From 7cc68b512ed095ebc158bcfa6c47e3ddcd0fa24e Mon Sep 17 00:00:00 2001
From: postscriptum <postscriptum@gemlog>
Date: Sun, 13 Jul 2025 16:04:14 +0300
Subject: [PATCH] implement snac markdown filter with tests

---
 src/nex/template.rs | 103 +++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 92 insertions(+), 11 deletions(-)

diff --git a/src/nex/template.rs b/src/nex/template.rs
index 4e3c16c..16c8f38 100644
--- a/src/nex/template.rs
+++ b/src/nex/template.rs
@@ -27,17 +27,7 @@ impl Template {
     ) -> String {
         let mut c = String::with_capacity(content.len() + 128);
         for l in content.lines() {
-            if (l.starts_with("http://")
-                || l.starts_with("https://")
-                || l.starts_with("nex://")
-                || l.starts_with("gopher://")
-                || l.starts_with("gemini://"))
-                && !l.contains(' ')
-                && !matches!(self.format, Format::Plain)
-            {
-                c.push_str("=> ")
-            }
-            c.push_str(l);
+            format_line(&mut c, l, &self.format);
             c.push('\n')
         }
         self.pattern
@@ -110,3 +100,94 @@ impl Template {
             )
     }
 }
+
+/// Filter snac markdown
+/// https://comam.es/snac-doc/snac.5.html
+fn format_line(b: &mut String, l: &str, f: &Format) {
+    if l.starts_with('*') && l.ends_with('*') {
+        b.push_str(l.trim_matches('*').trim())
+    } else if l.starts_with('~') && l.ends_with('~') {
+        b.push_str(l.trim_matches('~').trim())
+    } else if l.starts_with('_') && l.ends_with('_') {
+        b.push_str(l.trim_matches('_').trim())
+    } else if l.starts_with('#') && !matches!(f, Format::Gemtext) {
+        b.push_str(l.trim_matches('#').trim())
+    } else if l.starts_with('>') && !matches!(f, Format::Gemtext) {
+        b.push_str(l.trim_matches('>').trim())
+    } else if (l.starts_with("http://")
+        || l.starts_with("https://")
+        || l.starts_with("nex://")
+        || l.starts_with("gopher://")
+        || l.starts_with("gemini://"))
+        && !l.contains(' ')
+        && matches!(f, Format::Gemtext | Format::Dir)
+    {
+        b.push_str("=> ");
+        b.push_str(l)
+    } else {
+        b.push_str(l)
+    }
+}
+
+#[test]
+fn test() {
+    fn test(a: &str, b: &str, f: &Format) {
+        let mut s = String::new();
+        format_line(&mut s, a, f);
+        assert_eq!(s, b);
+    }
+
+    let f = Format::Dir;
+
+    test("*t*", "t", &f);
+    test("**t**", "t", &f);
+    test("~~t~~", "t", &f);
+    test("__t__", "t", &f);
+
+    test("> t", "t", &f);
+    test("# t", "t", &f);
+    test("## t", "t", &f);
+    test("### t", "t", &f);
+
+    test("gemini://t", "=> gemini://t", &f);
+    test("gopher://t", "=> gopher://t", &f);
+    test("http://t", "=> http://t", &f);
+    test("https://t", "=> https://t", &f);
+    test("nex://t", "=> nex://t", &f);
+
+    let f = Format::Gemtext;
+
+    test("*t*", "t", &f);
+    test("**t**", "t", &f);
+    test("~~t~~", "t", &f);
+    test("__t__", "t", &f);
+
+    test("> t", "> t", &f);
+    test("# t", "# t", &f);
+    test("## t", "## t", &f);
+    test("### t", "### t", &f);
+
+    test("gemini://t", "=> gemini://t", &f);
+    test("gopher://t", "=> gopher://t", &f);
+    test("http://t", "=> http://t", &f);
+    test("https://t", "=> https://t", &f);
+    test("nex://t", "=> nex://t", &f);
+
+    let f = Format::Plain;
+
+    test("*t*", "t", &f);
+    test("**t**", "t", &f);
+    test("~~t~~", "t", &f);
+    test("__t__", "t", &f);
+
+    test("> t", "t", &f);
+    test("# t", "t", &f);
+    test("## t", "t", &f);
+    test("### t", "t", &f);
+
+    test("gemini://t", "gemini://t", &f);
+    test("gopher://t", "gopher://t", &f);
+    test("http://t", "http://t", &f);
+    test("https://t", "https://t", &f);
+    test("nex://t", "nex://t", &f);
+}