From 7b8edd05e9305710d1071e5fca11ea5af24ba109 Mon Sep 17 00:00:00 2001
From: swrup <swrup@protonmail.com>
Date: Mon, 22 Dec 2025 19:20:32 +0100
Subject: [PATCH] use jsont for alt_unit_names

---
 src/config.ml       |  3 ++-
 src/http_keys.ml    |  2 +-
 src/parse_config.ml | 66 ++++++++++++++++++---------------------------
 3 files changed, 29 insertions(+), 42 deletions(-)

diff --git a/src/config.ml b/src/config.ml
index 2228421c..7c62ffb2 100644
--- a/src/config.ml
+++ b/src/config.ml
@@ -104,7 +104,8 @@ module Currency = struct
       fractional_normal_digits= get "fractional_normal_digits" |> int;
       fractional_trailing_zero_digits=
         get "fractional_trailing_zero_digits" |> int;
-      alt_unit_names= get "alt_unit_names" |> Alt_unit_names.parse;
+      alt_unit_names=
+        get "alt_unit_names" |> Alt_unit_names.decode |> Parse_config.unwrap_res;
     }
 
   let all_currencies = List.map parse_currency currency_sections
diff --git a/src/http_keys.ml b/src/http_keys.ml
index 48ae48ce..481c1f57 100644
--- a/src/http_keys.ml
+++ b/src/http_keys.ml
@@ -14,7 +14,7 @@ let mk_keys ~db_conn ~sm ~last_issue_date =
   let currency_specification =
     let v = Config.Currency.v in
     let alt_unit_names =
-      Parse_config.Alt_unit_names.to_json_string v.alt_unit_names
+      Parse_config.Alt_unit_names.encode_exn v.alt_unit_names
     in
     CurrencySpecification.
       {
diff --git a/src/parse_config.ml b/src/parse_config.ml
index 0f53e4d3..f40f1885 100644
--- a/src/parse_config.ml
+++ b/src/parse_config.ml
@@ -228,49 +228,35 @@ let ed25519 s =
   |> Result.map_error (fun e -> Fmt.str "%a" Mirage_crypto_ec.pp_error e)
   |> unwrap_res
 
-(* TODO alt_unit_names jsont *)
+(* TODO
+   move to another module
+   can we type the json as a Int_map directly? *)
 module Alt_unit_names = struct
-  let rm_brackets s =
-    let s = String.trim s in
-    match
-      String.starts_with ~prefix:"{" s && String.ends_with ~suffix:"}" s
-    with
-    | false -> fail "expected json, got `%s`" s
-    | true ->
-        let s = String.sub s 1 (String.length s - 2) in
-        s
+  open Syntax
+  module String_map = Map.Make (String)
 
-  let rm_quotes s =
-    let s = String.trim s in
-    match
-      String.starts_with ~prefix:"\"" s && String.ends_with ~suffix:"\"" s
-    with
-    | false -> fail "expected quoted string, got `%s`" s
-    | true ->
-        let s = String.sub s 1 (String.length s - 2) in
-        s
+  let string_map_jsont = Jsont.Object.as_string_map Jsont.string
 
-  let parse s =
-    let s = rm_brackets s in
-    String.split_on_char ',' s
-    |> List.map (String.split_on_char ':')
-    |> List.map (function
-      | [ k; v ] -> (k, v)
-      | _ -> fail "invalid json key-value map")
-    |> List.map (fun (k, v) ->
-        let k = rm_quotes k in
-        let v = rm_quotes v in
-        let k =
+  let decode s =
+    let* string_map = Jsont_bytesrw.decode_string string_map_jsont s in
+    let l = String_map.to_list string_map in
+    let* l =
+      list_map
+        (fun (k, v) ->
           match int_of_string_opt k with
-          | None ->
-              fail "invalid json key-value map, expected integer key, got `%s`"
-                k
-          | Some k -> k
-        in
-        (k, v))
+          | None -> Error "alt_unit_names has a non-integer key"
+          | Some k -> Ok (k, v))
+        l
+    in
+    match List.find_opt (fun (i, _) -> i = 0) l with
+    | None -> Error "alt_unit_names with no entry for base value \"0\""
+    | Some _ -> Ok l
 
-  let to_json_string l =
-    let l = List.map (fun (i, s) -> Fmt.str {|"%d": "%s"|} i s) l in
-    let s = String.concat "," l in
-    "{" ^ s ^ "}"
+  let encode l =
+    let l = List.map (fun (k, v) -> (string_of_int k, v)) l in
+    let string_map = String_map.of_list l in
+    let+ s = Jsont_bytesrw.encode_string string_map_jsont string_map in
+    s
+
+  let encode_exn l = encode l |> Result.get_ok
 end