# date_service.py
from datetime import datetime, timedelta
from dateutil.relativedelta import relativedelta
from PyQt5.QtCore import QDate
from config import EventConfig

class DateService:
    """Centralized date operations and utilities"""
    
    @staticmethod
    def format_date_for_display(date, format_string=None):
        """Format a datetime object for display"""
        if format_string is None:
            format_string = EventConfig.DATE_FORMAT
        
        if isinstance(date, datetime):
            return date.strftime(format_string.replace('dd', '%d').replace('MM', '%m').replace('yyyy', '%Y'))
        elif isinstance(date, QDate):
            return date.toString(format_string)
        return str(date)
    
    @staticmethod
    def parse_date_from_string(date_string):
        """Parse a date string to datetime object"""
        try:
            return datetime.fromisoformat(date_string)
        except ValueError:
            # Try alternative formats
            try:
                return datetime.strptime(date_string, "%d.%m.%Y")
            except ValueError:
                raise ValueError(f"Unable to parse date string: {date_string}")
    
    @staticmethod
    def calculate_days_between(start_date, end_date):
        """Calculate number of days between two dates"""
        if isinstance(start_date, str):
            start_date = DateService.parse_date_from_string(start_date)
        if isinstance(end_date, str):
            end_date = DateService.parse_date_from_string(end_date)
        
        return (end_date.date() - start_date.date()).days + 1
    
    @staticmethod
    def calculate_months_between(start_date, end_date):
        """Calculate number of months between two dates using relativedelta"""
        if isinstance(start_date, str):
            start_date = DateService.parse_date_from_string(start_date)
        if isinstance(end_date, str):
            end_date = DateService.parse_date_from_string(end_date)
        
        rd = relativedelta(end_date.date(), start_date.date())
        return rd.years * 12 + rd.months + 1
    
    @staticmethod
    def format_date_for_iso(date):
        """Format date for ISO string (yyyy-MM-dd)"""
        if isinstance(date, datetime):
            return date.strftime("%Y-%m-%d")
        elif isinstance(date, QDate):
            return date.toString("yyyy-MM-dd")
        return str(date)
    
    @staticmethod
    def get_current_date():
        """Get current date as datetime"""
        return datetime.now()