# Copyright (c) 2022-2025, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
#
# See LICENSE for license information.

from collections import OrderedDict
import math
import os
from typing import Dict, List, Tuple, Optional
import pytest
import copy
import random

import torch
import torch.nn as nn
from torch.nn import Parameter
from torch.utils.cpp_extension import IS_HIP_EXTENSION

from transformer_engine.pytorch.fp8 import (
    FP8GlobalStateManager,
    fp8_autocast,
    fp8_model_init,
)
from transformer_engine.pytorch.utils import (
    init_method_normal,
    scaled_init_method_normal,
    attention_mask_func,
    is_bf16_compatible,
)
from transformer_engine.pytorch import (
    DotProductAttention,
    LayerNormLinear,
    LayerNormMLP,
    Linear,
    GroupedLinear,
    BatchedLinear,
    MultiheadAttention,
    RMSNorm,
    TransformerLayer,
    LayerNorm,
    Fp8Padding,
    Fp8Unpadding,
)
from transformer_engine.pytorch import torch_version
from transformer_engine.pytorch.dot_product_attention.inference import InferenceParams
from transformer_engine.pytorch.distributed import checkpoint as te_checkpoint
from transformer_engine.pytorch.cpp_extensions import general_gemm, general_grouped_gemm, batchgemm
from transformer_engine.pytorch.tensor.float8_tensor import Float8Quantizer
from transformer_engine.pytorch.module.base import get_multi_stream_cublas_workspace, get_workspace
from transformer_engine.pytorch.utils import get_device_compute_capability
from transformer_engine.common import recipe
import transformer_engine_torch as tex

# Only run FP8 tests on supported devices.
fp8_available, reason_for_no_fp8 = FP8GlobalStateManager.is_fp8_available()
mxfp8_available, reason_for_no_mxfp8 = FP8GlobalStateManager.is_mxfp8_available()

sm_80plus = get_device_compute_capability() >= (8, 0)

seed = 1234
torch.manual_seed(seed)
torch.cuda.manual_seed(seed)
# Record initial RNG state from script run.
_cpu_rng_state = torch.get_rng_state()
_cuda_rng_state = torch.cuda.get_rng_state()

if torch_version() >= (2, 7, 0):
    torch._dynamo.config.recompile_limit = 16
else:
    torch._dynamo.config.cache_size_limit = 16

class ModelConfig:
    def __init__(self, hidden_size, eps, num_attention_heads, embed, num_layers, seq_len):
        self.hidden_size = hidden_size
        self.eps = eps
        self.num_attention_heads = num_attention_heads
        self.embed = embed
        self.num_layers = num_layers
        self.seq_len = seq_len


model_configs = {
    "small": ModelConfig(128, 1e-5, 8, 36, 4, 128),
    "126m": ModelConfig(768, 1e-5, 12, 64, 12, 2048),
}

model_configs_inference = {
    # hidden_size, eps, num_attention_heads, embed, num_layers, seq_len
    "126m": ModelConfig(768, 1e-5, 12, 64, 12, 256),
}
backends_inference = ["FlashAttention", "UnfusedAttention", "FusedAttention"]
module_inference = ["TransformerLayer", "MultiheadAttention"]
input_formats_inference = ["sbhd", "bshd"]

param_types = [torch.float32, torch.float16]
if is_bf16_compatible():  # bf16 requires sm_80 or higher
    param_types.append(torch.bfloat16)

batch_sizes = [1, 2]

all_boolean = [True, False]

all_activations = ["gelu", "relu", "reglu", "geglu", "swiglu", "qgelu", "srelu"]

all_normalizations = ["LayerNorm", "RMSNorm"]

mask_types = ["causal", "no_mask"]

fp8_recipes = [
    recipe.MXFP8BlockScaling(),
    recipe.DelayedScaling(),
    recipe.Float8CurrentScaling(),
]


def get_causal_attn_mask(sq: int) -> torch.Tensor:
    return torch.triu(torch.ones(sq, sq, device="cuda"), diagonal=1).bool()


def dtype_tols(dtype: torch.dtype) -> Dict[str, float]:
    """Estimated numerical error for a datatype

    Based on tolerances for torch.testing.assert_close.

    """
    if dtype == torch.float32:
        return dict(rtol=1.3e-6, atol=1e-5)
    if dtype == torch.float16:
        return dict(rtol=1e-3, atol=1e-5)
    if dtype == torch.bfloat16:
        return dict(rtol=1.6e-2, atol=1e-5)
    raise ValueError(f"Unsuppored dtype ({dtype})")


def assert_allclose(
    l1: List[torch.Tensor], l2: List[torch.Tensor], atol: float, rtol: float = None
) -> bool:
    """Ensures two lists are equal."""
    assert len(l1) == len(l2), "Unequal number of outputs."
    for i, (t1, t2) in enumerate(zip(l1, l2)):
        tols = dict(atol=atol)
        if rtol is not None:
            tols["rtol"] = rtol
        result = torch.allclose(t1, t2, **tols)
        if not result:
            diff = torch.abs(t1 - t2)
            tol = atol + (rtol * torch.abs(t2))
            exceed_mask = diff > tol
            if exceed_mask.any():
                indices = torch.nonzero(exceed_mask, as_tuple=True)
                max_diff = diff[exceed_mask].max()
                max_idx = (diff[exceed_mask] == max_diff).nonzero(as_tuple=True)[0][0]
                max_location = [idx[max_idx].item() for idx in indices]
                msg = (
                    f"Outputs not close enough in tensor at idx={i}. "
                    f"Maximum difference at location {max_location} "
                    f"with {t1[exceed_mask][max_idx].item()} vs {t2[exceed_mask][max_idx].item()} "
                    f"(diff {max_diff.item()})."
                )
            raise AssertionError(msg)


def reset_rng_states() -> None:
    """revert back to initial RNG state."""
    torch.set_rng_state(_cpu_rng_state)
    torch.cuda.set_rng_state(_cuda_rng_state)


@pytest.fixture(autouse=True)
def reset_global_fp8_state():
    yield
    FP8GlobalStateManager.reset()

def _test_batched_linear_accuracy(
    block, num_gemms, bs, dtype, config, recipe, fp8, fuse_wgrad_accumulation
):
    reset_rng_states()
    if fp8:
        FP8GlobalStateManager.reset()

    inp_hidden_states = torch.randn(
        (config.seq_len, bs, config.hidden_size),
        dtype=dtype,
        device="cuda",
        requires_grad=True,
    )
    inp_hidden_states.retain_grad()

    assert config.seq_len % num_gemms == 0
    m_splits = torch.tensor([config.seq_len // num_gemms for i in range(num_gemms)])
    assert m_splits.sum() == config.seq_len and len(m_splits) == num_gemms

    with fp8_autocast(enabled=fp8, fp8_recipe=recipe):
        if isinstance(block, BatchedLinear):
            m_splits = m_splits * bs
            out = block(inp_hidden_states, m_splits.tolist())
        else:
            out = torch.cat(
                [
                    block[i](inp)
                    for i, inp in enumerate(torch.split(inp_hidden_states, m_splits.tolist()))
                ]
            )
    loss = out.sum()
    loss.backward()

    torch.cuda.synchronize()
    outputs = [out, inp_hidden_states.grad]
    return outputs

@pytest.mark.parametrize("dtype", param_types)
@pytest.mark.parametrize("num_gemms", [4, 8])
@pytest.mark.parametrize("bs", batch_sizes)
@pytest.mark.parametrize("model", ["126m"])
@pytest.mark.parametrize("fp8", all_boolean)
@pytest.mark.parametrize("recipe", fp8_recipes)
@pytest.mark.parametrize("fp8_model_params", all_boolean)
@pytest.mark.parametrize("fuse_wgrad_accumulation", all_boolean)
def test_batched_linear_accuracy(
    dtype,
    num_gemms,
    bs,
    model,
    fp8,
    recipe,
    fp8_model_params,
    fuse_wgrad_accumulation,
    parallel_mode=None,
):
    batch_num = int(os.getenv("NVTE_MOE_BATCHCOUNT", "2"))
    if fp8 and not fp8_available:
        pytest.skip(reason_for_no_fp8)
    if recipe.mxfp8() and not mxfp8_available:
        pytest.skip(reason_for_no_mxfp8)
    if fp8 and recipe.mxfp8():  # TODO(ksivamani): debug mismatches
        pytest.skip("MXFP8 unsupported for batched linear.")
    if fp8 and recipe.float8_current_scaling():
        pytest.skip("Float8 Current Scaling unsupported for batched linear.")

    config = model_configs[model]
    if config.seq_len % 16 != 0 and fp8:
        pytest.skip("FP8 requires sequence length to be divisible by 16.")

    with fp8_model_init(enabled=fp8 and fp8_model_params, recipe=recipe):
        batched_linear = BatchedLinear(
            num_gemms,
            config.hidden_size,
            4 * config.hidden_size,
            bias=False,
            params_dtype=dtype,
            parallel_mode=parallel_mode,
            device="cuda",
            fuse_wgrad_accumulation=fuse_wgrad_accumulation,
        ).eval()
        sequential_linear = torch.nn.ModuleList(
            [
                Linear(
                    config.hidden_size,
                    4 * config.hidden_size,
                    bias=False,
                    params_dtype=dtype,
                    parallel_mode=parallel_mode,
                    device="cuda",
                    fuse_wgrad_accumulation=fuse_wgrad_accumulation,
                ).eval()
                for _ in range(num_gemms)
            ]
        )

    # Share params
    with torch.no_grad():
        for i in range(num_gemms // batch_num):
            weight = getattr(batched_linear, f"weight{i}").clone()
            # bias = getattr(batched_linear, f"bias{i}").clone()
            if fuse_wgrad_accumulation:
                weight_i = getattr(batched_linear, f"weight{i}")
                weight_i.main_grad = torch.rand_like(weight_i, dtype=torch.float32)
            for j in range(batch_num):
                sequential_linear[i * batch_num + j].weight = Parameter(weight[weight.shape[0] // batch_num * j : weight.shape[0] // batch_num * (j + 1)].clone())
                # sequential_linear[i * batch_num + j].bias = Parameter(bias[bias.shape[0] // batch_num * j : bias.shape[0] // batch_num * (j + 1)].clone())
                if fuse_wgrad_accumulation:
                    sequential_linear[i * batch_num + j].weight.main_grad = weight_i.main_grad[weight_i.main_grad.shape[0] // batch_num * j : weight_i.main_grad.shape[0] // batch_num * (j + 1)].clone()

    outputs_ref = _test_batched_linear_accuracy(
        sequential_linear, num_gemms, bs, dtype, config, recipe, fp8, fuse_wgrad_accumulation
    )
    outputs = _test_batched_linear_accuracy(
        batched_linear, num_gemms, bs, dtype, config, recipe, fp8, fuse_wgrad_accumulation
    )

    # Shoule be bit-wise match
    for i, (o, o_ref) in enumerate(zip(outputs, outputs_ref)):
        torch.testing.assert_close(o, o_ref, rtol=6e-3, atol=6e-3)

if __name__ == "__main__":
    test_batched_linear_accuracy(torch.float32, 2, 1, "126m", False, recipe.Float8CurrentScaling(), True, True)
