"""
Widget for multi-model constraints.
"""
import os

# numpy methods required for the validator! Don't remove.
# pylint: disable=unused-import,unused-wildcard-import,redefined-builtin
from numpy import *

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

from sas.qtgui.Perspectives.Fitting import FittingUtilities
import sas.qtgui.Utilities.GuiUtils as GuiUtils
from sas.qtgui.Perspectives.Fitting.Constraint import Constraint

#ALLOWED_OPERATORS = ['=','<','>','>=','<=']
ALLOWED_OPERATORS = ['=']

# Local UI
from sas.qtgui.Perspectives.Fitting.UI.ComplexConstraintUI import Ui_ComplexConstraintUI

class ComplexConstraint(QtWidgets.QDialog, Ui_ComplexConstraintUI):
    constraintReadySignal = QtCore.pyqtSignal(tuple)
    def __init__(self, parent=None, tabs=None):
        super(ComplexConstraint, self).__init__()

        self.setupUi(self)
        self.setModal(True)

        # Useful globals
        self.tabs = tabs
        self.params = None
        self.tab_names = None
        self.operator = '='
        self._constraint = Constraint()

        self.warning = self.lblWarning.text()
        self.setupData()
        self.setupSignals()
        self.setupWidgets()
        self.setupTooltip()

        # Default focus is on OK
        self.cmdOK.setFocus()

    def setupData(self):
        """
        Digs into self.tabs and pulls out relevant info
        """
        self.tab_names = [tab.kernel_module.name for tab in self.tabs]
        self.params = [tab.getParamNames() for tab in self.tabs]

    def setupSignals(self):
        """
        Signals from various elements
        """
        self.cmdOK.clicked.connect(self.onApply)
        self.cmdHelp.clicked.connect(self.onHelp)
        self.cmdRevert.clicked.connect(self.onRevert)
        self.txtConstraint.editingFinished.connect(self.validateFormula)

        self.cbParam1.currentIndexChanged.connect(self.onParamIndexChange)
        self.cbParam2.currentIndexChanged.connect(self.onParamIndexChange)
        self.cbOperator.currentIndexChanged.connect(self.onOperatorChange)

    def setupWidgets(self):
        """
        Setup widgets based on current parameters
        """
        self.txtName1.setText(self.tab_names[0])
        self.txtName2.setText(self.tab_names[1])

        self.setupParamWidgets()

        # Add menu to the Apply button
        all_menu   = QtWidgets.QMenu()
        self.actionAddAll = QtWidgets.QAction(self)
        self.actionAddAll.setObjectName("actionAddAll")
        self.actionAddAll.setText(QtCore.QCoreApplication.translate("self", "Add all"))
        ttip = "Add constraints between all identically named parameters in both fitpages"
        self.actionAddAll.setToolTip(ttip)
        self.actionAddAll.triggered.connect(self.onSetAll)
        all_menu.addAction(self.actionAddAll)
        # https://bugreports.qt.io/browse/QTBUG-13663
        all_menu.setToolTipsVisible(True)
        self.cmdOK.setMenu(all_menu)

    def setupParamWidgets(self):
        """
        Fill out comboboxes and set labels with non-constrained parameters
        """
        self.cbParam1.clear()
        items1 = [param for param in self.params[0] if not self.tabs[0].paramHasConstraint(param)]
        self.cbParam1.addItems(items1)

        # M2 doesn't have to be non-constrained
        self.cbParam2.clear()
        #items2 = [param for param in self.params[1] if not self.tabs[1].paramHasConstraint(param)]
        items2 = [param for param in self.params[1]]
        self.cbParam2.addItems(items2)

        self.txtParam.setText(self.tab_names[0] + ":" + self.cbParam1.currentText())

        self.cbOperator.clear()
        self.cbOperator.addItems(ALLOWED_OPERATORS)
        self.txtOperator.setText(self.cbOperator.currentText())

        self.txtConstraint.setText(self.tab_names[1]+"."+self.cbParam2.currentText())

        # disable Apply if no parameters available
        if len(items1)==0:
            self.cmdOK.setEnabled(False)
            txt = "No parameters in model "+self.tab_names[0] +\
                " are available for constraining."
            self.lblWarning.setText(txt)
        else:
            self.cmdOK.setEnabled(True)
            txt = ""
            self.lblWarning.setText(txt)

    def setupTooltip(self):
        """
        Tooltip for txtConstraint
        """
        p1 = self.tab_names[0] + ":" + self.cbParam1.currentText()
        p2 = self.tab_names[1]+"."+self.cbParam2.currentText()
        tooltip = "E.g.\n%s = 2.0 * (%s)\n" %(p1, p2)
        tooltip += "%s = sqrt(%s) + 5"%(p1, p2)
        self.txtConstraint.setToolTip(tooltip)

    def onParamIndexChange(self, index):
        """
        Respond to parameter combo box changes
        """
        # Find out the signal source
        source = self.sender().objectName()
        param1 = self.cbParam1.currentText()
        param2 = self.cbParam2.currentText()
        if source == "cbParam1":
            self.txtParam.setText(self.tab_names[0] + ":" + param1)
        else:
            self.txtConstraint.setText(self.tab_names[1] + "." + param2)
        # Check if any of the parameters are polydisperse
        params_list = [param1, param2]
        all_pars = [tab.model_parameters for tab in self.tabs]
        is2Ds = [tab.is2D for tab in self.tabs]
        txt = ""
        for pars, is2D in zip(all_pars, is2Ds):
            if any([FittingUtilities.isParamPolydisperse(p, pars, is2D) for p in params_list]):
                # no parameters are pd - reset the text to not show the warning
                txt = self.warning
        self.lblWarning.setText(txt)


    def onOperatorChange(self, index):
        """
        Respond to operator combo box changes
        """
        self.txtOperator.setText(self.cbOperator.currentText())

    def onRevert(self):
        """
        switch M1 <-> M2
        """
        # Switch parameters
        self.params[1], self.params[0] = self.params[0], self.params[1]
        self.tab_names[1], self.tab_names[0] = self.tab_names[0], self.tab_names[1]
        self.tabs[1], self.tabs[0] = self.tabs[0], self.tabs[1]
        # Try to swap parameter names in the line edit
        current_text = self.txtConstraint.text()
        new_text = current_text.replace(self.cbParam1.currentText(), self.cbParam2.currentText())
        self.txtConstraint.setText(new_text)
        # Update labels and tooltips
        index1 = self.cbParam1.currentIndex()
        index2 = self.cbParam2.currentIndex()
        indexOp = self.cbOperator.currentIndex()
        self.setupWidgets()

        # Original indices
        index2 = index2 if index2 >= 0 else 0
        index1 = index1 if index1 >= 0 else 0
        self.cbParam1.setCurrentIndex(index2)
        self.cbParam2.setCurrentIndex(index1)
        self.cbOperator.setCurrentIndex(indexOp)
        self.setupTooltip()

    def validateFormula(self):
        """
        Add visual cues when formula is incorrect
        """
        formula_is_valid = self.validateConstraint(self.txtConstraint.text())
        if not formula_is_valid:
            self.cmdOK.setEnabled(False)
            self.txtConstraint.setStyleSheet("QLineEdit {background-color: red;}")
        else:
            self.cmdOK.setEnabled(True)
            self.txtConstraint.setStyleSheet("QLineEdit {background-color: white;}")

    def validateConstraint(self, constraint_text):
        """
        Ensure the constraint has proper form
        """
        # 0. none or empty
        if not constraint_text or not isinstance(constraint_text, str):
            return False

        # M1.scale  --> model_str='M1', constraint_text='scale'
        param_str = self.cbParam2.currentText()
        constraint_text = constraint_text.strip()
        model_str = self.txtName2.text()

        # 0. Has to contain the model name
        if model_str != self.txtName2.text():
            return False

        # Remove model name from constraint
        constraint_text = constraint_text.replace(model_str+".",'')

        # 1. just the parameter
        if param_str == constraint_text:
            return True

        # 2. ensure the text contains parameter name
        parameter_string_start = constraint_text.find(param_str)
        if parameter_string_start < 0:
            return False

        # 3. replace parameter name with "1" and try to evaluate the expression
        try:
            expression_to_evaluate = constraint_text.replace(param_str, "1.0")
            eval(expression_to_evaluate)
        except Exception:
            # Too many cases to cover individually, just a blanket
            # Exception should be sufficient
            # Note that in current numpy things like sqrt(-1) don't
            # raise but just return warnings
            return False

        return True

    def constraint(self):
        """
        Return the generated constraint
        """
        param = self.cbParam1.currentText()
        value = self.cbParam2.currentText()
        func = self.txtConstraint.text()
        value_ex = self.txtName2.text() + "." + self.cbParam2.currentText()
        model1 = self.txtName1.text()
        operator = self.cbOperator.currentText()

        con = Constraint(self,
                         param=param,
                         value=value,
                         func=func,
                         value_ex=value_ex,
                         operator=operator)

        return (model1, con)

    def onApply(self):
        """
        Respond to Add constraint action.
        Send a signal that the constraint is ready to be applied
        """
        cons_tuple = self.constraint()
        self.constraintReadySignal.emit(cons_tuple)
        # reload the comboboxes
        self.setupParamWidgets()

    def onSetAll(self):
        """
        Set constraints on all identically named parameters between two fitpages
        """
        # loop over parameters in constrained model
        items1 = [param for param in self.params[0] if not self.tabs[0].paramHasConstraint(param)]
        #items2 = [param for param in self.params[1] if not self.tabs[1].paramHasConstraint(i)]
        items2 = self.params[1]
        for item in items1:
            if item not in items2: continue
            param = item
            value = item
            func = self.txtName2.text() + "." + param
            value_ex = self.txtName1.text() + "." + param
            model1 = self.txtName1.text()
            operator = self.cbOperator.currentText()

            con = Constraint(self,
                             param=param,
                             value=value,
                             func=func,
                             value_ex=value_ex,
                             operator=operator)

            self.constraintReadySignal.emit((model1, con))

        # reload the comboboxes
        self.setupParamWidgets()

    def onHelp(self):
        """
        Display related help section
        """
        try:
            help_location = GuiUtils.HELP_DIRECTORY_LOCATION + \
            "/user/qtgui/Perspectives/Fitting/fitting_help.html#simultaneous-fits-with-constraints"
            webbrowser.open('file://' + os.path.realpath(help_location))
        except AttributeError:
            # No manager defined - testing and standalone runs
            pass