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Qt World Summit Conference App

 import Felgo 4.0
 import QtQuick 2.0

 Item {
   id: dataModel

   // property to configure target dispatcher / logic
   property alias dispatcher: logicConnection.target

   // stored data
   property var version: undefined
   property var schedule: undefined
   property var speakers: undefined
   property var tracks: undefined
   property var favorites: undefined
   property var talks: undefined
   property var contacts: undefined
   property var ratings: undefined

   property var preparedTracks
   property var preparedSpeakers

   property int localAppStarts: 0
   property bool feedBackSent: false

   property string timeZone: "+0100"

   property var webStorage: undefined // reference to WebStorage for favorites
   readonly property bool loading: api.loadingCount > 0
   readonly property bool loaded: !!schedule && !!speakers

   property bool initialized: false

   property bool notificationsEnabled: true
   onNotificationsEnabledChanged: storage.setValue("notificationsEnabled", notificationsEnabled)

   signal loadingFailed()
   signal favoriteAdded(var talk)
   signal favoriteRemoved(var talk)

   Connections {
     id: logicConnection

     // action 1 - initializeDataModel from storage - get data from local storage
     onInitializeDataModel: webStorageItem => {
       dataModel.version = storage.getValue("version")
       dataModel.schedule = storage.getValue("schedule")
       dataModel.speakers = storage.getValue("speakers")
       dataModel.tracks = storage.getValue("tracks")
       dataModel.talks = storage.getValue("talks")
       dataModel.ratings = storage.getValue("ratings")
       dataModel.notificationsEnabled = storage.getValue("notificationsEnabled") !== undefined ? storage.getValue("notificationsEnabled") : true

       dataModel.localAppStarts = storage.getValue("localAppStarts") || 0
       dataModel.feedBackSent = storage.getValue("feedBackSent") || false

       // get favorites and contacts from web storage
       dataModel.webStorage = webStorageItem
       dataModel.favorites = webStorage.getValue("favorites")
       dataModel.contacts = webStorage.getValue("contacts")

       if(dataModel.speakers) dataModel.preparedSpeakers = viewHelper.prepareSpeakers(dataModel.speakers)
       if(dataModel.tracks) dataModel.preparedTracks = viewHelper.prepareTracks(dataModel.tracks)

       dataModel.initialized = true
     }

     onResetOrInitializeDataModel: userInitiallyInSync => {
       if(!userInitiallyInSync) {
         // initially in sync changed to false -> user switched, clear favorites
         dataModel.favorites = undefined
         dataModel.initialized = false
       }
       else if(!dataModel.initialized) {
         // initially in sync changed to true again -> initialize data
         logic.initializeDataModel(webStorage)
       }
     }

     // action 3 - increaseLocalAppStarts - increase local app start counter
     onIncreaseLocalAppStarts: {
       if(!initialized)
         return

       localAppStarts++
       storage.setValue("localAppStarts",localAppStarts)
     }

     // action 4 - loadData - fetches all data from Qt WS api
     onLoadData: {
       if(initialized && !loading) {
         api.checkAPIVersion() // checks version and loads data if necessary
       }
     }

     // action 5 - setFeedBackSent - store whether feedback was sent
     onSetFeedBackSent: value => {
       if(!initialized)
         return

       feedBackSent = !!value  // ensures boolean type
       storage.setValue("feedBackSent", feedBackSent)
     }

     // action 6 - storeRating
     onStoreRating: (id, rating) => {
       if(!ratings) ratings = {}
       ratings[id] = rating
       storage.setValue("ratings", ratings)
     }

     // action 7 - toggleFavorite - add or remove item from favorites
     onToggleFavorite: item => {
       if(dataModel.favorites === undefined)
         dataModel.favorites = { }

       if(dataModel.favorites[item.id]) {
         delete dataModel.favorites[item.id]
         dataModel.favoriteRemoved(item)
       }
       else {
         dataModel.favorites[item.id] = item.id
         dataModel.favoriteAdded(item)
       }

       // store favorites
       webStorage.setValue("favorites", dataModel.favorites, function(data) {
         // in case setValue merges favorites with data from server, we update the local value
         // the merged server data comes as stringified string, thus call json.parse here
         //dataModel.favorites = webStorage.getValue("favorites") // no need to call getValue() again, we get the value from the callback
         console.debug("server favorites data:", JSON.stringify(data))
         // only update the local favorites, if the server has new merged data, in this case conflict is true
         if(data["conflict"]) {
           dataModel.favorites = data.mergedData
         }

       })
       // call the changed here, to schedule the notifications with the new local data
       favoritesChanged()
     }

     // action 8 - removeContact - remove contact from list
     onRemoveContact: id => {
       if(dataModel.contacts !== undefined && dataModel.contacts[id]) {
         delete dataModel.contacts[id]

         // store contacts
         webStorage.setValue("contacts", dataModel.contacts, function(data) {
           // in case setValue merges contacts with data from server, we update the local value
           // only update the local favorites, if the server has new merged data, in this case conflict is true
           if(data["conflict"]) {
             dataModel.contacts = data.mergedData
           }
         })

         // signal that contacts changed
         dataModel.contactsChanged()
       }
     }

     // action 9 - loadContact - loads contact from Eventbrite
     onLoadContact: (id, successHandler, errorHandler) => {
       api.sendGetRequest(Qt.resolvedUrl("https://www.qtworldsummit.com/2019/api/attendee/show/?id=" + id),
                          successHandler, errorHandler)
     }

     // action 10 - addContact - store contact from barcode scanner
     onAddContact: (id, contact) => {
       if(dataModel.contacts === undefined)
         dataModel.contacts = { }

       // store contact
       dataModel.contacts[id] = contact
       webStorage.setValue("contacts", dataModel.contacts, function(data) {
         // in case setValue merges contacts with data from server, we update the local value
         // only update the local favorites, if the server has new merged data, in this case conflict is true
         if(data["conflict"]) {
           dataModel.contacts = data.mergedData
         }
       })

       // signal that contacts changed
       dataModel.contactsChanged()
     }

     // action 10 - clearContacts
     onClearContacts: {
       webStorage.setValue("contacts",{})
     }

     // action 11 - clears locally stored data
     onClearCache: {
       // reset dataModel, but keep favorites and contacts
       var favorites = dataModel.favorites
       var contacts = dataModel.contacts
       _.reset()
       dataModel.favorites = favorites
       dataModel.contacts = contacts

       // clear local storage, favorites and contacts are still in webStorage
       storage.clearAll()
       initialized = true // also reloads api data after reset
     }

     // action 12 - setNotificationsEnabled
     onSetNotificationsEnabled: value => {
       notificationsEnabled = value
     }
   }

   // api for data access
   QtWSApi {
     id: api
   }

   // storage for caching data
   Storage {
     id: storage
     databaseName: "localStorage"
   }

   // private
   Item {
     id: _

     // reset data model
     function reset() {
       dataModel.initialized = false
       dataModel.version = undefined
       dataModel.schedule = undefined
       dataModel.speakers = undefined
       dataModel.tracks = undefined
       dataModel.talks = undefined
       dataModel.ratings = undefined
       dataModel.favorites = undefined
       dataModel.contacts = undefined
       dataModel.notificationsEnabled = true

       localAppStarts = 0
       feedBackSent = false
     }
   }

   // isFavorite - check if item is favorited
   function isFavorite(id) {
     return dataModel.favorites !== undefined && dataModel.favorites[id] !== undefined
   }

   function getRating(id) {
     if(!ratings || !(id in ratings)) return -1