import itertools
from typing import Iterator, List

from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QMainWindow, QMessageBox

from bulk_reminders import api, undo
from bulk_reminders.api import Event
from bulk_reminders.gui_base import Ui_MainWindow
from bulk_reminders.load import LoadDialog
from bulk_reminders.oauth import OAuthDialog


class MainWindow(QMainWindow, Ui_MainWindow):
    def __init__(self, *args, **kwargs):
        # Initial UI setup
        super(MainWindow, self).__init__(*args, **kwargs)
        self.setupUi(self)
        self.show()

        self.calendar = api.Calendar()
        self.currentCalendarID = 'primary'

        # Authenticate user into Google API Engine
        self.authenticated = self.calendar.authenticate_via_token()
        if not self.authenticated:
            temp_dialog = OAuthDialog(callback=self.calendar.authenticate_via_oauth)
            temp_dialog.show()
        self.calendar.setupService()

        # Get Calendars, Setup Calendar Selection Combobox
        calendars = self.calendar.getCalendarsSimplified()
        self.comboModel = QtGui.QStandardItemModel()
        for id, summary in calendars:
            item = QtGui.QStandardItem(summary)
            item.setData(id)
            self.comboModel.appendRow(item)
        self.calendarCombobox.setModel(self.comboModel)
        self.calendarCombobox.currentIndexChanged[int].connect(self.comboBoxChanged)

        # Make sure the current calendar ID matches up
        self.currentCalendarID = self.comboModel.item(self.calendarCombobox.currentIndex()).data()

        # Setup Column View headers
        self.eventsView.setColumnCount(4)
        self.eventsView.setHorizontalHeaderLabels(['Summary', 'Status', 'Start', 'End'])
        header = self.eventsView.horizontalHeader()
        header.setSectionResizeMode(0, QtWidgets.QHeaderView.Stretch)
        header.setSectionResizeMode(1, QtWidgets.QHeaderView.ResizeToContents)
        header.setSectionResizeMode(2, QtWidgets.QHeaderView.ResizeToContents)
        header.setSectionResizeMode(3, QtWidgets.QHeaderView.ResizeToContents)
        self.eventsView.verticalHeader().hide()

        self.undoButton.clicked.connect(self.undo)
        self.submitButton.clicked.connect(self.submit)

        # Disable the undo button until undo stages are available
        if len(undo.stages) == 0:
            self.undoButton.setDisabled(True)

        self.loadEventsButton.clicked.connect(self.load_events)
        self.cachedLoadText = ''
        self.readyEvents = []

        self.populate()

    def load_events(self) -> None:
        """Open the event loading dialog"""
        dial = LoadDialog()
        dial.plainTextEdit.setPlainText(self.cachedLoadText)
        result = dial.exec()
        if result == QMessageBox.Accepted:
            self.cachedLoadText = dial.plainTextEdit.toPlainText()
            self.readyEvents = dial.parsed
            self.populate()
        elif result == QMessageBox.Cancel:
            pass

    def undo(self) -> None:
        # Get the latest undo stage and delete all events in that stage
        latest = undo.stages.pop(0)
        for entry in latest:
            self.calendar.service.events().delete(calendarId=entry.get('calendarId'), eventId=entry.get('eventId')).execute()

        # Disable the undo button until undo stages are available
        if len(undo.stages) == 0:
            self.undoButton.setDisabled(True)

    def getForeign(self) -> List[Event]:
        """Returns all events currently tracked that are not stored in the undo."""
        events = {event['id'] : event for event in self.apiEvents}
        undoableIDs = itertools.chain.from_iterable([[undoable['id'] for undoable in stage] for stage in undo.stages])
        foreignIDs = events.keys() - undoableIDs
        return [events[foreignID] for foreignID in foreignIDs]

    def submit(self) -> None:
        pass

    def populate(self) -> None:
        """Re-populate the table with all of the events"""
        self.apiEvents = self.calendar.getEvents(self.currentCalendarID)
        self.events = [Event.from_api(event) for event in self.apiEvents]
        ready, undoable, stage, foreign = len(self.readyEvents), undo.getTotal(), len(undo.stages), len(self.getForeign())
        total = ready + undoable + stage + foreign
        self.eventCountLabel.setText(f'{len(self.readyEvents)} ready, {undoable} undoable in {stage} stages, {foreign} foreign ({total})')
        self.eventsView.setRowCount(len(self.events))
        for row, event in enumerate(self.events):
            event.fill_row(row, self.eventsView)

    @QtCore.pyqtSlot(int)
    def comboBoxChanged(self, row) -> None:
        """When the Calendar Selection combobox"""
        self.currentCalendarID = self.comboModel.item(row).data()
        self.populate()