chore: rewrite on state machine, add tests

Author: r0b1n

packages/pluggableWidgets/events-web/src/helpers/TimerExecutor.ts

@@ -0,0 +1,99 @@
+type TimerState = "initial" | "idle" | "scheduled" | "pending" | "invoking" | "executing" | "completed";
+
+export class TimerExecutor {
+    private state: TimerState = "initial";
+    private intervalHandle: ReturnType<typeof setTimeout> | undefined;
+    private canExecute: boolean = false;
+
+    private delay?: number;
+    private interval?: number;
+    private repeat?: boolean;
+
+    private callback?: () => void;
+
+    setCallback(callback: () => void, newCanExecute: boolean): void {
+        this.callback = callback;
+        const prevCanExecute = this.canExecute;
+        this.canExecute = newCanExecute;
+
+        if (this.state === "invoking") {
+            if (prevCanExecute && !newCanExecute) {
+                // Action just started executing (canExecute went from true to false)
+                this.onExecutionStart();
+                return;
+            }
+        }
+
+        if (this.state === "executing") {
+            if (!prevCanExecute && newCanExecute) {
+                // Action completed successfully (canExecute went from false to true)
+                this.onExecutionFinish();
+                return;
+            }
+        }
+
+        this.tryExecute();
+    }
+
+    setParams(delay: number | undefined, interval: number | undefined, repeat: boolean): void {
+        this.delay = delay;
+        this.interval = interval;
+        this.repeat = repeat;
+
+        if (this.state === "initial") {
+            this.scheduleNext();
+        }
+    }
+
+    get isReady(): boolean {
+        return this.delay !== undefined && (!this.repeat || this.interval !== undefined);
+    }
+
+    stop(): void {
+        clearTimeout(this.intervalHandle);
+        this.intervalHandle = undefined;
+        this.delay = undefined;
+        this.interval = undefined;
+        this.repeat = false;
+        this.state = "initial";
+    }
+
+    private scheduleNext(): void {
+        if (!this.isReady || this.state === "executing" || this.state === "completed") {
+            return;
+        }
+
+        const isFirstTime = this.state === "initial";
+        const timeout = isFirstTime ? this.delay : this.interval;
+
+        this.state = "scheduled";
+        this.intervalHandle = setTimeout(() => {
+            this.onTimerFired();
+        }, timeout);
+    }
+
+    private onTimerFired(): void {
+        this.state = "pending";
+        this.tryExecute();
+    }
+
+    private tryExecute(): void {
+        if (this.state === "pending" && this.canExecute && this.callback) {
+            this.state = "invoking";
+            this.callback();
+        }
+    }
+
+    private onExecutionStart(): void {
+        this.state = "executing";
+    }
+
+    private onExecutionFinish(): void {
+        if (this.repeat) {
+            this.state = "idle";
+            this.scheduleNext();
+        } else {
+            this.state = "completed";
+        }
+    }
+}