/**
 * Copyright (c) 2015-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */
'use strict';

const address = require('address');
const fs = require('fs');
const path = require('path');
const url = require('url');
const chalk = require('chalk');
const detect = require('detect-port-alt');
const isRoot = require('is-root');
const inquirer = require('inquirer');
const clearConsole = require('./clearConsole');
const formatWebpackMessages = require('./formatWebpackMessages');
const getProcessForPort = require('./getProcessForPort');

const isInteractive = process.stdout.isTTY;
let handleCompile;

// You can safely remove this after ejecting.
// We only use this block for testing of Create React App itself:
const isSmokeTest = process.argv.some(arg => arg.indexOf('--smoke-test') > -1);
if (isSmokeTest) {
  handleCompile = (err, stats) => {
    if (err || stats.hasErrors() || stats.hasWarnings()) {
      process.exit(1);
    } else {
      process.exit(0);
    }
  };
}

function prepareUrls(protocol, host, port) {
  const formatUrl = hostname =>
    url.format({
      protocol,
      hostname,
      port,
      pathname: '/',
    });
  const prettyPrintUrl = hostname =>
    url.format({
      protocol,
      hostname,
      port: chalk.bold(port),
      pathname: '/',
    });

  const isUnspecifiedHost = host === '0.0.0.0' || host === '::';
  let prettyHost, lanUrlForConfig, lanUrlForTerminal;
  if (isUnspecifiedHost) {
    prettyHost = 'localhost';
    try {
      // This can only return an IPv4 address
      lanUrlForConfig = address.ip();
      if (lanUrlForConfig) {
        // Check if the address is a private ip
        // https://en.wikipedia.org/wiki/Private_network#Private_IPv4_address_spaces
        if (
          /^10[.]|^172[.](1[6-9]|2[0-9]|3[0-1])[.]|^192[.]168[.]/.test(
            lanUrlForConfig
          )
        ) {
          // Address is private, format it for later use
          lanUrlForTerminal = prettyPrintUrl(lanUrlForConfig);
        } else {
          // Address is not private, so we will discard it
          lanUrlForConfig = undefined;
        }
      }
    } catch (_e) {
      // ignored
    }
  } else {
    prettyHost = host;
  }
  const localUrlForTerminal = prettyPrintUrl(prettyHost);
  const localUrlForBrowser = formatUrl(prettyHost);
  return {
    lanUrlForConfig,
    lanUrlForTerminal,
    localUrlForTerminal,
    localUrlForBrowser,
  };
}

function printInstructions(appName, urls, useYarn) {
  console.log();
  console.log(`You can now view ${chalk.bold(appName)} in the browser.`);
  console.log();

  if (urls.lanUrlForTerminal) {
    console.log(
      `  ${chalk.bold('Local:')}            ${urls.localUrlForTerminal}`
    );
    console.log(
      `  ${chalk.bold('On Your Network:')}  ${urls.lanUrlForTerminal}`
    );
  } else {
    console.log(`  ${urls.localUrlForTerminal}`);
  }

  console.log();
  console.log('Note that the development build is not optimized.');
  console.log(
    `To create a production build, use ` +
      `${chalk.cyan(`${useYarn ? 'yarn' : 'npm run'} build`)}.`
  );
  console.log();
}

function createCompiler(webpack, config, appName, urls, useYarn) {
  // "Compiler" is a low-level interface to Webpack.
  // It lets us listen to some events and provide our own custom messages.
  let compiler;
  try {
    compiler = webpack(config, handleCompile);
  } catch (err) {
    console.log(chalk.red('Failed to compile.'));
    console.log();
    console.log(err.message || err);
    console.log();
    process.exit(1);
  }

  // "invalid" event fires when you have changed a file, and Webpack is
  // recompiling a bundle. WebpackDevServer takes care to pause serving the
  // bundle, so if you refresh, it'll wait instead of serving the old one.
  // "invalid" is short for "bundle invalidated", it doesn't imply any errors.
  compiler.plugin('invalid', () => {
    if (isInteractive) {
      clearConsole();
    }
    console.log('Compiling...');
  });

  let isFirstCompile = true;

  // "done" event fires when Webpack has finished recompiling the bundle.
  // Whether or not you have warnings or errors, you will get this event.
  compiler.plugin('done', stats => {
    if (isInteractive) {
      clearConsole();
    }

    // We have switched off the default Webpack output in WebpackDevServer
    // options so we are going to "massage" the warnings and errors and present
    // them in a readable focused way.
    const messages = formatWebpackMessages(stats.toJson({}, true));
    const isSuccessful = !messages.errors.length && !messages.warnings.length;
    if (isSuccessful) {
      console.log(chalk.green('Compiled successfully!'));
    }
    if (isSuccessful && (isInteractive || isFirstCompile)) {
      printInstructions(appName, urls, useYarn);
    }
    isFirstCompile = false;

    // If errors exist, only show errors.
    if (messages.errors.length) {
      // Only keep the first error. Others are often indicative
      // of the same problem, but confuse the reader with noise.
      if (messages.errors.length > 1) {
        messages.errors.length = 1;
      }
      console.log(chalk.red('Failed to compile.\n'));
      console.log(messages.errors.join('\n\n'));
      console.log('Finished compiling');
      return;
    }

    // Show warnings if no errors were found.
    if (messages.warnings.length) {
      console.log(chalk.yellow('Compiled with warnings.\n'));
      console.log(messages.warnings.join('\n\n'));

      // Teach some ESLint tricks.
      console.log(
        '\nSearch for the ' +
          chalk.underline(chalk.yellow('keywords')) +
          ' to learn more about each warning.'
      );
      console.log(
        'To ignore, add ' +
          chalk.cyan('// eslint-disable-next-line') +
          ' to the line before.\n'
      );
    }

    console.log('Finished compiling');
  });
  return compiler;
}

function resolveLoopback(proxy) {
  const o = url.parse(proxy);
  o.host = undefined;
  if (o.hostname !== 'localhost') {
    return proxy;
  }
  // Unfortunately, many languages (unlike node) do not yet support IPv6.
  // This means even though localhost resolves to ::1, the application
  // must fall back to IPv4 (on 127.0.0.1).
  // We can re-enable this in a few years.
  /*try {
    o.hostname = address.ipv6() ? '::1' : '127.0.0.1';
  } catch (_ignored) {
    o.hostname = '127.0.0.1';
  }*/

  try {
    // Check if we're on a network; if we are, chances are we can resolve
    // localhost. Otherwise, we can just be safe and assume localhost is
    // IPv4 for maximum compatibility.
    if (!address.ip()) {
      o.hostname = '127.0.0.1';
    }
  } catch (_ignored) {
    o.hostname = '127.0.0.1';
  }
  return url.format(o);
}

// We need to provide a custom onError function for httpProxyMiddleware.
// It allows us to log custom error messages on the console.
function onProxyError(proxy) {
  return (err, req, res) => {
    const host = req.headers && req.headers.host;
    console.log(
      chalk.red('Proxy error:') +
        ' Could not proxy request ' +
        chalk.cyan(req.url) +
        ' from ' +
        chalk.cyan(host) +
        ' to ' +
        chalk.cyan(proxy) +
        '.'
    );
    console.log(
      'See https://nodejs.org/api/errors.html#errors_common_system_errors for more information (' +
        chalk.cyan(err.code) +
        ').'
    );
    console.log();

    // And immediately send the proper error response to the client.
    // Otherwise, the request will eventually timeout with ERR_EMPTY_RESPONSE on the client side.
    if (res.writeHead && !res.headersSent) {
      res.writeHead(500);
    }
    res.end(
      'Proxy error: Could not proxy request ' +
        req.url +
        ' from ' +
        host +
        ' to ' +
        proxy +
        ' (' +
        err.code +
        ').'
    );
  };
}

function prepareProxy(proxy, appPublicFolder) {
  // `proxy` lets you specify alternate servers for specific requests.
  // It can either be a string or an object conforming to the Webpack dev server proxy configuration
  // https://webpack.github.io/docs/webpack-dev-server.html
  if (!proxy) {
    return undefined;
  }
  if (typeof proxy !== 'object' && typeof proxy !== 'string') {
    console.log(
      chalk.red(
        'When specified, "proxy" in package.json must be a string or an object.'
      )
    );
    console.log(
      chalk.red('Instead, the type of "proxy" was "' + typeof proxy + '".')
    );
    console.log(
      chalk.red(
        'Either remove "proxy" from package.json, or make it an object.'
      )
    );
    process.exit(1);
  }

  // Otherwise, if proxy is specified, we will let it handle any request except for files in the public folder.
  function mayProxy(pathname) {
    const maybePublicPath = path.resolve(appPublicFolder, pathname.slice(1));
    return !fs.existsSync(maybePublicPath);
  }

  // Support proxy as a string for those who are using the simple proxy option
  if (typeof proxy === 'string') {
    if (!/^http(s)?:\/\//.test(proxy)) {
      console.log(
        chalk.red(
          'When "proxy" is specified in package.json it must start with either http:// or https://'
        )
      );
      process.exit(1);
    }

    let target;
    if (process.platform === 'win32') {
      target = resolveLoopback(proxy);
    } else {
      target = proxy;
    }
    return [
      {
        target,
        logLevel: 'silent',
        // For single page apps, we generally want to fallback to /index.html.
        // However we also want to respect `proxy` for API calls.
        // So if `proxy` is specified as a string, we need to decide which fallback to use.
        // We use a heuristic: We want to proxy all the requests that are not meant
        // for static assets and as all the requests for static assets will be using 
        // `GET` method, we can proxy all non-`GET` requests.
        // For `GET` requests, if request `accept`s text/html, we pick /index.html.
        // Modern browsers include text/html into `accept` header when navigating.
        // However API calls like `fetch()` won’t generally accept text/html.
        // If this heuristic doesn’t work well for you, use a custom `proxy` object.
        context: function(pathname, req) {
          return (
            req.method !== 'GET' ||
            (mayProxy(pathname) &&
              req.headers.accept &&
              req.headers.accept.indexOf('text/html') === -1)
          );
        },
        onProxyReq: proxyReq => {
          // Browers may send Origin headers even with same-origin
          // requests. To prevent CORS issues, we have to change
          // the Origin to match the target URL.
          if (proxyReq.getHeader('origin')) {
            proxyReq.setHeader('origin', target);
          }
        },
        onError: onProxyError(target),
        secure: false,
        changeOrigin: true,
        ws: true,
        xfwd: true,
      },
    ];
  }

  // Otherwise, proxy is an object so create an array of proxies to pass to webpackDevServer
  return Object.keys(proxy).map(function(context) {
    if (!proxy[context].hasOwnProperty('target')) {
      console.log(
        chalk.red(
          'When `proxy` in package.json is as an object, each `context` object must have a ' +
            '`target` property specified as a url string'
        )
      );
      process.exit(1);
    }
    let target;
    if (process.platform === 'win32') {
      target = resolveLoopback(proxy[context].target);
    } else {
      target = proxy[context].target;
    }
    return Object.assign({}, proxy[context], {
      context: function(pathname) {
        return mayProxy(pathname) && pathname.match(context);
      },
      onProxyReq: proxyReq => {
        // Browers may send Origin headers even with same-origin
        // requests. To prevent CORS issues, we have to change
        // the Origin to match the target URL.
        if (proxyReq.getHeader('origin')) {
          proxyReq.setHeader('origin', target);
        }
      },
      target,
      onError: onProxyError(target),
    });
  });
}

function choosePort(host, defaultPort) {
  return detect(defaultPort, host).then(
    port =>
      new Promise(resolve => {
        if (port === defaultPort) {
          return resolve(port);
        }
        const message =
          process.platform !== 'win32' && defaultPort < 1024 && !isRoot()
            ? `Admin permissions are required to run a server on a port below 1024.`
            : `Something is already running on port ${defaultPort}.`;
        if (isInteractive) {
          clearConsole();
          const existingProcess = getProcessForPort(defaultPort);
          const question = {
            type: 'confirm',
            name: 'shouldChangePort',
            message:
              chalk.yellow(
                message +
                  `${existingProcess ? ` Probably:\n  ${existingProcess}` : ''}`
              ) + '\n\nWould you like to run the app on another port instead?',
            default: true,
          };
          inquirer.prompt(question).then(answer => {
            if (answer.shouldChangePort) {
              resolve(port);
            } else {
              resolve(null);
            }
          });
        } else {
          console.log(chalk.red(message));
          resolve(null);
        }
      }),
    err => {
      throw new Error(
        chalk.red(`Could not find an open port at ${chalk.bold(host)}.`) +
          '\n' +
          ('Network error message: ' + err.message || err) +
          '\n'
      );
    }
  );
}

module.exports = {
  choosePort,
  createCompiler,
  prepareProxy,
  prepareUrls,
};