import sys
from PyQt5.QtWidgets import (QApplication, QMainWindow, QWidget, QVBoxLayout, QHBoxLayout, 
                             QLabel, QLineEdit, QPushButton, QDateEdit, QTableWidget, 
                             QTableWidgetItem, QHeaderView, QDialog, QFormLayout, QComboBox,
                             QMessageBox, QSpinBox, QAction, QFileDialog, QMenuBar, QTextEdit)
from PyQt5.QtCore import Qt, QDate, QLocale
from PyQt5.QtGui import QFont, QFontDatabase
from datetime import datetime, timedelta
from dateutil.relativedelta import relativedelta
from calendar_manager import CalendarManager
from date_calculator import DateCalculator
from prediction_controller import PredictionController

DATEFORMAT = "dd.MM.yyyy"

class EventDialog(QDialog):
    def __init__(self, keyword_list, entry=None, parent=None, dateformat: str = DATEFORMAT):
        super().__init__(parent)
        
        self.keyword_list = keyword_list
        self.entry = entry
        self.dateformat = dateformat

        # Set title based on mode
        self.setWindowTitle("Neuer Eintrag" if not entry else "Eintrag editieren")                                                                     
        self.init_ui()
        
    def init_ui(self):
        layout = QFormLayout()
        
        # Apply Arial font
        font = QFont("Arial", 12)
        self.setFont(font) 
        
        # Start date selector
        self.start_date = QDateEdit()
        self.start_date.setCalendarPopup(True)
        self.start_date.setFont(font)
        self.start_date.setDisplayFormat(self.dateformat)
        
        # Set initial date based on mode
        if self.entry:
            entry_start = QDate(self.entry.start_date.year, 
                               self.entry.start_date.month, 
                               self.entry.start_date.day)
            self.start_date.setDate(entry_start)
        else:
            self.start_date.setDate(QDate.currentDate())
                                            
        
        # Connect start date change to validate end date
        self.start_date.dateChanged.connect(self.validate_end_date)
        
        layout.addRow("Startdatum:", self.start_date)
        
        # End date selector
        self.end_date = QDateEdit()
        self.end_date.setCalendarPopup(True)
        self.end_date.setFont(font)
        self.end_date.setDisplayFormat(self.dateformat)
        
        # Set initial date based on mode
        if self.entry:
            entry_end = QDate(self.entry.end_date.year, 
                             self.entry.end_date.month, 
                             self.entry.end_date.day)
            self.end_date.setDate(entry_end)
        else:
            self.end_date.setDate(QDate.currentDate().addDays(1))
        
        layout.addRow("Enddatum:", self.end_date)
        
        # Keyword selector
        self.keyword = QComboBox()
        self.keyword.setFont(font)
        self.keyword.addItems(self.keyword_list)
        
        # Set initial keyword based on mode
        if self.entry and self.entry.keyword in self.keyword_list:
            current_index = self.keyword_list.index(self.entry.keyword)
            self.keyword.setCurrentIndex(current_index)
            
        self.keyword.currentTextChanged.connect(self.on_keyword_changed)
        layout.addRow("Art:", self.keyword)
        
        # Commentary input
        self.commentary_input = QTextEdit()
        self.commentary_input.setFont(font)
        self.commentary_input.setFixedHeight(80)
        if self.entry and hasattr(self.entry, 'commentary') and self.entry.commentary:
            self.commentary_input.setPlainText(self.entry.commentary)
        layout.addRow("Kommentar:", self.commentary_input)
        
        # Store layout for later access
        self.layout = layout
        self.end_date_row = 1  # Index of end date row in the form layout
        
        # Buttons
        button_layout = QHBoxLayout()
        self.save_button = QPushButton("Speichern")
        self.save_button.setFont(font)
        self.save_button.clicked.connect(self.accept)
        
        self.cancel_button = QPushButton("Abbrechen")
        self.cancel_button.setFont(font)
        self.cancel_button.clicked.connect(self.reject)
        
        button_layout.addWidget(self.save_button)
        button_layout.addWidget(self.cancel_button)
        layout.addRow("", button_layout)
        
        self.setLayout(layout)
        
        # Handle initial keyword selection
        self.on_keyword_changed(self.keyword.currentText())
        
    def on_keyword_changed(self, keyword):
        """Handle visibility of the end_date field based on keyword"""
        # Get the widgets from the form layout
        end_date_label = self.layout.itemAt(self.end_date_row, QFormLayout.LabelRole).widget()
        end_date_field = self.layout.itemAt(self.end_date_row, QFormLayout.FieldRole).widget()
        
        if keyword == "EZ pauschal":
            # Hide end date field for EZ pauschals since they have fixed 4-week duration
            end_date_label.setVisible(False)
            end_date_field.setVisible(False)
            
            # Update end date automatically if changing to EZ pauschal
            start_dt = self.start_date.date().toPyDate()
            end_dt = start_dt + relativedelta(years = 2, days = -1)
            self.end_date.setDate(QDate(end_dt.year, end_dt.month, end_dt.day))
        else:
            # Show end date field for other event types
            end_date_label.setVisible(True)
            end_date_field.setVisible(True)
            
    def validate_end_date(self):
        """Ensure end date is not before start date"""
        if self.end_date.date() < self.start_date.date():
            self.end_date.setDate(self.start_date.date())
    def get_data(self):
        start_date = self.start_date.date().toString("yyyy-MM-dd")
        keyword = self.keyword.currentText()
        commentary = self.commentary_input.toPlainText().strip()
        
        if keyword == "EZ pauschal":
            # For EZ pauschals, calculate end date as start + 4 weeks
            start_dt = datetime.fromisoformat(start_date)
            end_dt = start_dt + relativedelta(years = 2, days = -1)
            end_date = end_dt.strftime("%Y-%m-%d")
        else:
            end_date = self.end_date.date().toString("yyyy-MM-dd")
        return start_date, end_date, keyword, commentary


class CalendarManagerGUI(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Ausfallzeitenrechner")
        self.setMinimumSize(800, 600)
        
        # Set application font
        self.app_font = QFont("Arial", 12)
        QApplication.setFont(self.app_font)
        
        # Get system locale for consistent date formatting
        self.locale = QLocale.system()
        self.dateformat = DATEFORMAT
        
        # Initialize backend components
        self.keyword_list = ["EZ 100%", "EZ 50%", "EZ pauschal", "Sonstige"]
        self.calendar_manager = CalendarManager()
        self.date_calculator = DateCalculator()
        self.prediction_controller = PredictionController(
            self.calendar_manager, 
            self.date_calculator, 
            self.keyword_list
        )
        
        self.init_ui()
        self.create_menus()
        
    def create_menus(self):
        # Create menu bar
        menubar = self.menuBar()
        menubar.setFont(self.app_font)
        
        # File menu
        file_menu = menubar.addMenu('Start')
        
        # Save action
        save_action = QAction('Speichern', self)
        save_action.setShortcut('Ctrl+S')
        save_action.triggered.connect(self.save_file)
        file_menu.addAction(save_action)
        
        # Load action
        load_action = QAction('Laden', self)
        load_action.setShortcut('Ctrl+L')
        load_action.triggered.connect(self.load_file)
        file_menu.addAction(load_action)
        
        # Clear action
        clear_action = QAction('Einträge löschen', self)
        clear_action.setShortcut('Ctrl+N')
        clear_action.triggered.connect(self.clear_entries)
        file_menu.addAction(clear_action)
        
        # Exit action
        exit_action = QAction('Beenden', self)
        exit_action.setShortcut('Ctrl+Q')
        exit_action.triggered.connect(self.close)
        file_menu.addAction(exit_action)
        
    def init_ui(self):        
        central_widget = QWidget()
        main_layout = QVBoxLayout()
        
        top_layout = QHBoxLayout()
        
        # Launch date input
        launch_date_layout = QVBoxLayout()
        launch_date_label = QLabel("Promotionsdatum:")
        launch_date_label.setFont(self.app_font)
        self.launch_date_edit = QDateEdit()
        self.launch_date_edit.setFont(self.app_font)
        self.launch_date_edit.setCalendarPopup(True)  # Enable calendar popup
        self.launch_date_edit.setDate(QDate.currentDate())
        self.launch_date_edit.setDisplayFormat(self.dateformat)
        self.launch_date_edit.dateChanged.connect(self.update_prediction)  # Auto-update on change
        launch_date_layout.addWidget(launch_date_label)
        launch_date_layout.addWidget(self.launch_date_edit)
        top_layout.addLayout(launch_date_layout)
        
        # Duration input
        duration_layout = QVBoxLayout()
        duration_label = QLabel("Bewerbungszeitraum (Jahre):")
        duration_label.setFont(self.app_font)
        self.duration_spin = QSpinBox()
        self.duration_spin.setFont(self.app_font)
        self.duration_spin.setRange(1, 99)
        self.duration_spin.setValue(1)
        self.duration_spin.valueChanged.connect(self.update_prediction)  # Auto-update on change
        duration_layout.addWidget(duration_label)
        duration_layout.addWidget(self.duration_spin)
        top_layout.addLayout(duration_layout)
        
        # Prediction result
        prediction_result_layout = QVBoxLayout()
        prediction_result_label = QLabel("Bewerbungsfrist:")
        prediction_result_label.setFont(self.app_font)
        self.prediction_result = QDateEdit()
        self.prediction_result.setFont(self.app_font)
        self.prediction_result.setReadOnly(True)
        self.prediction_result.setButtonSymbols(QDateEdit.ButtonSymbols.NoButtons)
        self.prediction_result.setDisplayFormat(self.dateformat)
        prediction_result_layout.addWidget(prediction_result_label)
        prediction_result_layout.addWidget(self.prediction_result)
        
        top_layout.addLayout(prediction_result_layout)
        
        main_layout.addLayout(top_layout)
        
        # Events section
        events_layout = QVBoxLayout()
        events_title = QLabel("<h3>Ausfallzeiten</h3>")
        events_title.setFont(self.app_font)
        events_layout.addWidget(events_title)
        
        # Add event button
        add_event_button = QPushButton("Eintrag hinzufügen")
        add_event_button.setFont(self.app_font)
        add_event_button.clicked.connect(self.add_event)
        events_layout.addWidget(add_event_button)
        
        # Events table
        self.events_table = QTableWidget()
        self.events_table.setFont(self.app_font)
        self.events_table.setColumnCount(7)  # ID (hidden), Start, End, Keyword, RelevantTime, Commentary, Actions
        self.events_table.setHorizontalHeaderLabels(["ID", "Anfangsdatum", "Enddatum", "Art", "Angerechneter Zeitraum", "Kommentar", "Aktionen"])
        self.events_table.horizontalHeader().setSectionResizeMode(QHeaderView.Stretch)
        self.events_table.horizontalHeader().setFont(self.app_font)
        self.events_table.setColumnHidden(0, True)  # Hide ID column
        events_layout.addWidget(self.events_table)
        
        main_layout.addLayout(events_layout)
        
        # Set main layout
        central_widget.setLayout(main_layout)
        self.setCentralWidget(central_widget)
        
        # Load initial data
        self.update_events_table()
        self.update_prediction()  # Calculate initial prediction
    
    def update_prediction(self):
        """Update prediction whenever needed"""
        try:
            launch_date = self.launch_date_edit.date().toString("yyyy-MM-dd")
            duration_years = self.duration_spin.value()
            
            self.prediction_controller.make_prediction(launch_date, duration_years)
            prediction_date = self.prediction_controller.get_prediction()
            
            if prediction_date:
                self.prediction_result.setDate(prediction_date)
                
            # Update table to show corrected dates
            self.update_events_table()
            
        except Exception as e:
            self.prediction_result.setText("Error in calculation")
            print(f"Error calculating prediction: {str(e)}")
    
    def add_event(self):
        dialog = EventDialog(self.keyword_list, parent=self, dateformat=self.dateformat)
        if dialog.exec_():
            start_date, end_date, keyword, commentary = dialog.get_data()
            try:
                self.calendar_manager.add_entry(start_date, end_date, keyword, commentary)
                self.update_events_table()
                self.update_prediction()  # Auto-update prediction
            except Exception as e:
                QMessageBox.critical(self, "Error", f"Error adding event: {str(e)}")
    
    def modify_event(self, event_id):
        entry = self.calendar_manager.get_entry_by_id(event_id)
        if entry:
            dialog = EventDialog(self.keyword_list, entry=entry, parent=self, dateformat=self.dateformat)
            if dialog.exec_():
                start_date, end_date, keyword, commentary = dialog.get_data()
                try:
                    self.calendar_manager.modify_entry(event_id, 
                                                     datetime.fromisoformat(start_date), 
                                                     datetime.fromisoformat(end_date), 
                                                     keyword,
                                                     commentary)
                    self.update_events_table()
                    self.update_prediction()  # Auto-update prediction
                except Exception as e:
                    QMessageBox.critical(self, "Error", f"Error modifying event: {str(e)}")
    
    def delete_event(self, event_id):
        reply = QMessageBox.question(self, "Eintrag löschen", 
                                     "Wollen Sie diesen Eintrag löschen?",
                                     QMessageBox.Yes | QMessageBox.No)
        if reply == QMessageBox.Yes:
            try:
                self.calendar_manager.delete_entry(event_id)
                self.update_events_table()
                self.update_prediction()  # Auto-update prediction
            except Exception as e:
                QMessageBox.critical(self, "Error", f"Error deleting event: {str(e)}")
    
    def update_events_table(self):
        # Clear table
        self.events_table.setRowCount(0)
        
        # Add entries to table
        entries = self.calendar_manager.list_entries()
        for i, entry in enumerate(entries):
            self.events_table.insertRow(i)
            
            # Set item data
            self.events_table.setItem(i, 0, QTableWidgetItem(entry.id))
            
            # Format dates using unified display format
            start_date_qdate = QDate(entry.start_date.year, entry.start_date.month, entry.start_date.day)
            end_date_qdate = QDate(entry.end_date.year, entry.end_date.month, entry.end_date.day)
            
            start_date_text = start_date_qdate.toString(self.dateformat)
            end_date_text = end_date_qdate.toString(self.dateformat)
            self.events_table.setItem(i, 1, QTableWidgetItem(start_date_text))
            self.events_table.setItem(i, 2, QTableWidgetItem(end_date_text))
            self.events_table.setItem(i, 3, QTableWidgetItem(entry.keyword))
            
            # Relevant accounted time based on corrected dates
            relevant_text = ""
            if entry.corrected_start_date and entry.corrected_end_date:
                start_dt = entry.corrected_start_date
                end_dt = entry.corrected_end_date
                if end_dt < start_dt:
                    start_dt, end_dt = end_dt, start_dt
                delta_days = (end_dt.date() - start_dt.date()).days + 1
                # Determine if less than 3 months using relativedelta
                rd = relativedelta(end_dt.date(), start_dt.date())
                total_months = rd.years * 12 + rd.months
                if total_months < 3:
                    relevant_text = f"{delta_days} Tage"
                else:
                    # Months and remaining days
                    # Compute month/day split precisely
                    month_start = start_dt.date()
                    month_split = month_start + relativedelta(months=+total_months)
                    remaining_days = (end_dt.date() - month_split).days + 1 if end_dt.date() >= month_split else delta_days
                    relevant_text = f"{total_months} Monate, {max(0, remaining_days)} Tage"
            self.events_table.setItem(i, 4, QTableWidgetItem(relevant_text))

            # Commentary
            commentary_text = getattr(entry, 'commentary', "") or ""
            self.events_table.setItem(i, 5, QTableWidgetItem(commentary_text))
            
            # Action buttons
            actions_widget = QWidget()
            actions_layout = QHBoxLayout()
            actions_layout.setContentsMargins(0, 0, 0, 0)
            
            modify_button = QPushButton("Editieren")
            modify_button.setFont(self.app_font)
            delete_button = QPushButton("Löschen")
            delete_button.setFont(self.app_font)
            
            # Use lambda with default argument to capture the correct event_id
            modify_button.clicked.connect(lambda checked, eid=entry.id: self.modify_event(eid))
            delete_button.clicked.connect(lambda checked, eid=entry.id: self.delete_event(eid))
            
            actions_layout.addWidget(modify_button)
            actions_layout.addWidget(delete_button)
            actions_widget.setLayout(actions_layout)
            
            self.events_table.setCellWidget(i, 6, actions_widget)
    
    def save_file(self):
        """Save calendar entries to a JSON file"""
        # if not self.calendar_manager.filename:
        file_path, _ = QFileDialog.getSaveFileName(self, "Einträge speichern", "", "JSON Files (*.json)")
        if not file_path:
            return
        self.calendar_manager.switch_file(file_path)
            
        try:
            self.calendar_manager.save_entries()
            QMessageBox.information(self, "Speichern erfolgreich", f"Einträge gespeichert in {self.calendar_manager.filename}")
        except Exception as e:
            QMessageBox.critical(self, "Error", f"Failed to save calendar: {str(e)}")
    
    def load_file(self):
        """Load calendar entries from a JSON file"""
        file_path, _ = QFileDialog.getOpenFileName(self, "Einträge laden", "", "JSON Files (*.json)")
        if not file_path:
            return
            
        try:
            self.calendar_manager.load_file(file_path)
            self.update_events_table()
            self.update_prediction()  # Auto-update prediction
            QMessageBox.information(self, "Laden erfolgreich", f"Einträge erfolgreich von {file_path} geladen")
        except Exception as e:
            QMessageBox.critical(self, "Error", f"Failed to load calendar: {str(e)}")
    
    def clear_entries(self):
        """Clear all calendar entries"""
        reply = QMessageBox.question(self, "Einträge löschen", 
                                    "Alle Einträge löschen?",
                                    QMessageBox.Yes | QMessageBox.No)
        if reply == QMessageBox.Yes:
            try:
                self.calendar_manager.clear_entries()
                self.update_events_table()
                self.update_prediction()  # Auto-update prediction
                QMessageBox.information(self, "Erfolg", "Alle Einträge gelöscht!")
            except Exception as e:
                QMessageBox.critical(self, "Error", f"Failed to clear calendar: {str(e)}")


def main():
    app = QApplication(sys.argv)
    app.setStyle('Fusion')
    # Ensure Arial is available
    QFontDatabase.addApplicationFont("Arial")
    window = CalendarManagerGUI()
    window.show()
    sys.exit(app.exec_())


if __name__ == "__main__":
    main()