Add JSON serialization to Firehose library, simplify demo

examples/firehose_demo/firehose_demo.ml

···
   | Firehose.Info m -> Printf.sprintf "#info name=%s" m.name
   | Firehose.StreamError err -> Printf.sprintf "#error %s" err
 
-let json_of_op blocks (op : Firehose.operation) =
-  let action =
-    match op.action with
-    | `Create -> "create"
-    | `Update -> "update"
-    | `Delete -> "delete"
+let json_of_op_with_record blocks (op : Firehose.operation) =
+  let base_json = Firehose.operation_to_json op in
+  match find_block blocks op with
+  | Some cbor ->
+      let record_json = Yojson.Safe.from_string (Dag_json.encode_string cbor) in
+      Firehose.add_record_to_op_json base_json record_json
+  | None -> base_json
+
+let json_of_event ?(rich = false) event =
+  let json =
+    match event with
+    | Firehose.Commit evt when rich -> (
+        let blocks = extract_blocks evt.blocks in
+        let ops = `List (List.map (json_of_op_with_record blocks) evt.ops) in
+        let base = Firehose.commit_event_to_json evt in
+        (* Replace the ops field with our enriched version *)
+        match base with
+        | `Assoc fields ->
+            `Assoc
+              (List.map
+                 (fun (k, v) -> if k = "ops" then (k, ops) else (k, v))
+                 fields)
+        | _ -> base)
+    | _ -> Firehose.event_to_json event
   in
-  let cid_json =
-    match op.cid with
-    | Some c -> ",\"cid\":\"" ^ Cid.to_string c ^ "\""
-    | None -> ""
-  in
-  let record_json =
-    match find_block blocks op with
-    | Some cbor -> ",\"record\":" ^ Dag_json.encode_string cbor
-    | None -> ""
-  in
-  Printf.sprintf "{\"action\":\"%s\",\"path\":\"%s\"%s%s}" action op.path
-    cid_json record_json
-
-let json_of_event ?(rich = false) = function
-  | Firehose.Commit evt ->
-      let blocks = if rich then extract_blocks evt.blocks else [] in
-      let ops = String.concat "," (List.map (json_of_op blocks) evt.ops) in
-      Printf.sprintf
-        "{\"type\":\"commit\",\"seq\":%Ld,\"repo\":\"%s\",\"ops\":[%s]}" evt.seq
-        evt.repo ops
-  | Firehose.Identity e ->
-      Printf.sprintf "{\"type\":\"identity\",\"seq\":%Ld,\"did\":\"%s\"}" e.seq
-        e.did
-  | Firehose.Account e ->
-      Printf.sprintf
-        "{\"type\":\"account\",\"seq\":%Ld,\"did\":\"%s\",\"active\":%b}" e.seq
-        e.did e.active
-  | Firehose.Handle e ->
-      Printf.sprintf
-        "{\"type\":\"handle\",\"seq\":%Ld,\"did\":\"%s\",\"handle\":\"%s\"}"
-        e.seq e.did e.handle
-  | Firehose.Tombstone e ->
-      Printf.sprintf "{\"type\":\"tombstone\",\"seq\":%Ld,\"did\":\"%s\"}" e.seq
-        e.did
-  | Firehose.Info m ->
-      Printf.sprintf "{\"type\":\"info\",\"name\":\"%s\"}" m.name
-  | Firehose.StreamError err ->
-      Printf.sprintf "{\"type\":\"error\",\"message\":\"%s\"}" err
+  Yojson.Safe.to_string json
 
 type filter =
   | Posts

lib/sync/firehose.ml

···
   | Tombstone e -> Some e.did
   | Info _ -> None
   | StreamError _ -> None
+
+(** {1 JSON Serialization} *)
+
+(** Convert an operation to JSON. Does not include record content - use
+    [add_record_to_op_json] to add it. *)
+let operation_to_json (op : operation) : Yojson.Safe.t =
+  let action =
+    match op.action with
+    | `Create -> "create"
+    | `Update -> "update"
+    | `Delete -> "delete"
+  in
+  let base = [ ("action", `String action); ("path", `String op.path) ] in
+  let with_cid =
+    match op.cid with
+    | Some c -> base @ [ ("cid", `String (Cid.to_string c)) ]
+    | None -> base
+  in
+  `Assoc with_cid
+
+(** Add a record field to an operation JSON object *)
+let add_record_to_op_json (op_json : Yojson.Safe.t) (record : Yojson.Safe.t) :
+    Yojson.Safe.t =
+  match op_json with
+  | `Assoc fields -> `Assoc (fields @ [ ("record", record) ])
+  | _ -> op_json
+
+(** Convert a commit event to JSON. Operations don't include record content. *)
+let commit_event_to_json (evt : commit_event) : Yojson.Safe.t =
+  let ops = `List (List.map operation_to_json evt.ops) in
+  `Assoc
+    [
+      ("type", `String "commit");
+      ("seq", `Intlit (Int64.to_string evt.seq));
+      ("repo", `String evt.repo);
+      ("rev", `String evt.rev);
+      ("commit", `String (Cid.to_string evt.commit));
+      ("ops", ops);
+    ]
+
+(** Convert an identity event to JSON *)
+let identity_event_to_json (e : identity_event) : Yojson.Safe.t =
+  let base =
+    [
+      ("type", `String "identity");
+      ("seq", `Intlit (Int64.to_string e.seq));
+      ("did", `String e.did);
+      ("time", `String e.time);
+    ]
+  in
+  let with_handle =
+    match e.handle with
+    | Some h -> base @ [ ("handle", `String h) ]
+    | None -> base
+  in
+  `Assoc with_handle
+
+(** Convert an account event to JSON *)
+let account_event_to_json (e : account_event) : Yojson.Safe.t =
+  let base =
+    [
+      ("type", `String "account");
+      ("seq", `Intlit (Int64.to_string e.seq));
+      ("did", `String e.did);
+      ("time", `String e.time);
+      ("active", `Bool e.active);
+    ]
+  in
+  let with_status =
+    match e.status with
+    | Some s -> base @ [ ("status", `String s) ]
+    | None -> base
+  in
+  `Assoc with_status
+
+(** Convert a handle event to JSON *)
+let handle_event_to_json (e : handle_event) : Yojson.Safe.t =
+  `Assoc
+    [
+      ("type", `String "handle");
+      ("seq", `Intlit (Int64.to_string e.seq));
+      ("did", `String e.did);
+      ("time", `String e.time);
+      ("handle", `String e.handle);
+    ]
+
+(** Convert a tombstone event to JSON *)
+let tombstone_event_to_json (e : tombstone_event) : Yojson.Safe.t =
+  `Assoc
+    [
+      ("type", `String "tombstone");
+      ("seq", `Intlit (Int64.to_string e.seq));
+      ("did", `String e.did);
+      ("time", `String e.time);
+    ]
+
+(** Convert an info message to JSON *)
+let info_message_to_json (m : info_message) : Yojson.Safe.t =
+  let base = [ ("type", `String "info"); ("name", `String m.name) ] in
+  let with_msg =
+    match m.message with
+    | Some msg -> base @ [ ("message", `String msg) ]
+    | None -> base
+  in
+  `Assoc with_msg
+
+(** Convert any event to JSON. For commit events, operations don't include
+    record content - extract blocks separately and use [add_record_to_op_json].
+*)
+let event_to_json = function
+  | Commit evt -> commit_event_to_json evt
+  | Identity e -> identity_event_to_json e
+  | Account e -> account_event_to_json e
+  | Handle e -> handle_event_to_json e
+  | Tombstone e -> tombstone_event_to_json e
+  | Info m -> info_message_to_json m
+  | StreamError msg ->
+      `Assoc [ ("type", `String "error"); ("message", `String msg) ]
+
+(** Convert an event to a JSON string *)
+let event_to_json_string evt = Yojson.Safe.to_string (event_to_json evt)