# Copyright (c) 2023, NVIDIA CORPORATION. All rights reserved.

import pytest

import torch

from megatron.core.transformer.module import Float16Module, MegatronModule
from megatron.core.transformer.transformer_config import TransformerConfig

DEVICE_CAPABILITY = None
if torch.cuda.is_available():
    DEVICE_CAPABILITY = torch.cuda.get_device_capability()


class DummyModule(MegatronModule):
    # def __init__(self, config: TransformerConfig, share_embeddings_and_output_weights=True):
    def __init__(self, config: TransformerConfig):
        super().__init__(config)

        self.linear = torch.nn.modules.Linear(in_features=2, out_features=1)

    def forward(self, x):
        return self.linear(x)


@pytest.fixture
def megatron_module(transformer_config):
    return DummyModule(config=transformer_config).cuda()


class TestMegatronModule:
    def test_megatron_module(self, megatron_module):
        assert megatron_module
        assert megatron_module.config.hidden_size == 12
        assert megatron_module.config.ffn_hidden_size == 48
        assert megatron_module.linear.weight.dtype == torch.float32

        x = torch.ones((2, 2)).cuda()
        assert megatron_module(x).dtype == torch.float32

        # TODO: test bad configs actually fail
        # failed_module = megatron_module
        # failed_module.fp16 = True
        # failed_module.bf16 = True


class TestFloat16Module:
    def test_fp16_module(self, transformer_config, megatron_module):
        transformer_config.fp16 = True
        fp16_module = Float16Module(config=transformer_config, module=megatron_module)

        assert fp16_module
        assert fp16_module.config.hidden_size == 12
        assert fp16_module.config.ffn_hidden_size == 48
        assert fp16_module.module.linear.weight.dtype == torch.float16

        x = torch.ones((2, 2)).cuda()
        # inputs are converted to fp16 then outputs are converted to fp32
        assert fp16_module(x).dtype == torch.float32

    pytest.mark.skipif(
        not DEVICE_CAPABILITY or DEVICE_CAPABILITY[0] < 8, reason='bfloat16 is not supported on this device'
    )

    def test_bf16_module(self, transformer_config, megatron_module):
        transformer_config.bf16 = True
        bf16_module = Float16Module(config=transformer_config, module=megatron_module)

        assert bf16_module
        assert bf16_module.config.hidden_size == 12
        assert bf16_module.config.ffn_hidden_size == 48
        assert bf16_module.module.linear.weight.dtype == torch.bfloat16

        x = torch.ones((2, 2)).cuda()
        # inputs are converted to bf16 then outputs are converted to fp32
        assert bf16_module(x).dtype == torch.float32