/**
 * Copyright (c) Microsoft Corporation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import { execSync } from 'child_process';
import fs from 'fs';
import os from 'os';
import { parseOSReleaseText } from '../utils/ubuntuVersion';

let cachedUserAgent: string | undefined;

export function getUserAgent(): string {
  if (cachedUserAgent)
    return cachedUserAgent;
  try {
    cachedUserAgent = determineUserAgent();
  } catch (e) {
    cachedUserAgent = 'Playwright/unknown';
  }
  return cachedUserAgent;
}

function determineUserAgent(): string {
  let osIdentifier = 'unknown';
  let osVersion = 'unknown';
  if (process.platform === 'win32') {
    const version = os.release().split('.');
    osIdentifier = 'windows';
    osVersion = `${version[0]}.${version[1]}`;
  } else if (process.platform === 'darwin') {
    const version = execSync('sw_vers -productVersion', { stdio: ['ignore', 'pipe', 'ignore'] }).toString().trim().split('.');
    osIdentifier = 'macOS';
    osVersion = `${version[0]}.${version[1]}`;
  } else if (process.platform === 'linux') {
    try {
      // List of /etc/os-release values for different distributions could be
      // found here: https://gist.github.com/aslushnikov/8ceddb8288e4cf9db3039c02e0f4fb75
      const osReleaseText = fs.readFileSync('/etc/os-release', 'utf8');
      const fields = parseOSReleaseText(osReleaseText);
      osIdentifier = fields.get('id') || 'unknown';
      osVersion = fields.get('version_id') || 'unknown';
    } catch (e) {
      // Linux distribution without /etc/os-release.
      // Default to linux/unknown.
      osIdentifier = 'linux';
    }
  }
  const additionalTokens = [];
  if (process.env.CI)
    additionalTokens.push('CI/1');
  const serializedTokens = additionalTokens.length ? ' ' + additionalTokens.join(' ') : '';

  const { langName, langVersion } = getClientLanguage();
  return `Playwright/${getPlaywrightVersion()} (${os.arch()}; ${osIdentifier} ${osVersion}) ${langName}/${langVersion}${serializedTokens}`;
}

export function getClientLanguage(): { langName: string, langVersion: string } {
  let langName = 'unknown';
  let langVersion = 'unknown';
  if (!process.env.PW_LANG_NAME) {
    langName = 'node';
    langVersion = process.version.substring(1).split('.').slice(0, 2).join('.');
  } else if (['node', 'python', 'java', 'csharp'].includes(process.env.PW_LANG_NAME)) {
    langName = process.env.PW_LANG_NAME;
    langVersion = process.env.PW_LANG_NAME_VERSION ?? 'unknown';
  }
  return { langName, langVersion };
}

export function getPlaywrightVersion(majorMinorOnly = false) {
  const packageJson = require('./../../package.json');
  return majorMinorOnly ? packageJson.version.split('.').slice(0, 2).join('.') : packageJson.version;
}
