/*
 * Copyright 2014 Mozilla Foundation
 *
 * 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.
 */
/*jslint node: true */

'use strict';

var os = require('os');
var fs = require('fs');
var path = require('path');
var spawn = require('child_process').spawn;
var testUtils = require('./testutils.js');
var shelljs = require('shelljs');
var crypto = require('crypto');

var tempDirPrefix = 'pdfjs_';

function WebBrowser(name, path) {
  this.name = name;
  this.path = path;
  this.tmpDir = null;
  this.profileDir = null;
  this.process = null;
  this.requestedExit = false;
  this.finished = false;
  this.callback = null;
  // Used to identify processes whose pid is lost. This string is directly used
  // as a command-line argument, so it only consists of letters.
  this.uniqStringId = 'webbrowser' + crypto.randomBytes(32).toString('hex');
}
WebBrowser.prototype = {
  start: function (url) {
    this.tmpDir = path.join(os.tmpdir(), tempDirPrefix + this.name);
    if (!fs.existsSync(this.tmpDir)) {
      fs.mkdirSync(this.tmpDir);
    }
    this.startProcess(url);
  },
  getProfileDir: function () {
    if (!this.profileDir) {
      var profileDir = path.join(this.tmpDir, 'profile');
      if (fs.existsSync(profileDir)) {
        testUtils.removeDirSync(profileDir);
      }
      fs.mkdirSync(profileDir);
      this.profileDir = profileDir;
      this.setupProfileDir(profileDir);
    }
    return this.profileDir;
  },
  buildArguments: function (url) {
    return [url];
  },
  setupProfileDir: function (dir) {
  },
  startProcess: function (url) {
    console.assert(!this.process, 'startProcess may be called only once');

    var args = this.buildArguments(url);
    args = args.concat('--' + this.uniqStringId);
    this.process = spawn(this.path, args);
    this.process.on('exit', function (code, signal) {
      this.process = null;
      var exitInfo = code !== null ? ' with status ' + code :
        ' in response to signal ' + signal;
      if (this.requestedExit) {
        this.log('Browser process exited' + exitInfo);
      } else {
        // This was observed on Windows bots with Firefox. Apparently the
        // Firefox Maintenance Service restarts Firefox shortly after starting
        // up. When this happens, we no longer know the pid of the process.
        this.log('Browser process unexpectedly exited' + exitInfo);
      }
    }.bind(this));
  },
  cleanup: function () {
    console.assert(this.requestedExit,
        'cleanup should only be called after an explicit stop() request');

    try {
      testUtils.removeDirSync(this.tmpDir);
    } catch (e) {
      if (e.code !== 'ENOENT') {
        this.log('Failed to remove profile directory: ' + e);
        if (!this.cleanupFailStart) {
          this.cleanupFailStart = Date.now();
        } else if (Date.now() - this.cleanupFailStart > 10000) {
          throw new Error('Failed to remove profile dir within 10 seconds');
        }
        this.log('Retrying in a second...');
        setTimeout(this.cleanup.bind(this), 1000);
        return;
      }
      // This should not happen, but we just warn instead of failing loudly
      // because the post-condition of cleanup is that the profile directory is
      // gone. If the directory does not exists, then this post-condition is
      // satisfied.
      this.log('Cannot remove non-existent directory: ' + e);
    }
    this.finished = true;
    this.log('Clean-up finished. Going to call callback...');
    this.callback();
  },
  stop: function (callback) {
    console.assert(this.tmpDir, '.start() must be called before stop()');
    // Require the callback to ensure that callers do not make any assumptions
    // on the state of this browser instance until the callback is called.
    console.assert(typeof callback === 'function', 'callback is required');
    console.assert(!this.requestedExit, '.stop() may be called only once');

    this.requestedExit = true;
    if (this.finished) {
      this.log('Browser already stopped, invoking callback...');
      callback();
    } else if (this.process) {
      this.log('Going to wait until the browser process has exited.');
      this.callback = callback;
      this.process.once('exit', this.cleanup.bind(this));
      this.process.kill('SIGTERM');
    } else {
      this.log('Process already exited, checking if the process restarted...');
      this.callback = callback;
      this.killProcessUnknownPid(this.cleanup.bind(this));
    }
  },
  killProcessUnknownPid: function(callback) {
    this.log('pid unknown, killing processes matching ' + this.uniqStringId);

    var cmdKillAll, cmdCheckAllKilled, isAllKilled;

    if (process.platform === 'win32') {
      var wmicPrefix = 'wmic process where "not Name = \'cmd.exe\' ' +
        'and not Name like \'%wmic%\' ' +
        'and CommandLine like \'%' + this.uniqStringId + '%\'" ';
      cmdKillAll = wmicPrefix + 'call terminate';
      cmdCheckAllKilled = wmicPrefix + 'get CommandLine';
      isAllKilled = function(exitCode, stdout) {
        return stdout.indexOf(this.uniqStringId) === -1;
      }.bind(this);
    } else {
      cmdKillAll = 'pkill -f ' + this.uniqStringId;
      cmdCheckAllKilled = 'pgrep -f ' + this.uniqStringId;
      isAllKilled = function(pgrepStatus) {
        return pgrepStatus === 1; // "No process matched.", per man pgrep.
      };
    }
    function execAsyncNoStdin(cmd, onExit) {
      var proc = shelljs.exec(cmd, {
        async: true,
        silent: true,
      }, onExit);
      // Close stdin, otherwise wmic won't run.
      proc.stdin.end();
    }
    var killDateStart = Date.now();
    // Note: First process' output it shown, the later outputs are suppressed.
    execAsyncNoStdin(cmdKillAll, function checkAlive(exitCode, firstStdout) {
      execAsyncNoStdin(cmdCheckAllKilled, function(exitCode, stdout) {
        if (isAllKilled(exitCode, stdout)) {
          callback();
        } else if (Date.now() - killDateStart > 10000) {
          // Should finish termination within 10 (generous) seconds.
          if (firstStdout) {
            this.log('Output of first command:\n' + firstStdout);
          }
          if (stdout) {
            this.log('Output of last command:\n' + stdout);
          }
          throw new Error('Failed to kill process of ' + this.name);
        } else {
          setTimeout(checkAlive.bind(this), 500);
        }
      }.bind(this));
    }.bind(this));
  },
  log: function(msg) {
    console.log('[' + this.name + '] ' + msg);
  },
};

var firefoxResourceDir = path.join(__dirname, 'resources', 'firefox');

function FirefoxBrowser(name, path) {
  if (os.platform() === 'darwin') {
    var m = /([^.\/]+)\.app(\/?)$/.exec(path);
    if (m) {
      path += (m[2] ? '' : '/') + 'Contents/MacOS/firefox';
    }
  }
  WebBrowser.call(this, name, path);
}
FirefoxBrowser.prototype = Object.create(WebBrowser.prototype);
FirefoxBrowser.prototype.buildArguments = function (url) {
  var profileDir = this.getProfileDir();
  var args = [];
  if (os.platform() === 'darwin') {
    args.push('-foreground');
  }
  args.push('-no-remote', '-profile', profileDir, url);
  return args;
};
FirefoxBrowser.prototype.setupProfileDir = function (dir) {
  testUtils.copySubtreeSync(firefoxResourceDir, dir);
};

function ChromiumBrowser(name, path) {
  if (os.platform() === 'darwin') {
    var m = /([^.\/]+)\.app(\/?)$/.exec(path);
    if (m) {
      path += (m[2] ? '' : '/') + 'Contents/MacOS/' + m[1];
      console.log(path);
    }
  }
  WebBrowser.call(this, name, path);
}
ChromiumBrowser.prototype = Object.create(WebBrowser.prototype);
ChromiumBrowser.prototype.buildArguments = function (url) {
  var profileDir = this.getProfileDir();
  return ['--user-data-dir=' + profileDir,
    '--no-first-run', '--disable-sync', url];
};

WebBrowser.create = function (desc) {
  var name = desc.name;
  var path = shelljs.which(desc.path);
  if (!path) {
    throw new Error('Browser executable not found: ' + desc.path);
  }

  if (/firefox/i.test(name)) {
    return new FirefoxBrowser(name, path);
  }
  if (/(chrome|chromium|opera)/i.test(name)) {
    return new ChromiumBrowser(name, path);
  }
  return new WebBrowser(name, path);
};


exports.WebBrowser = WebBrowser;
