import torch

import colossalai
from colossalai.testing import rerun_if_address_is_in_use, spawn
from colossalai.zero.legacy.gemini.tensor_utils import colo_model_data_tensor_move, colo_model_data_tensor_move_inline
from colossalai.zero.legacy.sharded_param import ShardedTensor


def run_tensor_move(rank, world_size, port):
    colossalai.launch(config={}, rank=0, world_size=world_size, host='localhost', port=port, backend='nccl')

    src_t = torch.ones(2, 3).cuda()
    tgt_t = torch.zeros(2, 3)

    colo_model_data_tensor_move(src_t, tgt_t)
    assert (torch.sum(tgt_t) == 6.0), f"{torch.sum(tgt_t.payload)} vs. 6.0"

    src_t = torch.ones(2, 3)
    tgt_t = torch.zeros(2, 3).cuda().half()
    colo_model_data_tensor_move(src_t, tgt_t)
    # the src_t has been removed
    assert (src_t.numel() == 0)
    assert (torch.sum(tgt_t) == 6.0), f"{torch.sum(tgt_t.payload)} vs. 6.0"

    src_t = ShardedTensor(torch.ones(2, 3))
    tgt_t = ShardedTensor(torch.zeros(2, 3).cuda().half())
    colo_model_data_tensor_move(src_t, tgt_t)
    assert (torch.sum(tgt_t.payload) == 6.0), f"{torch.sum(tgt_t.payload)} vs. 6.0"

    assert (tgt_t.device.type == 'cuda')
    colo_model_data_tensor_move_inline(tgt_t, torch.device('cpu'))
    assert (tgt_t.device.type == 'cpu')


@rerun_if_address_is_in_use()
def test_tensor_move():
    spawn(run_tensor_move, 1)


if __name__ == '__main__':
    test_tensor_move()