# global
import logging
import functools
from PyQt4 import QtGui, QtCore

from periodictable import formula as Formula

from sas.qtgui.Utilities.GuiUtils import FormulaValidator
from sas.qtgui.UI import main_resources_rc

# Local UI
from sas.qtgui.Calculators.UI.DensityPanel import Ui_DensityPanel

def enum(*sequential, **named):
    enums = dict(zip(sequential, range(len(sequential))), **named)
    return type('Enum', (), enums)

MODEL = enum(
    'MOLECULAR_FORMULA',
    'MOLAR_MASS',
    'MOLAR_VOLUME',
    'MASS_DENSITY',
)

MODES = enum(
    'VOLUME_TO_DENSITY',
    'DENSITY_TO_VOLUME',
)

def toMolarMass(formula):
    AVOGADRO = 6.02214129e23

    try:
        f = Formula(str(formula))
        return "%g" % (f.molecular_mass * AVOGADRO)
    except:
        return ""


class DensityPanel(QtGui.QDialog):

    def __init__(self, parent=None):
        super(DensityPanel, self).__init__()

        self.mode = None
        self.manager = parent
        self.setupUi()
        self.setupModel()
        self.setupMapper()

    def setupUi(self):
        self.ui = Ui_DensityPanel()
        self.ui.setupUi(self)

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

        # set validators
        self.ui.editMolecularFormula.setValidator(FormulaValidator(self.ui.editMolecularFormula))

        rx = QtCore.QRegExp("[+\-]?(?:0|[1-9]\d*)(?:\.\d*)?(?:[eE][+\-]?\d+)?")
        self.ui.editMolarVolume.setValidator(QtGui.QRegExpValidator(rx, self.ui.editMolarVolume))
        self.ui.editMassDensity.setValidator(QtGui.QRegExpValidator(rx, self.ui.editMassDensity))

        # signals
        self.ui.editMolarVolume.textEdited.connect(functools.partial(self.setMode, MODES.VOLUME_TO_DENSITY))
        self.ui.editMassDensity.textEdited.connect(functools.partial(self.setMode, MODES.DENSITY_TO_VOLUME))

        self.ui.buttonBox.button(QtGui.QDialogButtonBox.Reset).clicked.connect(self.modelReset)
        self.ui.buttonBox.button(QtGui.QDialogButtonBox.Help).clicked.connect(self.displayHelp)

    def setupModel(self):
        self.model = QtGui.QStandardItemModel(self)
        self.model.setItem(MODEL.MOLECULAR_FORMULA, QtGui.QStandardItem())
        self.model.setItem(MODEL.MOLAR_MASS       , QtGui.QStandardItem())
        self.model.setItem(MODEL.MOLAR_VOLUME     , QtGui.QStandardItem())
        self.model.setItem(MODEL.MASS_DENSITY     , QtGui.QStandardItem())

        self.model.dataChanged.connect(self.dataChanged)

        self.modelReset()

    def setupMapper(self):
        self.mapper = QtGui.QDataWidgetMapper(self)
        self.mapper.setModel(self.model)
        self.mapper.setOrientation(QtCore.Qt.Vertical)

        self.mapper.addMapping(self.ui.editMolecularFormula, MODEL.MOLECULAR_FORMULA)
        self.mapper.addMapping(self.ui.editMolarMass       , MODEL.MOLAR_MASS)
        self.mapper.addMapping(self.ui.editMolarVolume     , MODEL.MOLAR_VOLUME)
        self.mapper.addMapping(self.ui.editMassDensity     , MODEL.MASS_DENSITY)

        self.mapper.toFirst()

    def dataChanged(self, top, bottom):
        for index in xrange(top.row(), bottom.row() + 1):
            if index == MODEL.MOLECULAR_FORMULA:
                molarMass = toMolarMass(self.model.item(MODEL.MOLECULAR_FORMULA).text())
                self.model.item(MODEL.MOLAR_MASS).setText(molarMass)

                if self.mode == MODES.VOLUME_TO_DENSITY:
                    self._updateDensity()
                elif self.mode == MODES.DENSITY_TO_VOLUME:
                    self._updateVolume()

            elif index == MODEL.MOLAR_VOLUME and self.mode == MODES.VOLUME_TO_DENSITY:
                self._updateDensity()

            elif index == MODEL.MASS_DENSITY and self.mode == MODES.DENSITY_TO_VOLUME:
                self._updateVolume()

    def setMode(self, mode):
        self.mode = mode

    def _updateDensity(self):
        try:
            molarMass = float(toMolarMass(self.model.item(MODEL.MOLECULAR_FORMULA).text()))
            molarVolume = float(self.model.item(MODEL.MOLAR_VOLUME).text())

            molarDensity = molarMass / molarVolume
            self.model.item(MODEL.MASS_DENSITY).setText(str(molarDensity))

        except (ArithmeticError, ValueError):
            self.model.item(MODEL.MASS_DENSITY).setText("")

    def _updateVolume(self):
        try:
            molarMass = float(toMolarMass(self.model.item(MODEL.MOLECULAR_FORMULA).text()))
            molarDensity = float(self.model.item(MODEL.MASS_DENSITY).text())

            molarVolume = molarMass / molarDensity
            self.model.item(MODEL.MOLAR_VOLUME).setText(str(molarVolume))

        except (ArithmeticError, ValueError):
            self.model.item(MODEL.MOLAR_VOLUME).setText("")

    def modelReset(self):
        #self.model.beginResetModel()
        try:
            self.setMode(None)
            self.model.item(MODEL.MOLECULAR_FORMULA).setText("H2O")
            self.model.item(MODEL.MOLAR_VOLUME     ).setText("")
            self.model.item(MODEL.MASS_DENSITY     ).setText("")
        finally:
            pass
            #self.model.endResetModel()

    def displayHelp(self):
        try:
            location = self.manager.HELP_DIRECTORY_LOCATION + \
                "/user/sasgui/perspectives/calculator/density_calculator_help.html"

            self.manager._helpView.load(QtCore.QUrl(location))
            self.manager._helpView.show()
        except AttributeError:
            # No manager defined - testing and standalone runs
            pass