atom/src/package.js

const path = require('path')
const async = require('async')
const CSON = require('season')
const fs = require('fs-plus')
const {Emitter, CompositeDisposable} = require('event-kit')
const dedent = require('dedent')

const CompileCache = require('./compile-cache')
const ModuleCache = require('./module-cache')
const ScopedProperties = require('./scoped-properties')
const BufferedProcess = require('./buffered-process')

// Extended: Loads and activates a package's main module and resources such as
// stylesheets, keymaps, grammar, editor properties, and menus.
module.exports =
class Package {
  /*
  Section: Construction
  */

  constructor (params) {
    this.config = params.config
    this.packageManager = params.packageManager
    this.styleManager = params.styleManager
    this.commandRegistry = params.commandRegistry
    this.keymapManager = params.keymapManager
    this.notificationManager = params.notificationManager
    this.grammarRegistry = params.grammarRegistry
    this.themeManager = params.themeManager
    this.menuManager = params.menuManager
    this.contextMenuManager = params.contextMenuManager
    this.deserializerManager = params.deserializerManager
    this.viewRegistry = params.viewRegistry
    this.emitter = new Emitter()

    this.mainModule = null
    this.path = params.path
    this.preloadedPackage = params.preloadedPackage
    this.metadata =
      params.metadata ||
      this.packageManager.loadPackageMetadata(this.path)
    this.bundledPackage = params.bundledPackage != null
      ? params.bundledPackage
      : this.packageManager.isBundledPackagePath(this.path)
    this.name =
      params.name ||
      (this.metadata && this.metadata.name) ||
      path.basename(this.path)
    this.reset()
  }

  /*
  Section: Event Subscription
  */

  // Essential: Invoke the given callback when all packages have been activated.
  //
  // * `callback` {Function}
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  onDidDeactivate (callback) {
    return this.emitter.on('did-deactivate', callback)
  }

  /*
  Section: Instance Methods
  */

  enable () {
    return this.config.removeAtKeyPath('core.disabledPackages', this.name)
  }

  disable () {
    return this.config.pushAtKeyPath('core.disabledPackages', this.name)
  }

  isTheme () {
    return this.metadata && this.metadata.theme
  }

  measure (key, fn) {
    const startTime = Date.now()
    const value = fn()
    this[key] = Date.now() - startTime
    return value
  }

  getType () { return 'atom' }

  getStyleSheetPriority () { return 0 }

  preload () {
    this.loadKeymaps()
    this.loadMenus()
    this.registerDeserializerMethods()
    this.activateCoreStartupServices()
    this.registerURIHandler()
    this.configSchemaRegisteredOnLoad = this.registerConfigSchemaFromMetadata()
    this.requireMainModule()
    this.settingsPromise = this.loadSettings()

    this.activationDisposables = new CompositeDisposable()
    this.activateKeymaps()
    this.activateMenus()
    for (let settings of this.settings) {
      settings.activate()
    }
    this.settingsActivated = true
  }

  finishLoading () {
    this.measure('loadTime', () => {
      this.path = path.join(this.packageManager.resourcePath, this.path)
      ModuleCache.add(this.path, this.metadata)

      this.loadStylesheets()
      // Unfortunately some packages are accessing `@mainModulePath`, so we need
      // to compute that variable eagerly also for preloaded packages.
      this.getMainModulePath()
    })
  }

  load () {
    this.measure('loadTime', () => {
      try {
        ModuleCache.add(this.path, this.metadata)

        this.loadKeymaps()
        this.loadMenus()
        this.loadStylesheets()
        this.registerDeserializerMethods()
        this.activateCoreStartupServices()
        this.registerURIHandler()
        this.registerTranspilerConfig()
        this.configSchemaRegisteredOnLoad = this.registerConfigSchemaFromMetadata()
        this.settingsPromise = this.loadSettings()
        if (this.shouldRequireMainModuleOnLoad() && (this.mainModule == null)) {
          this.requireMainModule()
        }
      } catch (error) {
        this.handleError(`Failed to load the ${this.name} package`, error)
      }
    })
    return this
  }

  unload () {
    this.unregisterTranspilerConfig()
  }

  shouldRequireMainModuleOnLoad () {
    return !(
      this.metadata.deserializers ||
      this.metadata.viewProviders ||
      this.metadata.configSchema ||
      this.activationShouldBeDeferred() ||
      localStorage.getItem(this.getCanDeferMainModuleRequireStorageKey()) === 'true'
    )
  }

  reset () {
    this.stylesheets = []
    this.keymaps = []
    this.menus = []
    this.grammars = []
    this.settings = []
    this.mainInitialized = false
    this.mainActivated = false
  }

  initializeIfNeeded () {
    if (this.mainInitialized) return
    this.measure('initializeTime', () => {
      try {
        // The main module's `initialize()` method is guaranteed to be called
        // before its `activate()`. This gives you a chance to handle the
        // serialized package state before the package's derserializers and view
        // providers are used.
        if (!this.mainModule) this.requireMainModule()
        if (typeof this.mainModule.initialize === 'function') {
          this.mainModule.initialize(this.packageManager.getPackageState(this.name) || {})
        }
        this.mainInitialized = true
      } catch (error) {
        this.handleError(`Failed to initialize the ${this.name} package`, error)
      }
    })
  }

  activate () {
    if (!this.grammarsPromise) this.grammarsPromise = this.loadGrammars()
    if (!this.activationPromise) {
      this.activationPromise = new Promise((resolve, reject) => {
        this.resolveActivationPromise = resolve
        this.measure('activateTime', () => {
          try {
            this.activateResources()
            if (this.activationShouldBeDeferred()) {
              return this.subscribeToDeferredActivation()
            } else {
              return this.activateNow()
            }
          } catch (error) {
            return this.handleError(`Failed to activate the ${this.name} package`, error)
          }
        })
      })
    }

    return Promise.all([this.grammarsPromise, this.settingsPromise, this.activationPromise])
  }

  activateNow () {
    try {
      if (!this.mainModule) this.requireMainModule()
      this.configSchemaRegisteredOnActivate = this.registerConfigSchemaFromMainModule()
      this.registerViewProviders()
      this.activateStylesheets()
      if (this.mainModule && !this.mainActivated) {
        this.initializeIfNeeded()
        if (typeof this.mainModule.activateConfig === 'function') {
          this.mainModule.activateConfig()
        }
        if (typeof this.mainModule.activate === 'function') {
          this.mainModule.activate(this.packageManager.getPackageState(this.name) || {})
        }
        this.mainActivated = true
        this.activateServices()
      }
      if (this.activationCommandSubscriptions) this.activationCommandSubscriptions.dispose()
      if (this.activationHookSubscriptions) this.activationHookSubscriptions.dispose()
    } catch (error) {
      this.handleError(`Failed to activate the ${this.name} package`, error)
    }

    if (typeof this.resolveActivationPromise === 'function') this.resolveActivationPromise()
  }

  registerConfigSchemaFromMetadata () {
    const configSchema = this.metadata.configSchema
    if (configSchema) {
      this.config.setSchema(this.name, {type: 'object', properties: configSchema})
      return true
    } else {
      return false
    }
  }

  registerConfigSchemaFromMainModule () {
    if (this.mainModule && !this.configSchemaRegisteredOnLoad) {
      if (typeof this.mainModule.config === 'object') {
        this.config.setSchema(this.name, {type: 'object', properties: this.mainModule.config})
        return true
      }
    }
    return false
  }

  // TODO: Remove. Settings view calls this method currently.
  activateConfig () {
    if (this.configSchemaRegisteredOnLoad) return
    this.requireMainModule()
    this.registerConfigSchemaFromMainModule()
  }

  activateStylesheets () {
    if (this.stylesheetsActivated) return

    this.stylesheetDisposables = new CompositeDisposable()

    const priority = this.getStyleSheetPriority()
    for (let [sourcePath, source] of this.stylesheets) {
      const match = path.basename(sourcePath).match(/[^.]*\.([^.]*)\./)

      let context
      if (match) {
        context = match[1]
      } else if (this.metadata.theme === 'syntax') {
        context = 'atom-text-editor'
      }

      this.stylesheetDisposables.add(
        this.styleManager.addStyleSheet(
          source,
          {
            sourcePath,
            priority,
            context,
            skipDeprecatedSelectorsTransformation: this.bundledPackage
          }
        )
      )
    }

    this.stylesheetsActivated = true
  }

  activateResources () {
    if (!this.activationDisposables) this.activationDisposables = new CompositeDisposable()

    const packagesWithKeymapsDisabled = this.config.get('core.packagesWithKeymapsDisabled')
    if (packagesWithKeymapsDisabled && packagesWithKeymapsDisabled.includes(this.name)) {
      this.deactivateKeymaps()
    } else if (!this.keymapActivated) {
      this.activateKeymaps()
    }

    if (!this.menusActivated) {
      this.activateMenus()
    }

    if (!this.grammarsActivated) {
      for (let grammar of this.grammars) {
        grammar.activate()
      }
      this.grammarsActivated = true
    }

    if (!this.settingsActivated) {
      for (let settings of this.settings) {
        settings.activate()
      }
      this.settingsActivated = true
    }
  }

  activateKeymaps () {
    if (this.keymapActivated) return

    this.keymapDisposables = new CompositeDisposable()

    const validateSelectors = !this.preloadedPackage
    for (let [keymapPath, map] of this.keymaps) {
      this.keymapDisposables.add(this.keymapManager.add(keymapPath, map, 0, validateSelectors))
    }
    this.menuManager.update()

    this.keymapActivated = true
  }

  deactivateKeymaps () {
    if (!this.keymapActivated) return
    if (this.keymapDisposables) {
      this.keymapDisposables.dispose()
    }
    this.menuManager.update()
    this.keymapActivated = false
  }

  hasKeymaps () {
    for (let [, map] of this.keymaps) {
      if (map.length > 0) return true
    }
    return false
  }

  activateMenus () {
    const validateSelectors = !this.preloadedPackage
    for (const [menuPath, map] of this.menus) {
      if (map['context-menu']) {
        try {
          const itemsBySelector = map['context-menu']
          this.activationDisposables.add(this.contextMenuManager.add(itemsBySelector, validateSelectors))
        } catch (error) {
          if (error.code === 'EBADSELECTOR') {
            error.message += ` in ${menuPath}`
            error.stack += `\n  at ${menuPath}:1:1`
          }
          throw error
        }
      }
    }

    for (const [, map] of this.menus) {
      if (map.menu) this.activationDisposables.add(this.menuManager.add(map.menu))
    }

    this.menusActivated = true
  }

  activateServices () {
    let methodName, version, versions
    for (var name in this.metadata.providedServices) {
      ({versions} = this.metadata.providedServices[name])
      const servicesByVersion = {}
      for (version in versions) {
        methodName = versions[version]
        if (typeof this.mainModule[methodName] === 'function') {
          servicesByVersion[version] = this.mainModule[methodName]()
        }
      }
      this.activationDisposables.add(this.packageManager.serviceHub.provide(name, servicesByVersion))
    }

    for (name in this.metadata.consumedServices) {
      ({versions} = this.metadata.consumedServices[name])
      for (version in versions) {
        methodName = versions[version]
        if (typeof this.mainModule[methodName] === 'function') {
          this.activationDisposables.add(this.packageManager.serviceHub.consume(name, version, this.mainModule[methodName].bind(this.mainModule)))
        }
      }
    }
  }

  registerURIHandler () {
    const handlerConfig = this.getURIHandler()
    const methodName = handlerConfig && handlerConfig.method
    if (methodName) {
      this.uriHandlerSubscription = this.packageManager.registerURIHandlerForPackage(this.name, (...args) =>
        this.handleURI(methodName, args)
      )
    }
  }

  unregisterURIHandler () {
    if (this.uriHandlerSubscription) this.uriHandlerSubscription.dispose()
  }

  handleURI (methodName, args) {
    this.activate().then(() => {
      if (this.mainModule[methodName]) this.mainModule[methodName].apply(this.mainModule, args)
    })
    if (!this.mainActivated) this.activateNow()
  }

  registerTranspilerConfig () {
    if (this.metadata.atomTranspilers) {
      CompileCache.addTranspilerConfigForPath(this.path, this.name, this.metadata, this.metadata.atomTranspilers)
    }
  }

  unregisterTranspilerConfig () {
    if (this.metadata.atomTranspilers) {
      CompileCache.removeTranspilerConfigForPath(this.path)
    }
  }

  loadKeymaps () {
    if (this.bundledPackage && this.packageManager.packagesCache[this.name]) {
      this.keymaps = []
      for (const keymapPath in this.packageManager.packagesCache[this.name].keymaps) {
        const keymapObject = this.packageManager.packagesCache[this.name].keymaps[keymapPath]
        this.keymaps.push([`core:${keymapPath}`, keymapObject])
      }
    } else {
      this.keymaps = this.getKeymapPaths().map((keymapPath) => [
        keymapPath,
        CSON.readFileSync(keymapPath, {allowDuplicateKeys: false}) || {}
      ])
    }
  }

  loadMenus () {
    if (this.bundledPackage && this.packageManager.packagesCache[this.name]) {
      this.menus = []
      for (const menuPath in this.packageManager.packagesCache[this.name].menus) {
        const menuObject = this.packageManager.packagesCache[this.name].menus[menuPath]
        this.menus.push([`core:${menuPath}`, menuObject])
      }
    } else {
      this.menus = this.getMenuPaths().map((menuPath) => [
        menuPath,
        CSON.readFileSync(menuPath) || {}
      ])
    }
  }

  getKeymapPaths () {
    const keymapsDirPath = path.join(this.path, 'keymaps')
    if (this.metadata.keymaps) {
      return this.metadata.keymaps.map(name => fs.resolve(keymapsDirPath, name, ['json', 'cson', '']))
    } else {
      return fs.listSync(keymapsDirPath, ['cson', 'json'])
    }
  }

  getMenuPaths () {
    const menusDirPath = path.join(this.path, 'menus')
    if (this.metadata.menus) {
      return this.metadata.menus.map(name => fs.resolve(menusDirPath, name, ['json', 'cson', '']))
    } else {
      return fs.listSync(menusDirPath, ['cson', 'json'])
    }
  }

  loadStylesheets () {
    this.stylesheets = this.getStylesheetPaths().map(stylesheetPath =>
      [stylesheetPath, this.themeManager.loadStylesheet(stylesheetPath, true)]
    )
  }

  registerDeserializerMethods () {
    if (this.metadata.deserializers) {
      Object.keys(this.metadata.deserializers).forEach(deserializerName => {
        const methodName = this.metadata.deserializers[deserializerName]
        this.deserializerManager.add({
          name: deserializerName,
          deserialize: (state, atomEnvironment) => {
            this.registerViewProviders()
            this.requireMainModule()
            this.initializeIfNeeded()
            return this.mainModule[methodName](state, atomEnvironment)
          }
        })
      })
    }
  }

  activateCoreStartupServices () {
    const directoryProviderService =
      this.metadata.providedServices &&
      this.metadata.providedServices['atom.directory-provider']
    if (directoryProviderService) {
      this.requireMainModule()
      const servicesByVersion = {}
      for (let version in directoryProviderService.versions) {
        const methodName = directoryProviderService.versions[version]
        if (typeof this.mainModule[methodName] === 'function') {
          servicesByVersion[version] = this.mainModule[methodName]()
        }
      }
      this.packageManager.serviceHub.provide('atom.directory-provider', servicesByVersion)
    }
  }

  registerViewProviders () {
    if (this.metadata.viewProviders && !this.registeredViewProviders) {
      this.requireMainModule()
      this.metadata.viewProviders.forEach(methodName => {
        this.viewRegistry.addViewProvider(model => {
          this.initializeIfNeeded()
          return this.mainModule[methodName](model)
        })
      })
      this.registeredViewProviders = true
    }
  }

  getStylesheetsPath () {
    return path.join(this.path, 'styles')
  }

  getStylesheetPaths () {
    if (this.bundledPackage &&
        this.packageManager.packagesCache[this.name] &&
        this.packageManager.packagesCache[this.name].styleSheetPaths) {
      const {styleSheetPaths} = this.packageManager.packagesCache[this.name]
      return styleSheetPaths.map(styleSheetPath => path.join(this.path, styleSheetPath))
    } else {
      let indexStylesheet
      const stylesheetDirPath = this.getStylesheetsPath()
      if (this.metadata.mainStyleSheet) {
        return [fs.resolve(this.path, this.metadata.mainStyleSheet)]
      } else if (this.metadata.styleSheets) {
        return this.metadata.styleSheets.map(name => fs.resolve(stylesheetDirPath, name, ['css', 'less', '']))
      } else if ((indexStylesheet = fs.resolve(this.path, 'index', ['css', 'less']))) {
        return [indexStylesheet]
      } else {
        return fs.listSync(stylesheetDirPath, ['css', 'less'])
      }
    }
  }

  loadGrammarsSync () {
    if (this.grammarsLoaded) return

    let grammarPaths
    if (this.preloadedPackage && this.packageManager.packagesCache[this.name]) {
      ({grammarPaths} = this.packageManager.packagesCache[this.name])
    } else {
      grammarPaths = fs.listSync(path.join(this.path, 'grammars'), ['json', 'cson'])
    }

    for (let grammarPath of grammarPaths) {
      if (this.preloadedPackage && this.packageManager.packagesCache[this.name]) {
        grammarPath = path.resolve(this.packageManager.resourcePath, grammarPath)
      }

      try {
        const grammar = this.grammarRegistry.readGrammarSync(grammarPath)
        grammar.packageName = this.name
        grammar.bundledPackage = this.bundledPackage
        this.grammars.push(grammar)
        grammar.activate()
      } catch (error) {
        console.warn(`Failed to load grammar: ${grammarPath}`, error.stack || error)
      }
    }

    this.grammarsLoaded = true
    this.grammarsActivated = true
  }

  loadGrammars () {
    if (this.grammarsLoaded) return Promise.resolve()

    const loadGrammar = (grammarPath, callback) => {
      if (this.preloadedPackage) {
        grammarPath = path.resolve(this.packageManager.resourcePath, grammarPath)
      }

      return this.grammarRegistry.readGrammar(grammarPath, (error, grammar) => {
        if (error) {
          const detail = `${error.message} in ${grammarPath}`
          const stack = `${error.stack}\n  at ${grammarPath}:1:1`
          this.notificationManager.addFatalError(`Failed to load a ${this.name} package grammar`, {stack, detail, packageName: this.name, dismissable: true})
        } else {
          grammar.packageName = this.name
          grammar.bundledPackage = this.bundledPackage
          this.grammars.push(grammar)
          if (this.grammarsActivated) grammar.activate()
        }
        return callback()
      })
    }

    return new Promise(resolve => {
      if (this.preloadedPackage && this.packageManager.packagesCache[this.name]) {
        const { grammarPaths } = this.packageManager.packagesCache[this.name]
        return async.each(grammarPaths, loadGrammar, () => resolve())
      } else {
        const grammarsDirPath = path.join(this.path, 'grammars')
        fs.exists(grammarsDirPath, (grammarsDirExists) => {
          if (!grammarsDirExists) return resolve()
          fs.list(grammarsDirPath, ['json', 'cson'], (error, grammarPaths) => {
            if (error || !grammarPaths) return resolve()
            async.each(grammarPaths, loadGrammar, () => resolve())
          })
        })
      }
    })
  }

  loadSettings () {
    this.settings = []

    const loadSettingsFile = (settingsPath, callback) => {
      return ScopedProperties.load(settingsPath, this.config, (error, settings) => {
        if (error) {
          const detail = `${error.message} in ${settingsPath}`
          const stack = `${error.stack}\n  at ${settingsPath}:1:1`
          this.notificationManager.addFatalError(`Failed to load the ${this.name} package settings`, {stack, detail, packageName: this.name, dismissable: true})
        } else {
          this.settings.push(settings)
          if (this.settingsActivated) { settings.activate() }
        }
        return callback()
      })
    }

    return new Promise(resolve => {
      if (this.preloadedPackage && this.packageManager.packagesCache[this.name]) {
        for (let settingsPath in this.packageManager.packagesCache[this.name].settings) {
          const scopedProperties = this.packageManager.packagesCache[this.name].settings[settingsPath]
          const settings = new ScopedProperties(`core:${settingsPath}`, scopedProperties || {}, this.config)
          this.settings.push(settings)
          if (this.settingsActivated) { settings.activate() }
        }
        return resolve()
      } else {
        const settingsDirPath = path.join(this.path, 'settings')
        fs.exists(settingsDirPath, (settingsDirExists) => {
          if (!settingsDirExists) return resolve()
          fs.list(settingsDirPath, ['json', 'cson'], (error, settingsPaths) => {
            if (error || !settingsPaths) return resolve()
            async.each(settingsPaths, loadSettingsFile, () => resolve())
          })
        })
      }
    })
  }

  serialize () {
    if (this.mainActivated) {
      if (typeof this.mainModule.serialize === 'function') {
        try {
          return this.mainModule.serialize()
        } catch (error) {
          console.error(`Error serializing package '${this.name}'`, error.stack)
        }
      }
    }
  }

  async deactivate () {
    this.activationPromise = null
    this.resolveActivationPromise = null
    if (this.activationCommandSubscriptions) this.activationCommandSubscriptions.dispose()
    if (this.activationHookSubscriptions) this.activationHookSubscriptions.dispose()
    this.configSchemaRegisteredOnActivate = false
    this.unregisterURIHandler()
    this.deactivateResources()
    this.deactivateKeymaps()

    if (!this.mainActivated) {
      this.emitter.emit('did-deactivate')
      return
    }

    if (typeof this.mainModule.deactivate === 'function') {
      try {
        const deactivationResult = this.mainModule.deactivate()
        if (deactivationResult && typeof deactivationResult.then === 'function') {
          await deactivationResult
        }
      } catch (error) {
        console.error(`Error deactivating package '${this.name}'`, error.stack)
      }
    }

    if (typeof this.mainModule.deactivateConfig === 'function') {
      try {
        await this.mainModule.deactivateConfig()
      } catch (error) {
        console.error(`Error deactivating package '${this.name}'`, error.stack)
      }
    }

    this.mainActivated = false
    this.mainInitialized = false
    this.emitter.emit('did-deactivate')
  }

  deactivateResources () {
    for (let grammar of this.grammars) {
      grammar.deactivate()
    }
    for (let settings of this.settings) {
      settings.deactivate()
    }

    if (this.stylesheetDisposables) this.stylesheetDisposables.dispose()
    if (this.activationDisposables) this.activationDisposables.dispose()
    if (this.keymapDisposables) this.keymapDisposables.dispose()

    this.stylesheetsActivated = false
    this.grammarsActivated = false
    this.settingsActivated = false
    this.menusActivated = false
  }

  reloadStylesheets () {
    try {
      this.loadStylesheets()
    } catch (error) {
      this.handleError(`Failed to reload the ${this.name} package stylesheets`, error)
    }

    if (this.stylesheetDisposables) this.stylesheetDisposables.dispose()
    this.stylesheetDisposables = new CompositeDisposable()
    this.stylesheetsActivated = false
    this.activateStylesheets()
  }

  requireMainModule () {
    if (this.bundledPackage && this.packageManager.packagesCache[this.name]) {
      if (this.packageManager.packagesCache[this.name].main) {
        this.mainModule = require(this.packageManager.packagesCache[this.name].main)
        return this.mainModule
      }
    } else if (this.mainModuleRequired) {
      return this.mainModule
    } else if (!this.isCompatible()) {
      const nativeModuleNames = this.incompatibleModules.map(m => m.name).join(', ')
      console.warn(dedent `
        Failed to require the main module of '${this.name}' because it requires one or more incompatible native modules (${nativeModuleNames}).
        Run \`apm rebuild\` in the package directory and restart Atom to resolve.\
      `)
    } else {
      const mainModulePath = this.getMainModulePath()
      if (fs.isFileSync(mainModulePath)) {
        this.mainModuleRequired = true

        const previousViewProviderCount = this.viewRegistry.getViewProviderCount()
        const previousDeserializerCount = this.deserializerManager.getDeserializerCount()
        this.mainModule = require(mainModulePath)
        if ((this.viewRegistry.getViewProviderCount() === previousViewProviderCount) &&
            (this.deserializerManager.getDeserializerCount() === previousDeserializerCount)) {
          localStorage.setItem(this.getCanDeferMainModuleRequireStorageKey(), 'true')
        }
        return this.mainModule
      }
    }
  }

  getMainModulePath () {
    if (this.resolvedMainModulePath) return this.mainModulePath
    this.resolvedMainModulePath = true

    if (this.bundledPackage && this.packageManager.packagesCache[this.name]) {
      if (this.packageManager.packagesCache[this.name].main) {
        this.mainModulePath = path.resolve(this.packageManager.resourcePath, 'static', this.packageManager.packagesCache[this.name].main)
      } else {
        this.mainModulePath = null
      }
    } else {
      const mainModulePath = this.metadata.main
        ? path.join(this.path, this.metadata.main)
        : path.join(this.path, 'index')
      this.mainModulePath = fs.resolveExtension(mainModulePath, ['', ...CompileCache.supportedExtensions])
    }
    return this.mainModulePath
  }

  activationShouldBeDeferred () {
    return this.hasActivationCommands() || this.hasActivationHooks() || this.hasDeferredURIHandler()
  }

  hasActivationHooks () {
    const hooks = this.getActivationHooks()
    return hooks && hooks.length > 0
  }

  hasActivationCommands () {
    const object = this.getActivationCommands()
    for (let selector in object) {
      const commands = object[selector]
      if (commands.length > 0) return true
    }
    return false
  }

  hasDeferredURIHandler () {
    const handler = this.getURIHandler()
    return handler && handler.deferActivation !== false
  }

  subscribeToDeferredActivation () {
    this.subscribeToActivationCommands()
    this.subscribeToActivationHooks()
  }

  subscribeToActivationCommands () {
    this.activationCommandSubscriptions = new CompositeDisposable()
    const object = this.getActivationCommands()
    for (let selector in object) {
      const commands = object[selector]
      for (let command of commands) {
        ((selector, command) => {
          // Add dummy command so it appears in menu.
          // The real command will be registered on package activation
          try {
            this.activationCommandSubscriptions.add(this.commandRegistry.add(selector, command, function () {}))
          } catch (error) {
            if (error.code === 'EBADSELECTOR') {
              const metadataPath = path.join(this.path, 'package.json')
              error.message += ` in ${metadataPath}`
              error.stack += `\n  at ${metadataPath}:1:1`
            }
            throw error
          }

          this.activationCommandSubscriptions.add(this.commandRegistry.onWillDispatch(event => {
            if (event.type !== command) return
            let currentTarget = event.target
            while (currentTarget) {
              if (currentTarget.webkitMatchesSelector(selector)) {
                this.activationCommandSubscriptions.dispose()
                this.activateNow()
                break
              }
              currentTarget = currentTarget.parentElement
            }
          }))
        })(selector, command)
      }
    }
  }

  getActivationCommands () {
    if (this.activationCommands) return this.activationCommands

    this.activationCommands = {}

    if (this.metadata.activationCommands) {
      for (let selector in this.metadata.activationCommands) {
        const commands = this.metadata.activationCommands[selector]
        if (!this.activationCommands[selector]) this.activationCommands[selector] = []
        if (typeof commands === 'string') {
          this.activationCommands[selector].push(commands)
        } else if (Array.isArray(commands)) {
          this.activationCommands[selector].push(...commands)
        }
      }
    }

    return this.activationCommands
  }

  subscribeToActivationHooks () {
    this.activationHookSubscriptions = new CompositeDisposable()
    for (let hook of this.getActivationHooks()) {
      if (typeof hook === 'string' && hook.trim().length > 0) {
        this.activationHookSubscriptions.add(
          this.packageManager.onDidTriggerActivationHook(hook, () => this.activateNow())
        )
      }
    }
  }

  getActivationHooks () {
    if (this.metadata && this.activationHooks) return this.activationHooks

    if (this.metadata.activationHooks) {
      if (Array.isArray(this.metadata.activationHooks)) {
        this.activationHooks = Array.from(new Set(this.metadata.activationHooks))
      } else if (typeof this.metadata.activationHooks === 'string') {
        this.activationHooks = [this.metadata.activationHooks]
      } else {
        this.activationHooks = []
      }
    } else {
      this.activationHooks = []
    }

    return this.activationHooks
  }

  getURIHandler () {
    return this.metadata && this.metadata.uriHandler
  }

  // Does the given module path contain native code?
  isNativeModule (modulePath) {
    try {
      return fs.listSync(path.join(modulePath, 'build', 'Release'), ['.node']).length > 0
    } catch (error) {
      return false
    }
  }

  // Get an array of all the native modules that this package depends on.
  //
  // First try to get this information from
  // @metadata._atomModuleCache.extensions. If @metadata._atomModuleCache doesn't
  // exist, recurse through all dependencies.
  getNativeModuleDependencyPaths () {
    const nativeModulePaths = []

    if (this.metadata._atomModuleCache) {
      const relativeNativeModuleBindingPaths =
        (this.metadata._atomModuleCache.extensions && this.metadata._atomModuleCache.extensions['.node']) ||
        []
      for (let relativeNativeModuleBindingPath of relativeNativeModuleBindingPaths) {
        const nativeModulePath = path.join(this.path, relativeNativeModuleBindingPath, '..', '..', '..')
        nativeModulePaths.push(nativeModulePath)
      }
      return nativeModulePaths
    }

    var traversePath = nodeModulesPath => {
      try {
        for (let modulePath of fs.listSync(nodeModulesPath)) {
          if (this.isNativeModule(modulePath)) nativeModulePaths.push(modulePath)
          traversePath(path.join(modulePath, 'node_modules'))
        }
      } catch (error) {}
    }

    traversePath(path.join(this.path, 'node_modules'))

    return nativeModulePaths
  }

  /*
  Section: Native Module Compatibility
  */

  // Extended: Are all native modules depended on by this package correctly
  // compiled against the current version of Atom?
  //
  // Incompatible packages cannot be activated.
  //
  // Returns a {Boolean}, true if compatible, false if incompatible.
  isCompatible () {
    if (this.compatible == null) {
      if (this.preloadedPackage) {
        this.compatible = true
      } else if (this.getMainModulePath()) {
        this.incompatibleModules = this.getIncompatibleNativeModules()
        this.compatible =
          this.incompatibleModules.length === 0 &&
          this.getBuildFailureOutput() == null
      } else {
        this.compatible = true
      }
    }
    return this.compatible
  }

  // Extended: Rebuild native modules in this package's dependencies for the
  // current version of Atom.
  //
  // Returns a {Promise} that resolves with an object containing `code`,
  // `stdout`, and `stderr` properties based on the results of running
  // `apm rebuild` on the package.
  rebuild () {
    return new Promise(resolve =>
      this.runRebuildProcess(result => {
        if (result.code === 0) {
          global.localStorage.removeItem(this.getBuildFailureOutputStorageKey())
        } else {
          this.compatible = false
          global.localStorage.setItem(this.getBuildFailureOutputStorageKey(), result.stderr)
        }
        global.localStorage.setItem(this.getIncompatibleNativeModulesStorageKey(), '[]')
        resolve(result)
      })
    )
  }

  // Extended: If a previous rebuild failed, get the contents of stderr.
  //
  // Returns a {String} or null if no previous build failure occurred.
  getBuildFailureOutput () {
    return global.localStorage.getItem(this.getBuildFailureOutputStorageKey())
  }

  runRebuildProcess (done) {
    let stderr = ''
    let stdout = ''
    return new BufferedProcess({
      command: this.packageManager.getApmPath(),
      args: ['rebuild', '--no-color'],
      options: {cwd: this.path},
      stderr (output) { stderr += output },
      stdout (output) { stdout += output },
      exit (code) { done({code, stdout, stderr}) }
    })
  }

  getBuildFailureOutputStorageKey () {
    return `installed-packages:${this.name}:${this.metadata.version}:build-error`
  }

  getIncompatibleNativeModulesStorageKey () {
    const electronVersion = process.versions.electron
    return `installed-packages:${this.name}:${this.metadata.version}:electron-${electronVersion}:incompatible-native-modules`
  }

  getCanDeferMainModuleRequireStorageKey () {
    return `installed-packages:${this.name}:${this.metadata.version}:can-defer-main-module-require`
  }

  // Get the incompatible native modules that this package depends on.
  // This recurses through all dependencies and requires all modules that
  // contain a `.node` file.
  //
  // This information is cached in local storage on a per package/version basis
  // to minimize the impact on startup time.
  getIncompatibleNativeModules () {
    if (!this.packageManager.devMode) {
      try {
        const arrayAsString = global.localStorage.getItem(this.getIncompatibleNativeModulesStorageKey())
        if (arrayAsString) return JSON.parse(arrayAsString)
      } catch (error1) {}
    }

    const incompatibleNativeModules = []
    for (let nativeModulePath of this.getNativeModuleDependencyPaths()) {
      try {
        require(nativeModulePath)
      } catch (error) {
        let version
        try {
          ({version} = require(`${nativeModulePath}/package.json`))
        } catch (error2) {}
        incompatibleNativeModules.push({
          path: nativeModulePath,
          name: path.basename(nativeModulePath),
          version,
          error: error.message
        })
      }
    }

    global.localStorage.setItem(
      this.getIncompatibleNativeModulesStorageKey(),
      JSON.stringify(incompatibleNativeModules)
    )

    return incompatibleNativeModules
  }

  handleError (message, error) {
    if (atom.inSpecMode()) throw error

    let detail, location, stack
    if (error.filename && error.location && error instanceof SyntaxError) {
      location = `${error.filename}:${error.location.first_line + 1}:${error.location.first_column + 1}`
      detail = `${error.message} in ${location}`
      stack = 'SyntaxError: ' + error.message + '\n' + 'at ' + location
    } else if (error.less && error.filename && error.column != null && error.line != null) {
      location = `${error.filename}:${error.line}:${error.column}`
      detail = `${error.message} in ${location}`
      stack = 'LessError: ' + error.message + '\n' + 'at ' + location
    } else {
      detail = error.message
      stack = error.stack || error
    }

    this.notificationManager.addFatalError(message, {
      stack, detail, packageName: this.name, dismissable: true
    })
  }
}