"""
Tests for Nested-Core Tensor-Train Layer.
"""

import sys
import os
sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

import torch
import pytest
from src.tensor_layers import TTLinear, TTFeedForward


def test_nested_tt_slicing_shapes():
    in_dim, out_dim = 64, 128
    layer = TTLinear(in_dim, out_dim, max_rank=8)

    x = torch.randn(2, 4, in_dim)

    # Test all candidate ranks
    for r in [1, 2, 4, 8]:
        layer.set_rank(r)
        assert layer.rank == r
        out = layer(x)
        assert out.shape == (2, 4, out_dim), f"Expected (2, 4, {out_dim}), got {out.shape}"
        assert not torch.isnan(out).any(), f"NaN in output at rank {r}"
        traffic = layer.get_memory_traffic()
        assert traffic["total_bytes"] > 0
    print("✓ test_nested_tt_slicing_shapes passed")


def test_nested_tt_ffn():
    ffn = TTFeedForward(hidden_dim=64, ff_multiplier=4, rank=8)
    x = torch.randn(2, 64)

    for r in [1, 2, 4, 8]:
        ffn.set_rank(r)
        out = ffn(x)
        assert out.shape == (2, 64)
        assert ffn.active_params > 0
    print("✓ test_nested_tt_ffn passed")


if __name__ == "__main__":
    test_nested_tt_slicing_shapes()
    test_nested_tt_ffn()
    print("All Nested TT tests passed!")