Convert Natural Language Dates to Datetime in Python

from datetime import datetime, timedelta
import re

def parse_natural_date(text: str) -> datetime:
    """Convert common natural language date expressions to datetime objects."""
    now = datetime.now()
    text = text.lower().strip()
    
    # Handle relative dates
    patterns = {
        r"today": now,
        r"tomorrow": now + timedelta(days=1),
        r"yesterday": now - timedelta(days=1),
        r"next week": now + timedelta(weeks=1),
        r"last week": now - timedelta(weeks=1),
        r"next month": now.replace(month=now.month + 1 if now.month < 12 else 1),
        r"last month": now.replace(month=now.month - 1 if now.month > 1 else 12),
        r"next year": now.replace(year=now.year + 1),
        r"last year": now.replace(year=now.year - 1),
        r"in (\d+) days": lambda m: now + timedelta(days=int(m.group(1))),
        r"(\d+) days ago": lambda m: now - timedelta(days=int(m.group(1))),
        r"in (\d+) weeks": lambda m: now + timedelta(weeks=int(m.group(1))),
        r"(\d+) weeks ago": lambda m: now - timedelta(weeks=int(m.group(1))),
    }
    
    for pattern, handler in patterns.items():
        match = re.match(pattern, text)
        if match:
            result = handler(text) if isinstance(handler, dict) else handler
            if callable(handler):
                result = handler(match)
            return result if isinstance(result, datetime) else handler
        
        if isinstance(handler, datetime):
            if re.fullmatch(pattern, text):
                return handler
        else:
            if re.fullmatch(pattern, text):
                return handler
    
    return now

if __name__ == "__main__":
    tests = ["today", "tomorrow", "yesterday", "in 3 days", "5 days ago", "next week"]
    for test in tests:
        result = parse_natural_date(test)
        print(f"{test:15} -> {result.date()}")