# global
import sys
import os
import types
import webbrowser

from PyQt5 import QtCore
from PyQt5 import QtGui
from PyQt5 import QtWidgets

from sas.qtgui.UI import images_rc
from sas.qtgui.UI import main_resources_rc
import sas.qtgui.Utilities.GuiUtils as GuiUtils

from bumps import fitters
import bumps.options

from sas.qtgui.Perspectives.Fitting.UI.FittingOptionsUI import Ui_FittingOptions

# Set the default optimizer

class FittingMethodParameter:
    _shortName = None
    _longName = None
    _type = None
    _defaultValue = None
    value = None

    def __init__(self, shortName, longName, dtype, defaultValue):
        self._shortName = shortName
        self._longName = longName
        self._type = dtype
        self._defaultValue = defaultValue
        self.value = defaultValue

    @property
    def shortName(self):
        return self._shortName

    @property
    def longName(self):
        return self._longName

    @property
    def type(self):
        return self._type

    @property
    def defaultValue(self):
        return self._defaultValue

    def __str__(self):
        return "'{}' ({}): {} ({})".format(
                self.longName, self.sortName, self.defaultValue, self.type)

class FittingMethod:
    """
    Represents a generic fitting method.
    """
    _shortName = None
    _longName = None
    _params = None    # dict of <param short names>: <FittingMethodParam>

    def __init__(self, shortName, longName, params):
        self._shortName = shortName
        self._longName = longName
        self._params = dict(zip([p.shortName for p in params], params))

    @property
    def shortName(self):
        return self._shortName

    @property
    def longName(self):
        return self._longName

    @property
    def params(self):
        return self._params

    def __str__(self):
        return "\n".join(["{} ({})".format(self.longName, self.shortName)]
                + [str(p) for p in self.params])

class FittingMethods:
    """
    A container for the available fitting methods.
    Allows SasView to employ other methods than those provided by the bumps package.
    """
    _methods = None # a dict containing FitMethod objects
    _default = None

    def __init__(self):
        """Receives a list of FittingMethod instances to be initialized with."""
        self._methods = dict()

    def add(self, fittingMethod):
        if not isinstance(fittingMethod, FittingMethod):
            return
        self._methods[fittingMethod.longName] = fittingMethod

    def importFromBumps(self, ids):
        """
        Import fitting methods indicated by the provided list of ids from the bumps package.
        """
        for f in fitters.FITTERS:
            if f.id not in ids:
                continue
            params = []
            for shortName, defValue in f.settings:
                longName, dtype = bumps.options.FIT_FIELDS[shortName]
                param = FittingMethodParameter(shortName, longName, dtype, defValue)
                params.append(param)
            self.add(FittingMethod(f.id, f.name, params))

    @property
    def longNames(self):
        return list(self._methods.keys())

    @property
    def ids(self):
        return [fm.shortName for fm in self._methods.values()]

    def __getitem__(self, name):
        return self._methods[name]

    @property
    def default(self):
        return self._default

    def setDefault(self, methodName):
        assert methodName in self._methods # silently fail instead?
        self._default = self._methods[methodName]

    def __str__(self):
        return "\n".join(["{}: {}".format(key, fm) for key, fm in self._methods.items()])

class FittingOptions(QtWidgets.QDialog, Ui_FittingOptions):
    """
    Hard-coded version of the fit options dialog available from BUMPS.
    This should be make more "dynamic".
    bumps.options.FIT_FIELDS gives mapping between parameter names, parameter strings and field type
     (double line edit, integer line edit, combo box etc.), e.g.
        FIT_FIELDS = dict(
            samples = ("Samples", parse_int),
            xtol = ("x tolerance", float))

    bumps.fitters.<algorithm>.settings gives mapping between algorithm, parameter name and default value:
        e.g.
        settings = [('steps', 1000), ('starts', 1), ('radius', 0.15), ('xtol', 1e-6), ('ftol', 1e-8)]
    """
    fit_option_changed = QtCore.pyqtSignal(str)
    # storing of fitting methods here for now, dependencies might indicate a better place later
    fittingMethods = None

    def __init__(self, parent=None, config=None):
        super(FittingOptions, self).__init__(parent)
        self.setupUi(self)
        # disable the context help icon
        self.setWindowFlags(self.windowFlags() & ~QtCore.Qt.WindowContextHelpButtonHint)

        self.config = config

        # no reason to have this widget resizable
        self.setFixedSize(self.minimumSizeHint())

        self.setWindowTitle("Fit Algorithms")

        # Fill up the algorithm combo, based on what BUMPS says is available
        self.fittingMethods = FittingMethods()
        # option 1: hardcode the list of bumps fitting methods according to forms
        # option 2: create forms dynamically based on selected fitting methods
        self.fittingMethods.importFromBumps(fitters.FIT_ACTIVE_IDS)
        self.fittingMethods.add(FittingMethod('mcsas', 'McSAS', []))
        self.fittingMethods.setDefault('Levenberg-Marquardt')
        # build up the comboBox finally
        self.cbAlgorithm.addItems(self.fittingMethods.longNames)

        # Handle the Apply button click
        self.buttonBox.button(QtWidgets.QDialogButtonBox.Ok).clicked.connect(self.onApply)
        # handle the Help button click
        self.buttonBox.button(QtWidgets.QDialogButtonBox.Help).clicked.connect(self.onHelp)

        # Handle the combo box changes
        self.cbAlgorithm.currentIndexChanged.connect(self.onAlgorithmChange)

        # Set the default index
        default_index = self.cbAlgorithm.findText(self.fittingMethods.default.longName)
        self.cbAlgorithm.setCurrentIndex(default_index)
        # previous algorithm choice
        self.previous_index = default_index

        # Assign appropriate validators
        self.assignValidators()

        # Set defaults
        self.current_fitter_id = self.fittingMethods.default.shortName

        # OK has to be initialized to True, after initial validator setup
        self.buttonBox.button(QtWidgets.QDialogButtonBox.Ok).setEnabled(True)

    def assignValidators(self):
        """
        Use options.FIT_FIELDS to assert which line edit gets what validator
        """
        for option in bumps.options.FIT_FIELDS.keys():
            (f_name, f_type) = bumps.options.FIT_FIELDS[option]
            validator = None
            if type(f_type) == types.FunctionType:
                validator = QtGui.QIntValidator()
                validator.setBottom(0)
            elif f_type == float:
                validator = GuiUtils.DoubleValidator()
                validator.setBottom(0)
            else:
                continue
            for fitter_id in self.fittingMethods.ids:
                line_edit = self.widgetFromOption(str(option), current_fitter=str(fitter_id))
                if hasattr(line_edit, 'setValidator') and validator is not None:
                    line_edit.setValidator(validator)
                    line_edit.textChanged.connect(self.check_state)
                    line_edit.textChanged.emit(line_edit.text())

    def check_state(self, *args, **kwargs):
        sender = self.sender()
        validator = sender.validator()
        state = validator.validate(sender.text(), 0)[0]
        if state == QtGui.QValidator.Acceptable:
            color = '' # default
            self.buttonBox.button(QtWidgets.QDialogButtonBox.Ok).setEnabled(True)
        else:
            color = '#fff79a' # yellow
            self.buttonBox.button(QtWidgets.QDialogButtonBox.Ok).setEnabled(False)

        sender.setStyleSheet('QLineEdit { background-color: %s }' % color)

    def onAlgorithmChange(self, index):
        """
        Change the page in response to combo box index
        """
        # Find the algorithm ID from name
        selectedName = str(self.cbAlgorithm.currentText())
        if selectedName in self.fittingMethods.longNames:
            self.current_fitter_id = self.fittingMethods[selectedName].shortName

        # find the right stacked widget
        widget_name = "self.page_"+str(self.current_fitter_id)

        # Convert the name into widget instance
        try:
            widget_to_activate = eval(widget_name)
        except AttributeError:
            # We don't yet have this optimizer.
            # Show message
            msg = "This algorithm has not yet been implemented in SasView.\n"
            msg += "Please choose a different algorithm"
            QtWidgets.QMessageBox.warning(self,
                                        'Warning',
                                        msg,
                                        QtWidgets.QMessageBox.Ok)
            # Move the index to previous position
            self.cbAlgorithm.setCurrentIndex(self.previous_index)
            return

        index_for_this_id = self.stackedWidget.indexOf(widget_to_activate)

        # Select the requested widget
        self.stackedWidget.setCurrentIndex(index_for_this_id)

        self.updateWidgetFromBumps(self.current_fitter_id)

        self.assignValidators()

        # OK has to be reinitialized to True
        self.buttonBox.button(QtWidgets.QDialogButtonBox.Ok).setEnabled(True)

        # keep reference
        self.previous_index = index

    def onApply(self):
        """
        Update the fitter object
        """
        options = self.config.values[self.current_fitter_id]
        for option in options.keys():
            # Find the widget name of the option
            # e.g. 'samples' for 'dream' is 'self.samples_dream'
            widget_name = 'self.'+option+'_'+self.current_fitter_id
            try:
                line_edit = eval(widget_name)
            except AttributeError:
                # Skip bumps monitors
                continue
            if line_edit is None or not isinstance(line_edit, QtWidgets.QLineEdit):
                continue
            color = line_edit.palette().color(QtGui.QPalette.Background).name()
            if color == '#fff79a':
                # Show a custom tooltip and return
                tooltip = "<html><b>Please enter valid values in all fields.</html>"
                QtWidgets.QToolTip.showText(line_edit.mapToGlobal(
                    QtCore.QPoint(line_edit.rect().right(), line_edit.rect().bottom() + 2)), tooltip)
                return

        # Notify the perspective, so the window title is updated
        self.fit_option_changed.emit(self.cbAlgorithm.currentText())

        def bumpsUpdate(option):
            """
            Utility method for bumps state update
            """
            widget = self.widgetFromOption(option)
            if widget is None:
                return
            try:
                if isinstance(widget, QtWidgets.QComboBox):
                    new_value = widget.currentText()
                else:
                    try:
                        new_value = int(widget.text())
                    except ValueError:
                        new_value = float(widget.text())
                #new_value = widget.currentText() if isinstance(widget, QtWidgets.QComboBox) \
                #    else float(widget.text())
                self.config.values[self.current_fitter_id][option] = new_value
            except ValueError:
                # Don't update bumps if widget has bad data
                self.reject

        # Update the BUMPS singleton
        [bumpsUpdate(o) for o in self.config.values[self.current_fitter_id].keys()]
        self.close()

    def onHelp(self):
        """
        Show the "Fitting options" section of help
        """
        tree_location = GuiUtils.HELP_DIRECTORY_LOCATION
        tree_location += "/user/qtgui/Perspectives/Fitting/"

        # Actual file anchor will depend on the combo box index
        # Note that we can be clusmy here, since bad current_fitter_id
        # will just make the page displayed from the top
        helpfile = "optimizer.html#fit-" + self.current_fitter_id 
        help_location = tree_location + helpfile
        webbrowser.open('file://' + os.path.realpath(help_location))

    def widgetFromOption(self, option_id, current_fitter=None):
        """
        returns widget's element linked to the given option_id
        """
        if current_fitter is None:
            current_fitter = self.current_fitter_id
        if option_id not in list(bumps.options.FIT_FIELDS.keys()): return None
        option = option_id + '_' + current_fitter
        if not hasattr(self, option): return None
        return eval('self.' + option)

    def getResults(self):
        """
        Sends back the current choice of parameters
        """
        algorithm = self.cbAlgorithm.currentText()
        return algorithm

    def updateWidgetFromBumps(self, fitter_id):
        """
        Given the ID of the current optimizer, fetch the values
        and update the widget
        """
        options = self.config.values[fitter_id]
        for option in options.keys():
            # Find the widget name of the option
            # e.g. 'samples' for 'dream' is 'self.samples_dream'
            widget_name = 'self.'+option+'_'+fitter_id
            if option not in bumps.options.FIT_FIELDS:
                return
            if isinstance(bumps.options.FIT_FIELDS[option][1], bumps.options.ChoiceList):
                control = eval(widget_name)
                control.setCurrentIndex(control.findText(str(options[option])))
            else:
                eval(widget_name).setText(str(options[option]))

        pass