src/app/flashcards_tools.py

# -*- coding: utf-8 -*-
"""
Flashcards Tools - Enhanced with FlashcardGenerator and DifficultyScorer
"""

import json
import re
from pathlib import Path
from typing import Dict, List, Optional, Any

from deep_translator import GoogleTranslator

from .config import get_user_dir

# Import advanced generators (with fallback)
try:
    from .flashcard_generator import FlashcardGenerator
    HAS_FLASHCARD_GENERATOR = True
except ImportError:
    HAS_FLASHCARD_GENERATOR = False

try:
    from .difficulty_scorer import get_difficulty_scorer
    HAS_DIFFICULTY_SCORER = True
except ImportError:
    HAS_DIFFICULTY_SCORER = False


def _get_decks_dir(username: str) -> Path:
    """Returns the directory where all of a user's decks are stored."""
    user_dir = get_user_dir(username)
    decks_dir = user_dir / "decks"
    decks_dir.mkdir(parents=True, exist_ok=True)
    return decks_dir


def list_user_decks(username: str) -> Dict[str, Path]:
    """Returns a mapping of deck name -> deck json path."""
    decks_dir = _get_decks_dir(username)
    deck_files = sorted(decks_dir.glob("*.json"))
    decks: Dict[str, Path] = {}

    for path in deck_files:
        try:
            data = json.loads(path.read_text(encoding="utf-8"))
            name = data.get("name") or path.stem
        except Exception:
            name = path.stem

        if name in decks and decks[name] != path:
            name = f"{name} ({path.stem})"
        decks[name] = path

    return decks


def _ensure_card_stats(card: Dict) -> None:
    """Ensure that a card has simple spaced-repetition stats."""
    if "score" not in card:
        card["score"] = 0
    if "reviews" not in card:
        card["reviews"] = 0


def _add_difficulty_to_card(card: Dict) -> Dict:
    """Add difficulty scoring to a card if DifficultyScorer is available."""
    if HAS_DIFFICULTY_SCORER:
        try:
            scorer = get_difficulty_scorer()
            return scorer.score_flashcard(card)
        except Exception:
            pass
    return card


def load_deck(path: Path) -> Dict:
    """Loads a deck from JSON with stats for spaced repetition."""
    try:
        data = json.loads(path.read_text(encoding="utf-8"))
    except Exception:
        data = {}

    if "cards" not in data or not isinstance(data["cards"], list):
        data["cards"] = []
    if "name" not in data:
        data["name"] = path.stem
    if "tags" not in data or not isinstance(data["tags"], list):
        data["tags"] = []

    for card in data["cards"]:
        _ensure_card_stats(card)

    return data


def save_deck(path: Path, deck: Dict) -> None:
    """Saves deck to JSON."""
    if "cards" not in deck:
        deck["cards"] = []
    if "name" not in deck:
        deck["name"] = path.stem
    if "tags" not in deck or not isinstance(deck["tags"], list):
        deck["tags"] = []

    for card in deck["cards"]:
        _ensure_card_stats(card)

    path.write_text(json.dumps(deck, indent=2, ensure_ascii=False), encoding="utf-8")


def _extract_candidate_words(text: str) -> List[str]:
    """Simple tokenizer & filter for candidate vocab words."""
    tokens = re.findall(r"\b\w+\b", text, flags=re.UNICODE)
    out = []
    seen = set()
    for t in tokens:
        t_norm = t.strip()
        if len(t_norm) < 2:
            continue
        if any(ch.isdigit() for ch in t_norm):
            continue
        lower = t_norm.lower()
        if lower in seen:
            continue
        seen.add(lower)
        out.append(t_norm)
    return out


def generate_flashcards_from_ocr_results(
    username: str,
    ocr_results: List[Dict],
    deck_name: str = "ocr",
    target_lang: str = "en",
    tags: Optional[List[str]] = None,
    use_advanced_generator: bool = True,
) -> Path:
    """
    Takes OCR results and constructs a vocab deck.

    Args:
        username: User identifier
        ocr_results: List of OCR result dicts with 'text' key
        deck_name: Name for the deck
        target_lang: Target language for translations
        tags: Optional tags for the deck
        use_advanced_generator: Whether to use FlashcardGenerator

    Returns:
        Path to the saved deck
    """
    # Try advanced generator first
    if use_advanced_generator and HAS_FLASHCARD_GENERATOR:
        try:
            generator = FlashcardGenerator()
            flashcard_data = generator.generate_flashcards(ocr_results, target_lang)
            cards = flashcard_data.get('cards', [])

            if cards:
                # Add difficulty scores
                if HAS_DIFFICULTY_SCORER:
                    scorer = get_difficulty_scorer()
                    cards = scorer.score_all_flashcards(cards)

                # Ensure stats
                for card in cards:
                    _ensure_card_stats(card)

                decks_dir = _get_decks_dir(username)
                deck_path = decks_dir / f"{deck_name}.json"

                deck = {
                    "name": deck_name,
                    "cards": cards,
                    "tags": tags or ["ocr"],
                    "metadata": flashcard_data.get('metadata', {})
                }
                save_deck(deck_path, deck)
                return deck_path
        except Exception as e:
            print(f"[flashcards_tools] Advanced generator failed: {e}, using fallback")

    # Fallback to simple extraction
    all_text = []
    for res in ocr_results:
        t = res.get("text") or res.get("raw_text") or res.get("original_text") or ""
        if t:
            all_text.append(t)
    joined = "\n".join(all_text)

    words = _extract_candidate_words(joined)
    if not words:
        raise ValueError("No candidate words found in OCR results.")

    translator = GoogleTranslator(source="auto", target=target_lang)
    cards = []
    for w in words[:20]:  # Limit to 20 words
        try:
            trans = translator.translate(w)
        except Exception:
            continue
        if not trans:
            continue
        if trans.strip().lower() == w.strip().lower():
            continue

        card = {
            "front": w,
            "back": trans,
            "content_type": "ocr_vocab",
            "language": target_lang,
        }
        card = _add_difficulty_to_card(card)
        _ensure_card_stats(card)
        cards.append(card)

    if not cards:
        raise ValueError("No translatable words found to build cards.")

    decks_dir = _get_decks_dir(username)
    deck_path = decks_dir / f"{deck_name}.json"

    deck = {
        "name": deck_name,
        "cards": cards,
        "tags": tags or [],
    }
    save_deck(deck_path, deck)
    return deck_path


def generate_flashcards_from_text(
    username: str,
    text: str,
    deck_name: str = "conversation",
    target_lang: str = "en",
    tags: Optional[List[str]] = None,
    source_lang: Optional[str] = None,
) -> Path:
    """
    Build a vocab deck from raw text.

    Args:
        username: User identifier
        text: Raw text to extract vocabulary from
        deck_name: Name for the deck
        target_lang: Target language for translations
        tags: Optional tags for the deck
        source_lang: Source language (auto-detect if None)

    Returns:
        Path to the saved deck
    """
    # Try advanced generator first
    if HAS_FLASHCARD_GENERATOR:
        try:
            generator = FlashcardGenerator()

            # Create fake OCR result
            ocr_result = {
                'original_text': text,
                'text': text,
                'detected_language': source_lang or 'auto',
            }

            flashcard_data = generator.generate_flashcards([ocr_result], target_lang)
            cards = flashcard_data.get('cards', [])

            if cards:
                if HAS_DIFFICULTY_SCORER:
                    scorer = get_difficulty_scorer()
                    cards = scorer.score_all_flashcards(cards)

                for card in cards:
                    card['content_type'] = 'conversation_vocab'
                    _ensure_card_stats(card)

                decks_dir = _get_decks_dir(username)
                deck_path = decks_dir / f"{deck_name}.json"

                deck = {
                    "name": deck_name,
                    "cards": cards,
                    "tags": tags or ["conversation"],
                }
                save_deck(deck_path, deck)
                return deck_path
        except Exception as e:
            print(f"[flashcards_tools] Advanced generator failed: {e}, using fallback")

    # Fallback
    words = _extract_candidate_words(text)
    if not words:
        raise ValueError("No candidate words found in text.")

    translator = GoogleTranslator(source="auto", target=target_lang)
    cards = []
    for w in words[:20]:
        try:
            trans = translator.translate(w)
        except Exception:
            continue
        if not trans:
            continue
        if trans.strip().lower() == w.strip().lower():
            continue

        card = {
            "front": w,
            "back": trans,
            "content_type": "conversation_vocab",
            "language": target_lang,
        }
        card = _add_difficulty_to_card(card)
        _ensure_card_stats(card)
        cards.append(card)

    if not cards:
        raise ValueError("No translatable words found to build cards.")

    decks_dir = _get_decks_dir(username)
    deck_path = decks_dir / f"{deck_name}.json"

    deck = {
        "name": deck_name,
        "cards": cards,
        "tags": tags or ["conversation"],
    }
    save_deck(deck_path, deck)
    return deck_path


def add_difficulty_to_deck(deck: Dict) -> Dict:
    """Add difficulty scores to all cards in a deck."""
    if not HAS_DIFFICULTY_SCORER:
        return deck

    try:
        scorer = get_difficulty_scorer()
        deck["cards"] = scorer.score_all_flashcards(deck.get("cards", []))
        deck["statistics"] = scorer.get_statistics(deck["cards"])
    except Exception as e:
        print(f"[flashcards_tools] Difficulty scoring failed: {e}")

    return deck