#!/usr/bin/env python3
"""Base utilities for question generation."""
import random
import sys
import os

sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..'))
from db.init import get_db, get_question_type_id, insert_questions_batch


def shuffle_options(correct, wrongs, explanation=""):
    """Create options with correct answer randomly placed."""
    options = [correct] + wrongs[:3]
    # Map original correct to its letter
    indices = list(range(4))
    random.shuffle(indices)
    shuffled = [options[i] for i in indices]
    correct_letter = chr(65 + indices.index(0))  # A, B, C, D
    return {
        'option_a': str(shuffled[0]),
        'option_b': str(shuffled[1]),
        'option_c': str(shuffled[2]),
        'option_d': str(shuffled[3]),
        'correct_option': correct_letter,
        'explanation': explanation
    }


def make_question(qtype_id, text, correct, wrongs, explanation="", difficulty=1):
    """Build a question dict ready for DB insertion."""
    q = shuffle_options(correct, wrongs, explanation)
    q['question_type_id'] = qtype_id
    q['question_text'] = text
    q['difficulty'] = difficulty
    return q


def get_qtid(conn, subject, subtopic, topic, qtype):
    """Shorthand for get_question_type_id."""
    return get_question_type_id(conn, subject, subtopic, topic, qtype)


def nearby_wrong(val, spread=None):
    """Generate plausible wrong answers near the correct value."""
    if spread is None:
        spread = max(1, abs(val) // 5) if val != 0 else 5
    wrongs = set()
    attempts = 0
    while len(wrongs) < 3 and attempts < 50:
        offset = random.randint(1, max(1, spread))
        sign = random.choice([-1, 1])
        w = val + sign * offset
        if w != val and w not in wrongs:
            wrongs.add(w)
        attempts += 1
    # Fallback
    while len(wrongs) < 3:
        wrongs.add(val + len(wrongs) + 1)
    return [str(w) for w in wrongs]


def nearby_wrong_float(val, spread=None, decimals=2):
    """Generate plausible wrong answers for float values."""
    if spread is None:
        spread = max(0.5, abs(val) * 0.2)
    wrongs = set()
    attempts = 0
    while len(wrongs) < 3 and attempts < 50:
        offset = round(random.uniform(0.1, spread), decimals)
        sign = random.choice([-1, 1])
        w = round(val + sign * offset, decimals)
        if w != round(val, decimals) and w not in wrongs and w > 0:
            wrongs.add(w)
        attempts += 1
    while len(wrongs) < 3:
        wrongs.add(round(val + (len(wrongs) + 1) * 0.5, decimals))
    return [str(w) for w in wrongs]


def frac_str(num, den):
    """Format a fraction as string."""
    from math import gcd
    g = gcd(abs(num), abs(den))
    n, d = num // g, den // g
    if d == 1:
        return str(n)
    return f"{n}/{d}"