Initial commit

src/connected-devices/index.ts

@@ -0,0 +1,214 @@
+/*
+ * server component for the TimeLimit App
+ * Copyright (C) 2019 Jonas Lochmann
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import { EventEmitter } from 'events'
+import { Database } from '../database'
+
+export class ConnectedDevicesManager {
+  private deviceConnectionCounters = new Map<string, number>()
+  // event name = key, value = boolean/ isConnected
+  deviceConnectionChangeEmitter = new EventEmitter()
+
+  static buildKey = ({ familyId, deviceId }: {familyId: string, deviceId: string}) => `${familyId}_${deviceId}`
+
+  reportDeviceConnected = ({ key }: {key: string}) => {
+    const oldValue = this.deviceConnectionCounters.get(key) || 0
+    const newValue = oldValue + 1
+
+    this.deviceConnectionCounters.set(key, newValue)
+
+    if (oldValue === 0) {
+      this.deviceConnectionChangeEmitter.emit(key, true)
+    }
+  }
+
+  reportDeviceDisconnected = ({ key }: {key: string}) => {
+    const oldValue = this.deviceConnectionCounters.get(key) || 0
+    const newValue = Math.max(0, oldValue - 1)
+
+    if (newValue === 0) {
+      this.deviceConnectionCounters.delete(key)
+    } else {
+      this.deviceConnectionCounters.set(key, newValue)
+    }
+
+    if (oldValue !== 0 && newValue === 0) {
+      this.deviceConnectionChangeEmitter.emit(key, false)
+    }
+  }
+
+  isDeviceConnected = ({ key }: {key: string}) => (
+    this.deviceConnectionCounters.has(key) &&
+    (this.deviceConnectionCounters.get(key) !== 0)
+  )
+}
+
+export class VisibleConnectedDevicesManager {
+  connectedDevicesManager = new ConnectedDevicesManager()
+  private database: Database
+
+  constructor ({ database }: {
+    database: Database
+  }) {
+    this.database = database
+  }
+
+  private familyDeviceShareConnectedChangeEmitter = new EventEmitter()
+
+  notifyShareConnectedChanged = ({ familyId, deviceId, showDeviceConnected }: { familyId: string, deviceId: string, showDeviceConnected: boolean }) => {
+    this.familyDeviceShareConnectedChangeEmitter.emit(familyId, { deviceId, showDeviceConnected })
+  }
+
+  observeConnectedDevicesOfFamily = ({ familyId, listener }: {
+    familyId: string
+    listener: (deviceIds: Array<string>) => void
+  }): {
+    shutdown: () => void
+  } => {
+    let observesDevices = new Set<string>()
+    let devicesWithSharingEnabled = new Set<string>()
+    let connectedDevices = new Set<string>()
+    let sentConnectedDevices = new Set<string>()
+    let hasShutDown = false
+    let shutdownHooks: Array<() => void> = []
+
+    const shutdown = () => {
+      hasShutDown = true
+
+      shutdownHooks.forEach((hook) => hook())
+    }
+
+    const sendStatus = () => {
+      if (hasShutDown) {
+        return
+      }
+
+      let result: Array<string> = []
+
+      sentConnectedDevices.forEach((deviceId) => result.push(deviceId))
+
+      listener(result)
+    }
+
+    const addDevice = ({ deviceId, showDeviceConnected }: {
+      deviceId: string
+      showDeviceConnected: boolean
+    }) => {
+      const key = ConnectedDevicesManager.buildKey({ familyId, deviceId })
+      const isConnected = this.connectedDevicesManager.isDeviceConnected({ key })
+
+      if (!observesDevices.has(deviceId)) {
+        observesDevices.add(deviceId)
+
+        if (isConnected) {
+          connectedDevices.add(deviceId)
+        }
+
+        if (!hasShutDown) {
+          const listener = (nowConnected: boolean) => {
+            const oldConnected = connectedDevices.has(deviceId)
+
+            if (oldConnected !== nowConnected) {
+              if (nowConnected) {
+                connectedDevices.add(deviceId)
+
+                if (devicesWithSharingEnabled.has(deviceId)) {
+                  sentConnectedDevices.add(deviceId)
+                  sendStatus()
+                }
+              } else {
+                connectedDevices.delete(deviceId)
+
+                if (devicesWithSharingEnabled.has(deviceId)) {
+                  sentConnectedDevices.delete(deviceId)
+                  sendStatus()
+                }
+              }
+            }
+          }
+
+          this.connectedDevicesManager.deviceConnectionChangeEmitter.addListener(key, listener)
+
+          shutdownHooks.push(() => {
+            this.connectedDevicesManager.deviceConnectionChangeEmitter.removeListener(key, listener)
+          })
+        }
+      }
+
+      if (showDeviceConnected) {
+        if (!devicesWithSharingEnabled.has(deviceId)) {
+          devicesWithSharingEnabled.add(deviceId)
+        }
+
+        if (isConnected) {
+          if (!sentConnectedDevices.has(deviceId)) {
+            sentConnectedDevices.add(deviceId)
+            sendStatus()
+          }
+        }
+      } else {
+        if (devicesWithSharingEnabled.has(deviceId)) {
+          devicesWithSharingEnabled.delete(deviceId)
+
+          if (sentConnectedDevices.has(deviceId)) {
+            sentConnectedDevices.delete(deviceId)
+            sendStatus()
+          }
+        }
+      }
+    }
+
+    // add all current devices
+    ;(async () => {
+      const devicesUnsafe = await this.database.device.findAll({
+        where: {
+          familyId
+        },
+        attributes: [
+          'deviceId',
+          'showDeviceConnected'
+        ]
+      })
+
+      const devices = devicesUnsafe.map(({ deviceId, showDeviceConnected }) => ({
+        deviceId, showDeviceConnected
+      }))
+
+      devices.forEach(({ deviceId, showDeviceConnected }) => {
+        addDevice({ deviceId, showDeviceConnected })
+      })
+    })().catch((ex) => { /* ignore */ })
+
+    {
+      // add all new devices + apply changes of sharing
+      const listener = ({ deviceId, showDeviceConnected }: {
+        deviceId: string
+        showDeviceConnected: boolean
+      }) => {
+        addDevice({
+          deviceId,
+          showDeviceConnected
+        })
+      }
+
+      this.familyDeviceShareConnectedChangeEmitter.addListener(familyId, listener)
+      shutdownHooks.push(() => this.familyDeviceShareConnectedChangeEmitter.removeListener(familyId, listener))
+    }
+
+    return { shutdown }
+  }
+}