1 files changed, 74 insertions, 0 deletions
diff --git a/src/client-component.ffi.mjs b/src/client-component.ffi.mjs
new file mode 100644
index 0000000..0970e7f
--- /dev/null
+++ b/src/client-component.ffi.mjs
@@ -0,0 +1,74 @@
+import { Ok, Error, isEqual } from "./gleam.mjs";
+import { Dispatch, Shutdown } from "./lustre/runtime.mjs";
+import {
+  ComponentAlreadyRegistered,
+  BadComponentName,
+  NotABrowser,
+} from "./lustre.mjs";
+import { LustreClientApplication, is_browser } from "./client-runtime.ffi.mjs";
+
+export function register({ init, update, view, on_attribute_change }, name) {
+  if (!is_browser()) return new Error(new NotABrowser());
+  if (!name.includes("-")) return new Error(new BadComponentName(name));
+  if (window.customElements.get(name)) {
+    return new Error(new ComponentAlreadyRegistered(name));
+  }
+
+  window.customElements.define(
+    name,
+    class LustreClientComponent extends HTMLElement {
+      #root = document.createElement("div");
+      #application = null;
+
+      static get observedAttributes() {
+        return on_attribute_change.entries().map(([name, _]) => name);
+      }
+
+      constructor() {
+        super();
+        on_attribute_change.forEach((decoder, name) => {
+          Object.defineProperty(this, name, {
+            get() {
+              return this[`_${name}`] || this.getAttribute(name);
+            },
+
+            set(value) {
+              const prev = this[name];
+              const decoded = decoder(value);
+
+              if (decoded.isOk() && !isEqual(prev, value)) {
+                this.#application
+                  ? this.#application.send(new Dispatch(decoded[0]))
+                  : window.requestAnimationFrame(() =>
+                      this.#application.send(new Dispatch(decoded[0]))
+                    );
+              }
+
+              if (typeof value === "string") {
+                this.setAttribute(name, value);
+              } else {
+                this[`_${name}`] = value;
+              }
+            },
+          });
+        });
+      }
+
+      connectedCallback() {
+        this.#application = new LustreClientApplication(
+          init(),
+          update,
+          view,
+          this.#root
+        );
+        this.appendChild(this.#root);
+      }
+
+      disconnectedCallback() {
+        this.#application.send(new Shutdown());
+      }
+    }
+  );
+
+  return new Ok(null);
+}