1//! The page around a site's content: the head (type, look, the preview's tags, the one script
2//! Datastar) and the body's open and close.
3//!
4//! A site writes what is inside `<body>` with `components` and passes it here with the
5//! attributes the body carries (Datastar's `data-signals`, say). Everything that varies between
6//! sites is a field, so there is one head.
7
8use maud::{DOCTYPE, Markup, PreEscaped, html};
9
10use crate::asset;
11
12/// How the shared stylesheet and script reach the page.
13#[derive(Clone, Copy, Debug, PartialEq, Eq)]
14pub enum Assets {
15    /// `<link>` and `<script src>` to `/ui.css?v=…` and `/ui.js?v=…`. Needed when the site's
16    /// content security policy forbids inline script, as whiskers' does.
17    Linked,
18    /// The same bytes inside the page, as lmjtfy has them: one request fewer, and no policy
19    /// against inline script.
20    Inline,
21}
22
23/// One attribute on `<body>`.
24#[derive(Clone, Debug, PartialEq, Eq)]
25pub struct Attr {
26    name: String,
27    value: String,
28}
29
30impl Attr {
31    /// A name is letters, digits and `- _ . : ` only, which covers Datastar's `data-on:click__debounce.300ms`;
32    /// anything else would end the tag, so it stops the page being built.
33    pub fn new(name: &str, value: &str) -> Attr {
34        assert!(
35            !name.is_empty() && name.bytes().all(|b| b.is_ascii_alphanumeric() || b"-_.:".contains(&b)),
36            "{name:?} is not an attribute name"
37        );
38        Attr { name: name.to_owned(), value: value.to_owned() }
39    }
40}
41
42pub struct Head<'a> {
43    pub title: &'a str,
44    /// The preview's tags and any other `<meta>`: `preview::Preview::html`, a build id.
45    pub meta: Markup,
46    /// A site's own stylesheet text, inline after the shared one (it is the site's, small, and
47    /// changes with the site).
48    pub style: &'a str,
49    pub assets: Assets,
50    /// Whether the page loads Datastar, from this crate's `/datastar.js`.
51    pub datastar: bool,
52    /// An icon's address, if the site has one.
53    pub icon: Option<&'a str>,
54    /// Anything else the site needs in the head, after the shared parts (a linked sheet of its
55    /// own).
56    pub extra: Markup,
57}
58
59fn escape(text: &str) -> String {
60    text.replace('&', "&amp;").replace('<', "&lt;").replace('>', "&gt;").replace('"', "&quot;")
61}
62
63/// The whole document: `body` is what goes inside `<body>`, before the shared script.
64pub fn document(head: &Head<'_>, body_attrs: &[Attr], body: Markup) -> Markup {
65    let mut open = String::from("<body");
66    for Attr { name, value } in body_attrs {
67        open.push_str(&format!(" {name}=\"{}\"", escape(value)));
68    }
69    open.push('>');
70    html! {
71        (DOCTYPE)
72        html lang="en" {
73            head {
74                meta charset="utf-8";
75                meta name="viewport" content="width=device-width, initial-scale=1";
76                title { (head.title) }
77                (head.meta)
78                @if let Some(icon) = head.icon { link rel="icon" type="image/svg+xml" href=(icon); }
79                // The two faces the first screen is set in, so it does not draw twice.
80                @for font in [&asset::FONTS[0], &asset::FONTS[2]] {
81                    link rel="preload" href=(font.path) as="font" type="font/woff2" crossorigin;
82                }
83                @match head.assets {
84                    Assets::Linked => { link rel="stylesheet" href=(asset::CSS.href()); }
85                    Assets::Inline => { style { (PreEscaped(asset::CSS.text())) } }
86                }
87                @if !head.style.is_empty() { style { (PreEscaped(head.style)) } }
88                (head.extra)
89                @if head.datastar { script type="module" src=(asset::DATASTAR.path) {} }
90            }
91            (PreEscaped(open))
92            (body)
93            @match head.assets {
94                Assets::Linked => { script src=(asset::JS.href()) defer {} }
95                Assets::Inline => { script { (PreEscaped(asset::JS.text())) } }
96            }
97            (PreEscaped("</body>"))
98        }
99    }
100}
101
102#[cfg(test)]
103mod tests {
104    use super::*;
105
106    fn head(assets: Assets) -> Head<'static> {
107        Head { title: "T & T", meta: html! { meta name="description" content="d"; }, style: ".x{}", assets, datastar: true, icon: Some("/favicon.svg"), extra: html! {} }
108    }
109
110    #[test]
111    fn linked_assets_are_addresses_of_the_sites_own() {
112        let page = document(&head(Assets::Linked), &[], html! { p { "hi" } }).into_string();
113        assert!(page.contains("<!DOCTYPE html>") && page.contains("<html lang=\"en\">"));
114        assert!(page.contains("<title>T &amp; T</title>"));
115        assert!(page.contains(&format!("href=\"{}\"", asset::CSS.href())));
116        assert!(page.contains(&format!("src=\"{}\"", asset::JS.href())));
117        assert!(page.contains("src=\"/datastar.js\""));
118        assert!(!page.contains("fonts.googleapis") && !page.contains("://"), "nothing is fetched from another site");
119        assert!(!page.contains("<script>"), "no inline script when the assets are linked");
120        assert!(page.ends_with("</body></html>"));
121    }
122
123    #[test]
124    fn inline_assets_carry_the_same_bytes() {
125        let page = document(&head(Assets::Inline), &[], html! { p { "hi" } }).into_string();
126        assert!(page.contains(asset::CSS.text()) && page.contains(asset::JS.text()));
127        assert!(!page.contains("rel=\"stylesheet\""));
128    }
129
130    #[test]
131    fn the_site_style_comes_after_the_shared_one_and_the_body_is_between_head_and_script() {
132        let page = document(&head(Assets::Linked), &[], html! { p #here { "hi" } }).into_string();
133        assert!(page.find("rel=\"stylesheet\"").unwrap() < page.find(".x{}").unwrap());
134        assert!(page.find("</head>").unwrap() < page.find("id=\"here\"").unwrap());
135        assert!(page.find("id=\"here\"").unwrap() < page.find("/ui.js").unwrap());
136    }
137
138    #[test]
139    fn body_attributes_are_escaped() {
140        let attrs = [Attr::new("data-signals", "{\"a\": \"<b>\"}"), Attr::new("data-on-interval__duration.1s", "x && y")];
141        let page = document(&head(Assets::Linked), &attrs, html! {}).into_string();
142        assert!(page.contains("<body data-signals=\"{&quot;a&quot;: &quot;&lt;b&gt;&quot;}\" data-on-interval__duration.1s=\"x &amp;&amp; y\">"));
143    }
144
145    #[test]
146    #[should_panic(expected = "is not an attribute name")]
147    fn an_attribute_name_that_would_end_the_tag_is_refused() {
148        Attr::new("a\"><script>", "x");
149    }
150}