DriverInfo = (function() {
  // ---------------------------------------------------------------------------
  // Debug info handling

  function info(str) {
    window.console.log('Info: ' + str);
  }

  // ---------------------------------------------------------------------------
  // OS and driver identification
  //   Stolen from dom/canvas/test/webgl/test_webgl_conformance_test_suite.html
  function detectDriverInfo() {
    var canvas = document.createElement("canvas");
    canvas.width = 1;
    canvas.height = 1;

    var type = "";
    var gl = null;
    try {
      gl = canvas.getContext("experimental-webgl");
    } catch(e) {}

    if (!gl) {
      info('Failed to create WebGL context for querying driver info.');
      throw 'WebGL failed';
    }

    var ext = gl.getExtension("WEBGL_debug_renderer_info");
    if (!ext)
      throw 'WEBGL_debug_renderer_info not available';

    var webglRenderer = gl.getParameter(ext.UNMASKED_RENDERER_WEBGL);
    return webglRenderer;
  }

  function detectOSInfo() {
    var os = null;
    var version = null;
    if (navigator.platform.indexOf('Win') == 0) {
      os = OS.WINDOWS;

      var versionMatch = /Windows NT (\d+.\d+)/.exec(navigator.userAgent);
      version = versionMatch ? parseFloat(versionMatch[1]) : null;
      // Version 6.0 is Vista, 6.1 is 7.

    } else if (navigator.platform.indexOf('Mac') == 0) {
      os = OS.MAC;

      var versionMatch = /Mac OS X (\d+.\d+)/.exec(navigator.userAgent);
      version = versionMatch ? parseFloat(versionMatch[1]) : null;

    } else if (navigator.appVersion.includes('Android')) {
      os = OS.ANDROID;

      try {
        // From layout/tools/reftest/reftest.js:
        version = SpecialPowers.Services.sysinfo.getProperty('version');
      } catch (e) {
        info('No SpecialPowers: can\'t query android version');
      }

    } else if (navigator.platform.indexOf('Linux') == 0) {
      // Must be checked after android, as android also has a 'Linux' platform string.
      os = OS.LINUX;
    }

    return [os, version];
  }

  var OS = {
    WINDOWS: 'windows',
    MAC: 'mac',
    LINUX: 'linux',
    ANDROID: 'android',
  };

  var DRIVER = {
    INTEL: 'intel',
    MESA: 'mesa',
    NVIDIA: 'nvidia',
    ANDROID_X86_EMULATOR: 'android x86 emulator',
    ANGLE: 'angle',
  };

  var kOS = null;
  var kOSVersion = null;
  var kRawDriver = null;
  var kDriver = null;

  try {
    [kOS, kOSVersion] = detectOSInfo();
  } catch (e) {
    // Generally just fails when we don't have SpecialPowers.
  }

  try {
    kRawDriver = detectDriverInfo();

    if (kRawDriver.includes('llvmpipe')) {
      kDriver = DRIVER.MESA;
    } else if (kRawDriver.includes('Android Emulator')) {
      kDriver = DRIVER.ANDROID_X86_EMULATOR;
    } else if (kRawDriver.includes('ANGLE')) {
      kDriver = DRIVER.ANGLE;
    } else if (kRawDriver.includes('NVIDIA')) {
      kDriver = DRIVER.NVIDIA;
    } else if (kRawDriver.includes('Intel')) {
      kDriver = DRIVER.INTEL;
    }
  } catch (e) {
    // detectDriverInfo is fallible where WebGL fails.
  }

  function dump(line_out_func) {
    let lines = [
      '[DriverInfo] userAgent: ' + navigator.userAgent,
      '[DriverInfo] kRawDriver: ' + kRawDriver,
      '[DriverInfo] kDriver: ' + kDriver,
      '[DriverInfo] kOS: ' + kOS,
      '[DriverInfo] kOSVersion: ' + kOSVersion,
    ];
    lines.forEach(line_out_func);
  }

  dump(x => console.log(x));

  return {
    DRIVER: DRIVER,
    OS: OS,
    dump: dump,
    getDriver: function() { return kDriver; },
    getOS: function() { return kOS; },
    getOSVersion: function() { return kOSVersion; },
  };
})();

