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

import * as os from 'os';
import { ManagedIdentityCredential } from '@azure/identity';

import { KnowledgeBaseAnswers } from '../qnamaker-interfaces/knowledgeBaseAnswers';
import { QnAMakerEndpoint } from '../qnamaker-interfaces/qnamakerEndpoint';
import { QnAMakerResults } from '../qnamaker-interfaces/qnamakerResults';

import { getFetch } from '../globals';
const fetch = getFetch();

// eslint-disable-next-line @typescript-eslint/no-require-imports
const pjson: Record<'name' | 'version', string> = require('../../package.json');
/**
 * Http request utils class.
 *
 * @summary
 * This class is helper class for all the http request operations.
 */
export class HttpRequestUtils {
    /**
     * Execute Http request.
     *
     * @param {string} requestUrl Http request url.
     * @param {string} payloadBody Http request body.
     * @param {QnAMakerEndpoint} endpoint QnA Maker endpoint details.
     * @param {number} timeout (Optional)Timeout for http call
     * @returns {QnAMakerResults} a promise that resolves to the QnAMakerResults
     */
    async executeHttpRequest(
        requestUrl: string,
        payloadBody: string,
        endpoint: QnAMakerEndpoint,
        timeout?: number,
    ): Promise<QnAMakerResults | KnowledgeBaseAnswers | undefined> {
        if (!requestUrl) {
            throw new TypeError('Request url cannot be null.');
        }

        if (!payloadBody) {
            throw new TypeError('Payload body cannot be null.');
        }

        if (!endpoint) {
            throw new TypeError('Endpoint body cannot be null.');
        }

        const headers = await this.getHeaders(endpoint);

        const qnaResult = await fetch(requestUrl, {
            method: 'POST',
            headers: headers,
            timeout: timeout,
            body: payloadBody,
        });

        return qnaResult.status !== 204 ? await qnaResult.json() : undefined;
    }

    /**
     * Sets headers for request to QnAMaker service.
     *
     * The [QnAMakerEndpointKey](#QnAMakerEndpoint.QnAMakerEndpointKey) is set as the value of
     * `Authorization` header for v4.0 and later of QnAMaker service.
     *
     * Legacy QnAMaker services use the `Ocp-Apim-Subscription-Key` header for the QnAMakerEndpoint value instead.
     *
     * [QnAMaker.getHeaders()](#QnAMaker.getHeaders) also gets the User-Agent header value.
     *
     * @private
     */
    private async getHeaders(endpoint: QnAMakerEndpoint): Promise<Record<string, string>> {
        const headers = {};

        if (endpoint.endpointKey) {
            headers['Ocp-Apim-Subscription-Key'] = endpoint.endpointKey;
            headers['Authorization'] = `EndpointKey ${endpoint.endpointKey}`;
        } else if (endpoint.managedIdentityClientId) {
            const client = new ManagedIdentityCredential({ clientId: endpoint.managedIdentityClientId });
            const tokenResponse = await client.getToken('https://cognitiveservices.azure.com/.default');
            headers['Authorization'] = `Bearer ${tokenResponse.token}`;
        }
        headers['User-Agent'] = this.getUserAgent();
        headers['Content-Type'] = 'application/json';

        return headers;
    }

    private getUserAgent(): string {
        const packageUserAgent = `${pjson.name}/${pjson.version}`;
        const platformUserAgent = `(${os.arch()}-${os.type()}-${os.release()}; Node.js,Version=${process.version})`;

        return `${packageUserAgent} ${platformUserAgent}`;
    }
}