# app/utils/parser.py
import re
from typing import List, Dict

def parse_questions(raw_text: str) -> List[Dict]:
    """
    Parse a model-generated block into list of question dicts with keys:
    number, question, options [A,B,C,D], answer, explanation, detailed_solution (optional)
    """
    if not raw_text:
        return []

    text = raw_text.replace("\r\n", "\n").strip()

    # Try to separate Detailed Solutions section if present
    sol_section = ""
    m = re.search(r'(?:Detailed Solutions:|Solutions:)\s*([\s\S]*)$', text, re.IGNORECASE)
    if m:
        sol_section = m.group(1).strip()
        main_text = text[:m.start(0)].strip()
    else:
        main_text = text

    parts = re.split(r'\n(?=\d+\.)', main_text)
    questions = []
    for idx, part in enumerate(parts):
        part = part.strip()
        if not part:
            continue

        q_text = re.split(r'\nA\)', part, maxsplit=1)[0]
        q_text = re.sub(r'^\s*\d+\.\s*', '', q_text).strip()

        opts = []
        for letter in ['A','B','C','D']:
            m_opt = re.search(rf'{letter}\)\s*(.*?)(?=\n[A-D]\)|\nAnswer:|\nExplanation:|$)', part, re.DOTALL)
            opts.append(m_opt.group(1).strip() if m_opt else "")

        ans_m = re.search(r'Answer:\s*([A-D])', part, re.IGNORECASE)
        answer = ans_m.group(1).upper() if ans_m else ""

        expl_m = re.search(r'Explanation:\s*([\s\S]*?)(?=$)', part, re.IGNORECASE)
        explanation = expl_m.group(1).strip() if expl_m else ""

        questions.append({
            "number": idx + 1,
            "question": q_text,
            "options": opts,
            "answer": answer,
            "explanation": explanation,
            "detailed_solution": ""
        })

    # Map detailed solutions if present
    if sol_section:
        sol_parts = re.split(r'\n(?=\d+\.)', sol_section)
        sol_list = []
        for sp in sol_parts:
            sp = sp.strip()
            if not sp:
                continue
            sp_text = re.sub(r'^\s*\d+\.\s*', '', sp).strip()
            sol_list.append(sp_text)
        for i, q in enumerate(questions):
            if i < len(sol_list):
                q['detailed_solution'] = sol_list[i]
            else:
                q['detailed_solution'] = q.get('explanation', '')

    else:
        for q in questions:
            q['detailed_solution'] = q.get('explanation', '')

    return questions