feat(GUI): add convenience localstorage class (#2276)

* feat(GUI): add convenience localstorage class

We add a class `Storage` and accompanying helper methods that makes
localStorage usage easier.

Change-Type: patch
Changelog-Entry: Add a convenience Storage class on top of localStorage.

lib/gui/app/models/local-settings.js

@@ -21,6 +21,7 @@ const _ = require('lodash')
 const fs = require('fs')
 const path = require('path')
 const os = require('os')
+const Storage = require('./storage')
 
 /**
  * @summary Local storage settings key
@@ -28,6 +29,7 @@ const os = require('os')
  * @type {String}
  */
 const LOCAL_STORAGE_SETTINGS_KEY = 'etcher-settings'
+const settingsStorage = new Storage(LOCAL_STORAGE_SETTINGS_KEY)
 
 /**
  * @summary Local settings filename
@@ -86,7 +88,7 @@ exports.readAll = () => {
   const workdirConfigPath = path.join(process.cwd(), RCFILE)
   const settings = {}
   return Bluebird.try(() => {
-    _.merge(settings, JSON.parse(window.localStorage.getItem(LOCAL_STORAGE_SETTINGS_KEY)))
+    _.merge(settings, settingsStorage.getAll())
   }).return(readConfigFile(homeConfigPath))
     .then((homeConfig) => {
       _.merge(settings, homeConfig)
@@ -114,9 +116,8 @@ exports.readAll = () => {
  * });
  */
 exports.writeAll = (settings) => {
-  const INDENTATION_SPACES = 2
   return Bluebird.try(() => {
-    window.localStorage.setItem(LOCAL_STORAGE_SETTINGS_KEY, JSON.stringify(settings, null, INDENTATION_SPACES))
+    settingsStorage.setAll(settings)
   })
 }
 
@@ -137,6 +138,6 @@ exports.writeAll = (settings) => {
  */
 exports.clear = () => {
   return Bluebird.try(() => {
-    window.localStorage.removeItem(LOCAL_STORAGE_SETTINGS_KEY)
+    settingsStorage.clearAll()
   })
 }

lib/gui/app/models/storage.js

@@ -0,0 +1,164 @@
+/*
+ * Copyright 2018 resin.io
+ *
+ * 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.
+ */
+
+'use strict'
+
+const INDENTATION_SPACES = 2
+
+/**
+ * @summary Localstorage class and helper functions
+ * @class
+ * @public
+ */
+class Storage {
+  /**
+   * @function
+   * @public
+   *
+   * @param {String} superkey - superkey
+   *
+   * @example
+   * const potatoStorage = new Storage('potato')
+   */
+  constructor (superkey) {
+    this.superkey = superkey
+  }
+
+  /**
+   * @summary Get the whole object under the superkey
+   * @function
+   * @public
+   *
+   * @returns {Object}
+   *
+   * @example
+   * for (const key in potatoStorage.getAll()) {
+   *   console.log(key)
+   * }
+   */
+  getAll () {
+    try {
+      // JSON.parse(null) === null, so we fallback to {}
+      return JSON.parse(window.localStorage.getItem(this.superkey)) || {}
+    } catch (err) {
+      this.setAll({})
+      throw err
+    }
+  }
+
+  /**
+   * @summary Set the whole object under the superkey
+   * @function
+   * @public
+   *
+   * @param {Any} value - any valid JSON value
+   *
+   * @example
+   * potatoStorage.setAll({
+   *   location: 'somewhere',
+   *   freshness: 100,
+   *   edible: true
+   * })
+   */
+  setAll (value) {
+    window.localStorage.setItem(this.superkey, JSON.stringify(value, null, INDENTATION_SPACES))
+  }
+
+  /**
+   * @summary Clear the whole object under the superkey
+   * @function
+   * @public
+   *
+   * @example
+   * potatoStorage.clearAll()
+   */
+  clearAll () {
+    window.localStorage.removeItem(this.superkey)
+  }
+
+  /**
+   * @summary Get a stored value
+   * @function
+   * @public
+   *
+   * @param {String} key - object field key
+   * @param {Any} defaultValue - any valid JSON value
+   * @returns {Any} - the JSON parsed value
+   *
+   * @example
+   * potatoStorage.get('location', 'my farm')
+   */
+  get (key, defaultValue) {
+    const value = this.getAll()[key]
+
+    // eslint-disable-next-line no-undefined
+    if (value === undefined) {
+      return defaultValue
+    }
+
+    return value
+  }
+
+  /**
+   * @summary Modify a stored value
+   * @function
+   * @public
+   *
+   * @param {String} key - object field key
+   * @param {Function} func - function to apply to the value
+   * @param {Any} defaultValue - fallback value
+   * @returns {Any} - the value returned by the function applied above
+   *
+   * @example
+   * potatoStorage.modify('freshness', (freshness) => {
+   *   return freshness + 1
+   * })
+   */
+  modify (key, func, defaultValue) {
+    const obj = this.getAll()
+
+    let result = null
+    // eslint-disable-next-line no-undefined
+    if (obj[key] === undefined) {
+      result = func(defaultValue)
+    } else {
+      result = func(obj[key])
+    }
+
+    // eslint-disable-next-line lodash/prefer-lodash-method
+    this.setAll(Object.assign(obj, { [key]: result }))
+    return result
+  }
+
+  /**
+   * @summary Set a stored value
+   * @function
+   * @public
+   *
+   * @param {String} key - object field key
+   * @param {Any} value - value to set
+   *
+   * @example
+   * potatoStorage.set('edible', true)
+   */
+  set (key, value) {
+    this.modify(key, () => {
+      return value
+    })
+  }
+}
+
+module.exports = Storage

tests/gui/models/storage.spec.js

@@ -0,0 +1,97 @@
+/*
+ * Copyright 2018 resin.io
+ *
+ * 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.
+ */
+
+'use strict'
+
+const _ = require('lodash')
+const m = require('mochainon')
+const Storage = require('../../../lib/gui/app/models/storage')
+
+describe('Browser: storage', function () {
+  beforeEach(function () {
+    this.testStorage = new Storage('test')
+
+    this.superObject = {
+      fieldA: 1,
+      fieldB: 2
+    }
+
+    this.testStorage.setAll(this.superObject)
+  })
+
+  afterEach(function () {
+    this.testStorage.clearAll()
+  })
+
+  describe('.getAll()', function () {
+    it('should return the super-object', function () {
+      m.chai.expect(this.testStorage.getAll()).to.deep.equal(this.superObject)
+    })
+  })
+
+  describe('.setAll()', function () {
+    it('should set the super-object', function () {
+      const superObject = { fieldC: 3, fieldD: 4 }
+      this.testStorage.setAll(superObject)
+      m.chai.expect(this.testStorage.getAll()).to.deep.equal(superObject)
+    })
+  })
+
+  describe('.clearAll()', function () {
+    it('should remove the super-object', function () {
+      this.testStorage.clearAll()
+      m.chai.expect(this.testStorage.getAll()).to.deep.equal({})
+    })
+  })
+
+  describe('.get()', function () {
+    it('should retrieve the value', function () {
+      m.chai.expect(this.testStorage.get('fieldA')).to.equal(1)
+    })
+  })
+
+  describe('.modify()', function () {
+    it('should change the value', function () {
+      this.testStorage.modify('fieldA', (fieldA) => {
+        return fieldA + 1
+      })
+      m.chai.expect(this.testStorage.get('fieldA')).to.equal(2)
+    })
+
+    it('should return a value', function () {
+      const value = this.testStorage.modify('fieldA', (fieldA) => {
+        return fieldA + 1
+      })
+      m.chai.expect(value).to.equal(2)
+    })
+
+    it('should use the fallback default value if field doesn\'t exist', function () {
+      const FALLBACK = 1.5
+      m.chai.expect(this.testStorage.modify('fieldC', _.ceil, FALLBACK)).to.equal(2)
+    })
+
+    it('should be undefined if no fallback default value is given', function () {
+      m.chai.expect(this.testStorage.modify('fieldC', _.identity)).to.be.undefined
+    })
+  })
+
+  describe('.set()', function () {
+    it('should set a value', function () {
+      this.testStorage.set('fieldC', 3)
+      m.chai.expect(this.testStorage.get('fieldC')).to.equal(3)
+    })
+  })
+})