Time Capsule Calculator

from datetime import date, timedelta
from dateutil.relativedelta import relativedelta

def time_capsule_info(seal_date: date, open_date: date) -> dict:
    """Calculate time capsule duration and milestones."""
    if open_date <= seal_date:
        raise ValueError("Open date must be after seal date")

    delta = relativedelta(open_date, seal_date)
    total_days = (open_date - seal_date).days
    days_remaining = (open_date - date.today()).days

    # Milestone dates
    milestones = {}
    for pct, label in [(25, "25%"), (50, "Halfway"), (75, "75%")]:
        days_offset = int(total_days * pct / 100)
        milestones[label] = seal_date + timedelta(days=days_offset)

    return {
        "seal_date": seal_date.isoformat(),
        "open_date": open_date.isoformat(),
        "duration_years": delta.years,
        "duration_months": delta.months,
        "duration_days": delta.days,
        "total_days": total_days,
        "days_remaining": max(0, days_remaining),
        "milestones": {k: v.isoformat() for k, v in milestones.items()},
        "decade": f"{(open_date.year // 10) * 10}s",
    }

info = time_capsule_info(date(2025, 1, 1), date(2035, 1, 1))
print(f"Duration: {info['duration_years']} years, {info['duration_months']} months")
print(f"Total days: {info['total_days']}")
print(f"Days remaining: {info['days_remaining']}")
print(f"Opening decade: the {info['decade']}")
for label, dt in info["milestones"].items():
    print(f"  {label}: {dt}")