1 files changed, 136 insertions, 0 deletions
diff --git a/packages/instant/src/components/simulated_progress_bar.tsx b/packages/instant/src/components/simulated_progress_bar.tsx
new file mode 100644
index 000000000..3a957aca6
--- /dev/null
+++ b/packages/instant/src/components/simulated_progress_bar.tsx
@@ -0,0 +1,136 @@
+import * as _ from 'lodash';
+import * as React from 'react';
+import { Dispatch } from 'redux';
+
+import { PROGRESS_STALL_AT_PERCENTAGE, PROGRESS_TICK_INTERVAL_MS } from '../constants';
+import { Action, actions } from '../redux/actions';
+
+import { ColorOption } from '../style/theme';
+
+import { Container } from './ui/container';
+import { Flex } from './ui/flex';
+import { Text } from './ui/text';
+
+const TICKS_PER_SECOND = 1000 / PROGRESS_TICK_INTERVAL_MS;
+
+const curTimeUnix = () => {
+    return new Date().getTime();
+};
+
+export interface SimulatedProgressBarProps {
+    startTimeUnix: number;
+    expectedEndTimeUnix: number;
+    ended: boolean;
+}
+enum TickingRunState {
+    None,
+    Running,
+    Finishing,
+}
+interface TickingNoneStatus {
+    runState: TickingRunState.None;
+}
+interface TickingRunningStatus {
+    runState: TickingRunState.Running;
+}
+interface TickingFinishingStatus {
+    runState: TickingRunState.Finishing;
+    increasePercentageEveryTick: number;
+}
+type TickingStatus = TickingNoneStatus | TickingRunningStatus | TickingFinishingStatus;
+
+export interface SimulatedProgressState {
+    percentageDone: number;
+    intervalId?: number;
+    tickingStatus: TickingStatus;
+}
+export class SimulatedProgressBar extends React.Component<SimulatedProgressBarProps, SimulatedProgressState> {
+    public constructor(props: SimulatedProgressBarProps) {
+        super(props);
+
+        // TODO: look into using assert library here?
+        if (props.expectedEndTimeUnix <= props.startTimeUnix) {
+            throw new Error('End time before start time');
+        }
+
+        const intervalId = window.setInterval(this._tick.bind(this), PROGRESS_TICK_INTERVAL_MS);
+        this.state = {
+            percentageDone: 0,
+            intervalId,
+            tickingStatus: { runState: TickingRunState.Running },
+        };
+    }
+
+    public componentDidUpdate(prevProps: SimulatedProgressBarProps, prevState: SimulatedProgressState): void {
+        const percentLeft = 100 - this.state.percentageDone;
+        const increasePercentageEveryTick = percentLeft / TICKS_PER_SECOND;
+
+        if (prevProps.ended === false && this.props.ended === true) {
+            this.setState({
+                tickingStatus: {
+                    runState: TickingRunState.Finishing,
+                    increasePercentageEveryTick,
+                },
+            });
+        }
+    }
+
+    public componentWillUnmount(): void {
+        this._clearTimer();
+    }
+
+    public render(): React.ReactNode {
+        // TODO: Consider moving to seperate component
+        return (
+            <Container padding="20px 20px 0px 20px" width="100%">
+                <Container width="100%" backgroundColor={ColorOption.lightGrey} borderRadius="6px">
+                    <Container
+                        width={`${this.state.percentageDone}%`}
+                        backgroundColor={ColorOption.primaryColor}
+                        borderRadius="6px"
+                        height="6px"
+                    />
+                </Container>
+            </Container>
+        );
+    }
+
+    private _tick(): void {
+        const rawPercentageDone =
+            this.state.tickingStatus.runState === TickingRunState.Finishing
+                ? this._getNewPercentageFinishing(this.state.tickingStatus)
+                : this._getNewPercentageNormal();
+
+        const maxPercentage =
+            this.state.tickingStatus.runState === TickingRunState.Finishing ? 100 : PROGRESS_STALL_AT_PERCENTAGE;
+        const percentageDone = Math.floor(Math.min(rawPercentageDone, maxPercentage));
+
+        this.setState({
+            percentageDone,
+        });
+
+        if (percentageDone >= 100) {
+            this._clearTimer();
+        }
+    }
+
+    private _clearTimer(): void {
+        if (this.state.intervalId) {
+            window.clearTimeout(this.state.intervalId);
+        }
+    }
+
+    // TODO: consider not taking in a parameter here, might be confusing
+    private _getNewPercentageFinishing(tickingStatus: TickingFinishingStatus): number {
+        return this.state.percentageDone + tickingStatus.increasePercentageEveryTick;
+    }
+
+    private _getNewPercentageNormal(): number {
+        const elapsedTimeMs = curTimeUnix() - this.props.startTimeUnix;
+        const safeElapsedTimeMs = Math.max(elapsedTimeMs, 1);
+
+        const expectedAmountOfTimeMs = this.props.expectedEndTimeUnix - this.props.startTimeUnix;
+        const percentageDone = safeElapsedTimeMs / expectedAmountOfTimeMs * 100;
+        return percentageDone;
+    }
+}