from app.db import query
from app import SYDNEY_TZ
from datetime import datetime, timedelta


def calculate_streak(user_id):
    """Calculate current and best consecutive-day check-in streaks."""
    rows = query(
        """SELECT DISTINCT (checked_in_at AT TIME ZONE 'UTC' AT TIME ZONE 'Australia/Sydney')::date AS d
           FROM checkins WHERE user_id = %s ORDER BY d DESC""",
        (user_id,),
    )
    if not rows:
        return {"current": 0, "best": 0}

    days = [r["d"] for r in rows]
    today = datetime.now(SYDNEY_TZ).date()

    # Current streak: must include today or yesterday to count
    current = 0
    expected = today
    if days[0] == today or days[0] == today - timedelta(days=1):
        expected = days[0]
        for d in days:
            if d == expected:
                current += 1
                expected -= timedelta(days=1)
            else:
                break

    # Best streak
    best = 1
    run = 1
    for i in range(1, len(days)):
        if days[i] == days[i - 1] - timedelta(days=1):
            run += 1
            best = max(best, run)
        else:
            run = 1

    best = max(best, current)
    return {"current": current, "best": best}