"""Tests for spell backward task generation"""

import pytest

from reasoning_gym.algorithmic.spell_backward import SpellBackwardConfig, SpellBackwardDataset


def test_spell_backward_config_validation():
    """Test that invalid configs raise appropriate errors"""
    with pytest.raises(AssertionError):
        config = SpellBackwardConfig(min_word_len=0)
        config.validate()


def test_spell_backward_dataset_deterministic():
    """Test that dataset generates same items with same seed"""
    config = SpellBackwardConfig(seed=42, size=10)
    dataset1 = SpellBackwardDataset(config)
    dataset2 = SpellBackwardDataset(config)

    for i in range(len(dataset1)):
        assert dataset1[i] == dataset2[i]


def test_spell_backward_dataset_items():
    """Test basic properties of generated items"""
    config = SpellBackwardConfig(min_word_len=3, size=10, seed=42)
    dataset = SpellBackwardDataset(config)

    for i in range(len(dataset)):
        item = dataset[i]
        # Check item structure
        assert isinstance(item, dict)
        assert "question" in item
        assert "answer" in item
        assert "metadata" in item

        # Check metadata
        assert "word" in item["metadata"]
        assert "word_len" in item["metadata"]

        # Verify word length constraint
        word = item["metadata"]["word"]
        assert len(word) >= config.min_word_len

        # Verify answer is correct
        assert item["answer"] == word[::-1]


def test_spell_backward_dataset_iteration():
    """Test that iteration respects dataset size"""
    config = SpellBackwardConfig(size=5, seed=42)
    dataset = SpellBackwardDataset(config)

    items = list(dataset)
    assert len(items) == config.size

    # Test multiple iterations yield same items
    assert items == list(dataset)