from typing import Dict

import torch
from torch.fx import GraphModule
from torch.fx.node import Node

from colossalai.auto_parallel.meta_profiler import MetaInfo
from colossalai.auto_parallel.passes.runtime_apply_pass import runtime_apply, runtime_comm_spec_apply
from colossalai.auto_parallel.tensor_shard.sharding_strategy import MemoryCost, TrainCycleItem
from colossalai.tensor.comm_spec import CommSpec
from colossalai.tensor.shape_consistency import ShapeConsistencyManager
from colossalai.tensor.sharding_spec import ShardingSpec

shape_consistency_manager = ShapeConsistencyManager()


def _construct_meta_info(node: Node, origin_sharding_spec: ShardingSpec,
                         target_sharding_spec: ShardingSpec) -> MetaInfo:
    # get comm_action_sequence and total_cost from shape_consistency_manager
    _, comm_action_sequence, total_cost = shape_consistency_manager.shape_consistency(
        origin_sharding_spec, target_sharding_spec)

    meta_info = MetaInfo()
    # NOTE: the cost in shape_consistency_manager.mem_cost is the count in number of numel
    # get mem cost for MetaInfo
    mem_cost = shape_consistency_manager.mem_cost(comm_action_sequence)
    # extract user that has _meta_data and extract element length
    input_node = next(n for n in node._input_nodes if hasattr(n, '_meta_data'))
    element_length = input_node._meta_data.element_size()

    mem_cost.fwd.activation *= element_length
    mem_cost.fwd.temp *= element_length
    mem_cost.bwd.activation *= element_length
    mem_cost.bwd.temp *= element_length
    mem_cost.total.activation *= element_length

    meta_info.memory_cost = mem_cost

    # get computation cost for MetaInfo
    meta_info.compute_cost = TrainCycleItem(total_cost['forward'] * element_length,
                                            total_cost['backward'] * element_length,
                                            total_cost['total'] * element_length)

    # get tensor shape for MetaInfo
    origin_sharding_spec: ShardingSpec
    target_sharding_spec: ShardingSpec
    input_shape = origin_sharding_spec.get_sharded_shape_per_device()
    output_shape = target_sharding_spec.get_sharded_shape_per_device()

    meta_info.fwd_in = [torch.rand(input_shape, device='meta')]
    meta_info.fwd_buffer = []
    meta_info.fwd_out = [torch.rand(output_shape, device='meta')]

    return meta_info


def _runtime_apply_meta_info(node: Node, origin_spec_dict, sharding_spec_dict) -> MetaInfo:
    """
    This method is used to construct `MetaInto` for shape consistency node
    """

    # extract node index and user node index
    args = node.args
    node_index, user_node_index = args[3], args[4]
    origin_sharding_spec, target_sharding_spec = origin_spec_dict[node_index], sharding_spec_dict[node_index][
        user_node_index]

    return _construct_meta_info(node, origin_sharding_spec, target_sharding_spec)


def _runtime_comm_spec_apply_meta_info(node: Node, comm_actions_dict: Dict) -> MetaInfo:
    # extract node_index and op_data_name
    node_index, op_data_name = node.args[2], node.args[3]

    comm_action = comm_actions_dict[node_index][op_data_name]
    if isinstance(comm_action.comm_spec, CommSpec):
        # this case is for all_reduce, there will be no memory cost
        meta_info = MetaInfo()
        meta_info.memory_cost = TrainCycleItem(MemoryCost(), MemoryCost(), MemoryCost)
        output_node = next(n for n in node.users if hasattr(n, '_meta_data'))
        element_length = output_node._meta_data.element_size()

        total_cost = comm_action.comm_spec.get_comm_cost()
        meta_info.compute_cost = TrainCycleItem(total_cost['forward'] * element_length,
                                                total_cost['backward'] * element_length,
                                                total_cost['total'] * element_length)

        input_shape = output_shape = comm_action.comm_spec.sharding_spec.get_sharded_shape_per_device()
        meta_info.fwd_in = [torch.rand(input_shape, device='meta')]
        meta_info.fwd_buffer = []
        meta_info.fwd_out = [torch.rand(output_shape, device='meta')]
    else:
        # this case will be handled by shape consistency manager
        origin_sharding_spec, target_sharding_spec = comm_action.comm_spec['src_spec'], comm_action.comm_spec[
            'tgt_spec']
        meta_info = _construct_meta_info(node, origin_sharding_spec, target_sharding_spec)

    return meta_info


def comm_metainfo_pass(gm: GraphModule, sharding_spec_dict: Dict, origin_spec_dict: Dict,
                       comm_actions_dict: Dict) -> GraphModule:
    """
    The method manages all the metainfo of the communication node (run_time_apply, runtime_comm_spec_apply) in the graph.
    """
    for node in gm.graph.nodes:
        if node.target == runtime_apply:
            setattr(node, 'best_metainfo', _runtime_apply_meta_info(node, origin_spec_dict, sharding_spec_dict))
        elif node.target == runtime_comm_spec_apply:
            setattr(node, 'best_metainfo', _runtime_comm_spec_apply_meta_info(node, comm_actions_dict))
        else:
            pass
    return gm