Add blog homepage and article metadata display

src/blog.ml

+type article =
+  { date : int * int * int
+  ; title : string
+  ; authors : string list
+  ; tags : string list
+  ; category : string
+  ; content : string
+  ; url : string
+  }
+
+let string_of_file file =
+  let chan = open_in ("src/content/" ^ file) in
+  let rec aux acc chan =
+    match input_line chan with
+    | exception End_of_file -> acc
+    | line -> aux (acc ^ "\n" ^ line) chan
+  in
+  let res = aux "" chan in
+  close_in chan;
+  res
+
 let get_value field = List.hd (List.rev (String.split_on_char ':' field))
 
-let post_header t a d c tg =
-  let title = get_value t in
-  let authors = get_value a in
-  let date = get_value d in
-  let category = get_value c in
-  let tags = get_value tg in
+let extract_date date =
+  match String.split_on_char '-' date with
+  | [ year; month; day ] ->
+    (int_of_string year, int_of_string month, int_of_string day)
+  | _ -> (0, 0, 0)
+
+let article_of_string post url =
+  match String.split_on_char '\n' post with
+  | title :: authors :: date :: category :: tags :: r ->
+    Some
+      { date = extract_date (get_value date)
+      ; title = get_value title
+      ; authors =
+          (let authors = get_value authors in
+           match String.split_on_char ',' authors with
+           | [] -> [ "Unspecified authors!" ]
+           | auth -> auth )
+      ; tags =
+          (let tags = get_value tags in
+           match String.split_on_char ',' tags with
+           | [] -> [ "Unspecified tags!" ]
+           | tags -> tags )
+      ; category = get_value category
+      ; content = String.concat "\n" r
+      ; url
+      }
+  | _ -> None
+
+let post_header title authors (year, month, day) category tags =
   Format.asprintf
     {|<h1 id="page-title">%s</h1>
     <div class="row">
       <div class="col-lg-3">
       <img src="/blog/assets/img/icon_person.svg" style="max-width:1em"/>
-        Authors: %s
+        Authors: %a
       </div>
       <div class="col-lg-3">
       <img src="/blog/assets/img/icon_calendar.svg" style="max-width:1em"/>
-        Date: %s
+        Date: %4d-%2d-%2d
       </div>
       <div class="col-lg-3">
       <img src="/blog/assets/img/icon_category.svg" style="max-width:1em"/>
@@ -23,9 +67,48 @@ let post_header t a d c tg =
       </div>
       <div class="col-lg-3">
       <img src="/blog/assets/img/icon_tags.svg" style="max-width:1em"/>
-        Tags: %s
+        Tags: %a
       </div>
     </div>
     <hr class="featurette-divider"/>
   |}
-    title authors date category tags
+    title
+    (Format.pp_print_list
+       ~pp_sep:(fun fmt () -> Format.fprintf fmt ", ")
+       Format.pp_print_string )
+    authors year month day category
+    (Format.pp_print_list
+       ~pp_sep:(fun fmt () -> Format.fprintf fmt ", ")
+       Format.pp_print_string )
+    tags
+
+let pp_articles fmt articles_data_list =
+  List.iter
+    (fun article ->
+      Format.fprintf fmt {|<a href="%s">%s</a>@.<br />|} article.url
+        article.title )
+    articles_data_list
+
+let home_page home =
+  let articles =
+    List.find_all
+      (fun file ->
+        (String.length file >= 5 && String.equal (String.sub file 0 5) "blog/")
+        && Filename.check_suffix file ".md" )
+      Content.file_list
+  in
+  let articles_data =
+    List.map
+      (fun article ->
+        match Content.read article with
+        | None -> failwith "invalid article data"
+        | Some data -> (
+          match article_of_string data (Filename.chop_suffix article ".md") with
+          | None -> failwith "invalid article data"
+          | Some data -> data ) )
+      articles
+  in
+  let articles_by_date =
+    List.sort (fun a1 a2 -> compare a2.date a1.date) articles_data
+  in
+  Format.asprintf "%s%a" home pp_articles articles_by_date

src/content/blog.md

 <h1 id="page-title">Blog</h1>
-
-This is our blog

src/content/blog/opam_2.1.0_is_released.md

-title: opam 2.1.0 is released!
-authors: rjbou
-date: 2021-08-05
-category: tooling
-tags: opam
+title:opam 2.1.0 is released!
+authors:rjbou
+date:2021-08-05
+category:tooling
+tags:opam
 
 <div class="row">
   <div class="col-lg-12" align="center">

src/server.ml

@@ -14,18 +14,24 @@ let blog_asset_loader _root path _request =
 let page path =
   match Content.read (path ^ ".md") with
   | None -> None
-  | Some page -> Some (Omd.of_string page |> Omd.to_html)
+  | Some page -> (
+    match path with
+    | "blog" -> Some (Omd.of_string (Blog.home_page page) |> Omd.to_html)
+    | _any_other_page -> Some (Omd.of_string page |> Omd.to_html) )
 
 let article path =
   match Content.read ("blog/" ^ path ^ ".md") with
   | None -> None
-  | Some blog_article -> (
-    match String.split_on_char '\n' blog_article with
-    | title :: authors :: date :: category :: tags :: article ->
-      let header = Blog.post_header title authors date category tags in
-
-      Some (header ^ (Omd.of_string (String.concat "\n" article) |> Omd.to_html))
-    | _ -> None )
+  | Some blog_article -> begin
+    match Blog.article_of_string blog_article path with
+    | None -> None
+    | Some article ->
+      let header =
+        Blog.post_header article.title article.authors article.date
+          article.category article.tags
+      in
+      Some (header ^ (Omd.of_string article.content |> Omd.to_html))
+  end
 
 let () =
   Dream.run @@ Dream.logger