timeseries.py

    sigSensorAdded = pyqtSignal(SensorInstrument)
    sigSensorRemoved = pyqtSignal(SensorInstrument)

    sigSourcesAdded = pyqtSignal(list)
    sigSourcesRemoved = pyqtSignal(list)



    _sep = ';'

    def __init__(self, imageFiles=None):
        super(TimeSeries, self).__init__()
        self.mTSDs = list()
        self.mSensors = []
        self.mShape = None
        self.mDateTimePrecision = DateTimePrecision.Original

        self.mCurrentDates = []

        self.cnDate = 'Date'
        self.cnSensor = 'Sensor'
        self.cnNS = 'ns'
        self.cnNL = 'nl'
        self.cnNB = 'nb'
        self.cnCRS = 'CRS'
        self.cnImages = 'Source Image(s)'
        self.mColumnNames = [self.cnDate, self.cnSensor,
                             self.cnNS, self.cnNL, self.cnNB,
                             self.cnCRS, self.cnImages]

        self.mRootIndex = QModelIndex()


        self.mTasks = list()

        if imageFiles is not None:
            self.addSources(imageFiles)


    def setCurrentDates(self, tsds:list):


        self.mCurrentDates.clear()
        self.mCurrentDates.extend(tsds)
        for tsd in tsds:
            assert isinstance(tsd, TimeSeriesDatum)
            if tsd in self:
                idx = self.tsdToIdx(tsd)
                # force reset of background color
                idx2 = self.index(idx.row(), self.columnCount()-1)
                self.dataChanged.emit(idx, idx2, [Qt.BackgroundColorRole])

    def sensor(self, sensorID:str)->SensorInstrument:
        """
        Returns the sensor with sid = sid
        :param sensorID: str, sensor id
        :return: SensorInstrument
        """
        assert isinstance(sensorID, str)
        for sensor in self.mSensors:
            assert isinstance(sensor, SensorInstrument)
            if sensor.id() == sensorID:
                return sensor
        return None


    def sensors(self)->list:
        """
        Returns the list of sensors derived from the TimeSeries data sources
        :return: [list-of-SensorInstruments]
        """
        return self.mSensors[:]

    def loadFromFile(self, path, n_max=None, progressDialog:QProgressDialog=None):
        """
        Loads a CSV file with source images of a TimeSeries
        :param path: str, Path of CSV file
        :param n_max: optional, maximum number of files to load
        """

        images = []
        masks = []
        with open(path, 'r') as f:
            lines = f.readlines()
            for l in lines:
                if re.match('^[ ]*[;#&]', l):
                    continue

                parts = re.split('[\n'+TimeSeries._sep+']', l)
                parts = [p for p in parts if p != '']
                images.append(parts[0])
                if len(parts) > 1:
                    masks.append(parts[1])


        if n_max:
            n_max = min([len(images), n_max])
            self.addSources(images[0:n_max], progressDialog=progressDialog)
        else:
            self.addSources(images, progressDialog=progressDialog)
        #self.addMasks(masks)


    def saveToFile(self, path):
        """
        Saves the TimeSeries sources into a CSV file
        :param path: str, path of CSV file
        :return: path of CSV file
        """
        if path is None or len(path) == 0:
            return None

        lines = []
        lines.append('#Time series definition file: {}'.format(np.datetime64('now').astype(str)))
        lines.append('#<image path>')
        for TSD in self.mTSDs:
            assert isinstance(TSD, TimeSeriesDatum)
            for pathImg in TSD.sourceUris():
                lines.append(pathImg)

        lines = [l+'\n' for l in lines]


        with open(path, 'w') as f:
            f.writelines(lines)
            messageLog('Time series source images written to {}'.format(path))

        return path

    def pixelSizes(self):
        """
        Returns the pixel sizes of all SensorInstruments
        :return: [list-of-QgsRectangles]
        """

        r = []
        for sensor in self.mSensors2TSDs.keys():
            r.append((QgsRectangle(sensor.px_size_x, sensor.px_size_y)))
        return r


    def maxSpatialExtent(self, crs=None)->SpatialExtent:
        """
        Returns the maximum SpatialExtent of all images of the TimeSeries
        :param crs: QgsCoordinateSystem to express the SpatialExtent coordinates.
        :return:
        """
        extent = None
        for i, tsd in enumerate(self.mTSDs):
            assert isinstance(tsd, TimeSeriesDatum)
            ext = tsd.spatialExtent()
            if isinstance(extent, SpatialExtent):
                extent = extent.combineExtentWith(ext)
            else:
                extent = ext

        return extent

    def getTSD(self, pathOfInterest):
        """
        Returns the TimeSeriesDatum related to an image source
        :param pathOfInterest: str, image source uri
        :return: TimeSeriesDatum
        """
        for tsd in self.mTSDs:
            assert isinstance(tsd, TimeSeriesDatum)
            if pathOfInterest in tsd.sourceUris():
                return tsd
        return None

    def tsd(self, date: np.datetime64, sensor)->TimeSeriesDatum:
        """
        Returns the TimeSeriesDatum identified by date and sensorID
        :param date:
        :param sensor: SensorInstrument | str with sensor id
        :return:
        """
        assert isinstance(date, np.datetime64)
        if isinstance(sensor, str):
            sensor = self.sensor(sensor)
        if isinstance(sensor, SensorInstrument):
            for tsd in self.mTSDs:
                if tsd.date() == date and tsd.sensor() == sensor:
                    return tsd
        return None

    def insertTSD(self, tsd: TimeSeriesDatum)->TimeSeriesDatum:
        """
        Inserts a TimeSeriesDatum
        :param tsd: TimeSeriesDatum
        """
        #insert sorted by time & sensor
        assert tsd not in self.mTSDs
        assert tsd.sensor() in self.mSensors

        tsd.mTimeSeries = self
        tsd.sigRemoveMe.connect(lambda: self.removeTSDs([tsd]))
        tsd.rowsAboutToBeRemoved.connect(self.onSourcesAboutToBeRemoved)
        tsd.rowsRemoved.connect(self.onSourcesRemoved)
        tsd.rowsAboutToBeInserted.connect(self.onSourcesAboutToBeInserted)
        tsd.rowsInserted.connect(self.onSourcesInserted)
        tsd.sigSourcesAdded.connect(self.sigSourcesAdded)
        tsd.sigSourcesRemoved.connect(self.sigSourcesRemoved)

        row = bisect.bisect(self.mTSDs, tsd)
        self.beginInsertRows(self.mRootIndex, row, row)
        self.mTSDs.insert(row, tsd)
        self.endInsertRows()
        #self.rowsInserted()

        return tsd

    def onSourcesAboutToBeRemoved(self, parent, first, last):
        s = ""
        pass

    def onSourcesRemoved(self, parent, first, last):
        s = ""
    
    def onSourcesAboutToBeInserted(self, parent, first, last):
        s = ""
        
    def onSourcesInserted(self, parent, first, last):
        s = ""
        
  
    def removeTSDs(self, tsds):
        """
        Removes a list of TimeSeriesDatum
        :param tsds: [list-of-TimeSeriesDatum]
        """

        removed = list()
        for tsd in tsds:
            assert isinstance(tsd, TimeSeriesDatum)
            row = self.mTSDs.index(tsd)
            self.beginRemoveRows(self.mRootIndex, row, row)
            self.mTSDs.remove(tsd)
            tsd.mTimeSeries = None
            removed.append(tsd)
            self.endRemoveRows()

        if len(removed) > 0:
            self.sigTimeSeriesDatesRemoved.emit(removed)





    def tsds(self, date:np.datetime64=None, sensor:SensorInstrument=None)->list:

        """
        Returns a list of  TimeSeriesDatum of the TimeSeries. By default all TimeSeriesDatum will be returned.
        :param date: numpy.datetime64 to return the TimeSeriesDatum for
        :param sensor: SensorInstrument of interest to return the [list-of-TimeSeriesDatum] for.
        :return: [list-of-TimeSeriesDatum]
        """
        tsds = self.mTSDs[:]
        if date:
            tsds = [tsd for tsd in tsds if tsd.date() == date]
        if sensor:
            tsds = [tsd for tsd in tsds if tsd.sensor() == sensor]
        return tsds

    def clear(self):
        """
        Removes all data sources from the TimeSeries (which will be empty after calling this routine).
        """
        self.removeTSDs(self[:])






    def addSensor(self, sensor:SensorInstrument):
        """
        Adds a Sensor
        :param sensor: SensorInstrument
        """

        if not sensor in self.mSensors:
            self.mSensors.append(sensor)
            self.sigSensorAdded.emit(sensor)
            return sensor
        else:
            return None

    def checkSensorList(self):
        """
        Removes sensors without linked TSD / no data
        """
        to_remove = []
        for sensor in self.sensors():
            tsds = [tsd for tsd in self.mTSDs if tsd.sensor() == sensor]
            if len(tsds) == 0:
                to_remove.append(sensor)
        for sensor in to_remove:
            self.removeSensor(sensor)

    def removeSensor(self, sensor:SensorInstrument)->SensorInstrument:
        """
        Removes a sensor and all linked images
        :param sensor: SensorInstrument
        :return: SensorInstrument or none, if sensor was not defined in the TimeSeries
        """
        assert isinstance(sensor, SensorInstrument)
        if sensor in self.mSensors:
            tsds = [tsd for tsd in self.mTSDs if tsd.sensor() == sensor]
            self.removeTSDs(tsds)
            self.mSensors.remove(sensor)
            self.sigSensorRemoved.emit(sensor)
            return sensor
        return None

    def addSourcesAsync(self, sources:list, nWorkers:int = 1):

        tm = QgsApplication.taskManager()
        assert isinstance(tm, QgsTaskManager)
        assert isinstance(nWorkers, int) and nWorkers >= 1


        # see https://stackoverflow.com/questions/312443/how-do-you-split-a-list-into-evenly-sized-chunks
        def chunks(l, n):
            """Yield successive n-sized chunks from l."""
            for i in range(0, len(l), n):
                yield l[i:i + n]

        n = int(len(sources) / nWorkers)
        #for subset in chunks(sources, n):
        for source in sources:
            subset = [source]
            dump = pickle.dumps(subset)
            #taskDescription = 'Load EOTSV {} sources {}'.format(len(subset), uuid.uuid4())
            taskDescription = 'Load {}'.format(source)
            qgsTask = QgsTask.fromFunction(taskDescription, doLoadTimeSeriesSourcesTask, dump, on_finished=self.onAddSourcesAsyncFinished)
            self.mTasks.append(qgsTask)

            if False: # for debugging
                resultDump = doLoadTimeSeriesSourcesTask(qgsTask, dump)
                self.onAddSourcesAsyncFinished(None, resultDump)
            else:
                tm.addTask(qgsTask)

    def onAddSourcesAsyncFinished(self, *args):
        # print(':: onAddSourcesAsyncFinished')
        error = args[0]
        if error is None:
            try:
                addedDates = []
                dump = args[1]
                sources = pickle.loads(dump)
                for source in sources:
                    newTSD = self._addSource(source)
                    if isinstance(newTSD, TimeSeriesDatum):
                        addedDates.append(newTSD)

                if len(addedDates) > 0:
                    self.sigTimeSeriesDatesAdded.emit(addedDates)


            except Exception as ex:
                s = ""
        else:
            s = ""
        #self._cleanTasks()

    def _cleanTasks(self):
        toRemove = []
        for task in self.mTasks:
            if isinstance(task, QgsTask):
                if task.status() in [QgsTask.Complete, QgsTask.Terminated]:
                    toRemove.append(task)

        for t in toRemove:
            self.mTasks.remove(t)

    def addSources(self, sources:list, progressDialog:QProgressDialog=None):
        """
        Adds new data sources to the TimeSeries
        :param sources: [list-of-TimeSeriesSources]
        """
        assert isinstance(sources, list)

        nMax = len(sources)
        #self.sigTimeSeriesSourcesAboutToBeChanged.emit()

        self.sigLoadingProgress.emit(0, nMax, 'Start loading {} sources...'.format(nMax))
        
        if isinstance(progressDialog, QProgressDialog):
            progressDialog.setRange(0, nMax)
            progressDialog.setLabelText('Load rasters...'.format(nMax))
        # 1. read sources
        # this could be excluded into a parallel process
        addedDates = []
        for i, source in enumerate(sources):
            newTSD = None
            msg = None
            if False: #debug
                newTSD = self._addSource(source)
            else:
                try:
                    newTSD = self._addSource(source)
                except Exception as ex:
                    msg = 'Unable to add: {}\n{}'.format(str(source), str(ex))
                    print(msg, file=sys.stderr)

            if isinstance(progressDialog, QProgressDialog):
                if progressDialog.wasCanceled():
                    break
                progressDialog.setValue(i)
                progressDialog.setLabelText('{}/{}'.format(i+1, nMax))

            if (i+1) % 10 == 0:
                self.sigLoadingProgress.emit(i+1, nMax, msg)

            if (i+1) % 50 == 0:
                QGuiApplication.processEvents()

            if isinstance(newTSD, TimeSeriesDatum):
                addedDates.append(newTSD)

        #if len(addedDates) > 0:

        if isinstance(progressDialog, QProgressDialog):
            progressDialog.setLabelText('Create map widgets...')

        if len(addedDates) > 0:
            self.sigTimeSeriesDatesAdded.emit(addedDates)

    def _addSource(self, source:TimeSeriesSource)->TimeSeriesDatum:
        """
        :param source:
        :return: TimeSeriesDatum (if new created)
        """
        if isinstance(source, TimeSeriesSource):
            tss = source
        else:
            tss = TimeSeriesSource.create(source)

        assert isinstance(tss, TimeSeriesSource)

        newTSD = None

        tsdDate = self.date2date(tss.date())
        tssDate = tss.date()
        sid = tss.sid()
        sensor = self.sensor(sid)
        # if necessary, add a new sensor instance
        if not isinstance(sensor, SensorInstrument):
            sensor = self.addSensor(SensorInstrument(sid))
        assert isinstance(sensor, SensorInstrument)
        tsd = self.tsd(tsdDate, sensor)
        # if necessary, add a new TimeSeriesDatum instance
        if not isinstance(tsd, TimeSeriesDatum):
            tsd = self.insertTSD(TimeSeriesDatum(self, tsdDate, sensor))
            newTSD = tsd
            # addedDates.append(tsd)
        assert isinstance(tsd, TimeSeriesDatum)
        # add the source
        tsd.addSource(tss)
        return newTSD

    def setDateTimePrecision(self, mode:DateTimePrecision):
        """
        Sets the precision with which the parsed DateTime information will be handled.
        :param mode: TimeSeriesViewer:DateTimePrecision
        :return:
        """
        self.mDateTimePrecision = mode

        #do we like to update existing sources?




    def date2date(self, date:np.datetime64)->np.datetime64:
        """
        Converts a date of arbitrary precission into the date with precission according to the EOTSV settions.
        :param date: numpy.datetime64
        :return: numpy.datetime64
        """
        assert isinstance(date, np.datetime64)
        if self.mDateTimePrecision == DateTimePrecision.Original:
            return date
        else:
            date = np.datetime64(date, self.mDateTimePrecision.value)

        return date

    def sources(self) -> list:
        """
        Returns the input sources
        :return: iterator over [list-of-TimeSeriesSources]
        """

        for tsd in self:
            for source in tsd:
                yield source



    def sourceUris(self)->list:
        """
        Returns the uris of all sources
        :return: [list-of-str]
        """
        uris = []
        for tsd in self:
            assert isinstance(tsd, TimeSeriesDatum)
            uris.extend(tsd.sourceUris())
        return uris

    def __len__(self):
        return len(self.mTSDs)

    def __iter__(self):
        return iter(self.mTSDs)

    def __getitem__(self, slice):
        return self.mTSDs[slice]

    def __delitem__(self, slice):
        self.removeTSDs(slice)

    def __contains__(self, item):
        return item in self.mTSDs

    def __repr__(self):
        info = []
        info.append('TimeSeries:')
        l = len(self)
        info.append('  Scenes: {}'.format(l))


        return '\n'.join(info)

    def headerData(self, section, orientation, role):
        assert isinstance(section, int)

        if orientation == Qt.Horizontal and role == Qt.DisplayRole:

            if len(self.mColumnNames) > section:
                return self.mColumnNames[section]
            else:
                return ''

        else:
            return None

    def parent(self, index: QModelIndex) -> QModelIndex:
        """
        Returns the parent index of a QModelIndex `index`
        :param index: QModelIndex
        :return: QModelIndex
        """
        if not index.isValid():
            return QModelIndex()

        node = index.internalPointer()
        tsd = None
        tss = None

        if isinstance(node, TimeSeriesDatum):
            return self.mRootIndex

        elif isinstance(node, TimeSeriesSource):
            tss = node
            tsd = node.timeSeriesDatum()
            return self.createIndex(self.mTSDs.index(tsd), 0, tsd)

    def rowCount(self, index: QModelIndex=None) -> int:
        """
        Return the row-count, i.e. number of child node for a TreeNode as index `index`.
        :param index: QModelIndex
        :return: int
        """
        if index is None:
            index = QModelIndex()

        if not index.isValid():
            return len(self)

        node = index.internalPointer()
        if isinstance(node, TimeSeriesDatum):
            return len(node)

        if isinstance(node, TimeSeriesSource):
            return 0


    def columnNames(self) -> list:
        """
        Returns the column names
        :return: [list-of-string]
        """
        return self.mColumnNames[:]

    def columnCount(self, index:QModelIndex = None) -> int:
        """
        Returns the number of columns
        :param index: QModelIndex
        :return:
        """

        return len(self.mColumnNames)


    def connectTreeView(self, treeView):
        self.mTreeView = treeView

    def index(self, row: int, column: int, parent: QModelIndex = None) -> QModelIndex:
        """
        Returns the QModelIndex
        :param row: int
        :param column: int
        :param parent: QModelIndex
        :return: QModelIndex
        """
        if parent is None:
            parent = self.mRootIndex
        else:
            assert isinstance(parent, QModelIndex)

        if row < 0 or row >= len(self):
            return QModelIndex()
        if column < 0 or column >= len(self.mColumnNames):
            return QModelIndex()


        if parent == self.mRootIndex:
            # TSD node
            if row < 0 or row >= len(self):
                return QModelIndex()
            return self.createIndex(row, column, self[row])

        elif parent.parent() == self.mRootIndex:
            # TSS node
            tsd = self.tsdFromIdx(parent)
            if row < 0 or row >= len(tsd):
                return QModelIndex()
            return self.createIndex(row, column, tsd[row])

        return QModelIndex()

    def tsdToIdx(self, tsd:TimeSeriesDatum)->QModelIndex:
        """
        Returns an QModelIndex pointing on a TimeSeriesDatum of interest
        :param tsd: TimeSeriesDatum
        :return: QModelIndex
        """
        row = self.mTSDs.index(tsd)
        return self.index(row, 0)

    def tsdFromIdx(self, index: QModelIndex) -> TimeSeriesDatum:
        """
        Returns the TimeSeriesDatum related to an QModelIndex `index`.
        :param index: QModelIndex
        :return: TreeNode
        """

        if index.row() == -1 and index.column() == -1:
            return None
        elif not index.isValid():
            return None
        else:
            node = index.internalPointer()
            if isinstance(node, TimeSeriesDatum):
                return node
            elif isinstance(node, TimeSeriesSource):
                return node.timeSeriesDatum()

        return None

    def data(self, index, role):
        """

        :param index: QModelIndex
        :param role: Qt.ItemRole
        :return: object
        """
        assert isinstance(index, QModelIndex)
        if not index.isValid():
            return None

        node = index.internalPointer()
        tsd = None
        tss = None
        if isinstance(node, TimeSeriesSource):
            tsd = node.timeSeriesDatum()
            tss = node
        elif isinstance(node, TimeSeriesDatum):
            tsd = node

        if role == Qt.UserRole:
            return node

        cName = self.mColumnNames[index.column()]

        if isinstance(tss, TimeSeriesSource):
            if role in [Qt.DisplayRole]:
                if cName == self.cnDate:
                    return str(tsd.date())
                if cName == self.cnImages:
                    return tss.uri()
                if cName == self.cnNB:
                    return tss.nb
                if cName == self.cnNL:
                    return tss.nl
                if cName == self.cnNS:
                    return tss.ns
                if cName == self.cnCRS:
                    return tss.crs().description()

        if isinstance(tsd, TimeSeriesDatum):
            if role in [Qt.DisplayRole]:
                if cName == self.cnSensor:
                    return tsd.sensor().name()
                if cName == self.cnImages:
                    return len(tsd)
                if cName == self.cnDate:
                    return str(tsd.date())

            if role == Qt.BackgroundColorRole and tsd in self.mCurrentDates:
                return QColor('yellow')

        if isinstance(node, TimeSeriesDatum) and index.column() == 0:
            if role == Qt.CheckStateRole:
                return Qt.Checked if tsd.isVisible() else Qt.Unchecked



        return None

    def setData(self, index: QModelIndex, value: typing.Any, role: int):

        if not index.isValid():
            return False

        result = False

        node = index.internalPointer()
        if isinstance(node, TimeSeriesDatum):
            if role == Qt.CheckStateRole and index.column() == 0:
                node.setVisibility(value == Qt.Checked)
                result = True

        if result == True:
            self.dataChanged.emit(index, index, [role])

        return result

    def flags(self, index):
        assert isinstance(index, QModelIndex)
        if not index.isValid():
            return Qt.NoItemFlags
        #cName = self.mColumnNames.index(index.column())
        flags = Qt.ItemIsEnabled | Qt.ItemIsSelectable
        if isinstance(index.internalPointer(), TimeSeriesDatum) and index.column() == 0:
            flags = flags | Qt.ItemIsUserCheckable
        return flags


class TimeSeriesTableModel(QAbstractTableModel):

    def __init__(self, TS:TimeSeries, parent=None, *args):

        super(TimeSeriesTableModel, self).__init__()
        assert isinstance(TS, TimeSeries)

        self.cnDate = 'Date'
        self.cnSensor = 'Sensor'
        self.cnNS = 'ns'
        self.cnNL = 'nl'
        self.cnNB = 'nb'
        self.cnCRS = 'CRS'
        self.cnImages = 'Image(s)'
        self.mColumnNames = [self.cnDate, self.cnSensor,
                             self.cnNS, self.cnNL, self.cnNB,
                             self.cnCRS, self.cnImages]
        self.mTimeSeries = TS
        self.mSensors = set()
        self.mTimeSeries.sigTimeSeriesDatesRemoved.connect(self.removeTSDs)
        self.mTimeSeries.sigTimeSeriesDatesAdded.connect(self.addTSDs)

        self.items = []

        self.addTSDs([tsd for tsd in self.mTimeSeries])

    def timeSeries(self)->TimeSeries:
        """
        :return: TimeSeries
        """
        return self.mTimeSeries

    def removeTSDs(self, tsds:list):
        """
        Removes TimeSeriesDatum instances
        :param tsds: list
        """
        for tsd in tsds:
            if tsd in self.mTimeSeries:
                self.mTimeSeries.removeTSDs([tsd])
            elif tsd in self.items:
                idx = self.getIndexFromDate(tsd)
                self.removeRows(idx.row(), 1)

    def tsdChanged(self, tsd:TimeSeriesDatum):
        idx = self.getIndexFromDate(tsd)
        self.dataChanged.emit(idx, idx)

    def sensorsChanged(self, sensor):
        i = self.mColumnNames.index(self.cnSensor)
        idx0 = self.createIndex(0, i)
        idx1 = self.createIndex(self.rowCount(), i)
        self.dataChanged.emit(idx0, idx1)

    def addTSDs(self, tsds):

        for tsd in tsds:
            assert isinstance(tsd, TimeSeriesDatum)
            row = bisect.bisect_left(self.items, tsd)
            self.beginInsertRows(QModelIndex(), row, row)
            self.items.insert(row, tsd)
            self.endInsertRows()

            #self.sort(self.sortColumnIndex, self.sortOrder)

        for tsd in tsds:
            assert isinstance(tsd, TimeSeriesDatum)
            tsd.sigVisibilityChanged.connect(lambda: self.tsdChanged(tsd))

        for sensor in set([tsd.sensor() for tsd in tsds]):
            if sensor not in self.mSensors:
                self.mSensors.add(sensor)
                sensor.sigNameChanged.connect(self.sensorsChanged)

    def rowCount(self, parent = QModelIndex())->int:
        return len(self.items)


    def removeRows(self, row, count , parent=QModelIndex()):
        self.beginRemoveRows(parent, row, row+count-1)
        toRemove = self.items[row:row+count]
        for tsd in toRemove:
            self.items.remove(tsd)
        self.endRemoveRows()

    def getIndexFromDate(self, tsd:TimeSeriesDatum)->QModelIndex:
        assert isinstance(tsd, TimeSeriesDatum)
        return self.createIndex(self.items.index(tsd),0)

    def getDateFromIndex(self, index:QModelIndex)->TimeSeriesDatum:
        assert isinstance(index, QModelIndex)
        if index.isValid():
            return self.items[index.row()]
        return None

    def getTimeSeriesDatumFromIndex(self, index:QModelIndex)->TimeSeriesDatum:
        assert isinstance(index, QModelIndex)
        if index.isValid():
            i = index.row()
            if i >= 0 and i < len(self.items):
                return self.items[i]

        return None

    def columnCount(self, parent = QModelIndex())->int:
        return len(self.mColumnNames)

    def data(self, index, role = Qt.DisplayRole):
        if role is None or not index.isValid():
            return None

        value = None
        columnName = self.mColumnNames[index.column()]

        TSD = self.getTimeSeriesDatumFromIndex(index)
        assert isinstance(TSD, TimeSeriesDatum)
        keys = list(TSD.__dict__.keys())
        tssList = TSD.sources()

        if role == Qt.DisplayRole or role == Qt.ToolTipRole:
            if columnName == self.cnSensor:
                if role == Qt.ToolTipRole:
                    value = TSD.sensor().description()
                else:
                    value = TSD.sensor().name()
            elif columnName == self.cnDate:
                value = '{}'.format(TSD.date())
            elif columnName == self.cnImages:
                value = '\n'.join(TSD.sourceUris())
            elif columnName == self.cnCRS:
                value = '\n'.join([tss.crs().description() for tss in tssList])
            elif columnName == self.cnNB:
                value = TSD.sensor().nb
            elif columnName == self.cnNL:
                value = '\n'.join([str(tss.nl) for tss in tssList])
            elif columnName == self.cnNS:
                value = '\n'.join([str(tss.ns) for tss in tssList])
            elif columnName == self.cnSensor:
                value = TSD.sensor().name()

            elif columnName in keys:
                value = TSD.__dict__[columnName]
            else:
                s = ""
        elif role == Qt.CheckStateRole:
            if columnName == self.cnDate:
                value = Qt.Checked if TSD.isVisible() else Qt.Unchecked

        elif role == Qt.BackgroundColorRole:
            value = None
        elif role == Qt.UserRole:
            value = TSD

        return value

    def setData(self, index, value, role=None):
        if role is None or not index.isValid():
            return None

        if role is Qt.UserRole:

            s = ""

        columnName = self.mColumnNames[index.column()]

        TSD = self.getTimeSeriesDatumFromIndex(index)
        if columnName == self.cnDate and role == Qt.CheckStateRole:
            TSD.setVisibility(value != Qt.Unchecked)
            return True
        else:
            return False

        return False

    def flags(self, index):
        if index.isValid():
            columnName = self.mColumnNames[index.column()]
            flags = Qt.ItemIsEnabled | Qt.ItemIsSelectable
            if columnName == self.cnDate: # allow check state
                flags = flags | Qt.ItemIsUserCheckable

            return flags
            # return item.qt_flags(index.column())
        return None

    def headerData(self, col, orientation, role):
        if Qt is None:
            return None
        if orientation == Qt.Horizontal and role == Qt.DisplayRole:
            return self.mColumnNames[col]
        elif orientation == Qt.Vertical and role == Qt.DisplayRole:
            return col
        return None


def getSpatialPropertiesFromDataset(ds):
    assert isinstance(ds, gdal.Dataset)

    nb = ds.RasterCount
    nl = ds.RasterYSize
    ns = ds.RasterXSize
    proj = ds.GetGeoTransform()
    px_x = float(abs(proj[1]))
    px_y = float(abs(proj[5]))

    crs = QgsCoordinateReferenceSystem(ds.GetProjection())

    return nb, nl, ns, crs, px_x, px_y











def extractWavelengths(ds):
    wl = None
    wlu = None

    # see http://www.harrisgeospatial.com/docs/ENVIHeaderFiles.html for supported wavelength units
    regWLkey = re.compile('.*wavelength[_ ]*$', re.I)
    regWLUkey = re.compile('.*wavelength[_ ]*units?$', re.I)
    regNumeric = re.compile(r"([-+]?\d*\.\d+|[-+]?\d+)", re.I)
    regWLU = re.compile('((micro|nano|centi)meters)|(um|nm|mm|cm|m|GHz|MHz)', re.I)

    if isinstance(ds, QgsRasterLayer):
        lyr = ds
        md = [l.split('=') for l in str(lyr.metadata()).splitlines() if 'wavelength' in l.lower()]
        #see http://www.harrisgeospatial.com/docs/ENVIHeaderFiles.html for supported wavelength units
        for kv in md:
            key, value = kv
            key = key.lower()