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

/**
 * Defines the level of severity for the event.
 */
export enum Severity {
    Verbose = 0,
    Information = 1,
    Warning = 2,
    Error = 3,
    Critical = 4,
}

/**
 * Key used to store and fetch a [BotTelemetryClient](xref:botbuilder-core.BotTelemetryClient) from [TurnContext.turnState](xref:botbuilder-core.TurnContextStateCollection)
 */
export const BotTelemetryClientKey = 'BotTelemetryClient';

export interface BotTelemetryClient {
    trackDependency(telemetry: TelemetryDependency);
    trackEvent(telemetry: TelemetryEvent);
    trackException(telemetry: TelemetryException);
    trackTrace(telemetry: TelemetryTrace);
    flush();
}

export interface BotPageViewTelemetryClient {
    trackPageView(telemetry: TelemetryPageView);
}

export interface TelemetryDependency {
    dependencyTypeName: string;
    target: string;
    name: string;
    data: string;
    duration: number;
    success: boolean;
    resultCode: number;
}

export interface TelemetryEvent {
    name: string;
    properties?: { [key: string]: any };
    metrics?: { [key: string]: number };
}

export interface TelemetryException {
    exception: Error;
    handledAt?: string;
    properties?: { [key: string]: string };
    measurements?: { [key: string]: number };
    severityLevel?: Severity;
}

export interface TelemetryTrace {
    message: string;
    properties?: { [key: string]: string };
    severityLevel?: Severity;
}

export interface TelemetryPageView {
    name: string;
    properties?: { [key: string]: string };
    metrics?: { [key: string]: number };
}

/**
 * A null bot telemetry client that implements [BotTelemetryClient](xref:botbuilder-core.BotTelemetryClient).
 */
export class NullTelemetryClient implements BotTelemetryClient, BotPageViewTelemetryClient {
    /**
     * Creates a new instance of the [NullTelemetryClient](xref:botbuilder-core.NullTelemetryClient) class.
     *
     * @param _settings Optional. Settings for the telemetry client.
     */
    constructor(_settings?: any) {
        // noop
    }

    /**
     * Logs an Application Insights page view.
     *
     * @param _telemetry An object implementing [TelemetryPageView](xref:botbuilder-core.TelemetryPageView).
     */
    trackPageView(_telemetry: TelemetryPageView) {
        // noop
    }

    /**
     * Sends information about an external dependency (outgoing call) in the application.
     *
     * @param _telemetry An object implementing [TelemetryDependency](xref:botbuilder-core.TelemetryDependency).
     */
    trackDependency(_telemetry: TelemetryDependency) {
        // noop
    }

    /**
     * Logs custom events with extensible named fields.
     *
     * @param _telemetry An object implementing [TelemetryEvent](xref:botbuilder-core.TelemetryEvent).
     */
    trackEvent(_telemetry: TelemetryEvent) {
        // noop
    }

    /**
     * Logs a system exception.
     *
     * @param _telemetry An object implementing [TelemetryException](xref:botbuilder-core.TelemetryException).
     */
    trackException(_telemetry: TelemetryException) {
        // noop
    }

    /**
     * Sends a trace message.
     *
     * @param _telemetry An object implementing [TelemetryTrace](xref:botbuilder-core.TelemetryTrace).
     */
    trackTrace(_telemetry: TelemetryTrace) {
        // noop
    }

    /**
     * Flushes the in-memory buffer and any metrics being pre-aggregated.
     */
    flush() {
        // noop
    }
}

/**
 * Logs a DialogView using the [trackPageView](xref:botbuilder-core.BotTelemetryClient.trackPageView) method on the [BotTelemetryClient](xref:botbuilder-core.BotTelemetryClient) if [BotPageViewTelemetryClient](xref:botbuilder-core.BotPageViewTelemetryClient) has been implemented.
 * Alternatively logs the information out via TrackTrace.
 *
 * @param telemetryClient TelemetryClient that implements [BotTelemetryClient](xref:botbuilder-core.BotTelemetryClient).
 * @param dialogName Name of the dialog to log the entry / start for.
 * @param properties Named string values you can use to search and classify events.
 * @param metrics Measurements associated with this event.
 */
export function telemetryTrackDialogView(
    telemetryClient: BotTelemetryClient,
    dialogName: string,
    properties?: { [key: string]: any },
    metrics?: { [key: string]: number },
): void {
    if (!clientSupportsTrackDialogView(telemetryClient)) {
        throw new TypeError('"telemetryClient" parameter does not have methods trackPageView() or trackTrace()');
    }
    if (instanceOfBotPageViewTelemetryClient(telemetryClient)) {
        telemetryClient.trackPageView({ name: dialogName, properties: properties, metrics: metrics });
    } else {
        telemetryClient.trackTrace({ message: 'Dialog View: ' + dialogName, severityLevel: Severity.Information });
    }
}

function instanceOfBotPageViewTelemetryClient(object: any): object is BotPageViewTelemetryClient {
    return 'trackPageView' in object;
}

function clientSupportsTrackDialogView(client: any): boolean {
    if (!client) {
        return false;
    }
    if (typeof client.trackPageView !== 'function' && typeof client.trackTrace !== 'function') {
        return false;
    }
    return true;
}