# This is a data viewer for glue data objects that have a spectral axis. For
# more information about how this viewer is written, see the following
# documentation page:
#
# Writing a custom viewer for glue with Qt
# http://docs.glueviz.org/en/latest/customizing_guide/qt_viewer.html

import os
from collections import OrderedDict

import astropy.units as u

from glue.core import Component, Data
from glue.core.coordinates import coordinates_from_header
from glue.core.data_combo_helper import ComponentIDComboHelper
from glue.core.exceptions import IncompatibleAttribute
from glue.external.echo import (CallbackProperty, SelectionCallbackProperty,
                                keep_in_sync)
from glue.external.echo.qt import autoconnect_callbacks_to_qt
from glue.utils.qt import load_ui
from glue.viewers.common.layer_artist import LayerArtist
from glue.viewers.common.qt.data_viewer import DataViewer
from glue.viewers.common.state import LayerState, ViewerState
from qtpy.QtCore import Qt
from qtpy.QtWidgets import QMdiArea, QMessageBox, QWidget, QAction, QToolButton, QMenu
from qtpy.QtGui import QIcon, QColor
import numpy as np
import logging
from pyqtgraph import InfiniteLine

from .utils import glue_data_has_spectral_axis, glue_data_to_spectrum1d
from ...app import Application
from ...widgets.workspace import Workspace
from .operation_handler import SpectralOperationHandler
from ...core.hub import Hub
from ...core.operations import FunctionalOperation

__all__ = ['SpecvizDataViewer']

FUNCTIONS = OrderedDict([('maximum', 'Maximum'),
                         ('minimum', 'Minimum'),
                         ('mean', 'Mean'),
                         ('median', 'Median'),
                         ('sum', 'Sum')])


class SpecvizViewerState(ViewerState):
    pass

class SpecvizLayerState(LayerState):
    """

    """
    color = CallbackProperty(docstring='The color used to display the data')
    alpha = CallbackProperty(docstring='The transparency used to display the data')
    linewidth = CallbackProperty(1, docstring='The width of the line for the data')

    attribute = SelectionCallbackProperty(docstring='The attribute to use for the spectrum')
    statistic = SelectionCallbackProperty(docstring='The statistic to use to collapse data')

    def __init__(self, viewer_state=None, **kwargs):

        super(SpecvizLayerState, self).__init__(viewer_state=viewer_state, **kwargs)

        self.color = self.layer.style.color
        self.alpha = self.layer.style.alpha

        self._sync_color = keep_in_sync(self, 'color', self.layer.style, 'color')
        self._sync_alpha = keep_in_sync(self, 'alpha', self.layer.style, 'alpha')

        self._att_helper = ComponentIDComboHelper(self, 'attribute')
        self.add_callback('layer', self._on_layer_change)
        self._on_layer_change()

        SpecvizLayerState.statistic.set_choices(self, list(FUNCTIONS))
        SpecvizLayerState.statistic.set_display_func(self, FUNCTIONS.get)

    def _on_layer_change(self, *args):
        if self.layer is None:
            self._att_helper.set_multiple_data([])
        else:
            self._att_helper.set_multiple_data([self.layer])


class SpecvizLayerArtist(LayerArtist):
    """

    """
    _layer_state_cls = SpecvizLayerState

    def __init__(self, specviz_window, *args, **kwargs):

        super(SpecvizLayerArtist, self).__init__(*args, **kwargs)

        self.specviz_window = specviz_window
        self.plot_widget = self.specviz_window.current_plot_window.plot_widget

        self.state.add_callback('attribute', self.update)
        self.state.add_callback('statistic', self.update)

        self.state.add_callback('zorder', self.update_visual)
        self.state.add_callback('visible', self.update_visual)
        self.state.add_callback('color', self.update_visual)
        self.state.add_callback('alpha', self.update_visual)
        self.state.add_callback('linewidth', self.update_visual)

        self.data_item = None
        self._init_plot = True

        self.specviz_window.current_plot_window.color_changed.connect(
            self.on_color_changed)

    def on_color_changed(self, plot_data_item, color):
        """
        Called when the color of a plot data item is changed from specviz.

        Parameters
        ----------
        plot_data_item : ``PlotDataItem``
            The plot data item whose colors has been changed.
        color : ``QColor``
            The qt representation of the color.
        """
        self.state.layer.style.color = color.name()

    def remove(self):
        """

        """
        if self.data_item is not None:
            # Remove from plot
            plot_data_item = self.specviz_window.proxy_model.item_from_id(
                self.data_item.identifier)
            self.specviz_window.current_plot_window.plot_widget.remove_plot(
                item=plot_data_item)

            # Delete from model
            self.specviz_window.model.remove_data(self.data_item.identifier)
            self.data_item = None

    def clear(self):
        """

        """
        self.remove()

    def redraw(self):
        """

        """
        pass

    @property
    def plot_data_item(self):
        """
        Get the PlotDataItem corresponding to this layer artist.
        """
        if self.data_item is None:
            return None
        else:
            return self.plot_widget.proxy_model.item_from_id(self.data_item.identifier)

    def update_visual(self, *args, **kwargs):
        """

        Parameters
        ----------
        args
        kwargs
        """
        plot_data_item = self.plot_data_item
        if plot_data_item is not None:
            plot_data_item.visible = self.state.visible
            plot_data_item.zorder = self.state.zorder
            plot_data_item.width = self.state.linewidth
            color = QColor(self.state.layer.style.color)
            color.setAlphaF(self.state.layer.style.alpha)
            plot_data_item.color = color

    def update(self, *args, **kwargs):
        """

        Parameters
        ----------
        args
        kwargs

        Returns
        -------

        """
        if self.state.layer is None or self.state.attribute is None:
            return

        try:
            spectrum = glue_data_to_spectrum1d(self.state.layer,
                                               self.state.attribute,
                                               statistic=self.state.statistic)
        except IncompatibleAttribute:
            self.disable_invalid_attributes(self.state.attribute)
            return

        self.enable()

        if self.data_item is None:
            self.data_item = self.specviz_window.model.add_data(spectrum,
                                                                name=self.state.layer.label)
            self.plot_widget.add_plot(self.plot_data_item,
                                      visible=True,
                                      initialize=True)
        else:
            self.plot_data_item.data_item.set_data(spectrum)
            self.plot_data_item.set_data()

        self.update_visual()

        if self._init_plot:
            self.plot_widget.autoRange(
                items=[item for item in self.plot_widget.listDataItems()
                       if not isinstance(item, InfiniteLine)])
            self._init_plot = False


class SpecvizViewerStateWidget(QWidget):
    """

    """
    def __init__(self, viewer_state=None, session=None):

        super(SpecvizViewerStateWidget, self).__init__()

        self.ui = load_ui('viewer_state.ui', self,
                          directory=os.path.dirname(__file__))

        self.viewer_state = viewer_state
        autoconnect_callbacks_to_qt(self.viewer_state, self.ui)


class SpecvizLayerStateWidget(QWidget):
    """

    """
    def __init__(self, layer_artist):

        super(SpecvizLayerStateWidget, self).__init__()

        self.ui = load_ui('layer_state.ui', self,
                          directory=os.path.dirname(__file__))

        connect_kwargs = {'alpha': dict(value_range=(0, 1))}

        autoconnect_callbacks_to_qt(layer_artist.state, self.ui, connect_kwargs)

class SpecvizDataViewer(DataViewer):
    """

    """
    LABEL = 'SpecViz viewer'
    _state_cls = SpecvizViewerState
    _options_cls = SpecvizViewerStateWidget
    _layer_style_widget_cls = SpecvizLayerStateWidget
    _data_artist_cls = SpecvizLayerArtist
    _subset_artist_cls = SpecvizLayerArtist
    _inherit_tools = False
    tools = []
    subtools = {}

    def __init__(self, *args, layout=None, include_line=False, **kwargs):
        # Load specviz plugins
        Application.load_local_plugins()

        super(SpecvizDataViewer, self).__init__(*args, **kwargs)
        self.statusBar().hide()

        # Instantiate workspace widget
        self.current_workspace = Workspace()
        self.hub = Hub(self.current_workspace)

        # Store a reference to the cubeviz layout instance
        self._layout = layout

        # Add an initially empty plot window
        self.current_workspace.add_plot_window()

        self.setCentralWidget(self.current_workspace)

        self.options.gridLayout.addWidget(self.current_workspace.list_view)

        # When a new data item is added to the specviz model, create a new
        # glue data component and add it to the glue data list
        # self.current_workspace.model.data_added.connect(self.reverse_add_data)

        self.current_workspace.mdi_area.setViewMode(QMdiArea.SubWindowView)
        self.current_workspace.current_plot_window.setWindowFlags(Qt.FramelessWindowHint)
        self.current_workspace.current_plot_window.showMaximized()

        # Create and attach a movable vertical line indicating the current
        # slice position in the cube
        if include_line:
            self._slice_indicator = InfiniteLine(0, movable=True,
                                                 pen={'color': 'g', 'width': 3})
            self.current_workspace.current_plot_window.plot_widget.addItem(
                self._slice_indicator)

    def reverse_add_data(self, data_item):
        """
        Adds data from specviz to glue.

        Parameters
        ----------
        data_item : :class:`specviz.core.items.DataItem`
            The data item recently added to model.
        """
        new_data = Data(label=data_item.name)
        new_data.coords = coordinates_from_header(data_item.spectrum.wcs)

        flux_component = Component(data_item.spectrum.flux,
                                   data_item.spectrum.flux.unit)
        new_data.add_component(flux_component, "Flux")

        disp_component = Component(data_item.spectrum.spectral_axis,
                                   data_item.spectrum.spectral_axis.unit)
        new_data.add_component(disp_component, "Dispersion")

        if data_item.spectrum.uncertainty is not None:
            uncert_component = Component(data_item.spectrum.uncertainty.array,
                                         data_item.spectrum.uncertainty.unit)
            new_data.add_component(uncert_component, "Uncertainty")

        self._session.data_collection.append(new_data)

    def add_data(self, data):
        """

        Parameters
        ----------
        data

        Returns
        -------

        """
        if not glue_data_has_spectral_axis(data):
            QMessageBox.critical(self, "Error", "Data is not a 1D spectrum",
                                 buttons=QMessageBox.Ok)
            return False
        return super(SpecvizDataViewer, self).add_data(data)

    def add_subset(self, subset):
        """

        Parameters
        ----------
        subset

        Returns
        -------

        """
        if not glue_data_has_spectral_axis(subset):
            QMessageBox.critical(self, "Error", "Subset is not a 1D spectrum",
                                 buttons=QMessageBox.Ok)
            return False
        return super(SpecvizDataViewer, self).add_subset(subset)

    def get_layer_artist(self, cls, layer=None, layer_state=None):
        """

        Parameters
        ----------
        cls
        layer
        layer_state

        Returns
        -------

        """
        return cls(self.current_workspace, self.state, layer=layer, layer_state=layer_state)

    def initialize_toolbar(self):
        """

        """
        # Merge the main tool bar and the plot tool bar to get back some
        # real estate
        self.current_workspace.addToolBar(
            self.current_workspace.current_plot_window.tool_bar)

        # Hide the first five actions in the default specviz tool bar
        for act in self.current_workspace.main_tool_bar.actions()[:6]:
            act.setVisible(False)

        # Hide the tabs of the mdiarea in specviz.
        self.current_workspace.mdi_area.setViewMode(QMdiArea.SubWindowView)
        self.current_workspace.current_plot_window.setWindowFlags(Qt.FramelessWindowHint)
        self.current_workspace.current_plot_window.showMaximized()

        if self._layout is not None:
            cube_ops = QAction(QIcon(":/icons/cube.svg"), "Cube Operations",
                               self.current_workspace.main_tool_bar)
            self.current_workspace.main_tool_bar.addAction(cube_ops)
            self.current_workspace.main_tool_bar.addSeparator()

            button = self.current_workspace.main_tool_bar.widgetForAction(cube_ops)
            button.setPopupMode(QToolButton.InstantPopup)
            menu = QMenu(self.current_workspace.main_tool_bar)
            button.setMenu(menu)

            # Create operation actions
            act = QAction("Simple Linemap", self)
            act.triggered.connect(self._create_simple_linemap)
            menu.addAction(act)

            act = QAction("Fitted Linemap", self)
            act.triggered.connect(self.create_fitted_linemap)
            menu.addAction(act)

            act = QAction("Spectral Smoothing", self)
            act.triggered.connect(self.spectral_smoothing)
            menu.addAction(act)

    def update_units(self, spectral_axis_unit=None, data_unit=None):
        """
        Interface for data viewers to update the plotted axis units in specviz.

        Parameters
        ----------
        spectral_axis_unit : str or :class:`~astropy.unit.Quantity`
            The spectral axis unit to convert to.
        data_unit : str or :class:`~astropy.unit.Quantity`
            The data axis unit to convert to.
        """
        if spectral_axis_unit is not None:
            if isinstance(spectral_axis_unit, u.Quantity):
                spectral_axis_unit = spectral_axis_unit.to_string()

            # Return if the units are already the same.
            if spectral_axis_unit == self.hub.plot_widget.spectral_axis_unit:
                return

            if self._slice_indicator is not None:
                cur_slice_pos = u.Quantity(self._slice_indicator.value(),
                                           self.hub.plot_widget.spectral_axis_unit)
                new_slice_pos = cur_slice_pos.to(spectral_axis_unit,
                                                 equivalencies=u.spectral()).value

                self._slice_indicator.blockSignals(True)
                self._slice_indicator.setPos(new_slice_pos)
                self._slice_indicator.blockSignals(False)

            self.hub.plot_widget.spectral_axis_unit = spectral_axis_unit

        if data_unit is not None:
            if isinstance(data_unit, u.Quantity):
                data_unit = data_unit.to_string()

            self.hub.plot_widget.data_unit = data_unit

    def _create_simple_linemap(self):
        def threadable_function(data, tracker):
            out = np.empty(shape=data.shape)
            mask = self.hub.region_mask

            for x in range(data.shape[1]):
                for y in range(data.shape[2]):
                    out[:, x, y] = np.sum(data[:, x, y][mask])
                    tracker()

            return out, data.meta.get('unit')

        spectral_operation = SpectralOperationHandler(
            data=self.layers[0].state.layer,
            function=threadable_function,
            operation_name="Simple Linemap",
            component_id=self.layers[0].state.attribute,
            layout=self._layout,
            ui_settings={
                'title': "Simple Linemap",
                'group_box_title': "Choose the component to use for linemap "
                                   "generation",
                'description': "Sums the values of the chosen component in the "
                               "range of the current ROI in the spectral view "
                               "for each spectrum in the data cube."})

        spectral_operation.exec_()

    def create_fitted_linemap(self):
        # Check to see if the model fitting plugin is loaded
        model_editor_plugin = self.current_workspace._plugin_bars.get("Model Editor")

        if model_editor_plugin is None:
            logging.error("Model editor plugin is not loaded.")
            return

        if (model_editor_plugin.model_tree_view.model() is None or
                model_editor_plugin.model_tree_view.model().evaluate() is None):
            QMessageBox.warning(self,
                                "No evaluable model.",
                                "There is currently no model or the created "
                                "model is empty. Unable to perform fitted "
                                "linemap operation.")
            return

        def threadable_function(data, tracker):
            from astropy.modeling.fitting import LevMarLSQFitter

            out = np.empty(shape=data.shape)
            mask = self.hub.region_mask

            spectral_axis = self.hub.plot_item.spectral_axis
            model = model_editor_plugin.model_tree_view.model().evaluate()

            for x in range(data.shape[1]):
                for y in range(data.shape[2]):
                    flux = data[:, x, y].value

                    fitter = LevMarLSQFitter()
                    fit_model = fitter(model,
                                       spectral_axis[mask],
                                       flux[mask])

                    new_data = fit_model(spectral_axis)

                    out[:, x, y] = new_data

                    tracker()

            return out, data.meta.get('unit')

        spectral_operation = SpectralOperationHandler(
            data=self.layers[0].state.layer,
            function=threadable_function,
            operation_name="Fitted Linemap",
            component_id=self.layers[0].state.attribute,
            layout=self._layout,
            ui_settings={
                'title': "Fitted Linemap",
                'group_box_title': "Choose the component to use for linemap "
                                   "generation",
                'description': "Fits the current model to the values of the "
                               "chosen component in the range of the current "
                               "ROI in the spectral view for each spectrum in "
                               "the data cube."})

        spectral_operation.exec_()

    def spectral_smoothing(self):
        def threadable_function(func, data, tracker, **kwargs):
            out = np.empty(shape=data.shape)

            for x in range(data.shape[1]):
                for y in range(data.shape[2]):
                    out[:, x, y] = func(data[:, x, y],
                                        data.spectral_axis)
                    tracker()

            return out, data.meta.get('unit')

        stack = FunctionalOperation.operations()[::-1]

        if len(stack) == 0:
            QMessageBox.warning(self,
                                "No smoothing in history.",
                                "To apply a smoothing operation to the entire "
                                "cube, first do a local smoothing operation "
                                "(Operations > Smoothing). Once done, the "
                                "operation can then be performed over the "
                                "entire cube.")
            return

        spectral_operation = SpectralOperationHandler(
            data=self.layers[0].state.layer,
            func_proxy=threadable_function,
            stack=stack,
            component_id=self.layers[0].state.attribute,
            layout=self._layout,
            ui_settings={
                'title': "Spectral Smoothing",
                'group_box_title': "Choose the component to smooth.",
                'description': "Performs a previous smoothing operation over "
                               "the selected component for the entire cube."})

        spectral_operation.exec_()
