From df8692ed4d70efe7218a66310cb1fd0dcb5692f8 Mon Sep 17 00:00:00 2001
From: Alexander Heldt <me@alexanderheldt.se>
Date: Sun, 9 Nov 2025 21:29:59 +0100
Subject: [PATCH] Add `ipc` module

---
 src/ipc.gleam   | 62 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/ipc_ffi.erl |  8 +++++++
 2 files changed, 70 insertions(+)
 create mode 100644 src/ipc.gleam
 create mode 100644 src/ipc_ffi.erl

diff --git a/src/ipc.gleam b/src/ipc.gleam
new file mode 100644
index 0000000..07e099b
--- /dev/null
+++ b/src/ipc.gleam
@@ -0,0 +1,62 @@
+import gleam/bytes_tree
+
+pub type Socket
+
+// https://www.erlang.org/doc/apps/kernel/inet#t:address_family/0
+// local socket
+type Local {
+  Local(socket_path: String)
+}
+
+type ModeValue {
+  Binary
+}
+
+type IPCOption {
+  Active(Bool)
+  Mode(ModeValue)
+}
+
+pub type IPCError {
+  IPCError(reason: String)
+}
+
+pub fn connect(socket_path: String) -> Result(Socket, IPCError) {
+  let options = [Mode(Binary), Active(False)]
+
+  // timeout in ms
+  let timeout = 1000
+
+  case gen_tcp_connect(Local(socket_path), 0, options, timeout) {
+    Error(err) -> Error(err)
+    Ok(socket) -> Ok(socket)
+  }
+}
+
+pub fn send(socket: Socket, message: String) -> Result(Nil, IPCError) {
+  gen_tcp_send(socket, bytes_tree.from_string(message))
+}
+
+pub fn close(socket: Socket) -> Nil {
+  gen_tcp_close(socket)
+}
+
+// https://www.erlang.org/doc/apps/kernel/gen_tcp.html#connect/4
+@external(erlang, "gen_tcp", "connect")
+fn gen_tcp_connect(
+  address: Local,
+  port: Int,
+  options: List(IPCOption),
+  timeout: Int,
+) -> Result(Socket, IPCError)
+
+// https://www.erlang.org/doc/apps/kernel/gen_tcp.html#send/2
+@external(erlang, "ipc_ffi", "send")
+fn gen_tcp_send(
+  socket: Socket,
+  packet: bytes_tree.BytesTree,
+) -> Result(Nil, IPCError)
+
+// https://www.erlang.org/doc/apps/kernel/gen_tcp.html#close/1
+@external(erlang, "gen_tcp", "close")
+fn gen_tcp_close(socket: Socket) -> Nil
diff --git a/src/ipc_ffi.erl b/src/ipc_ffi.erl
new file mode 100644
index 0000000..6c303c2
--- /dev/null
+++ b/src/ipc_ffi.erl
@@ -0,0 +1,8 @@
+-module(ipc_ffi).
+-export([send/2]).
+
+send(Socket, Packet) ->
+  case gen_tcp:send(Socket, Packet) of
+    ok -> {ok, nil};
+    Res -> Res
+  end.
\ No newline at end of file