1 files changed, 64 insertions, 0 deletions
diff --git a/packages/instant/src/components/time_counter.tsx b/packages/instant/src/components/time_counter.tsx
new file mode 100644
index 000000000..26deb82bd
--- /dev/null
+++ b/packages/instant/src/components/time_counter.tsx
@@ -0,0 +1,64 @@
+import * as React from 'react';
+
+import { timeUtil } from '../util/time';
+
+import { Flex } from './ui/flex';
+import { Text } from './ui/text';
+
+export interface TimeCounterProps {
+    estimatedTimeMs: number;
+    ended: boolean;
+}
+interface TimeCounterState {
+    elapsedSeconds: number;
+}
+
+export class TimeCounter extends React.Component<TimeCounterProps, TimeCounterState> {
+    public state = {
+        elapsedSeconds: 0,
+    };
+    private _timerId?: number;
+
+    public componentDidMount(): void {
+        this._setupTimerBasedOnProps();
+    }
+
+    public componentWillUnmount(): void {
+        this._clearTimer();
+    }
+
+    public componentDidUpdate(prevProps: TimeCounterProps): void {
+        if (prevProps.ended !== this.props.ended) {
+            this._setupTimerBasedOnProps();
+        }
+    }
+
+    public render(): React.ReactNode {
+        const estimatedTimeSeconds = this.props.estimatedTimeMs / 1000;
+        return (
+            <Flex justify="space-between">
+                <Text>Est. Time ({timeUtil.secondsToHumanDescription(estimatedTimeSeconds)})</Text>
+                <Text>Time: {timeUtil.secondsToStopwatchTime(this.state.elapsedSeconds)}</Text>
+            </Flex>
+        );
+    }
+
+    private _setupTimerBasedOnProps(): void {
+        this.props.ended ? this._clearTimer() : this._newTimer();
+    }
+
+    private _newTimer(): void {
+        this._clearTimer();
+        this._timerId = window.setInterval(() => {
+            this.setState({
+                elapsedSeconds: this.state.elapsedSeconds + 1,
+            });
+        }, 1000);
+    }
+
+    private _clearTimer(): void {
+        if (this._timerId) {
+            window.clearInterval(this._timerId);
+        }
+    }
+}