"""
This module exists to smooth out some of the differences between PySide and PyQt4:

* Automatically import either PyQt4 or PySide depending on availability
* Allow to import QtCore/QtGui pyqtgraph.Qt without specifying which Qt wrapper
  you want to use.
* Declare QtCore.Signal, .Slot in PyQt4
* Declare loadUiType function for Pyside

"""

import os, sys, re, time

from .python2_3 import asUnicode

PYSIDE = 'PySide'
PYSIDE2 = 'PySide2'
PYQT4 = 'PyQt4'
PYQT5 = 'PyQt5'

QT_LIB = os.getenv('PYQTGRAPH_QT_LIB')

## Automatically determine which Qt package to use (unless specified by
## environment variable).
## This is done by first checking to see whether one of the libraries
## is already imported. If not, then attempt to import PyQt4, then PySide.
if QT_LIB is None:
    libOrder = [PYQT4, PYSIDE, PYQT5, PYSIDE2]

    for lib in libOrder:
        if lib in sys.modules:
            QT_LIB = lib
            break

if QT_LIB is None:
    for lib in libOrder:
        try:
            __import__(lib)
            QT_LIB = lib
            break
        except ImportError:
            pass

if QT_LIB is None:
    raise Exception("PyQtGraph requires one of PyQt4, PyQt5, PySide or PySide2; none of these packages could be imported.")


class FailedImport(object):
    """Used to defer ImportErrors until we are sure the module is needed.
    """
    def __init__(self, err):
        self.err = err
        
    def __getattr__(self, attr):
        raise self.err


def _isQObjectAlive(obj):
    """An approximation of PyQt's isQObjectAlive().
    """
    try:
        if hasattr(obj, 'parent'):
            obj.parent()
        elif hasattr(obj, 'parentItem'):
            obj.parentItem()
        else:
            raise Exception("Cannot determine whether Qt object %s is still alive." % obj)
    except RuntimeError:
        return False
    else:
        return True


# Make a loadUiType function like PyQt has

# Credit:
# http://stackoverflow.com/questions/4442286/python-code-genration-with-pyside-uic/14195313#14195313

class _StringIO(object):
    """Alternative to built-in StringIO needed to circumvent unicode/ascii issues"""
    def __init__(self):
        self.data = []
    
    def write(self, data):
        self.data.append(data)
        
    def getvalue(self):
        return ''.join(map(asUnicode, self.data)).encode('utf8')

    
def _loadUiType(uiFile):
    """
    PySide lacks a "loadUiType" command like PyQt4's, so we have to convert
    the ui file to py code in-memory first and then execute it in a
    special frame to retrieve the form_class.

    from stackoverflow: http://stackoverflow.com/a/14195313/3781327

    seems like this might also be a legitimate solution, but I'm not sure
    how to make PyQt4 and pyside look the same...
        http://stackoverflow.com/a/8717832
    """

    if QT_LIB == "PYSIDE":
        import pysideuic
    else:
        import pyside2uic as pysideuic
    import xml.etree.ElementTree as xml

    parsed = xml.parse(uiFile)
    widget_class = parsed.find('widget').get('class')
    form_class = parsed.find('class').text
    
    with open(uiFile, 'r') as f:
        o = _StringIO()
        frame = {}

        pysideuic.compileUi(f, o, indent=0)
        pyc = compile(o.getvalue(), '<string>', 'exec')
        exec(pyc, frame)

        #Fetch the base_class and form class based on their type in the xml from designer
        form_class = frame['Ui_%s'%form_class]
        base_class = eval('QtGui.%s'%widget_class)

    return form_class, base_class


if QT_LIB == PYSIDE:
    from PySide import QtGui, QtCore

    try:
        from PySide import QtOpenGL
    except ImportError as err:
        QtOpenGL = FailedImport(err)
    try:
        from PySide import QtSvg
    except ImportError as err:
        QtSvg = FailedImport(err)

    try:
        from PySide import QtTest
    except ImportError as err:
        QtTest = FailedImport(err)
    
    try:
        from PySide import shiboken
        isQObjectAlive = shiboken.isValid
    except ImportError:
        # use approximate version
        isQObjectAlive = _isQObjectAlive
    
    import PySide
    VERSION_INFO = 'PySide ' + PySide.__version__ + ' Qt ' + QtCore.__version__
    
elif QT_LIB == PYQT4:
    from PyQt4 import QtGui, QtCore, uic
    try:
        from PyQt4 import QtSvg
    except ImportError as err:
        QtSvg = FailedImport(err)
    try:
        from PyQt4 import QtOpenGL
    except ImportError as err:
        QtOpenGL = FailedImport(err)
    try:
        from PyQt4 import QtTest
    except ImportError as err:
        QtTest = FailedImport(err)

    VERSION_INFO = 'PyQt4 ' + QtCore.PYQT_VERSION_STR + ' Qt ' + QtCore.QT_VERSION_STR

elif QT_LIB == PYQT5:
    # We're using PyQt5 which has a different structure so we're going to use a shim to
    # recreate the Qt4 structure for Qt5
    from PyQt5 import QtGui, QtCore, QtWidgets, uic
    
    # PyQt5, starting in v5.5, calls qAbort when an exception is raised inside
    # a slot. To maintain backward compatibility (and sanity for interactive
    # users), we install a global exception hook to override this behavior.
    ver = QtCore.PYQT_VERSION_STR.split('.')
    if int(ver[1]) >= 5:
        if sys.excepthook == sys.__excepthook__:
            sys_excepthook = sys.excepthook
            def pyqt5_qabort_override(*args, **kwds):
                return sys_excepthook(*args, **kwds)
            sys.excepthook = pyqt5_qabort_override
    
    try:
        from PyQt5 import QtSvg
    except ImportError as err:
        QtSvg = FailedImport(err)
    try:
        from PyQt5 import QtOpenGL
    except ImportError as err:
        QtOpenGL = FailedImport(err)
    try:
        from PyQt5 import QtTest
        QtTest.QTest.qWaitForWindowShown = QtTest.QTest.qWaitForWindowExposed
    except ImportError as err:
        QtTest = FailedImport(err)

    VERSION_INFO = 'PyQt5 ' + QtCore.PYQT_VERSION_STR + ' Qt ' + QtCore.QT_VERSION_STR

elif QT_LIB == PYSIDE2:
    from PySide2 import QtGui, QtCore, QtWidgets
    
    try:
        from PySide2 import QtSvg
    except ImportError as err:
        QtSvg = FailedImport(err)
    try:
        from PySide2 import QtOpenGL
    except ImportError as err:
        QtOpenGL = FailedImport(err)
    try:
        from PySide2 import QtTest
        QtTest.QTest.qWaitForWindowShown = QtTest.QTest.qWaitForWindowExposed
    except ImportError as err:
        QtTest = FailedImport(err)

    try:
        import shiboken2
        isQObjectAlive = shiboken2.isValid
    except ImportError:
        # use approximate version
        isQObjectAlive = _isQObjectAlive    
    import PySide2
    VERSION_INFO = 'PySide2 ' + PySide2.__version__ + ' Qt ' + QtCore.__version__

else:
    raise ValueError("Invalid Qt lib '%s'" % QT_LIB)


# common to PyQt5 and PySide2
if QT_LIB in [PYQT5, PYSIDE2]:
    # We're using Qt5 which has a different structure so we're going to use a shim to
    # recreate the Qt4 structure
    
    __QGraphicsItem_scale = QtWidgets.QGraphicsItem.scale

    def scale(self, *args):
        if args:
            sx, sy = args
            tr = self.transform()
            tr.scale(sx, sy)
            self.setTransform(tr)
        else:
            return __QGraphicsItem_scale(self)

    QtWidgets.QGraphicsItem.scale = scale

    def rotate(self, angle):
        tr = self.transform()
        tr.rotate(angle)
        self.setTransform(tr)
    QtWidgets.QGraphicsItem.rotate = rotate

    def translate(self, dx, dy):
        tr = self.transform()
        tr.translate(dx, dy)
        self.setTransform(tr)
    QtWidgets.QGraphicsItem.translate = translate

    def setMargin(self, i):
        self.setContentsMargins(i, i, i, i)
    QtWidgets.QGridLayout.setMargin = setMargin

    def setResizeMode(self, *args):
        self.setSectionResizeMode(*args)
    QtWidgets.QHeaderView.setResizeMode = setResizeMode

    
    QtGui.QApplication = QtWidgets.QApplication
    QtGui.QGraphicsScene = QtWidgets.QGraphicsScene
    QtGui.QGraphicsObject = QtWidgets.QGraphicsObject
    QtGui.QGraphicsWidget = QtWidgets.QGraphicsWidget

    QtGui.QApplication.setGraphicsSystem = None
    
    # Import all QtWidgets objects into QtGui
    for o in dir(QtWidgets):
        if o.startswith('Q'):
            setattr(QtGui, o, getattr(QtWidgets,o) )
    

# Common to PySide and PySide2
if QT_LIB in [PYSIDE, PYSIDE2]:
    QtVersion = QtCore.__version__
    loadUiType = _loadUiType
        
    # PySide does not implement qWait
    if not isinstance(QtTest, FailedImport):
        if not hasattr(QtTest.QTest, 'qWait'):
            @staticmethod
            def qWait(msec):
                start = time.time()
                QtGui.QApplication.processEvents()
                while time.time() < start + msec * 0.001:
                    QtGui.QApplication.processEvents()
            QtTest.QTest.qWait = qWait


# Common to PyQt4 and 5
if QT_LIB in [PYQT4, PYQT5]:
    QtVersion = QtCore.QT_VERSION_STR
    
    import sip
    def isQObjectAlive(obj):
        return not sip.isdeleted(obj)
    
    loadUiType = uic.loadUiType

    QtCore.Signal = QtCore.pyqtSignal
    

# USE_XXX variables are deprecated
USE_PYSIDE = QT_LIB == PYSIDE
USE_PYQT4 = QT_LIB == PYQT4
USE_PYQT5 = QT_LIB == PYQT5

    
## Make sure we have Qt >= 4.7
versionReq = [4, 7]
m = re.match(r'(\d+)\.(\d+).*', QtVersion)
if m is not None and list(map(int, m.groups())) < versionReq:
    print(list(map(int, m.groups())))
    raise Exception('pyqtgraph requires Qt version >= %d.%d  (your version is %s)' % (versionReq[0], versionReq[1], QtVersion))


QAPP = None
def mkQApp():
    global QAPP    
    QAPP = QtGui.QApplication.instance()
    if QAPP is None:
        QAPP = QtGui.QApplication([])
    return QAPP
