Reenable link rewriting for colocated assets

All credits go to https://github.com/getzola/zola/pull/1779

components/markdown/src/markdown.rs

@@ -9,6 +9,7 @@ use libs::tera;
 use crate::context::RenderContext;
 use errors::{Context, Error, Result};
 use libs::pulldown_cmark::escape::escape_html;
+use libs::regex::Regex;
 use utils::site::resolve_internal_link;
 use utils::slugs::slugify_anchors;
 use utils::table_of_contents::{make_table_of_contents, Heading};
@@ -22,6 +23,13 @@ const CONTINUE_READING: &str = "<span id=\"continue-reading\"></span>";
 const ANCHOR_LINK_TEMPLATE: &str = "anchor-link.html";
 static EMOJI_REPLACER: Lazy<EmojiReplacer> = Lazy::new(EmojiReplacer::new);
 
+/// Although there exists [a list of registered URI schemes][uri-schemes], a link may use arbitrary,
+/// private schemes. This regex checks if the given string starts with something that just looks
+/// like a scheme, i.e., a case-insensitive identifier followed by a colon.
+///
+/// [uri-schemes]: https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml
+static STARTS_WITH_SCHEMA_RE: Lazy<Regex> = Lazy::new(|| Regex::new(r"^[0-9A-Za-z\-]+:").unwrap());
+
 /// Efficiently insert multiple element in their specified index.
 /// The elements should sorted in ascending order by their index.
 ///
@@ -42,6 +50,11 @@ fn insert_many<T>(input: &mut Vec<T>, elem_to_insert: Vec<(usize, T)>) {
     *input = inserted;
 }
 
+/// Colocated asset links refers to the files in the same directory.
+fn is_colocated_asset_link(link: &str) -> bool {
+    !link.starts_with('/') && !link.starts_with('#') && !STARTS_WITH_SCHEMA_RE.is_match(link)
+}
+
 #[derive(Debug)]
 pub struct Rendered {
     pub body: String,
@@ -364,6 +377,14 @@ pub fn markdown_to_html(
                     code_block = None;
                     events.push(Event::Html("</code></pre>\n".into()));
                 }
+                Event::Start(Tag::Image(link_type, src, title)) => {
+                    if is_colocated_asset_link(&src) {
+                        let link = format!("{}{}", context.current_page_permalink, &*src);
+                        events.push(Event::Start(Tag::Image(link_type, link.into(), title)));
+                    } else {
+                        events.push(Event::Start(Tag::Image(link_type, src, title)));
+                    }
+                }
                 Event::Start(Tag::Link(link_type, link, title)) if link.is_empty() => {
                     error = Some(Error::msg("There is a link that is missing a URL"));
                     events.push(Event::Start(Tag::Link(link_type, "#".into(), title)));

components/markdown/tests/common.rs

@@ -63,7 +63,7 @@ fn configurable_render(
         &tera,
         &config,
         &config.default_language,
-        "",
+        "https://www.getzola.org/test/",
         &permalinks,
         insert_anchor,
     );

components/markdown/tests/snapshots/markdown__can_render_basic_markdown.snap

@@ -1,8 +1,6 @@
 ---
-source: components/rendering/tests/markdown.rs
-assertion_line: 29
+source: components/markdown/tests/markdown.rs
 expression: body
-
 ---
 <p>Hello world</p>
 <h1 id="hello-world">Hello world</h1>
@@ -11,5 +9,5 @@ Hello
 world
 Non rendered emoji :smile:
 <a href="image.jpg">a link</a>
-<img src="image.jpg" alt="alt text" /></p>
+<img src="https://www.getzola.org/test/image.jpg" alt="alt text" /></p>
 <h1>some html</h1>

components/markdown/tests/snapshots/shortcodes__can_grab_lang_in_md_shortcodes.snap

@@ -1,8 +1,6 @@
 ---
-source: components/rendering/tests/shortcodes.rs
-assertion_line: 63
+source: components/markdown/tests/shortcodes.rs
 expression: body
-
 ---
-<p><img src="cover.en.png" alt="Book cover in en" /></p>
+<p><img src="https://www.getzola.org/test/cover.en.png" alt="Book cover in en" /></p>