched and used in the
rendering of the article. If there are @racket[note]s in the doc, they are parsed and saved
individually to the SQLite cache. If any of the notes use the @code{#:disposition} attribute,
information about the disposition is parsed out and used in the rendering of the article.

@deftogether[(@defproc[(list/articles [type (or/c 'listing_full_html 
                                                  'listing_short_html
                                                  'listing_excerpt_html)]
                                      [#:series series (or/c string? boolean?) #t]
                                      [#:limit limit stringish? -1]
                                      [order string? "DESC"]) (listof string?)]
              @defproc[(list/articles+notes [type (or/c 'listing_full_html 
                                                        'listing_short_html
                                                        'listing_excerpt_html)]
                                            [#:series series (or/c string? boolean?) #t]
                                            [#:limit limit stringish? -1]
                                            [order string? "DESC"]) (listof string?)])]

Fetches the HTML for all articles from the SQLite cache and returns a list of strings containing the
HTML for each. The articles will be ordered by publish date according to @racket[_order] and
optionally limited to the series specified in @racket[_series].

If @racket[_series] expression evaluates to @racket[#f], articles will not be filtered by series. If
it evaluates to @racket[#t] (the default), articles will be filtered by those that specify the
current output of @racket[here-output-path] in their @tt{series_pagenode} column in the SQLite
cache. If a string is supplied, articles will be filtered by those containing that exact value in
their @tt{series_pagenode} column in the SQLite cache.

The @racket[_order] expression must evaluate to either @racket["ASC"] or @racket["DESC"] and the
@racket[_limit] expressions must evaluate to a value suitable for use in the @tt{LIMIT} clause of
@ext-link["https://sqlite.org/lang_select.html"]{a SQLite @tt{SELECT} statement}. An expression that
evaluates to a negative integer (the default) is the same as having no limit.

@deftogether[(@defproc[(listing<>-short/articles [#:series series (or/c string? boolean?) #t]
                                            [#:limit limit stringish? -1]
                                            [order string? "DESC"]) txexpr?]
              @defproc[(listing<>-full/articles  [#:series series (or/c string? boolean?) #t]
                                            [#:limit limit stringish? -1]
                                            [order string? "DESC"]) txexpr?])]

@margin-note{Notice how the functions that start with @tt{list/} return lists and the functions that
start with @tt{listing<>} return fenced HTML strings. Maybe this is ugly, but it helps me keep these
otherwise too-similar sets of functions straight in my head.}

Fetches the HTML for all articles from the SQLite cache and returns the HTML strings fenced inside
a @racket['style] tagged X-expression. The articles will be ordered by publish date according to
@racket[_order] and optionally limited to the series specified in @racket[_series].

If @racket[_series] expression evaluates to @racket[#f], articles will not be filtered by series. If
it evaluates to @racket[#t] (the default), articles will be filtered by those that specify the
current output of @racket[here-output-path] in their @tt{series_pagenode} column in the SQLite
cache. If a string is supplied, articles will be filtered by those containing that exact value in
their @tt{series_pagenode} column in the SQLite cache.

The @racket[_order] expression must evaluate to either @racket["ASC"] or @racket["DESC"] and the
@racket[_limit] expressions must evaluate to a value suitable for use in the @tt{LIMIT} clause of
@ext-link["https://sqlite.org/lang_select.html"]{a SQLite @tt{SELECT} statement}. An expression that
evaluates to a negative integer (the default) is the same as having no limit.

The reason for enclosing the results in a @racket['style] txexpr is to prevent the HTML from being
escaped by @racket[->html] in the template. This tag was picked for the job because there will
generally never be a need to include any actual CSS information inside a @tt{<style>} tag in any
page, so it can be safely filtered out later. To remove the enclosing @tt{<style>} tag, see
@racket[unfence].

@defproc[(listing<>-full/articles+notes [#:series series (or/c string? #f) #f]
                                   [#:limit limit exact-integer? -1]
                                   [order string? "DESC"]) txexpr?]

Like @racket[listing<>-full/articles] except that notes and articles are combined side by side in
the results.

@defproc[(unfence [html string?]) string?]

Returns @racket[_html] with all occurrences of @racket["<style>"] and @racket["</style>"] removed.
The contents of the style tags are left intact.

Use this with strings returned from @racket[->html] when called on docs containing
@racket[listing<>-full/articles] or its siblings.

@defproc[(article-plain-title [pagenode pagenode?]) non-empty-string?]

Fetches the “plain” title (i.e., with no HTML markup) for the given article from the SQLite cache.
If the article did not specify a title, a default title is supplied. If the article contained
a @racket[note] that used the @code{#:disposition} attribute, the disposition-mark may be included
in the title.

Note that this needs to be called @emph{after} @racket[crystalize-article!] in order to get an
up-to-date value.
