feat(turbo): add turbo-poll controller

app/javascript/controllers/index.ts

@@ -1,18 +1,20 @@
 import { Application } from '@hotwired/stimulus';
 
-import { ReactController } from './react_controller';
-import { TurboEventController } from './turbo_event_controller';
-import { GeoAreaController } from './geo_area_controller';
-import { TurboInputController } from './turbo_input_controller';
 import { AutosaveController } from './autosave_controller';
 import { AutosaveStatusController } from './autosave_status_controller';
+import { GeoAreaController } from './geo_area_controller';
 import { MenuButtonController } from './menu_button_controller';
+import { ReactController } from './react_controller';
+import { TurboEventController } from './turbo_event_controller';
+import { TurboInputController } from './turbo_input_controller';
+import { TurboPollController } from './turbo_poll_controller';
 
 const Stimulus = Application.start();
+Stimulus.register('autosave-status', AutosaveStatusController);
+Stimulus.register('autosave', AutosaveController);
+Stimulus.register('geo-area', GeoAreaController);
+Stimulus.register('menu-button', MenuButtonController);
 Stimulus.register('react', ReactController);
 Stimulus.register('turbo-event', TurboEventController);
-Stimulus.register('geo-area', GeoAreaController);
 Stimulus.register('turbo-input', TurboInputController);
-Stimulus.register('autosave', AutosaveController);
+Stimulus.register('turbo-poll', TurboPollController);
-Stimulus.register('autosave-status', AutosaveStatusController);
-Stimulus.register('menu-button', MenuButtonController);

app/javascript/controllers/turbo_poll_controller.ts

@@ -0,0 +1,94 @@
+import { httpRequest } from '@utils';
+
+import { ApplicationController } from './application_controller';
+
+const DEFAULT_POLL_INTERVAL = 3000;
+const DEFAULT_MAX_CHECKS = 5;
+
+// Periodically check the state of a URL.
+//
+// Each time the given URL is requested, a turbo-stream is rendered, causing the state to be refreshed.
+//
+// This is used mainly to refresh attachments during the anti-virus check,
+// but also to refresh the state of a pending spreadsheet export.
+export class TurboPollController extends ApplicationController {
+  static values = {
+    url: String,
+    maxChecks: { type: Number, default: DEFAULT_MAX_CHECKS },
+    interval: { type: Number, default: DEFAULT_POLL_INTERVAL }
+  };
+
+  declare readonly urlValue: string;
+  declare readonly intervalValue: number;
+  declare readonly maxChecksValue: number;
+
+  #timer?: number;
+  #abortController?: AbortController;
+
+  connect(): void {
+    const state = this.nextState();
+    if (state) {
+      this.schedule(state);
+    }
+  }
+
+  disconnect(): void {
+    this.cancel();
+  }
+
+  refresh() {
+    this.cancel();
+    this.#abortController = new AbortController();
+
+    httpRequest(this.urlValue, { signal: this.#abortController.signal })
+      .turbo()
+      .catch(() => null);
+  }
+
+  private schedule(state: PollState): void {
+    this.cancel();
+    this.#timer = setTimeout(() => {
+      this.refresh();
+    }, state.interval);
+  }
+
+  private cancel(): void {
+    clearTimeout(this.#timer);
+    this.#abortController?.abort();
+    this.#abortController = window.AbortController
+      ? new AbortController()
+      : undefined;
+  }
+
+  private nextState(): PollState | false {
+    const state = pollers.get(this.urlValue);
+    if (!state) {
+      return this.resetState();
+    }
+    state.interval *= 1.5;
+    state.checks += 1;
+    if (state.checks <= this.maxChecksValue) {
+      return state;
+    } else {
+      this.resetState();
+      return false;
+    }
+  }
+
+  private resetState(): PollState {
+    const state = {
+      interval: this.intervalValue,
+      checks: 0
+    };
+    pollers.set(this.urlValue, state);
+    return state;
+  }
+}
+
+type PollState = {
+  interval: number;
+  checks: number;
+};
+
+// We keep a global state of the pollers. It will be reset on every page change.
+const pollers = new Map<string, PollState>();