import pytest
import torch
import torch.nn.functional as F

from fla.ops.delta_rule import chunk_delta_rule, fused_recurrent_delta_rule
from fla.utils import assert_close, device, device_platform


@pytest.mark.parametrize(
    ('B', 'T', 'H', 'D', 'scale', 'use_qk_l2norm_in_kernel', 'dtype'),
    [
        pytest.param(*test, id="B{}-T{}-H{}-D{}-scale{}-{}".format(*test))
        for test in [
            (1, 63, 1, 64, 1, False, torch.float16),
            (2, 100, 4, 60, 0.1, False, torch.float16),
            (2, 1000, 3, 128, 0.1, False, torch.float16),
            (2, 1024, 4, 128, 1, True, torch.float16),
            (3, 2000, 4, 128, 0.1, False, torch.float16),
            (4, 2048, 8, 64, 0.1, False, torch.float16),
        ]
    ],
)
@pytest.mark.skipif(
    device_platform == 'intel',
    reason='Intel Triton Failure',
)
def test_chunk(
    B: int,
    T: int,
    H: int,
    D: int,
    scale: float,
    use_qk_l2norm_in_kernel: bool,
    dtype: torch.dtype,
):
    torch.manual_seed(42)
    q = torch.randn(B, T, H, D, dtype=dtype)
    k = torch.randn(B, T, H, D, dtype=dtype)
    v = torch.randn(B, T, H, D, dtype=dtype)
    beta = torch.randn(B, T, H, dtype=dtype).sigmoid()
    h0 = torch.randn(B, H, D, D, dtype=torch.float32)
    q, k, v, beta, h0 = map(lambda x: x.to(device).requires_grad_(True), (q, k, v, beta, h0))
    do = torch.rand_like(v)
    dht = torch.rand_like(h0)

    tri, tri_ht = chunk_delta_rule(
        q=F.normalize(q.clone(), p=2, dim=-1) if not use_qk_l2norm_in_kernel else q.clone(),
        k=F.normalize(k.clone(), p=2, dim=-1) if not use_qk_l2norm_in_kernel else k.clone(),
        v=v.clone(),
        beta=beta.clone(),
        scale=scale,
        output_final_state=True,
        initial_state=h0.clone(),
        use_qk_l2norm_in_kernel=use_qk_l2norm_in_kernel,
    )
    ((tri * do).sum() + (tri_ht * dht).sum()).backward(retain_graph=True)
    tri_dq, tri_dk, tri_dv, tri_dbeta, tri_dh0 = q.grad, k.grad, v.grad, beta.grad, h0.grad
    q.grad = k.grad = v.grad = beta.grad = h0.grad = None

    ref, ref_ht = fused_recurrent_delta_rule(
        q=F.normalize(q.clone(), p=2, dim=-1) if not use_qk_l2norm_in_kernel else q.clone(),
        k=F.normalize(k.clone(), p=2, dim=-1) if not use_qk_l2norm_in_kernel else k.clone(),
        v=v.clone(),
        beta=beta.clone(),
        scale=scale,
        output_final_state=True,
        initial_state=h0.clone(),
        use_qk_l2norm_in_kernel=use_qk_l2norm_in_kernel,
    )
    ((ref * do).sum() + (ref_ht * dht).sum()).backward(retain_graph=True)
    ref_dq, ref_dk, ref_dv, ref_dbeta, ref_dh0 = q.grad, k.grad, v.grad, beta.grad, h0.grad

    assert_close('o', ref, tri, 0.006)
    assert_close('ht', ref_ht, tri_ht, 0.006)
    assert_close('dq', ref_dq, tri_dq, 0.008)
    assert_close('dk', ref_dk, tri_dk, 0.008)
    assert_close('dv', ref_dv, tri_dv, 0.008)
    assert_close('db', ref_dbeta, tri_dbeta, 0.008)
    assert_close('dh0', ref_dh0, tri_dh0, 0.008)


@pytest.mark.parametrize(
    ('H', 'D', 'cu_seqlens', 'dtype'),
    [
        pytest.param(*test, id="H{}-D{}-cu_seqlens{}-{}".format(*test))
        for test in [
            (2, 64, [0, 15], torch.float16),
            (3, 60, [0, 111, 500], torch.float16),
            (3, 64, [0, 256, 500, 900, 1000], torch.float16),
            (4, 100, [0, 15, 100, 300, 1200, 1599, 1800, 2000], torch.float16),
        ]
    ],
)
@pytest.mark.skipif(
    device_platform == 'intel',
    reason='Intel Triton Failure',
)
def test_chunk_varlen(
    H: int,
    D: int,
    cu_seqlens: list[int],
    dtype: torch.dtype,
):
    torch.manual_seed(42)
    T = cu_seqlens[-1]
    N = len(cu_seqlens) - 1
    cu_seqlens = torch.tensor(cu_seqlens, dtype=torch.int32, device=device)

    # seq-first required for inputs with variable lengths
    q = torch.randn((1, T, H, D), dtype=dtype)
    k = F.normalize(torch.randn(1, T, H, D, dtype=torch.float32), p=2, dim=-1).to(dtype)
    v = torch.randn((1, T, H, D), dtype=dtype)
    beta = torch.randn(1, T, H, dtype=dtype).sigmoid()
    h0 = torch.randn(N, H, D, D, dtype=dtype)
    q, k, v, beta, h0 = map(lambda x: x.to(device).requires_grad_(), (q, k, v, beta, h0))
    do = torch.randn_like(v)
    dht = torch.rand_like(h0)

    ref, ref_ht = fused_recurrent_delta_rule(
        q=q.clone(),
        k=k.clone(),
        v=v.clone(),
        beta=beta.clone(),
        output_final_state=True,
        initial_state=h0.clone(),
        cu_seqlens=cu_seqlens,
    )
    ((ref * do).sum() + (ref_ht * dht).sum()).backward(retain_graph=True)
    ref_dq, ref_dk, ref_dv, ref_dbeta, ref_dh0 = q.grad, k.grad, v.grad, beta.grad, h0.grad

    tri, tri_ht = chunk_delta_rule(
        q=q.clone(),
        k=k.clone(),
        v=v.clone(),
        beta=beta.clone(),
        output_final_state=True,
        initial_state=h0.clone(),
        cu_seqlens=cu_seqlens,
    )
    ((tri * do).sum() + (tri_ht * dht).sum()).backward(retain_graph=True)
    tri_dq, tri_dk, tri_dv, tri_dbeta, tri_dh0 = q.grad, k.grad, v.grad, beta.grad, h0.grad
    q.grad = k.grad = v.grad = beta.grad = h0.grad = None

    assert_close('o', ref, tri, 0.005)
    assert_close('ht', ref_ht, tri_ht, 0.005)
    assert_close('dq', ref_dq, tri_dq, 0.008)
    assert_close('dk', ref_dk, tri_dk, 0.008)
    assert_close('dv', ref_dv, tri_dv, 0.008)
    assert_close('db', ref_dbeta, tri_dbeta, 0.008)
    assert_close('dh0', ref_dh0, tri_dh0, 0.008)