2 files changed, 124 insertions, 0 deletions
diff --git a/compat/lustre_websocket/src/ffi.mjs b/compat/lustre_websocket/src/ffi.mjs
new file mode 100644
index 0000000..56f11fd
--- /dev/null
+++ b/compat/lustre_websocket/src/ffi.mjs
@@ -0,0 +1,39 @@
+let ws_handler_registry = {}
+
+export const init_websocket = path => {
+    let ws
+    if (typeof WebSocket === "function") {
+        // we're in the browser
+        let url = new URL(document.URL)
+        let protocol = url.protocol === "http:" ? "ws" : "wss"
+        let ws_url = protocol + "://" + url.host + url.pathname + path
+        ws = new WebSocket(ws_url)
+    } else {
+        // we're NOT in the browser, prolly running tests
+        ws = {}
+    }
+    ws_handler_registry[ws.url] = { ws: ws }
+
+    ws.onopen = evt => {
+        ws_handler_registry[ws.url]?.on_open?.()
+    }
+    ws.onclose = evt => {
+        ws_handler_registry[ws.url]?.on_close?.(evt.code)
+        delete ws_handler_registry[ws.url]
+    }
+    ws.onmessage = event => ws_handler_registry[ws.url]?.on_message?.(event.data)
+    ws.onerror = error => console.log("ws", ws.url, "error", error, "no handler, since I have no clue what errors we might be talking about")
+    return ws
+}
+
+export const register_websocket_handler = (ws, on_open, on_message, on_close) => {
+    const reg_entry = ws_handler_registry[ws.url]
+    reg_entry.on_open = on_open
+    reg_entry.on_message = on_message
+    reg_entry.on_close = on_close
+    console.log("ws reg", ws_handler_registry)
+}
+
+export const send_over_websocket = (ws, msg) => {
+    ws.send(msg)
+}
diff --git a/compat/lustre_websocket/src/lustre_websocket.gleam b/compat/lustre_websocket/src/lustre_websocket.gleam
new file mode 100644
index 0000000..ce46a4a
--- /dev/null
+++ b/compat/lustre_websocket/src/lustre_websocket.gleam
@@ -0,0 +1,85 @@
+import lustre/effect.{Effect}
+
+pub type WebSocket
+
+pub type WebSocketCloseReason {
+  // 1000
+  Normal
+  // 1001
+  GoingAway
+  // 1002
+  ProtocolError
+  // 1003
+  UnexpectedTypeOfData
+  // 1004 Reserved
+  // 1005
+  NoCodeFromServer
+  // 1006, no close frame
+  AbnormalClose
+  // 1007
+  IncomprehensibleFrame
+  // 1008
+  PolicyViolated
+  // 1009
+  MessageTooBig
+  // 1010
+  FailedExtensionNegotation
+  // 1011
+  UnexpectedFailure
+  // 1015
+  FailedTLSHandshake
+}
+
+pub type WebSocketEvent {
+  OnOpen(WebSocket)
+  OnMessage(String)
+  OnClose(WebSocketCloseReason)
+}
+
+/// Initialize a websocket. These constructs are fully asynchronous, so you must provide a wrapper
+/// that takes a `WebSocketEvent` and turns it into a lustre message of your application.
+pub fn init(path: String, wrapper: fn(WebSocketEvent) -> a) -> Effect(a) {
+  let ws = do_init(path)
+  use dispatch <- effect.from
+  let on_open = fn() { dispatch(wrapper(OnOpen(ws))) }
+  let on_message = fn(in_msg) { dispatch(wrapper(OnMessage(in_msg))) }
+  let on_close = fn(code) {
+    case code {
+      1000 -> dispatch(wrapper(OnClose(Normal)))
+      1001 -> dispatch(wrapper(OnClose(GoingAway)))
+      1002 -> dispatch(wrapper(OnClose(ProtocolError)))
+      1003 -> dispatch(wrapper(OnClose(UnexpectedTypeOfData)))
+      1005 -> dispatch(wrapper(OnClose(NoCodeFromServer)))
+      1006 -> dispatch(wrapper(OnClose(AbnormalClose)))
+      1007 -> dispatch(wrapper(OnClose(IncomprehensibleFrame)))
+      1008 -> dispatch(wrapper(OnClose(PolicyViolated)))
+      1009 -> dispatch(wrapper(OnClose(MessageTooBig)))
+      1010 -> dispatch(wrapper(OnClose(FailedExtensionNegotation)))
+      1011 -> dispatch(wrapper(OnClose(UnexpectedFailure)))
+      1015 -> dispatch(wrapper(OnClose(FailedTLSHandshake)))
+    }
+  }
+
+  do_register(ws, on_open, on_message, on_close)
+}
+
+external fn do_init(path) -> WebSocket =
+  "./ffi.mjs" "init_websocket"
+
+external fn do_register(
+  ws: WebSocket,
+  on_open: fn() -> Nil,
+  on_message: fn(String) -> Nil,
+  on_close: fn(Int) -> Nil,
+) -> Nil =
+  "./ffi.mjs" "register_websocket_handler"
+
+/// Send a text message over the web socket. This is asynchronous. There is no
+/// expectation of a reply. See `init`. Only works on an Non-Closed socket.
+/// Returns a `Effect(a)` that you must pass as second entry in the lustre `update` return.
+pub fn send(ws: WebSocket, msg: String) -> Effect(a) {
+  effect.from(fn(_) { do_send(ws, msg) })
+}
+
+external fn do_send(ws: WebSocket, msg: String) -> Nil =
+  "./ffi.mjs" "send_over_websocket"