Implement permission request handler

src/main/permissionRequestHandler.js

@@ -0,0 +1,88 @@
+const {dialog} = require('electron');
+const {URL} = require('url');
+const fs = require('fs');
+
+const PERMISSION_GRANTED = 'granted';
+const PERMISSION_DENIED = 'denied';
+
+class PermissionManager {
+  constructor(file) {
+    this.file = file;
+    if (fs.existsSync(file)) {
+      this.permissions = JSON.parse(fs.readFileSync(this.file, 'utf-8'));
+    } else {
+      this.permissions = {};
+    }
+  }
+
+  writeFileSync() {
+    fs.writeFileSync(this.file, JSON.stringify(this.permissions, null, '  '));
+  }
+
+  grant(origin, permission) {
+    if (!this.permissions[origin]) {
+      this.permissions[origin] = {};
+    }
+    this.permissions[origin][permission] = PERMISSION_GRANTED;
+    this.writeFileSync();
+  }
+
+  deny(origin, permission) {
+    if (!this.permissions[origin]) {
+      this.permissions[origin] = {};
+    }
+    this.permissions[origin][permission] = PERMISSION_DENIED;
+    this.writeFileSync();
+  }
+
+  clear(origin, permission) {
+    delete this.permissions[origin][permission];
+  }
+
+  isGranted(origin, permission) {
+    return this.permissions[origin] && this.permissions[origin][permission] === PERMISSION_GRANTED;
+  }
+
+  isDenied(origin, permission) {
+    return this.permissions[origin] && this.permissions[origin][permission] === PERMISSION_DENIED;
+  }
+}
+
+function permissionRequestHandler(mainWindow, permissionFile) {
+  const permissionManager = new PermissionManager(permissionFile);
+  return (webContents, permission, callback) => {
+    const targetURL = new URL(webContents.getURL());
+    if (permissionManager.isDenied(targetURL.origin, permission)) {
+      callback(false);
+      return;
+    }
+    if (permissionManager.isGranted(targetURL.origin, permission)) {
+      callback(true);
+      return;
+    }
+
+    const buttons = ['Allow', 'Deny', 'Skip'];
+    const result = dialog.showMessageBox(mainWindow, {
+      type: 'warning',
+      buttons,
+      title: 'Permission Required',
+      message: `${targetURL.host} is requesting "${permission}" permission`,
+      cancelId: 2,
+      noLink: false
+    });
+    switch (result) {
+    case buttons.indexOf('Allow'):
+      permissionManager.grant(targetURL.origin, permission);
+      callback(true);
+      return;
+    case buttons.indexOf('Deny'):
+      permissionManager.deny(targetURL.origin, permission);
+      callback(false);
+      return;
+    default:
+      callback(false);
+    }
+  };
+}
+
+module.exports = permissionRequestHandler;