WIP: checking for fonts

Author: heathhenley

lib/pretty/dune

@@ -3,5 +3,6 @@
  (libraries
   ansifmt
   shell
+  str
   ;; Internal dependencies
   extra))

lib/pretty/icon.ml

@@ -12,15 +12,58 @@ type t = {
   issue_char : string;
 }
 
-let fc_list_cmd = {| fc-list | grep 'Hack Nerd Font Mono' |}
+let hack_nerd_font = "Hack Nerd Font Mono"
+let fc_list_cmd = Printf.sprintf "fc-list | grep '%s'" hack_nerd_font
+let uname_cmd = {| uname |}
 
-(** Use fc-list to check if Hack Nerd Font is installed - this might be a little
-    brittle, but it's simple - update if it becomes an issue. **)
-let nerd_font_installed () =
-  fc_list_cmd |> Shell.proc_stdout |> String.trim |> String.length > 0
+type os_name =
+  | Linux
+  | MacOS
+
+let uname_result =
+  Shell.proc_stdout uname_cmd |> String.trim |> function
+  | "Linux" -> Some Linux
+  | "Darwin" -> Some MacOS
+  | _ -> None
+
+(* Based on the list of possible folders here: https://github.com/adrg/xdg/blob/master/README.md#other-directories*)
+let mac_font_dirs =
+  [
+    "~/Library/Fonts";
+    "/Library/Fonts";
+    "/System/Library/Fonts";
+    "/Network/Library/Fonts";
+  ]
+
+let string_contains str substr =
+  let re = Str.regexp_string substr in
+  try
+    ignore (Str.search_forward re str 0);
+    true
+  with Not_found -> false
+
+let rec font_exists_in_dirs font_name = function
+  | [] -> false
+  | dir :: dirs ->
+      if Sys.file_exists dir then
+        let files = Sys.readdir dir in
+        if Array.exists (fun file -> string_contains file font_name) files then
+          true
+        else font_exists_in_dirs font_name dirs
+      else font_exists_in_dirs font_name dirs
+
+(* We only support mac and linux right now - if the system is unix based and
+it's linux, we can use the fc-list cmd, otherwise on mac we look in common
+directories manually for our font *)
+let nerd_font_installed =
+  match uname_result with
+  | Some Linux ->
+      Shell.proc_stdout fc_list_cmd |> String.trim |> String.length > 0
+  | Some MacOS -> font_exists_in_dirs hack_nerd_font mac_font_dirs
+  | None -> false (* do we want this be false or true if we can't tell? *)
 
 let icons =
-  if nerd_font_installed () then
+  if nerd_font_installed then
     {
       closed_char = "\u{ebda}";
       open_char = "\u{ea64}";