/*
 * Copyright (c) Microsoft Corporation. All rights reserved.
 * Licensed under the MIT License.
 */

import {
    Constants,
    InProgressPerformanceEvent,
    IPerformanceClient,
    Logger,
    PerformanceClient,
    PerformanceEvent,
    PerformanceEvents,
    PreQueueEvent,
    SubMeasurement,
} from "@azure/msal-common";
import { Configuration } from "../config/Configuration";
import { name, version } from "../packageMetadata";
import {
    BROWSER_PERF_ENABLED_KEY,
    BrowserCacheLocation,
} from "../utils/BrowserConstants";

/**
 * Returns browser performance measurement module if session flag is enabled. Returns undefined otherwise.
 */
function getPerfMeasurementModule() {
    let sessionStorage: Storage | undefined;
    try {
        sessionStorage = window[BrowserCacheLocation.SessionStorage];
        const perfEnabled = sessionStorage?.getItem(BROWSER_PERF_ENABLED_KEY);
        if (Number(perfEnabled) === 1) {
            return import("./BrowserPerformanceMeasurement");
        }
        // Mute errors if it's a non-browser environment or cookies are blocked.
    } catch (e) {}

    return undefined;
}

/**
 * Returns boolean, indicating whether browser supports window.performance.now() function.
 */
function supportsBrowserPerformanceNow(): boolean {
    return (
        typeof window !== "undefined" &&
        typeof window.performance !== "undefined" &&
        typeof window.performance.now === "function"
    );
}

/**
 * Returns event duration in milliseconds using window performance API if available. Returns undefined otherwise.
 * @param startTime {DOMHighResTimeStamp | undefined}
 * @returns {number | undefined}
 */
function getPerfDurationMs(
    startTime: DOMHighResTimeStamp | undefined
): number | undefined {
    if (!startTime || !supportsBrowserPerformanceNow()) {
        return undefined;
    }

    return Math.round(window.performance.now() - startTime);
}

export class BrowserPerformanceClient
    extends PerformanceClient
    implements IPerformanceClient
{
    constructor(configuration: Configuration, intFields?: Set<string>) {
        super(
            configuration.auth.clientId,
            configuration.auth.authority || `${Constants.DEFAULT_AUTHORITY}`,
            new Logger(
                configuration.system?.loggerOptions || {},
                name,
                version
            ),
            name,
            version,
            configuration.telemetry?.application || {
                appName: "",
                appVersion: "",
            },
            intFields
        );
    }

    generateId(): string {
        return window.crypto.randomUUID();
    }

    private getPageVisibility(): string | null {
        return document.visibilityState?.toString() || null;
    }

    private deleteIncompleteSubMeasurements(
        inProgressEvent: InProgressPerformanceEvent
    ): void {
        void getPerfMeasurementModule()?.then((module) => {
            const rootEvent = this.eventsByCorrelationId.get(
                inProgressEvent.event.correlationId
            );
            const isRootEvent =
                rootEvent &&
                rootEvent.eventId === inProgressEvent.event.eventId;
            const incompleteMeasurements: SubMeasurement[] = [];
            if (isRootEvent && rootEvent?.incompleteSubMeasurements) {
                rootEvent.incompleteSubMeasurements.forEach(
                    (subMeasurement: SubMeasurement) => {
                        incompleteMeasurements.push({ ...subMeasurement });
                    }
                );
            }
            // Clean up remaining marks for incomplete sub-measurements
            module.BrowserPerformanceMeasurement.flushMeasurements(
                inProgressEvent.event.correlationId,
                incompleteMeasurements
            );
        });
    }

    /**
     * Starts measuring performance for a given operation. Returns a function that should be used to end the measurement.
     * Also captures browser page visibilityState.
     *
     * @param {PerformanceEvents} measureName
     * @param {?string} [correlationId]
     * @returns {((event?: Partial<PerformanceEvent>) => PerformanceEvent| null)}
     */
    startMeasurement(
        measureName: string,
        correlationId?: string
    ): InProgressPerformanceEvent {
        // Capture page visibilityState and then invoke start/end measurement
        const startPageVisibility = this.getPageVisibility();
        const inProgressEvent = super.startMeasurement(
            measureName,
            correlationId
        );
        const startTime: number | undefined = supportsBrowserPerformanceNow()
            ? window.performance.now()
            : undefined;

        const browserMeasurement = getPerfMeasurementModule()?.then(
            (module) => {
                return new module.BrowserPerformanceMeasurement(
                    measureName,
                    inProgressEvent.event.correlationId
                );
            }
        );
        void browserMeasurement?.then((measurement) =>
            measurement.startMeasurement()
        );

        return {
            ...inProgressEvent,
            end: (
                event?: Partial<PerformanceEvent>
            ): PerformanceEvent | null => {
                const res = inProgressEvent.end({
                    ...event,
                    startPageVisibility,
                    endPageVisibility: this.getPageVisibility(),
                    durationMs: getPerfDurationMs(startTime),
                });
                void browserMeasurement?.then((measurement) =>
                    measurement.endMeasurement()
                );
                this.deleteIncompleteSubMeasurements(inProgressEvent);

                return res;
            },
            discard: () => {
                inProgressEvent.discard();
                void browserMeasurement?.then((measurement) =>
                    measurement.flushMeasurement()
                );
                this.deleteIncompleteSubMeasurements(inProgressEvent);
            },
        };
    }

    /**
     * Adds pre-queue time to preQueueTimeByCorrelationId map.
     * @param {PerformanceEvents} eventName
     * @param {?string} correlationId
     * @returns
     */
    setPreQueueTime(
        eventName: PerformanceEvents,
        correlationId?: string
    ): void {
        if (!supportsBrowserPerformanceNow()) {
            this.logger.trace(
                `BrowserPerformanceClient: window performance API not available, unable to set telemetry queue time for ${eventName}`
            );
            return;
        }

        if (!correlationId) {
            this.logger.trace(
                `BrowserPerformanceClient: correlationId for ${eventName} not provided, unable to set telemetry queue time`
            );
            return;
        }

        const preQueueEvent: PreQueueEvent | undefined =
            this.preQueueTimeByCorrelationId.get(correlationId);
        /**
         * Manually complete queue measurement if there is an incomplete pre-queue event.
         * Incomplete pre-queue events are instrumentation bugs that should be fixed.
         */
        if (preQueueEvent) {
            this.logger.trace(
                `BrowserPerformanceClient: Incomplete pre-queue ${preQueueEvent.name} found`,
                correlationId
            );
            this.addQueueMeasurement(
                preQueueEvent.name,
                correlationId,
                undefined,
                true
            );
        }
        this.preQueueTimeByCorrelationId.set(correlationId, {
            name: eventName,
            time: window.performance.now(),
        });
    }

    /**
     * Calculates and adds queue time measurement for given performance event.
     *
     * @param {PerformanceEvents} eventName
     * @param {?string} correlationId
     * @param {?number} queueTime
     * @param {?boolean} manuallyCompleted - indicator for manually completed queue measurements
     * @returns
     */
    addQueueMeasurement(
        eventName: string,
        correlationId?: string,
        queueTime?: number,
        manuallyCompleted?: boolean
    ): void {
        if (!supportsBrowserPerformanceNow()) {
            this.logger.trace(
                `BrowserPerformanceClient: window performance API not available, unable to add queue measurement for ${eventName}`
            );
            return;
        }

        if (!correlationId) {
            this.logger.trace(
                `BrowserPerformanceClient: correlationId for ${eventName} not provided, unable to add queue measurement`
            );
            return;
        }

        const preQueueTime = super.getPreQueueTime(eventName, correlationId);
        if (!preQueueTime) {
            return;
        }

        const currentTime = window.performance.now();
        const resQueueTime =
            queueTime || super.calculateQueuedTime(preQueueTime, currentTime);

        return super.addQueueMeasurement(
            eventName,
            correlationId,
            resQueueTime,
            manuallyCompleted
        );
    }
}
