import os
import time
import urllib.request as req
from types import SimpleNamespace
from unittest.mock import patch

import mock
import numpy as np
import pytest
import torch

import megatron.core.utils as util
import megatron.training.utils as training_util
from megatron.core import config
from megatron.core.distributed import DistributedDataParallel, DistributedDataParallelConfig
from megatron.core.optimizer import OptimizerConfig, get_megatron_optimizer
from megatron.core.transformer import TransformerConfig
from tests.unit_tests.test_utilities import Utils

success_string = "hello,world"


@util.experimental_cls(introduced_with_version="0.1.0")
class A:

    def __init__(self):
        pass

    def some_method(self):
        return success_string

    @classmethod
    def some_static_method(cls):
        return success_string


def test_divide_properly():
    assert util.divide(4, 2) == 2


def test_divide_improperly():
    with pytest.raises(AssertionError):
        util.divide(4, 5)


def test_experimental_cls_init():
    with patch.object(config, 'ENABLE_EXPERIMENTAL', True):
        # Check that initialization works
        a = A()
        assert a.__class__.__qualname__ == "A"
        assert a.some_method() == success_string
        assert a.is_experimental is True


def test_experimental_cls_static():
    with patch.object(config, 'ENABLE_EXPERIMENTAL', True):
        # Check that static methods work
        assert A.__class__.__qualname__ == "A"
        assert A.some_static_method() == success_string
        assert A.is_experimental is True


def test_experimental_cls_exception_init():
    with patch.object(config, 'ENABLE_EXPERIMENTAL', False), pytest.raises(
        util.ExperimentalNotEnabledError
    ):
        a = A()
        assert a.some_method() == success_string
        assert a.is_experimental is False


def test_experimental_cls_exception_static():
    with patch.object(config, 'ENABLE_EXPERIMENTAL', False), pytest.raises(
        util.ExperimentalNotEnabledError
    ):
        assert A.some_static_method() == success_string

    assert A.is_experimental is False


def test_global_memory_buffer():
    global_memory_buffer = util.GlobalMemoryBuffer()
    obtained_tensor = global_memory_buffer.get_tensor((3, 2), torch.float32, "test_tensor")
    expected_tensor = torch.empty((3, 2), dtype=torch.float32, device=torch.cuda.current_device())
    assert obtained_tensor.shape == expected_tensor.shape


def test_make_viewless_tensor():
    inp = torch.rand((3, 4))
    assert torch.equal(inp, util.make_viewless_tensor(inp, True, True))
    assert torch.equal(inp, util.make_viewless_tensor(inp, True, False))


def test_safely_set_viewless_tensor_data():
    tensor = torch.zeros((3, 4))
    new_data_tensor = torch.tensor(np.random.rand(3, 4))
    util.safely_set_viewless_tensor_data(tensor, new_data_tensor)
    assert torch.equal(tensor, new_data_tensor)


def test_assert_viewless_tensor():
    tensor = torch.rand((3, 4))
    assert torch.equal(util.assert_viewless_tensor(tensor), tensor)
    input_tensor_list = [tensor, tensor, tensor]
    output_tensor_list = util.assert_viewless_tensor(input_tensor_list)
    for inp, out in zip(input_tensor_list, output_tensor_list):
        assert torch.equal(inp, out)


# Initialize torch.distributed; do not call init_process_group here, call
# Utils.initialize_distributed() instead.
def _init_distributed(world, rank):
    Utils.initialize_distributed()
    assert torch.distributed.is_initialized() == True
    assert torch.distributed.get_rank() == rank
    assert torch.cuda.device_count() == world
    torch.distributed.barrier()


# Deinitialization and cleanup.
# Do not call torch.distributed.destroy_process_group, may be needed by other tests.
def _deinit_distributed():
    assert torch.distributed.is_initialized() == True
    torch.distributed.barrier()


@pytest.mark.flaky_in_dev
def test_check_param_hashes_across_dp_replicas():
    world = int(os.getenv('WORLD_SIZE', '1'))
    rank = int(os.getenv('RANK', '0'))

    # Setup.
    _init_distributed(world, rank)
    Utils.initialize_model_parallel()
    model = torch.nn.Linear(100, 100, bias=False, device='cuda')

    # First check case where all replicas agree.
    model.weight.data.fill_(1.0)
    assert util.check_param_hashes_across_dp_replicas([model])

    # Now check case where replica 0 disagrees with all other replicas.
    if rank == 0:
        model.weight.data.fill_(0.0)
    param_hashes_match = util.check_param_hashes_across_dp_replicas([model])
    expected_param_hashes_match = rank == 0
    assert param_hashes_match == expected_param_hashes_match

    # Teardown.
    _deinit_distributed()


@pytest.mark.flaky_in_dev
def test_cross_check_param_hashes_across_dp_replicas():
    world = int(os.getenv('WORLD_SIZE', '1'))
    rank = int(os.getenv('RANK', '0'))

    # Setup.
    _init_distributed(world, rank)
    Utils.initialize_model_parallel()
    model = torch.nn.Linear(100, 100, bias=False, device='cuda')

    # First check case where all replicas agree.
    model.weight.data.fill_(1.0)
    assert util.check_param_hashes_across_dp_replicas([model], True)

    # Now check case where replica 0 disagrees with all other replicas.
    if rank == 0:
        model.weight.data.fill_(0.0)
    assert not util.check_param_hashes_across_dp_replicas([model], True)

    # Teardown.
    _deinit_distributed()


@pytest.mark.parametrize("use_distributed_optimizer", [False, True])
@pytest.mark.flaky_in_dev
def test_param_norm(use_distributed_optimizer: bool):
    world = int(os.getenv('WORLD_SIZE', '1'))
    rank = int(os.getenv('RANK', '0'))

    # Setup: distributed, model, mock_args.
    _init_distributed(world, rank)
    Utils.initialize_model_parallel()
    model = torch.nn.Linear(100, 100, bias=False, dtype=torch.bfloat16, device='cuda')
    model.requires_grad_(True)
    model.weight.data.fill_(1.0)
    ddp_config = DistributedDataParallelConfig(use_distributed_optimizer=use_distributed_optimizer)
    # Use dummy TransformerConfig which doesn't trigger __post_init__ assertions.
    model = DistributedDataParallel(
        TransformerConfig(num_attention_heads=1, num_layers=1), ddp_config, model
    )
    for param in model.parameters():
        assert param.requires_grad
    mock_args = SimpleNamespace(bf16=True)

    with mock.patch('megatron.training.utils.get_args', new=lambda: mock_args):
        # Make sure norm is correct when `main_param` attribute is not available.
        assert training_util.calc_params_l2_norm(
            model, force_create_fp32_copy=False
        ) == pytest.approx(100.0)
        assert training_util.calc_params_l2_norm(
            model, force_create_fp32_copy=True
        ) == pytest.approx(100.0)

        # Make sure norm is correct when `main_param` attribute is available.
        optimizer_config = OptimizerConfig(
            bf16=True, use_distributed_optimizer=use_distributed_optimizer
        )
        _ = get_megatron_optimizer(optimizer_config, [model])
        for param in model.parameters():
            assert hasattr(param, 'main_param')
            if use_distributed_optimizer:
                assert getattr(param, 'main_param_sharded', False)
        assert training_util.calc_params_l2_norm(
            model, force_create_fp32_copy=False
        ) == pytest.approx(100.0)
        assert training_util.calc_params_l2_norm(
            model, force_create_fp32_copy=True
        ) == pytest.approx(100.0)

    # Teardown.
    _deinit_distributed()


@pytest.mark.flaky_in_dev
def test_straggler_detector():
    world = int(os.getenv('WORLD_SIZE', '1'))
    rank = int(os.getenv('RANK', '0'))
    master = os.getenv('MASTER_ADDR', 'localhost')
    port = 65535

    # Checks if the instance is disabled.
    def straggler_detector_disabled():
        assert stimer.enabled == False

    # Checks if the instance is enabled.
    def straggler_detector_enabled():
        assert stimer.enabled == True

    # Enable.
    def straggler_detector_enable():
        if rank == 0:
            resp = req.urlopen(f"http://{master}:{port}").read().decode().split()
            assert resp[3] == "ON"
        # Call the report function, this will propagate the change.
        stimer.report()

    # Time an operation.
    def straggler_detector_timeit():
        s = 2  # Sleep for 2 seconds.
        M = 20
        K = 30
        N = 40
        mat1 = torch.randn(M, K, device='cuda')
        mat2 = torch.randn(K, N, device='cuda')
        # batch_data.
        with stimer(bdata=True):
            time.sleep(s)
        # GEMM.
        with stimer:
            res = torch.matmul(mat1, mat2)
        delta, batch_delta, _, _, _, _ = stimer.elapsed()
        assert delta > 0.0
        assert batch_delta >= s

    # Test function to raise ValueError
    def straggler_value_error():
        raise ValueError("Exception value raised")

    # Check that exception is not suppressed.
    def straggler_detector_exception_propagate():
        # batch_data
        with pytest.raises(ZeroDivisionError):
            with stimer(bdata=True):
                x = 1 / 0
        # non-batch-data
        with pytest.raises(ValueError, match=r".* value .*"):
            with stimer():
                straggler_value_error()

    # Reporting.
    def straggler_detector_report():
        s = 2  # Sleep for 2 seconds.
        N = 20
        P = 30
        M = 40
        mat1 = torch.randn(N, P, device='cuda')
        mat2 = torch.randn(P, M, device='cuda')
        tfp = (N * M) * (2 * P - 1)  # Theoretical.
        iter = 10  # Mock.
        # batch_data.
        with stimer(bdata=True):
            time.sleep(s)
        # GEMM.
        with stimer:
            res = torch.matmul(mat1, mat2)
        r = stimer.report(total_flops=tfp, log_interval=iter)
        rb = True if rank == 0 else False
        assert r == rb

    # Start test.
    # Setup.
    _init_distributed(world, rank)

    # Create a straggler_detector with enabled set to false.
    stimer = util.StragglerDetector()
    stimer.configure(world, rank, enabled=False, port=port)
    # Check if configuration was success.
    assert stimer.configured == True

    # Check if the instance is in disabled state.
    straggler_detector_disabled()
    # Enable it now, must call report.
    straggler_detector_enable()
    # Check if all ranks have straggler detector enabled.
    straggler_detector_enabled()
    # Time some operation.
    straggler_detector_timeit()
    # Report only from rank 0.
    straggler_detector_report()
    # Check that exception is not suppressed.
    straggler_detector_exception_propagate()
    util.StragglerDetector._configured = False
    # Teardown.
    _deinit_distributed()
