from __future__ import annotations

_XP_TABLE = {"easy": 10, "medium": 20, "hard": 40}
_BOSS_XP = 75
_WEAK_THRESHOLD = 0.5
_STREAK_LABELS = {0: "", 1: "Nice!", 2: "Good!", 3: "Great!", 4: "Excellent!"}

def xp_for_question(difficulty: str, is_boss: bool) -> int:
    if is_boss:
        return _BOSS_XP
    return _XP_TABLE.get(difficulty, 10)

def streak_label(consecutive: int) -> str:
    if consecutive >= 5:
        return "LEGENDARY!"
    return _STREAK_LABELS.get(consecutive, "")

def compute_grade(score: int, total: int) -> str:
    if total == 0:
        return "Apprentice"
    pct = score / total * 100
    if pct >= 80: return "Champion"
    if pct >= 60: return "Warrior"
    return "Apprentice"

def compute_mastery_delta(correct: int, total: int) -> float:
    if total == 0:
        return 0.0
    return correct / total

def should_unlock_revision_quest(mastery: float) -> bool:
    return mastery < _WEAK_THRESHOLD

def mastery_recommendation(mastery: float) -> str:
    if mastery < 0.3:
        return "Seriously review this topic before moving on."
    if mastery < 0.5:
        return "More practice needed — try the revision quest."
    if mastery < 0.8:
        return "Getting there — a few more battles will sharpen this."
    return "Strong mastery — ready for the next challenge!"