add content-type header

src/util.ml

@@ -1,29 +1,36 @@
 (* TODO Taler documentation
    markdown mimetype should be the prefered one, and be supported, according to DD
    we take text/plain as default instead for now *)
+let default_mimetype = ("text", "plain")
 let default_extension = "txt"
 
-let is_valid_filename, media_to_extension =
-  let mimetype_ext_assoc =
-    [
-      (("text", "plain"), "txt"); (("text", "markdown"), "md")
-    ; (("text", "html"), "html"); (("text", "html"), "htm")
-    ; (("application", "pdf"), "pdf"); (("image", "jpeg"), "jpg")
-    ; (("image", "jpeg"), "jpeg"); (("image", "png"), "png")
-    ; (("image", "gif"), "gif")
-    ]
-  in
-  (* <> than the actual set of "supported" extension (which depends on config files) *)
-  let all_known_extensions = mimetype_ext_assoc |> List.split |> snd in
-  let is_valid_filename path = Fpath.mem_ext all_known_extensions path in
-  let media_to_extension = function
-    | Cohttp.Accept.MediaType (m, m_sub) ->
-        List.assoc_opt (m, m_sub) mimetype_ext_assoc
-    | AnyMediaSubtype m ->
-        List.find_map
-          (fun ((m', _), ext) ->
-            match String.equal m m' with false -> None | true -> Some ext)
-          mimetype_ext_assoc
-    | AnyMedia -> Some default_extension
-  in
-  (is_valid_filename, media_to_extension)
+let mimetype_ext_assoc =
+  [
+    (("text", "plain"), "txt"); (("text", "markdown"), "md")
+  ; (("text", "html"), "html"); (("text", "html"), "htm")
+  ; (("application", "pdf"), "pdf"); (("image", "jpeg"), "jpg")
+  ; (("image", "jpeg"), "jpeg"); (("image", "png"), "png")
+  ; (("image", "gif"), "gif")
+  ]
+
+(* <> than the actual set of "supported" extension (which depends on config files) *)
+let all_known_mimetypes, all_known_extensions = List.split mimetype_ext_assoc
+let is_valid_filename path = Fpath.mem_ext all_known_extensions path
+
+let media_to_known_mimetype = function
+  | Cohttp.Accept.MediaType (m, m_sub) ->
+      List.find_opt (( = ) (m, m_sub)) all_known_mimetypes
+  | AnyMediaSubtype m ->
+      List.find_opt (fun (m', _) -> String.equal m m') all_known_mimetypes
+  | AnyMedia -> Some default_mimetype
+
+let mimetype_to_extension (m, m_sub) =
+  assert (m <> "*");
+  assert (m_sub <> "*");
+  List.assoc_opt (m, m_sub) mimetype_ext_assoc
+
+let extension_to_mimetype ext =
+  List.find_map
+    (fun (mime, ext') ->
+      match String.equal ext ext' with false -> None | true -> Some mime)
+    mimetype_ext_assoc