from datetime import date

from app.models.habit import ALL_WEEKDAYS_MASK, HABIT_DIFFICULTY_TARGET_DAYS, Habit, HabitDifficulty
from app.services.log_service import MILESTONE_STREAKS

_DAY_LABELS = ["월", "화", "수", "목", "금", "토", "일"]

_DIFFICULTY_LABELS: dict[HabitDifficulty, str] = {
    HabitDifficulty.EASY: "하 (21일)",
    HabitDifficulty.MEDIUM: "중 (66일)",
    HabitDifficulty.HARD: "상 (254일)",
    HabitDifficulty.UNLIMITED: "기간 무제한",
}


def is_milestone_streak(streak: int) -> bool:
    return streak in MILESTONE_STREAKS


def weekday_label(mask: int) -> str:
    if mask == ALL_WEEKDAYS_MASK:
        return "매일"
    days = [label for i, label in enumerate(_DAY_LABELS) if mask & (1 << i)]
    return ", ".join(days) if days else "선택된 요일 없음"


def difficulty_label(difficulty: HabitDifficulty) -> str:
    return _DIFFICULTY_LABELS[difficulty]


def goal_progress(habit: Habit) -> dict | None:
    """습관의 목표 기간 진행 상황. 기간 무제한(UNLIMITED)이면 None."""
    target_days = HABIT_DIFFICULTY_TARGET_DAYS[habit.difficulty]
    if target_days is None:
        return None
    elapsed = (date.today() - habit.created_at.date()).days + 1  # 시작일을 1일차로 계산
    elapsed = max(elapsed, 1)
    return {
        "elapsed": min(elapsed, target_days),
        "target": target_days,
        "remaining": max(target_days - elapsed, 0),
        "reached": elapsed >= target_days,
    }


def heatmap_opacity(checked_count: int, scheduled_count: int) -> float:
    """월별 캘린더 히트맵 셀의 배경 투명도(0~0.9)를 계산한다."""
    if not scheduled_count:
        return 0.0
    ratio = checked_count / scheduled_count
    if ratio <= 0:
        return 0.0
    return round(0.12 + ratio * 0.78, 2)