/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the Source EULA. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import * as os from 'os';
import * as fs from 'fs';
import * as request from 'request';
import * as vscode from 'vscode';
import axios, { AxiosRequestConfig } from 'axios';
import * as constants from '../common/constants';

const DownloadTimeoutMs = 20000;

/**
 * Class includes method for making http request
 */
export class HttpClient {
	private static cache: Map<string, any> = new Map();

	/**
	 * Makes http GET request to the given url. If useCache is set to true, returns the result from cache if exists
	 * @param url url to make http GET request against
	 * @param useCache if true and result is already cached the cached value will be returned
	 * @returns result of http GET request
	 */
	public static async getRequest(url: string, useCache = false): Promise<any> {

		if (useCache) {
			if (HttpClient.cache.has(url)) {
				return HttpClient.cache.get(url);
			}
		}

		const config: AxiosRequestConfig = {
			headers: {
				'Content-Type': 'application/json'
			},
			validateStatus: () => true // Never throw
		};
		const response = await axios.get(url, config);
		if (response.status !== 200) {
			let errorMessage: string[] = [];
			errorMessage.push(response.status.toString());
			errorMessage.push(response.statusText);
			if (response.data?.error) {
				errorMessage.push(`${response.data?.error?.code} : ${response.data?.error?.message}`);
			}
			throw new Error(errorMessage.join(os.EOL));
		}

		if (useCache) {
			HttpClient.cache.set(url, response.data);
		}
		return response.data;
	}

	/**
	 * Gets a file/fileContents at the given URL. Function is copied from Machine Learning extension extensions/machine-learning/src/common/httpClient.ts
	 * @param downloadUrl The URL to download the file from
	 * @param targetPath The path to download the file to
	 * @param outputChannel The output channel to output status messages to
	 * @returns Full path to the downloaded file or the contents of the file at the given downloadUrl
	 */
	public download(downloadUrl: string, targetPath: string, outputChannel?: vscode.OutputChannel): Promise<void> {
		return new Promise((resolve, reject) => {
			let totalMegaBytes: number | undefined = undefined;
			let receivedBytes = 0;
			let printThreshold = 0.1;
			let downloadRequest = request.get(downloadUrl, { timeout: DownloadTimeoutMs })
				.on('error', downloadError => {
					outputChannel?.appendLine(constants.downloadError);
					reject(downloadError);
				})
				.on('response', (response) => {
					if (response.statusCode !== 200) {
						outputChannel?.appendLine(constants.downloadError);
						return reject(response.statusMessage);
					}
					let contentLength = response.headers['content-length'];
					let totalBytes = parseInt(contentLength || '0');
					totalMegaBytes = totalBytes / (1024 * 1024);
					outputChannel?.appendLine(`${constants.downloading} ${downloadUrl} (0 / ${totalMegaBytes.toFixed(2)} MB)`);
				})
				.on('data', (data) => {
					receivedBytes += data.length;
					if (totalMegaBytes) {
						let receivedMegaBytes = receivedBytes / (1024 * 1024);
						let percentage = receivedMegaBytes / totalMegaBytes;
						if (percentage >= printThreshold) {
							outputChannel?.appendLine(`${constants.downloadProgress} (${receivedMegaBytes.toFixed(2)} / ${totalMegaBytes.toFixed(2)} MB)`);
							printThreshold += 0.1;
						}
					}
				});
			downloadRequest.pipe(fs.createWriteStream(targetPath))
				.on('close', async () => {
					resolve();
				})
				.on('error', (downloadError) => {
					reject(downloadError);
					downloadRequest.abort();
				});
		});
	}
}