add blog ordering

Author: benev0

content/blogs/blog1.md

@@ -1,6 +1,7 @@
 ---
 title = "The First blog"
 url = "blog_1"
+published = 2025-06-18T04:08:41+00:00
 ---
 
 # Hello There

content/blogs/blog2.md

@@ -1,6 +1,7 @@
 ---
 title = "The Second blog"
 url = "blog_2"
+published = 2025-06-18T04:10:41+00:00
 ---
 
 # General Kenobi

content/blogs/headers.md

@@ -1,6 +1,7 @@
 ---
 title = "Headers"
 url = "headers"
+published = 2025-06-18T04:11:41+00:00
 ---
 
 # H1

content/blogs/math_test.md

@@ -2,6 +2,7 @@
 title = "Test of Math Rendering"
 url = "math_test"
 math = true
+published = 2025-06-19T04:07:45+00:00
 ---
 
 # Math

src/blog/render.gleam

@@ -1,6 +1,7 @@
 import blog/posts
 import gleam/dict
 import gleam/list
+import gleam/order
 import gleam/result
 import lustre/attribute
 import lustre/element/html.{a, body, div, head, html, link, p, script, text}
@@ -87,28 +88,86 @@ pub fn render_md(md: String, asset_path: String) -> vnode.Element(_) {
 
 pub fn render_matter(
   base: String,
-  matter: #(String, String),
+  matter: #(String, String, tom.DateTime),
 ) -> vnode.Element(_) {
   div([attribute.class("blog-link")], [
     p([], [text(matter.0)]),
     p([], [a([attribute.href(base <> "/" <> matter.1)], [text(matter.1)])]),
   ])
 }
 
+fn cmp_datetime(d1: tom.DateTime, d2: tom.DateTime) -> order.Order {
+  let year = case d1.date.year - d2.date.year {
+    0 -> order.Eq
+    diff if diff < 0 -> order.Gt
+    _ -> order.Lt
+  }
+
+  use <- order.lazy_break_tie(year)
+
+  let month = case d1.date.month - d2.date.month {
+    0 -> order.Eq
+    diff if diff < 0 -> order.Gt
+    _ -> order.Lt
+  }
+
+  use <- order.lazy_break_tie(month)
+
+  let day = case d1.date.day - d2.date.day {
+    0 -> order.Eq
+    diff if diff < 0 -> order.Gt
+    _ -> order.Lt
+  }
+
+  use <- order.lazy_break_tie(day)
+
+  let hour = case d1.time.hour - d2.time.hour {
+    0 -> order.Eq
+    diff if diff < 0 -> order.Gt
+    _ -> order.Lt
+  }
+
+  use <- order.lazy_break_tie(hour)
+
+  let minute = case d1.time.minute - d2.time.minute {
+    0 -> order.Eq
+    diff if diff < 0 -> order.Gt
+    _ -> order.Lt
+  }
+
+  use <- order.lazy_break_tie(minute)
+
+  let second = case d1.time.second - d2.time.second {
+    0 -> order.Eq
+    diff if diff < 0 -> order.Gt
+    _ -> order.Lt
+  }
+
+  use <- order.lazy_break_tie(second)
+
+  let _millisecond = case d1.time.millisecond - d2.time.millisecond {
+    0 -> order.Eq
+    diff if diff < 0 -> order.Gt
+    _ -> order.Lt
+  }
+}
+
 pub fn render_links(base: String, sources: List(posts.PostSource)) {
   // matters should be fallible (remove asserts)
   let matters = {
     use post <- list.map(sources)
     use matter <- result.try(djot.metadata(post.data))
     let assert Ok(tom.String(title)) = dict.get(matter, "title")
     let assert Ok(tom.String(url)) = dict.get(matter, "url")
-    Ok(#(title, url))
+    let assert Ok(tom.DateTime(datetime)) = dict.get(matter, "published")
+    Ok(#(title, url, datetime))
   }
 
   let assert Ok(matters) = result.all(matters)
 
   let rendered_matters =
     matters
+    |> list.sort(fn(t1, t2) { cmp_datetime(t1.2, t2.2) })
     |> list.map(render_matter(base, _))
 
   [html.h1([], [text("Blogs")]), ..rendered_matters]