"""Word reversal task generator"""
from dataclasses import dataclass
import re
from random import Random
from typing import List, Optional

from reasoning_gym.data import read_data_file

@dataclass
class WordReversalConfig:
    """Configuration for word reversal task generation"""
    min_words: int = 3          # Minimum words in list
    max_words: int = 8          # Maximum words in list
    seed: Optional[int] = None
    size: int = 500            # Virtual dataset size

    def validate(self):
        """Validate configuration parameters"""
        assert self.min_words > 0, "min_words must be positive"
        assert self.max_words >= self.min_words, "max_words must be >= min_words"


class WordReversalDataset:
    """Generates word reversal tasks from text spans"""

    def __init__(self, config: WordReversalConfig):
        self.config = config
        self.config.validate()
        self.seed = config.seed if config.seed is not None else Random().randint(0, 2**32)
        
        # Load and preprocess text
        text = read_data_file("in_the_year_2889.txt")
        # Extract words and clean them to contain only alphanumeric characters
        self.words = [word for word in re.findall(r'\b\w+\b', text) if word.isalnum()]

    def __len__(self) -> int:
        return self.config.size

    def __iter__(self):
        self._current_idx = 0
        return self

    def __next__(self):
        if self._current_idx >= self.config.size:
            raise StopIteration
        item = self[self._current_idx]
        self._current_idx += 1
        return item

    def __getitem__(self, idx: int) -> dict:
        """Generate a single word reversal task"""
        rng = Random(self.seed + idx)
        
        # Select random words
        num_words = rng.randint(self.config.min_words, self.config.max_words)
        word_indices = rng.sample(range(len(self.words)), num_words)
        words = [self.words[i] for i in word_indices]
        
        # Create question and answer
        question = ", ".join(words)
        answer = ", ".join(reversed(words))
        
        return {
            "question": f"Reverse this list of words: {question}",
            "answer": answer,
            "metadata": {
                "num_words": num_words,
                "words": words
            }
        }


def word_reversal_dataset(
    min_words: int = 3,
    max_words: int = 8,
    seed: Optional[int] = None,
    size: int = 500,
) -> WordReversalDataset:
    """Create a WordReversalDataset with the given configuration."""
    config = WordReversalConfig(
        min_words=min_words,
        max_words=max_words,
        seed=seed,
        size=size,
    )
    return WordReversalDataset(config)