utils.py

# -*- coding: utf-8 -*-
"""
/***************************************************************************
                              EO Time Series Viewer
                              -------------------
        begin                : 2015-08-20
        git sha              : $Format:%H$
        copyright            : (C) 2017 by HU-Berlin
        email                : benjamin.jakimow@geo.hu-berlin.de
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
"""
# noinspection PyPep8Naming

import os, sys, math, re, io, fnmatch, uuid


from collections import defaultdict
from qgis.core import *
from qgis.gui import *
import qgis.utils
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtXml import QDomDocument
from PyQt5 import uic
from osgeo import gdal, ogr

import weakref
import numpy as np

jp = os.path.join
dn = os.path.dirname

from timeseriesviewer import DIR_UI, DIR_REPO
from timeseriesviewer import messageLog
import timeseriesviewer
MAP_LAYER_STORES = [QgsProject.instance()]

def qgisInstance():
    """
    If existent, returns the QGIS Instance.
    :return: QgisInterface | None
    """

    from timeseriesviewer.main import TimeSeriesViewer
    if isinstance(qgis.utils.iface, QgisInterface) and \
        not isinstance(qgis.utils.iface, TimeSeriesViewer):
        return qgis.utils.iface
    else:
        return None


def findMapLayer(layer)->QgsMapLayer:
    """
    Returns the first QgsMapLayer out of all layers stored in MAP_LAYER_STORES that matches layer
    :param layer: str layer id or layer name or QgsMapLayer
    :return: QgsMapLayer
    """
    if isinstance(layer, QgsMapLayer):
        return layer
    elif isinstance(layer, str):
        #check for IDs
        for store in MAP_LAYER_STORES:
            l = store.mapLayer(layer)
            if isinstance(l, QgsMapLayer):
                return l
        #check for name
        for store in MAP_LAYER_STORES:
            l = store.mapLayersByName(layer)
            if len(l) > 0:
                return l[0]
    return None


def file_search(rootdir, pattern, recursive=False, ignoreCase=False, directories=False, fullpath=False):
    """
    Searches for files
    :param rootdir: root directory to search for files.
    :param pattern: wildcard ("my*files.*") or regular expression to describe the file name.
    :param recursive: set True to search recursively.
    :param ignoreCase: set True to ignore character case.
    :param directories: set True to search for directories instead of files.
    :return: [list-of-paths]
    """
    assert os.path.isdir(rootdir), "Path is not a directory:{}".format(rootdir)
    regType = type(re.compile('.*'))

    for entry in os.scandir(rootdir):
        if directories == False:
            if entry.is_file():
                if fullpath:
                    name = entry.path
                else:
                    name =  os.path.basename(entry.path)
                if isinstance(pattern, regType):
                    if pattern.search(name):
                        yield entry.path.replace('\\','/')

                elif (ignoreCase and fnmatch.fnmatch(name, pattern.lower())) \
                        or fnmatch.fnmatch(name, pattern):
                    yield entry.path.replace('\\','/')
            elif entry.is_dir() and recursive == True:
                for r in file_search(entry.path, pattern, recursive=recursive, directories=directories):
                    yield r
        else:
            if entry.is_dir():
                if recursive == True:
                    for d in file_search(entry.path, pattern, recursive=recursive, directories=directories):
                        yield d
                        
                if fullpath:
                    name = entry.path
                else:
                    name = os.path.basename(entry.path)
                if isinstance(pattern, regType):
                    if pattern.search(name):
                        yield entry.path.replace('\\','/')

                elif (ignoreCase and fnmatch.fnmatch(name, pattern.lower())) \
                        or fnmatch.fnmatch(name, pattern):
                    yield entry.path.replace('\\','/')






NEXT_COLOR_HUE_DELTA_CON = 10
NEXT_COLOR_HUE_DELTA_CAT = 100
def nextColor(color, mode='cat'):
    """
    Returns another color
    :param color: the previous color
    :param mode: 'cat' - for categorical color jump (next color looks pretty different to previous)
                 'con' - for continuous color jump (next color looks similar to previous)
    :return:
    """
    assert mode in ['cat','con']
    assert isinstance(color, QColor)
    hue, sat, value, alpha = color.getHsl()
    if mode == 'cat':
        hue += NEXT_COLOR_HUE_DELTA_CAT
    elif mode == 'con':
        hue += NEXT_COLOR_HUE_DELTA_CON
    if sat == 0:
        sat = 255
        value = 128
        alpha = 255
        s = ""
    while hue > 360:
        hue -= 360

    return QColor.fromHsl(hue, sat, value, alpha)





def createQgsField(name : str, exampleValue, comment:str=None):
    """
    Create a QgsField using a Python-datatype exampleValue
    :param name: field name
    :param exampleValue: value, can be any type
    :param comment: (optional) field comment.
    :return: QgsField
    """
    t = type(exampleValue)
    if t in [str]:
        return QgsField(name, QVariant.String, 'varchar', comment=comment)
    elif t in [bool]:
        return QgsField(name, QVariant.Bool, 'int', len=1, comment=comment)
    elif t in [int, np.int32, np.int64]:
        return QgsField(name, QVariant.Int, 'int', comment=comment)
    elif t in [float, np.double, np.float16, np.float32, np.float64]:
        return QgsField(name, QVariant.Double, 'double', comment=comment)
    elif isinstance(exampleValue, np.ndarray):
        return QgsField(name, QVariant.String, 'varchar', comment=comment)
    elif isinstance(exampleValue, list):
        assert len(exampleValue) > 0, 'need at least one value in provided list'
        v = exampleValue[0]
        prototype = createQgsField(name, v)
        subType = prototype.type()
        typeName = prototype.typeName()
        return QgsField(name, QVariant.List, typeName, comment=comment, subType=subType)
    else:
        raise NotImplemented()



def setQgsFieldValue(feature:QgsFeature, field, value):
    """
    Wrties the Python value v into a QgsFeature field, taking care of required conversions
    :param feature: QgsFeature
    :param field: QgsField | field name (str) | field index (int)
    :param value: any python value
    """

    if isinstance(field, int):
        field = feature.fields().at(field)
    elif isinstance(field, str):
        field = feature.fields().at(feature.fieldNameIndex(field))
    assert isinstance(field, QgsField)

    if value is None:
        value = QVariant.NULL
    if field.type() == QVariant.String:
        value = str(value)
    elif field.type() in [QVariant.Int, QVariant.Bool]:
        value = int(value)
    elif field.type() in [QVariant.Double]:
        value = float(value)
    else:
        raise NotImplementedError()

   # i = feature.fieldNameIndex(field.name())
    feature.setAttribute(field.name(), value)


def appendItemsToMenu(menu, itemsToAdd):
    """
    Appends items to QMenu "menu"
    :param menu: the QMenu to be extended
    :param itemsToAdd: QMenu or [list-of-QActions-or-QMenus]
    :return: menu
    """
    assert isinstance(menu, QMenu)
    if isinstance(itemsToAdd, QMenu):
        itemsToAdd = itemsToAdd.children()
    if not isinstance(itemsToAdd, list):
        itemsToAdd = [itemsToAdd]
    for item in itemsToAdd:
        if isinstance(item, QAction):
            #item.setParent(menu)


            a = menu.addAction(item.text(), item.triggered, item.shortcut())
            a.setEnabled(item.isEnabled())
            a.setIcon(item.icon())
            menu.addAction(a)
            s = ""
        elif isinstance(item, QMenu):
            item.setParent(menu)
            menu.addMenu(menu)
        else:
            s = ""

    return menu


def toVectorLayer(src) -> QgsVectorLayer:
    """
    Returns a QgsRasterLayer if it can be extracted from src
    :param src: any type of input
    :return: QgsRasterLayer or None
    """
    lyr = None
    try:
        if isinstance(src, str):
            lyr = QgsVectorLayer(src)
        elif isinstance(src, QgsMimeDataUtils.Uri):
            lyr, b = src.vectorLayer()
            if not b:
                lyr = None
        if isinstance(src, ogr.DataSource):
            path = src.GetDescription()
            bn = os.path.basename(path)
            lyr = QgsVectorLayer(path, bn, 'ogr')
        elif isinstance(src, QgsVectorLayer):
            lyr = src

    except Exception as ex:
        print(ex)

    return lyr

def toDataset(src, readonly=True)->gdal.Dataset:
    """
    Returns a gdal.Dataset if it can be extracted from src
    :param src: input source
    :param readonly: bool, true by default, set False to upen the gdal.Dataset in update mode
    :return: gdal.Dataset
    """
    ga = gdal.GA_ReadOnly if readonly else gdal.GA_Update
    if isinstance(src, str):
        return gdal.Open(src, ga)
    elif isinstance(src, QgsRasterLayer) and src.dataProvider().name() == 'gdal':
        return toDataset(src.source(), readonly=readonly)
    elif isinstance(src, gdal.Dataset):
        return src
    else:
        return None

def toQgsMimeDataUtilsUri(mapLayer:QgsMapLayer)->QgsMimeDataUtils.Uri:
    """
    Creates a QgsMimeDataUtils.Uri that describes the QgsMapLayer `mapLayer`
    :param mapLayer: QgsMapLayer
    :return: QgsMimeDataUtils.Uri
    """
    assert isinstance(mapLayer, QgsMapLayer)
    uri = QgsMimeDataUtils.Uri()
    uri.uri = mapLayer.source()
    uri.name = mapLayer.name()
    if uri.name == '':
        uri.name = os.path.basename(uri.uri)
    uri.providerKey = mapLayer.dataProvider().name()

    if isinstance(mapLayer, QgsRasterLayer):
        uri.layerType = 'raster'
    elif isinstance(mapLayer, QgsVectorLayer):
        uri.layerType = 'vector'
    elif isinstance(mapLayer, QgsPluginLayer):
        uri.layerType = 'plugin'
    else:
        raise NotImplementedError()
    return uri


def toMapLayer(src)->QgsMapLayer:
    """
    Return a QgsMapLayer if it can be extracted from src
    :param src: any type of input
    :return: QgsMapLayer
    """
    lyr = toRasterLayer(src)
    if isinstance(lyr, QgsMapLayer):
        return lyr
    lyr = toVectorLayer(src)
    if isinstance(lyr, QgsMapLayer):
        return lyr
    return lyr

def toRasterLayer(src) -> QgsRasterLayer:
    """
    Returns a QgsRasterLayer if it can be extracted from src
    :param src: any type of input
    :return: QgsRasterLayer or None
    """
    lyr = None
    try:
        if isinstance(src, str):
            lyr = QgsRasterLayer(src)
        elif isinstance(src, QgsMimeDataUtils.Uri):
            lyr, b = src.rasterLayer('')
            if not b:
                lyr = None
        elif isinstance(src, gdal.Dataset):
            lyr = QgsRasterLayer(src.GetFileList()[0], '', 'gdal')
        elif isinstance(src, QgsMapLayer) :
            lyr = src
        elif isinstance(src, gdal.Band):
            return toRasterLayer(src.GetDataset())

    except Exception as ex:
        print(ex)

    if isinstance(lyr, QgsRasterLayer) and lyr.isValid():
        return lyr
    else:
        return None


def allSubclasses(cls):
    """
    Returns all subclasses of class 'cls'
    Thx to: http://stackoverflow.com/questions/3862310/how-can-i-find-all-subclasses-of-a-class-given-its-name
    :param cls:
    :return:
    """
    return cls.__subclasses__() + [g for s in cls.__subclasses__()
                                   for g in allSubclasses(s)]

def scaledUnitString(num, infix=' ', suffix='B', div=1000):
    """
    Returns a human-readable file size string.
    thanks to Fred Cirera
    http://stackoverflow.com/questions/1094841/reusable-library-to-get-human-readable-version-of-file-size
    :param num: number in bytes
    :param suffix: 'B' for bytes by default.
    :param div: divisor of num, 1000 by default.
    :return: the file size string
    """
    for unit in ['','K','M','G','T','P','E','Z']:
        if abs(num) < div:
            return "{:3.1f}{}{}{}".format(num, infix, unit, suffix)
        num /= div
    return "{:.1f}{}{}{}".format(num, infix, unit, suffix)


class SpatialPoint(QgsPointXY):
    """
    Object to keep QgsPoint and QgsCoordinateReferenceSystem together
    """

    @staticmethod
    def fromMapCanvasCenter(mapCanvas):
        assert isinstance(mapCanvas, QgsMapCanvas)
        crs = mapCanvas.mapSettings().destinationCrs()
        return SpatialPoint(crs, mapCanvas.center())

    @staticmethod
    def fromMapLayerCenter(mapLayer:QgsMapLayer):
        assert isinstance(mapLayer, QgsMapLayer) and mapLayer.isValid()
        crs = mapLayer.crs()
        return SpatialPoint(crs, mapLayer.extent().center())

    @staticmethod
    def fromSpatialExtent(spatialExtent):
        assert isinstance(spatialExtent, SpatialExtent)
        crs = spatialExtent.crs()
        return SpatialPoint(crs, spatialExtent.center())

    def __init__(self, crs, *args):
        if not isinstance(crs, QgsCoordinateReferenceSystem):
            crs = QgsCoordinateReferenceSystem(crs)
        assert isinstance(crs, QgsCoordinateReferenceSystem)
        super(SpatialPoint, self).__init__(*args)
        self.mCrs = crs

    def __hash__(self):
        return hash(str(self))

    def setCrs(self, crs):
        assert isinstance(crs, QgsCoordinateReferenceSystem)
        self.mCrs = crs

    def crs(self):
        return self.mCrs

    def toPixelPosition(self, rasterDataSource, allowOutOfRaster=False):
        """
        Returns the pixel position of this SpatialPoint within the rasterDataSource
        :param rasterDataSource: gdal.Dataset
        :param allowOutOfRaster: set True to return out-of-raster pixel positions, e.g. QPoint(-1,0)
        :return: the pixel position as QPoint
        """
        ds = gdalDataset(rasterDataSource)
        ns, nl = ds.RasterXSize, ds.RasterYSize
        gt = ds.GetGeoTransform()

        pt = self.toCrs(ds.GetProjection())
        if pt is None:
            return None

        px = geo2px(pt, gt)
        if not allowOutOfRaster:
            if px.x() < 0 or px.x() >= ns:
                return None
            if px.y() < 0 or px.y() >= nl:
                return None
        return px

    def toCrs(self, crs):
        assert isinstance(crs, QgsCoordinateReferenceSystem)
        pt = QgsPointXY(self)

        if self.mCrs != crs:
            pt = saveTransform(pt, self.mCrs, crs)

        return SpatialPoint(crs, pt) if pt else None

    def __reduce_ex__(self, protocol):
        return self.__class__, (self.crs().toWkt(), self.x(), self.y()), {}

    def __eq__(self, other):
        if not isinstance(other, SpatialPoint):
            return False
        return self.x() == other.x() and \
               self.y() == other.y() and \
               self.crs() == other.crs()

    def copy(self):
        return self.__copy__()

    def __copy__(self):
        return SpatialPoint(self.crs(), self.x(), self.y())

    def __str__(self):
        return self.__repr__()

    def __repr__(self):

        if self.crs().mapUnits() == QgsUnitTypes.DistanceDegrees:
            return '{:.1f} {:.1f} {}'.format(self.x(), self.y(), self.crs().authid())
        else:
            return '{:.5f} {:.5f} {:}'.format(self.x(), self.y(), self.crs().authid())



def findParent(qObject, parentType, checkInstance = False):
    parent = qObject.parent()
    if checkInstance:
        while parent != None and not isinstance(parent, parentType):
            parent = parent.parent()
    else:
        while parent != None and type(parent) != parentType:
            parent = parent.parent()
    return parent

def saveTransform(geom, crs1, crs2):
    assert isinstance(crs1, QgsCoordinateReferenceSystem)
    assert isinstance(crs2, QgsCoordinateReferenceSystem)

    result = None
    if isinstance(geom, QgsRectangle):
        if geom.isEmpty():
            return None


        transform = QgsCoordinateTransform()
        transform.setSourceCrs(crs1)
        transform.setDestinationCrs(crs2)
        try:
            rect = transform.transformBoundingBox(geom)
            result = SpatialExtent(crs2, rect)
        except:
            messageLog('Can not transform from {} to {} on rectangle {}'.format( \
                crs1.description(), crs2.description(), str(geom)))

    elif isinstance(geom, QgsPointXY):

        transform = QgsCoordinateTransform()
        transform.setSourceCrs(crs1)
        transform.setDestinationCrs(crs2)
        try:
            pt = transform.transform(geom);
            result = SpatialPoint(crs2, pt)
        except:
            messageLog('Can not transform from {} to {} on QgsPointXY {}'.format( \
                crs1.description(), crs2.description(), str(geom)))
    return result


def gdalDataset(pathOrDataset, eAccess=gdal.GA_ReadOnly):
    """

    :param pathOrDataset: path or gdal.Dataset
    :return: gdal.Dataset
    """
    if not isinstance(pathOrDataset, gdal.Dataset):
        pathOrDataset = gdal.Open(pathOrDataset, eAccess)
    assert isinstance(pathOrDataset, gdal.Dataset)
    return pathOrDataset


def geo2pxF(geo, gt):
    """
    Returns the pixel position related to a Geo-Coordinate in floating point precision.
    :param geo: Geo-Coordinate as QgsPoint
    :param gt: GDAL Geo-Transformation tuple, as described in http://www.gdal.org/gdal_datamodel.html
    :return: pixel position as QPointF
    """
    assert isinstance(geo, QgsPointXY)
    # see http://www.gdal.org/gdal_datamodel.html
    px = (geo.x() - gt[0]) / gt[1]  # x pixel
    py = (geo.y() - gt[3]) / gt[5]  # y pixel
    return QPointF(px,py)

def createGeoTransform(gsd, ul_x, ul_y):
    """
    Create a GDAL Affine GeoTransform vector for north-up images.
    See http://www.gdal.org/gdal_datamodel.html for details
    :param gsd: ground-sampling-distance / pixel-size
    :param ul_x: upper-left X
    :param ul_y: upper-left Y
    :return: (tuple)
    """
    if isinstance(gsd, tuple) or isinstance(gsd, list):
        gt1 = gsd[0] #pixel width
        gt5 = gsd[1] #pixel height
    else:
        gsd = float(gsd)
        gt1 = gt5 = gsd #pixel width == pixel height

    gt0 = ul_x
    gt3 = ul_y

    gt2 = gt4 = 0

    return (gt0, gt1, gt2, gt3, gt4, gt5)

def geo2px(geo, gt):
    """
    Returns the pixel position related to a Geo-Coordinate as integer number.
    Floating-point coordinate are casted to integer coordinate, e.g. the pixel coordinate (0.815, 23.42) is returned as (0,23)
    :param geo: Geo-Coordinate as QgsPointXY
    :param gt: GDAL Geo-Transformation tuple, as described in http://www.gdal.org/gdal_datamodel.html
    :return: pixel position as QPpint
    """
    px = geo2pxF(geo, gt)
    return QPoint(int(px.x()), int(px.y()))


def px2geo(px, gt, pxCenter=True):
    """
    Converts a pixel coordinate into a geo-coordinate
    :param px: QPoint() with pixel coordinates
    :param gt: geo-transformation
    :param pxCenter: True to return geo-coordinate of pixel center, False to return upper-left edge
    :return:
    """

    #see http://www.gdal.org/gdal_datamodel.html

    gx = gt[0] + px.x()*gt[1]+px.y()*gt[2]
    gy = gt[3] + px.x()*gt[4]+px.y()*gt[5]

    if pxCenter:
        p2 = px2geo(QPoint(px.x()+1, px.y()+1), gt, pxCenter=False)

        gx = 0.5*(gx + p2.x())
        gy = 0.5*(gy + p2.y())

    return QgsPointXY(gx, gy)





class SpatialExtent(QgsRectangle):
    """
    Object to keep QgsRectangle and QgsCoordinateReferenceSystem together
    """
    @staticmethod
    def fromMapCanvas(mapCanvas, fullExtent=False):
        assert isinstance(mapCanvas, QgsMapCanvas)

        if fullExtent:
            extent = mapCanvas.fullExtent()
        else:
            extent = mapCanvas.extent()
        crs = mapCanvas.mapSettings().destinationCrs()
        return SpatialExtent(crs, extent)

    @staticmethod
    def world():
        crs = QgsCoordinateReferenceSystem('EPSG:4326')
        ext = QgsRectangle(-180,-90,180,90)
        return SpatialExtent(crs, ext)


    @staticmethod
    def fromRasterSource(pathSrc):
        ds = gdalDataset(pathSrc)
        assert isinstance(ds, gdal.Dataset)
        ns, nl = ds.RasterXSize, ds.RasterYSize
        gt = ds.GetGeoTransform()
        crs = QgsCoordinateReferenceSystem(ds.GetProjection())

        xValues = []
        yValues = []
        for x in [0, ns]:
            for y in [0, nl]:
                px = px2geo(QPoint(x,y), gt)
                xValues.append(px.x())
                yValues.append(px.y())

        return SpatialExtent(crs, min(xValues), min(yValues),
                                  max(xValues), max(yValues))





    @staticmethod
    def fromLayer(mapLayer):
        assert isinstance(mapLayer, QgsMapLayer)
        extent = mapLayer.extent()
        crs = mapLayer.crs()
        return SpatialExtent(crs, extent)

    def __init__(self, crs, *args):
        if not isinstance(crs, QgsCoordinateReferenceSystem):
            crs = QgsCoordinateReferenceSystem(crs)
        assert isinstance(crs, QgsCoordinateReferenceSystem)
        super(SpatialExtent, self).__init__(*args)
        self.mCrs = crs

    def setCrs(self, crs):
        assert isinstance(crs, QgsCoordinateReferenceSystem)
        self.mCrs = crs

    def crs(self):
        return self.mCrs

    def toCrs(self, crs):
        assert isinstance(crs, QgsCoordinateReferenceSystem)
        box = QgsRectangle(self)
        if self.mCrs != crs:
            box = saveTransform(box, self.mCrs, crs)
        return SpatialExtent(crs, box) if box else None

    def spatialCenter(self):
        return SpatialPoint(self.crs(), self.center())

    def combineExtentWith(self, *args):
        if args is None:
            return
        elif isinstance(args[0], SpatialExtent):
            ext = args[0]
            extent2 = ext.toCrs(self.crs())
            self.combineExtentWith(QgsRectangle(extent2))
        else:
            super(SpatialExtent, self).combineExtentWith(*args)

        return self

    def setCenter(self, centerPoint:SpatialPoint, crs=None):
        """
        Sets the center. Can be used to move the SpatialExtent
        :param centerPoint:
        :param crs: QgsCoordinateReferenceSystem
        :return:
        """
        if isinstance(centerPoint, SpatialPoint):
            crs = centerPoint.crs()

        if isinstance(crs, QgsCoordinateReferenceSystem) and crs != self.crs():
            trans = QgsCoordinateTransform()
            trans.setSourceCrs(crs)
            trans.setDestinationCrs(self.crs())
            centerPoint = trans.transform(centerPoint)

        delta = centerPoint - self.center()
        self.setXMaximum(self.xMaximum() + delta.x())
        self.setXMinimum(self.xMinimum() + delta.x())
        self.setYMaximum(self.yMaximum() + delta.y())
        self.setYMinimum(self.yMinimum() + delta.y())

        return self

    def __cmp__(self, other):
        if other is None: return 1
        s = ""

    def upperRightPt(self):
        return QgsPointXY(*self.upperRight())

    def upperLeftPt(self):
        return QgsPointXY(*self.upperLeft())

    def lowerRightPt(self):
        return QgsPointXY(*self.lowerRight())

    def lowerLeftPt(self):
        return QgsPointXY(*self.lowerLeft())


    def upperRight(self):
        return self.xMaximum(), self.yMaximum()

    def upperLeft(self):
        return self.xMinimum(), self.yMaximum()

    def lowerRight(self):
        return self.xMaximum(), self.yMinimum()

    def lowerLeft(self):
        return self.xMinimum(), self.yMinimum()


    def __eq__(self, other):
        if not isinstance(other, SpatialExtent):
            return False
        return self.toString() == other.toString()

    def __sub__(self, other):
        raise NotImplementedError()

    def __mul__(self, other):
        raise NotImplementedError()

    def __copy__(self):
        return SpatialExtent(self.crs(), QgsRectangle(self))

    def __reduce_ex__(self, protocol):
        return self.__class__, (self.crs().toWkt(),
                                self.xMinimum(), self.yMinimum(),
                                self.xMaximum(), self.yMaximum()
                                ), {}


    def __hash__(self):
        return hash(str(self))

    def __str__(self):
        return self.__repr__()

    def __repr__(self):

        return '{} {} {}'.format(self.upperLeft(), self.lowerRight(), self.crs().authid())




def saveFilePath(text : str):
    """
    Normalizes string, converts to lowercase, removes non-alpha characters,
    and converts spaces to hyphens.
    see https://stackoverflow.com/questions/295135/turn-a-string-into-a-valid-filename
    :return: path
    """
    text = re.sub(r'[^\w\s.-]', '', text).strip().lower()
    text = re.sub(r'[-\s]+', '_', text)
    return re.sub(r'[ ]+]','',text)


def value2str(value, sep=' '):
    """
    Converts a value into a string
    :param value:
    :param sep:
    :return:
    """
    if isinstance(value, list):
        value = sep.join([str(v) for v in value])
    elif isinstance(value, np.array):
        value = value2str(value.astype(list), sep=sep)
    elif value is None:
        value = ''
    else:
        value = str(value)
    return value


# works in Python 2 & 3
class _Singleton(type):
    """ A metaclass that creates a Singleton base class when called. """
    _instances = {}
    def __call__(cls, *args, **kwargs):
        if cls not in cls._instances:
            cls._instances[cls] = super(_Singleton, cls).__call__(*args, **kwargs)
        return cls._instances[cls]

class Singleton(_Singleton('SingletonMeta', (object,), {})): pass

"""
#work, but require metaclass pattern 
class Singleton(type):
    _instances = {}

    def __call__(cls, *args, **kwds):
        if cls not in cls._instances:
            cls._instances[cls] = super(Singleton, cls).__call__(*args,**kwds)
        return cls._instances[cls]
"""

class KeepRefs(object):
    __refs__ = defaultdict(list)
    def __init__(self):
        self.__refs__[self.__class__].append(weakref.ref(self))

    @classmethod
    def instances(cls):
        for inst_ref in cls.__refs__[cls]:
            inst = inst_ref()
            if inst is not None:
                yield inst



def defaultBands(dataset):
    """
    Returns a list of 3 default bands
    :param dataset:
    :return:
    """
    if isinstance(dataset, str):
        return defaultBands(gdal.Open(dataset))
    elif isinstance(dataset, QgsRasterDataProvider):
        return defaultBands(dataset.dataSourceUri())
    elif isinstance(dataset, QgsRasterLayer):
        return defaultBands(dataset.source())
    elif isinstance(dataset, gdal.Dataset):

        db = dataset.GetMetadataItem(str('default_bands'), str('ENVI'))
        if db != None:
            db = [int(n) for n in re.findall(r'\d+')]
            return db
        db = [0, 0, 0]
        cis = [gdal.GCI_RedBand, gdal.GCI_GreenBand, gdal.GCI_BlueBand]
        for b in range(dataset.RasterCount):
            band = dataset.GetRasterBand(b + 1)
            assert isinstance(band, gdal.Band)
            ci = band.GetColorInterpretation()
            if ci in cis:
                db[cis.index(ci)] = b
        if db != [0, 0, 0]:
            return db

        rl = QgsRasterLayer(dataset.GetFileList()[0])
        defaultRenderer = rl.renderer()
        if isinstance(defaultRenderer, QgsRasterRenderer):
            db = defaultRenderer.usesBands()
            if len(db) == 0:
                return [0, 1, 2]
            if len(db) > 3:
                db = db[0:3]
            db = [b-1 for b in db]
        return db

    else:
        raise Exception()

######### Lookup  tables
METRIC_EXPONENTS = {
    "nm": -9, "um": -6, u"µm": -6, "mm": -3, "cm": -2, "dm": -1, "m": 0, "hm": 2, "km": 3
}
# add synonyms
METRIC_EXPONENTS['nanometers'] = METRIC_EXPONENTS['nm']
METRIC_EXPONENTS['micrometers'] = METRIC_EXPONENTS['um']
METRIC_EXPONENTS['millimeters'] = METRIC_EXPONENTS['mm']
METRIC_EXPONENTS['centimeters'] = METRIC_EXPONENTS['cm']
METRIC_EXPONENTS['decimeters'] = METRIC_EXPONENTS['dm']
METRIC_EXPONENTS['meters'] = METRIC_EXPONENTS['m']
METRIC_EXPONENTS['hectometers'] = METRIC_EXPONENTS['hm']
METRIC_EXPONENTS['kilometers'] = METRIC_EXPONENTS['km']


LUT_WAVELENGTH = dict({'B': 480,
                       'G': 570,
                       'R': 660,
                       'NIR': 850,
                       'SWIR': 1650,
                       'SWIR1': 1650,
                       'SWIR2': 2150
                       })

def convertMetricUnit(value, u1, u2):
    """converts value, given in unit u1, to u2"""
    assert u1 in METRIC_EXPONENTS.keys()
    assert u2 in METRIC_EXPONENTS.keys()

    e1 = METRIC_EXPONENTS[u1]
    e2 = METRIC_EXPONENTS[u2]

    return value * 10 ** (e1 - e2)

def bandClosestToWavelength(dataset, wl, wl_unit='nm'):
    """
    Returns the band index (!) of an image dataset closest to wavelength `wl`.
    :param dataset: str | gdal.Dataset
    :param wl: wavelength to search the closed band for
    :param wl_unit: unit of wavelength. Default = nm
    :return: band index | 0 of wavelength information is not provided
    """
    if isinstance(wl, str):
        assert wl.upper() in LUT_WAVELENGTH.keys(), wl
        return bandClosestToWavelength(dataset, LUT_WAVELENGTH[wl.upper()], wl_unit='nm')
    else:
        try:
            wl = float(wl)
            ds_wl, ds_wlu = parseWavelength(dataset)

            if ds_wl is None or ds_wlu is None:
                return 0


            if ds_wlu != wl_unit:
                wl = convertMetricUnit(wl, wl_unit, ds_wlu)
            return int(np.argmin(np.abs(ds_wl - wl)))
        except:
            pass
    return 0

def cloneRenderer(renderer):

    assert isinstance(renderer, QgsRasterRenderer)
    cloned = renderer.clone()

    #handle specific issues if cloning is not exactly the same
    if isinstance(cloned, QgsSingleBandPseudoColorRenderer):
        cloned.setClassificationMin(renderer.classificationMin())
        cloned.setClassificationMax(renderer.classificationMax())

    return cloned


def parseWavelength(dataset):
    """
    Returns the wavelength + wavelength unit of a dataset
    :param dataset:
    :return: (wl, wl_u) or (None, None), if not existing
    """

    wl = None
    wlu = None

    if isinstance(dataset, str):
        return parseWavelength(gdal.Open(dataset))
    elif isinstance(dataset, QgsRasterDataProvider):
        return parseWavelength(dataset.dataSourceUri())