1 files changed, 143 insertions, 0 deletions
diff --git a/src/server-runtime.ffi.mjs b/src/server-runtime.ffi.mjs
new file mode 100644
index 0000000..e82e82d
--- /dev/null
+++ b/src/server-runtime.ffi.mjs
@@ -0,0 +1,143 @@
+import { Ok, isEqual } from "./gleam.mjs";
+import {
+  AddRenderer,
+  Dispatch,
+  Event,
+  RemoveRenderer,
+  Shutdown,
+} from "./lustre/runtime.mjs";
+
+export class LustreServerApplication {
+  #queue = [];
+  #effects = [];
+  #didUpdate = false;
+
+  #vdom = null;
+  #handlers = new Map();
+  #renderers = new Set();
+
+  #model = null;
+  #update = null;
+  #view = null;
+
+  static start(flags, init, update, view) {
+    const app = new LustreServerApplication(init(flags), update, view, root);
+
+    return new Ok((msg) => app.send(msg));
+  }
+
+  // PUBLIC METHODS ------------------------------------------------------------
+
+  constructor([model, effects], update, view) {
+    this.#model = model;
+    this.#update = update;
+    this.#view = view;
+    this.#vdom = this.#view(this.#model);
+    this.#effects = effects.all.toArray();
+    this.#didUpdate = true;
+
+    globalThis.queueMicrotask(() => this.#tick());
+  }
+
+  send(action) {
+    switch (true) {
+      case action instanceof AddRenderer: {
+        this.#renderers.add(action[0]);
+        return;
+      }
+
+      case action instanceof Dispatch: {
+        this.#queue.push(action[0]);
+        this.#tick();
+
+        return;
+      }
+
+      case action instanceof Event: {
+        const [event, data] = action;
+
+        if (this.#handlers.has(event)) {
+          const msg = this.#handlers.get(event)(data);
+
+          if (msg.isOk()) {
+            this.#queue.push(msg[0]);
+            this.#tick();
+          }
+        }
+      }
+
+      case action instanceof RemoveRenderer: {
+        this.#renderers.delete(action[0]);
+        return;
+      }
+
+      case action instanceof Shutdown: {
+        this.#shutdown();
+        return;
+      }
+
+      default:
+        return;
+    }
+  }
+
+  // PRIVATE METHODS -----------------------------------------------------------
+
+  #tick() {
+    this.#flush_queue();
+
+    if (this.#didUpdate) {
+      this.#vdom = this.#view(this.#model);
+
+      for (const renderer of this.#renderers) {
+        renderer.render(this.#vdom);
+      }
+    }
+  }
+
+  #flush_queue(iterations = 0) {
+    while (this.#queue.length) {
+      const [next, effects] = this.#update(this.#model, this.#queue.shift());
+
+      this.#model = next;
+      this.#didUpdate ||= !isEqual(this.#model, next);
+      this.#effects = this.#effects.concat(effects.all.toArray());
+    }
+
+    while (this.#effects.length) {
+      this.#effects.shift()(
+        (msg) => this.send(new Dispatch(msg)),
+        (event, data) => this.emit(event, data)
+      );
+    }
+
+    if (this.#queue.length) {
+      if (iterations < 5) {
+        this.#flush_queue(++iterations);
+      } else {
+        window.requestAnimationFrame(() => this.#tick());
+      }
+    }
+  }
+
+  #shutdown() {
+    this.#model = null;
+    this.#queue = [];
+    this.#effects = [];
+    this.#didUpdate = false;
+    this.#update = () => {};
+    this.#view = () => {};
+    this.#vdom = null;
+    this.#handlers = new Map();
+    this.#renderers = new Set();
+  }
+}
+
+export const start = (app, selector, flags) =>
+  LustreClientApplication.start(
+    flags,
+    selector,
+    app.init,
+    app.update,
+    app.view
+  );