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"""This module defines a widget able to convert a numpy array from n-dimensions
to a numpy array with less dimensions.
"""

__authors__ = ["V. Valls"]
__license__ = "MIT"
__date__ = "29/01/2018"

import logging
import numpy
import functools
from silx.gui.widgets.FrameBrowser import HorizontalSliderWithBrowser
from silx.gui import qt
from silx.gui.utils import blockSignals
import silx.utils.weakref


_logger = logging.getLogger(__name__)


class _Axis(qt.QWidget):
    """Widget displaying an axis.

    It allows to display and scroll in the axis, and provide a widget to
    map the axis with a named axis (the one from the view).
    """

    valueChanged = qt.Signal(int)
    """Emitted when the location on the axis change."""

    axisNameChanged = qt.Signal(object)
    """Emitted when the user change the name of the axis."""

    def __init__(self, parent=None):
        """Constructor

        :param parent: Parent of the widget
        """
        super(_Axis, self).__init__(parent)
        self.__axisNumber = None
        self.__customAxisNames = set([])
        self.__label = qt.QLabel(self)
        self.__axes = qt.QComboBox(self)
        self.__axes.currentIndexChanged[int].connect(self.__axisMappingChanged)
        self.__slider = HorizontalSliderWithBrowser(self)
        self.__slider.valueChanged[int].connect(self.__sliderValueChanged)
        layout = qt.QHBoxLayout(self)
        layout.setContentsMargins(0, 0, 0, 0)
        layout.addWidget(self.__label)
        layout.addWidget(self.__axes)
        layout.addWidget(self.__slider, 10000)
        layout.addStretch(1)
        self.setLayout(layout)

    def slider(self):
        """Returns the slider used to display axes location.

        :rtype: HorizontalSliderWithBrowser
        """
        return self.__slider

    def setAxis(self, number, position, size):
        """Set axis information.

        :param int number: The number of the axis (from the original numpy
            array)
        :param int position: The current position in the axis (for a slicing)
        :param int size: The size of this axis (0..n)
        """
        self.__label.setText("Dimension %s" % number)
        self.__axisNumber = number
        self.__slider.setMaximum(size - 1)

    def axisNumber(self):
        """Returns the axis number.

        :rtype: int
        """
        return self.__axisNumber

    def setAxisName(self, axisName):
        """Set the current used axis name.

        If this name is not available an exception is raised. An empty string
        means that no name is selected.

        :param str axisName: The new name of the axis
        :raise ValueError: When the name is not available
        """
        if axisName == "" and self.__axes.count() == 0:
            self.__axes.setCurrentIndex(-1)
            self.__updateSliderVisibility()
            return

        for index in range(self.__axes.count()):
            name = self.__axes.itemData(index)
            if name == axisName:
                self.__axes.setCurrentIndex(index)
                self.__updateSliderVisibility()
                return
        raise ValueError("Axis name '%s' not found", axisName)

    def axisName(self):
        """Returns the selected axis name.

        If no name is selected, an empty string is returned.

        :rtype: str
        """
        index = self.__axes.currentIndex()
        if index == -1:
            return ""
        return self.__axes.itemData(index)

    def setAxisNames(self, axesNames):
        """Set the available list of names for the axis.

        :param List[str] axesNames: List of available names
        """
        self.__axes.clear()
        with blockSignals(self.__axes):
            self.__axes.addItem(" ", "")
            for axis in axesNames:
                self.__axes.addItem(axis, axis)

        self.__updateSliderVisibility()

    def setCustomAxis(self, axesNames):
        """Set the available list of named axis which can be set to a value.

        :param List[str] axesNames: List of customable axis names
        """
        self.__customAxisNames = set(axesNames)
        self.__updateSliderVisibility()

    def __axisMappingChanged(self, index):
        """Called when the selected name change.

        :param int index: Selected index
        """
        self.__updateSliderVisibility()
        name = self.axisName()
        self.axisNameChanged.emit(name)

    def __updateSliderVisibility(self):
        """Update the visibility of the slider according to axis names and
        customable axis names."""
        name = self.axisName()
        isVisible = name == "" or name in self.__customAxisNames
        self.__slider.setVisible(isVisible)

    def value(self):
        """Returns the currently selected position in the axis.

        :rtype: int
        """
        return self.__slider.value()

    def setValue(self, value):
        """Set the currently selected position in the axis.

        :param int value:
        """
        self.__slider.setValue(value)

    def __sliderValueChanged(self, value):
        """Called when the selected position in the axis change.

        :param int value: Position of the axis
        """
        self.valueChanged.emit(value)

    def setNamedAxisSelectorVisibility(self, visible):
        """Hide or show the named axis combobox.

        If both the selector and the slider are hidden, hide the entire widget.

        :param visible: boolean
        """
        self.__axes.setVisible(visible)
        name = self.axisName()
        self.setVisible(visible or name == "")


class NumpyAxesSelector(qt.QWidget):
    """Widget to select a view from a numpy array.

    .. image:: img/NumpyAxesSelector.png

    The widget is set with an input data using :meth:`setData`, and a requested
    output dimension using :meth:`setAxisNames`.

    Widgets are provided to selected expected input axis, and a slice on the
    non-selected axis.

    The final selected array can be reached using the getter
    :meth:`selectedData`, and the event `selectionChanged`.

    If the input data is a HDF5 Dataset, the selected output data will be a
    new numpy array.
    """

    dataChanged = qt.Signal()
    """Emitted when the input data change"""

    selectedAxisChanged = qt.Signal()
    """Emitted when the selected axis change"""

    selectionChanged = qt.Signal()
    """Emitted when the selected data change"""

    customAxisChanged = qt.Signal(str, int)
    """Emitted when a custom axis change"""

    def __init__(self, parent=None):
        """Constructor

        :param parent: Parent of the widget
        """
        super(NumpyAxesSelector, self).__init__(parent)

        self.__data = None
        self.__selectedData = None
        self.__axis = []
        self.__axisNames = []
        self.__customAxisNames = set([])
        self.__namedAxesVisibility = True
        layout = qt.QVBoxLayout(self)
        layout.setContentsMargins(0, 0, 0, 0)
        layout.setSizeConstraint(qt.QLayout.SetMinAndMaxSize)
        self.setLayout(layout)

    def clear(self):
        """Clear the widget."""
        self.setData(None)

    def setAxisNames(self, axesNames):
        """Set the axis names of the output selected data.

        Axis names are defined from slower to faster axis.

        The size of the list will constrain the dimension of the resulting
        array.

        :param List[str] axesNames: List of distinct strings identifying axis names
        """
        self.__axisNames = list(axesNames)
        assert len(set(self.__axisNames)) == len(self.__axisNames), (
            "Non-unique axes names: %s" % self.__axisNames
        )

        delta = len(self.__axis) - len(self.__axisNames)
        if delta < 0:
            delta = 0
        for index, axis in enumerate(self.__axis):
            with blockSignals(axis):
                axis.setAxisNames(self.__axisNames)
                if index >= delta and index - delta < len(self.__axisNames):
                    axis.setAxisName(self.__axisNames[index - delta])
                else:
                    axis.setAxisName("")
        self.__updateSelectedData()

    def setCustomAxis(self, axesNames):
        """Set the available list of named axis which can be set to a value.

        :param List[str] axesNames: List of customable axis names
        """
        self.__customAxisNames = set(axesNames)
        for axis in self.__axis:
            axis.setCustomAxis(self.__customAxisNames)

    def setData(self, data):
        """Set the input data unsed by the widget.

        :param numpy.ndarray data: The input data
        """
        if self.__data is not None:
            # clean up
            for widget in self.__axis:
                self.layout().removeWidget(widget)
                widget.deleteLater()
            self.__axis = []

        self.__data = data

        if data is not None:
            # create expected axes
            dimensionNumber = len(data.shape)
            delta = dimensionNumber - len(self.__axisNames)
            for index in range(dimensionNumber):
                axis = _Axis(self)
                axis.setAxis(index, 0, data.shape[index])
                axis.setAxisNames(self.__axisNames)
                axis.setCustomAxis(self.__customAxisNames)
                if index >= delta and index - delta < len(self.__axisNames):
                    axis.setAxisName(self.__axisNames[index - delta])
                # this weak method was expected to be able to delete sub widget
                callback = functools.partial(
                    silx.utils.weakref.WeakMethodProxy(self.__axisValueChanged), axis
                )
                axis.valueChanged.connect(callback)
                # this weak method was expected to be able to delete sub widget
                callback = functools.partial(
                    silx.utils.weakref.WeakMethodProxy(self.__axisNameChanged), axis
                )
                axis.axisNameChanged.connect(callback)
                axis.setNamedAxisSelectorVisibility(self.__namedAxesVisibility)
                self.layout().addWidget(axis)
                self.__axis.append(axis)
        self.__normalizeAxisGeometry()

        self.dataChanged.emit()
        self.__updateSelectedData()

    def __normalizeAxisGeometry(self):
        """Update axes geometry to align all axes components together."""
        if len(self.__axis) <= 0:
            return
        lineEditWidth = max(
            [a.slider().lineEdit().minimumSize().width() for a in self.__axis]
        )
        limitWidth = max(
            [a.slider().limitWidget().minimumSizeHint().width() for a in self.__axis]
        )
        for a in self.__axis:
            a.slider().lineEdit().setFixedWidth(lineEditWidth)
            a.slider().limitWidget().setFixedWidth(limitWidth)

    def __axisValueChanged(self, axis, value):
        name = axis.axisName()
        if name in self.__customAxisNames:
            self.customAxisChanged.emit(name, value)
        else:
            self.__updateSelectedData()

    def __axisNameChanged(self, axis, name):
        """Called when an axis name change.

        :param _Axis axis: The changed axis
        :param str name: The new name of the axis
        """
        names = [x.axisName() for x in self.__axis]
        missingName = set(self.__axisNames) - set(names) - set("")
        if len(missingName) == 0:
            missingName = None
        elif len(missingName) == 1:
            missingName = list(missingName)[0]
        else:
            raise Exception("Unexpected state")

        axisChanged = True

        if axis.axisName() == "":
            # set the removed label to another widget if it is possible
            availableWidget = None
            for widget in self.__axis:
                if widget is axis:
                    continue
                if widget.axisName() == "":
                    availableWidget = widget
                    break
            if availableWidget is None:
                # If there is no other solution we set the name at the same place
                axisChanged = False
                availableWidget = axis
            with blockSignals(availableWidget):
                availableWidget.setAxisName(missingName)
        else:
            # there is a duplicated name somewhere
            # we swap it with the missing name or with nothing
            dupWidget = None
            for widget in self.__axis:
                if widget is axis:
                    continue
                if widget.axisName() == axis.axisName():
                    dupWidget = widget
                    break
            if missingName is None:
                missingName = ""
            with blockSignals(dupWidget):
                dupWidget.setAxisName(missingName)

        if self.__data is None:
            return
        if axisChanged:
            self.selectedAxisChanged.emit()
        self.__updateSelectedData()

    def __updateSelectedData(self):
        """Update the selected data according to the state of the widget.

        It fires a `selectionChanged` event.
        """
        permutation = self.permutation()

        if self.__data is None or permutation is None:
            # No data or not all the expected axes are there
            if self.__selectedData is not None:
                self.__selectedData = None
                self.selectionChanged.emit()
            return

        # get a view with few fixed dimensions
        # with a h5py dataset, it create a copy
        # TODO we can reuse the same memory in case of a copy
        self.__selectedData = numpy.transpose(
            self.__data[self.selection()], permutation
        )
        self.selectionChanged.emit()

    def data(self):
        """Returns the input data.

        :rtype: Union[numpy.ndarray,None]
        """
        if self.__data is None:
            return None
        else:
            return numpy.asarray(self.__data)

    def selectedData(self):
        """Returns the output data.

        This is equivalent to::

          numpy.transpose(self.data()[self.selection()], self.permutation())

        :rtype: Union[numpy.ndarray,None]
        """
        if self.__selectedData is None:
            return None
        else:
            return numpy.asarray(self.__selectedData)

    def permutation(self):
        """Returns the axes permutation to convert data subset to selected data.

        If permutation cannot be computer, it returns None.

        :rtype: Union[List[int],None]
        """
        if self.__data is None:
            return None
        else:
            indices = []
            for name in self.__axisNames:
                index = 0
                for axis in self.__axis:
                    if axis.axisName() == name:
                        indices.append(index)
                        break
                    if axis.axisName() != "":
                        index += 1
                else:
                    _logger.warning("No axis corresponding to: %s", name)
                    return None
            return tuple(indices)

    def selection(self):
        """Returns the selection tuple used to slice the data.

        :rtype: tuple
        """
        if self.__data is None:
            return tuple()
        else:
            return tuple(
                [
                    axis.value() if axis.axisName() == "" else slice(None)
                    for axis in self.__axis
                ]
            )

    def setSelection(self, selection, permutation=None):
        """Set the selection along each dimension.

        tuple returned by :meth:`selection` can be provided as input,
        provided that it is for the same the number of axes and
        the same number of dimensions of the data.

        :param List[Union[int,slice,None]] selection:
            The selection tuple with as one element for each dimension of the data.
            If an element is None, then the whole dimension is selected.
        :param  Union[List[int],None] permutation:
            The data axes indices to transpose.
            If not given, no permutation is applied
        :raise ValueError:
            When the selection does not match current data shape and number of axes.
        """
        data_shape = self.__data.shape if self.__data is not None else ()

        # Check selection
        if len(selection) != len(data_shape):
            raise ValueError(
                "Selection length (%d) and data ndim (%d) mismatch"
                % (len(selection), len(data_shape))
            )

        # Check selection type
        selectedDataNDim = 0
        for element, size in zip(selection, data_shape):
            if isinstance(element, int):
                if not 0 <= element < size:
                    raise ValueError(
                        "Selected index (%d) outside data dimension range [0-%d]"
                        % (element, size)
                    )
            elif element is None or element == slice(None):
                selectedDataNDim += 1
            else:
                raise ValueError("Unsupported element in selection: %s" % element)

        ndim = len(self.__axisNames)
        if selectedDataNDim != ndim:
            raise ValueError(
                "Selection dimensions (%d) and number of axes (%d) mismatch"
                % (selectedDataNDim, ndim)
            )

        # check permutation
        if permutation is None:
            permutation = tuple(range(ndim))

        if set(permutation) != set(range(ndim)):
            raise ValueError(
                "Error in provided permutation: "
                "Wrong size, elements out of range or duplicates"
            )

        inversePermutation = numpy.argsort(permutation)

        axisNameChanged = False
        customValueChanged = []
        with blockSignals(*self.__axis):
            index = 0
            for element, axis in zip(selection, self.__axis):
                if isinstance(element, int):
                    name = ""
                else:
                    name = self.__axisNames[inversePermutation[index]]
                    index += 1

                if axis.axisName() != name:
                    axis.setAxisName(name)
                    axisNameChanged = True

            for element, axis in zip(selection, self.__axis):
                value = element if isinstance(element, int) else 0
                if axis.value() != value:
                    axis.setValue(value)

                    name = axis.axisName()
                    if name in self.__customAxisNames:
                        customValueChanged.append((name, value))

        # Send signals that where disabled
        if axisNameChanged:
            self.selectedAxisChanged.emit()
        for name, value in customValueChanged:
            self.customAxisChanged.emit(name, value)
        self.__updateSelectedData()

    def setNamedAxesSelectorVisibility(self, visible):
        """Show or hide the combo-boxes allowing to map the plot axes
        to the data dimension.

        :param visible: Boolean
        """
        self.__namedAxesVisibility = visible
        for axis in self.__axis:
            axis.setNamedAxisSelectorVisibility(visible)
