Change error output, add Omd AST for preview text folding

src/blog.ml

@@ -8,6 +8,54 @@ type article =
   ; url : string
   }
 
+let error msg =
+  Format.eprintf "error: %s@." msg;
+  Format.pp_print_flush Format.err_formatter ();
+  exit 1
+
+(* The code below is used to extract a small preview from the content field of a article type with the help of Omd *)
+open Omd
+
+let rec handle_inline = function
+  | Concat (attr, attr_inline_list) ->
+    Concat (attr, List.map handle_inline attr_inline_list)
+  | Text (attr, s) -> Text (attr, s)
+  | Emph (attr, attr_inline) -> Emph (attr, handle_inline attr_inline)
+  | Strong (attr, attr_inline) -> Strong (attr, handle_inline attr_inline)
+  | Code (attr, s) -> Code (attr, s)
+  | Hard_break attr -> Hard_break attr
+  | Soft_break attr -> Soft_break attr
+  | Link (attr, attr_link) -> Link (attr, attr_link)
+  | Image (attr, attr_link) -> Image (attr, attr_link)
+  | Html (attr, s) -> Html (attr, s)
+
+let rec handle_block = function
+  | Paragraph (attr, inline) -> Paragraph (attr, handle_inline inline)
+  | List (attr, list_type, list_spacing, attr_block_list_list) ->
+    List
+      ( attr
+      , list_type
+      , list_spacing
+      , List.map (List.map handle_block) attr_block_list_list )
+  | Blockquote (attr, attr_block_list) ->
+    Blockquote (attr, List.map handle_block attr_block_list)
+  | Thematic_break attr -> Thematic_break attr
+  | Heading (attr, i, attr_inline) ->
+    Heading (attr, i, handle_inline attr_inline)
+  | Code_block (attr, s1, s2) -> Code_block (attr, s1, s2)
+  | Html_block (attr, str) -> Html_block (attr, str)
+  | Definition_list (attr, attr_def_elt_list) ->
+    Definition_list (attr, attr_def_elt_list)
+
+let find_preview doc = Omd.to_html (List.map handle_block doc)
+
+let preview article_content =
+  let _content = Omd.of_string article_content |> find_preview in
+  Format.sprintf "%s..." "This will hold some preview of article soon"
+(* The code above is used to extract a small preview from the content field of a article type with the help of Omd *)
+
+(** [normalize_url target] takes a target URL and rids it of unwanted
+    characters, such as utf8, and spaces *)
 let normalize_url target =
   String.map
     (function
@@ -27,8 +75,6 @@ let allowed_categories =
   ; "Rust"
   ]
 
-let category_urls = List.map normalize_url allowed_categories
-
 (** [raw_articles] List of all raw text in all articles in /content/blog/
     subdirectory *)
 let raw_articles =
@@ -70,13 +116,17 @@ let article_of_string post url =
       ; category =
           begin
             let c = get_meta_value category in
-            if not @@ List.mem c allowed_categories then
-              failwith
-                (Format.asprintf {|Category (%s) invalid, try: %a|} c
-                   (Format.pp_print_list
-                      ~pp_sep:(fun fmt () -> Format.fprintf fmt ", ")
-                      Format.pp_print_string )
-                   allowed_categories );
+            if not @@ List.mem c allowed_categories then (
+              let err_msg =
+                Format.asprintf {|Category (%s) invalid, try: %a@.|} c
+                  (Format.pp_print_list
+                     ~pp_sep:(fun fmt () -> Format.fprintf fmt ", ")
+                     Format.pp_print_string )
+                  allowed_categories
+              in
+              Format.pp_print_flush Format.str_formatter ();
+              error err_msg
+            );
             c
           end
       ; content = String.concat "\n" r
@@ -180,7 +230,7 @@ let pp_article_excerpt fmt article =
       </div>
     </div>
     <br />
-    <a href="/blog/%s">Read more...</a>
+    %s<a href="/blog/%s">(Read more...)</a>
     <hr class="featurette-divider"/>
   <br />|}
     article.url article.title
@@ -195,7 +245,7 @@ let pp_article_excerpt fmt article =
     (Format.pp_print_list
        ~pp_sep:(fun fmt () -> Format.fprintf fmt ", ")
        Format.pp_print_string )
-    article.tags article.url
+    article.tags (preview article.content) article.url
 
 let pp_blog_posts fmt articles_data_list =
   List.iter (Format.fprintf fmt "%a" pp_article_excerpt) articles_data_list