import time
from functools import partial
from typing import Any, Iterable, Optional, Union

import torch
import torch.cuda
from torch.nn import Module
from torch.utils._pytree import tree_map

from colossalai.accelerator import get_accelerator
from colossalai.inference.engine.microbatch_manager import MicroBatchManager, Status
from colossalai.pipeline.p2p import PipelineP2PCommunication
from colossalai.pipeline.stage_manager import PipelineStageManager

from ._utils import get_batch_size, get_micro_batch, model_forward, to_device
from .base import PipelineSchedule


class ActionIntervalBuffer:
    """
    The buffer to save the interval hidden states and new token for stage to use.

    """

    def __int__(self):
        self.hidden_states = None
        self.new_token = None

    def clear(self):
        self.hidden_states = None
        self.new_token = None


class GenerateSchedule(PipelineSchedule):
    """
    GenerateSchedule is a class that handles the pipeline parallel inference.
    In our schedule, we place tie weight layer, embedding and lm_head in the same device to save space, so in
    this schedule, the out for each encoding progress is on rank0.

    Args:
        stage_manager (`PipelineStageManager`): Pipeline stage manager.
        mb_manager (`MicroBatchManager`): Micro batch manager.
        verbose (bool): Whether to verbose the information of the pipeline.
    """

    def __init__(self, stage_manager: PipelineStageManager, mb_manager: MicroBatchManager, verbose: bool) -> None:
        super().__init__(stage_manager)
        self.comm = PipelineP2PCommunication(stage_manager)
        self.mb_manager = mb_manager
        self.microbatch_size = mb_manager.micro_batch_size
        self.batch: Optional[Any] = None
        self.batch_size: Optional[int] = None
        self.microbatch_offset: Optional[int] = None
        self.num_microbatches: Optional[int] = None
        self.action_interval_buffer = ActionIntervalBuffer()
        self.verbose = verbose
        self.timestamps = None
        self.comm_dtype = None

    def load_batch(self, data_iter: Iterable, device: Optional[torch.device] = None) -> None:
        """Load a batch from data iterator.

        Args:
            data_iter (Iterable): Data iterator.
            device (Optional[torch.device], optional): Target device. Defaults to None.
        """
        batch = next(data_iter)
        if device is not None:
            batch = tree_map(partial(to_device, device=device), batch)
        self.batch = batch
        self.batch_size = get_batch_size(batch)
        if self.stage_manager.num_stages == 1:
            self.microbatch_size = self.batch_size
        self.microbatch_offset = 0
        assert (
            self.batch_size % self.microbatch_size == 0
        ), f"Batch size should divided by the number of microbatches, {self.batch_size}, {self.num_microbatches}"
        self.num_microbatches = self.batch_size // self.microbatch_size
        self.round = self.num_microbatches // self.stage_manager.num_stages

    def load_micro_batch(self) -> Any:
        """Load a micro batch from the current batch.

        Returns:
            Any: Micro batch.
        """
        micro_batch = get_micro_batch(self.batch, self.microbatch_offset, self.microbatch_size)
        self.microbatch_offset += self.microbatch_size
        return tree_map(partial(to_device, device=get_accelerator().get_current_device()), micro_batch)

    def _prepare_inputs_for_interval_stage(self):
        """
        Prepare inputs for interval stage, for all the interval stage, the inputs is just the past_key_values

        Returns:
            dict: inputs for interval stage, `{'past_key_values': torch.Tensor}` or `None`
        """
        model_inputs = {"infer_state": self.mb_manager.cur_description.infer_state}
        return model_inputs

    def _prepare_inputs_for_new_token(self, new_token: torch.Tensor):
        """
        Prepare inputs for new token, the inputs is a dict with `input_ids`, `attention_mask` and `past_key_values`
        `input_ids` is the new token, `attention_mask` is the previous mask add `1` in the end,
        `past_key_values` is the past_key_values save in the micro batch manager

        Returns:
            dict: inputs for new token, `{'input_ids': torch.Tensor, 'attention_mask': torch.Tensor, 'past_key_values': torch.Tensor}`
        """
        new_mask = self.mb_manager.cur_description.attn_mask

        return dict(input_ids=new_token, attention_mask=new_mask)

    def _get_token_id(self, hidden_state: torch.Tensor) -> torch.Tensor:
        last_hidden_state = hidden_state[:, -1]
        input_ids = torch.argmax(last_hidden_state, dim=-1).unsqueeze(1)
        return input_ids

    def _recv_pre_stage(self) -> Any:
        """
        Receive the output from previous stage

        Returns:
            Any: The output from previous stage
        """
        if self.stage_manager.num_stages == 2:
            return self.comm.p2p_recv()
        return self.comm.recv_forward()

    def _init_infer_state_action(self) -> None:
        """
        This action is only for no first stage, to load batch and init infer_state.
        1.Load micro_batch 2.Use the current micro_batch to init the current infer_state
        """
        inputs_dict = self.load_micro_batch()
        self.mb_manager.add_description(inputs_dict)

    def _load_stage_action(self, model: Module) -> None:
        """
        This action is only for first stage, load, init and do forward.
        1.load micro_batch 2.do the forward 3.step to update
        """
        inputs_dict = self.load_micro_batch()
        self.mb_manager.add_description(inputs_dict)
        if self.verbose and self.stage_manager.is_first_stage():
            torch.cuda.synchronize()
            self.timestamps[self.mb_manager.idx].append(time.time())
        interval_inputs = {"infer_state": self.mb_manager.cur_infer_state}
        output_dict = model_forward(model, inputs_dict, interval_inputs)

        self.action_interval_buffer.hidden_states = output_dict["hidden_states"]

    def _gen_token_action(self, model: Module):
        """
        This action is only for first stage
        1.do the forward with hidden_states to generate new tokens 2.step to update
        """
        hidden_states = self.action_interval_buffer.hidden_states
        assert hidden_states is not None, "When first stage in GENERATE phase, the hidden states should not be None"
        interval_inputs = {"hidden_states": hidden_states, "infer_state": self.mb_manager.cur_infer_state}
        logits = model_forward(model, None, interval_inputs)
        if self.verbose and self.stage_manager.is_first_stage():
            torch.cuda.synchronize()
            self.timestamps[self.mb_manager.idx].append(time.time())
        assert (
            "logits" in logits
        ), f"When first stage in GENERATE phase, the ouput should have attribute `logits`, but has {logits.keys()}"
        new_token = self._get_token_id(logits["logits"])

        self.mb_manager.step(new_token)
        self.action_interval_buffer.new_token = new_token
        self.action_interval_buffer.hidden_states = None

    def _head_encoding_action(self, model: Module):
        """
        In this action, 1.prepare inputs for encoding for first stage. 2.do the forward to get hidden states 3.step to update
        """
        new_token = self.action_interval_buffer.new_token
        assert new_token is not None, "When first stage in GENERATE phase, the new token should not be None"
        inputs_dict = self._prepare_inputs_for_new_token(new_token)
        interval_inputs = {"infer_state": self.mb_manager.cur_infer_state}
        output_dict = model_forward(model, inputs_dict, interval_inputs)

        self.action_interval_buffer.hidden_states = output_dict["hidden_states"]

    def _body_encoding_action(self, model: Module):
        hidden_states = self.action_interval_buffer.hidden_states
        assert hidden_states is not None, "When not first stage, the hidden states should not be None"
        interval_inputs = {"hidden_states": hidden_states, "infer_state": self.mb_manager.cur_infer_state}
        output_dict = model_forward(model, None, interval_inputs)

        self.action_interval_buffer.hidden_states = output_dict["hidden_states"]

    def _comm_action(self, recv_pre: bool) -> torch.Tensor:
        """
        In this action, 1.receive the hidden_states from previous stage 2.send the hidden_states to next stage
        """
        hidden_states = self.action_interval_buffer.hidden_states
        ret = self.comm.p2p_communicate(hidden_states, recv_pre, comm_dtype=self.comm_dtype)

        self.action_interval_buffer.hidden_states = ret

    def _gen_action(self, model: Module):
        """
        In p2p step method, we use `P2POp` asynchronous communication method, so the communication need to be done
        at the begin of each microbatch, it's a more clear way to use an action list to do so. In this function, it will
        generate a sequence action for current state, and do the action one by one.

        Args:
            model (Module): Model to be run.

        Returns:
            List[Callable]: A list of action, each action is a callable function, and it will be called in order.
        """
        actions = []
        if self.stage_manager.is_first_stage():
            if self.mb_manager.cur_state is Status.PREFILL:
                actions.append(partial(self._comm_action, False))
                actions.append(partial(self._load_stage_action, model))
            elif self.stage_manager.is_first_stage() and self.mb_manager.cur_state is Status.GENERATE:
                actions.append(partial(self._comm_action, True))
                actions.append(partial(self._gen_token_action, model))
                actions.append(partial(self._head_encoding_action, model))
            elif self.stage_manager.is_first_stage() and self.mb_manager.cur_state is Status.COOLDOWN:
                actions.append(partial(self._comm_action, True))
                actions.append(partial(self._gen_token_action, model))
        # other stage
        else:
            if self.mb_manager.cur_state is Status.PREFILL:
                actions.append(partial(self._init_infer_state_action))
            actions.append(partial(self._comm_action, True))
            actions.append(partial(self._body_encoding_action, model))

        return actions

    def _gen_one_stage_action(self, model: Module):
        """
         In this function, it will generate a sequence action for current state, and do the action one by one.

        Args:
            model (Module): Model to be run.

        Returns:
            List[Callable]: A list of action, each action is a callable function, and it will be called in order.
        """
        actions = []

        if self.mb_manager.cur_state is Status.PREFILL:
            actions.append(partial(self._load_stage_action, model))
        elif self.mb_manager.cur_state is Status.GENERATE:
            actions.append(partial(self._gen_token_action, model))
            actions.append(partial(self._head_encoding_action, model))
        elif self.mb_manager.cur_state is Status.COOLDOWN:
            actions.append(partial(self._gen_token_action, model))

        return actions

    def generate_step(self, model: Module, data_iter: Iterable) -> Union[torch.Tensor, dict]:
        if self.stage_manager.num_stages == 1:
            return self.generate_step_one_stage(model, data_iter)
        elif self.stage_manager.num_stages == 2:
            return self.generate_step_p2p(model, data_iter)
        else:
            return self.generate_step_broadcast(model, data_iter)

    @torch.no_grad()
    def generate_step_one_stage(self, model: Module, data_iter: Iterable) -> Union[torch.Tensor, dict]:
        """
        Forward one step of the pipeline, when pipeline size is 1.

        Args:
            model (Module): Model to be run.
            data_iter (Iterable): Data iterator.

        Returns:
            Union[torch.Tensor, dict]: The intermediate output (dict) of the current stage. If it is the last stage, the output is the loss (Tensor).
        """
        output_sequence = []
        self.load_batch(data_iter)
        model.eval()
        self.comm_dtype = model.dtype

        whole_timestamp = []

        # run by round
        for _ in range(self.round):
            self.timestamps = [[] for _ in range(self.stage_manager.num_stages)] if self.verbose else None
            self.action_interval_buffer.clear()
            while self.mb_manager.is_micro_batch_done() is False:
                actions = self._gen_one_stage_action(model)
                for action in actions:
                    action()
                self.mb_manager.next()
            # All microbatch in current round is DONE
            output_sequence.extend(self.mb_manager.export_new_tokens())

            self.mb_manager.clear()
            if self.verbose:
                whole_timestamp.extend(self.timestamps)

        return output_sequence, whole_timestamp

    @torch.no_grad()
    def generate_step_p2p(self, model: Module, data_iter: Iterable) -> Union[torch.Tensor, dict]:
        """
        Forward one step of the pipeline, when pipeline size is 2, the schedule is a circle, broadcast communication will be
        blocked, so we use `P2POp` asynchronous communication method.

        Args:
            model (Module): Model to be run.
            data_iter (Iterable): Data iterator.

        Returns:
            Union[torch.Tensor, dict]: The intermediate output (dict) of the current stage. If it is the last stage, the output is the loss (Tensor).
        """
        output_sequence = []
        self.load_batch(data_iter)
        model.eval()
        self.comm_dtype = model.dtype

        whole_timestamp = []

        # run by round
        for _ in range(self.round):
            self.timestamps = (
                [[] for _ in range(self.stage_manager.num_stages)]
                if self.verbose and self.stage_manager.is_first_stage()
                else None
            )
            self.action_interval_buffer.clear()
            while self.mb_manager.is_micro_batch_done() is False:
                actions = self._gen_action(model)
                for action in actions:
                    action()
                self.mb_manager.next()
            # All microbatch in current round is DONE
            if self.stage_manager.is_first_stage():
                output_sequence.extend(self.mb_manager.export_new_tokens())
            else:
                self._comm_action(False)
            self.mb_manager.clear()
            if self.verbose and self.stage_manager.is_first_stage():
                whole_timestamp.extend(self.timestamps)

        return output_sequence, whole_timestamp

    @torch.no_grad()
    def generate_step_broadcast(self, model: Module, data_iter: Iterable) -> Union[torch.Tensor, dict]:
        """
        Forward one step of the pipeline

        Args:
            model (Module): Model to be run.
            data_iter (Iterable): Data iterator.

        Returns:
            Union[torch.Tensor, dict]: The intermediate output (dict) of the current stage. If it is the last stage, the output is the loss (Tensor).
        """
        output_sequence = []
        self.load_batch(data_iter)
        model.eval()

        whole_timestamp = []
        # run by round
        for _ in range(self.round):
            self.timestamps = (
                [[] for _ in range(self.stage_manager.num_stages)]
                if self.verbose and self.stage_manager.is_first_stage()
                else None
            )
            while self.mb_manager.is_micro_batch_done() is False:
                inputs_dict = None
                new_token = None
                output_dict = None

                # First stage and in PREFILL phase, just load the inputs
                if self.stage_manager.is_first_stage() and self.mb_manager.cur_state is Status.PREFILL:
                    inputs_dict = self.load_micro_batch()
                    if self.verbose and self.stage_manager.is_first_stage():
                        torch.cuda.synchronize()
                        self.timestamps[self.mb_manager.idx].append(time.time())
                    self.mb_manager.add_description(inputs_dict)
                    interval_inputs = {"infer_state": self.mb_manager.cur_infer_state}
                    output_dict = model_forward(model, inputs_dict, interval_inputs)
                # In GENERATE phase
                else:
                    # Get hidden_states from previous stage
                    hidden_states = self.comm.recv_forward()
                    if self.stage_manager.is_first_stage():
                        # First just generate a new token
                        assert (
                            hidden_states is not None
                        ), "When first stage in GENERATE phase, the hidden states should not be None"
                        interval_inputs = {
                            "hidden_states": hidden_states["hidden_states"],
                            "infer_state": self.mb_manager.cur_infer_state,
                        }
                        logits = model_forward(model, None, interval_inputs)
                        if self.verbose and self.stage_manager.is_first_stage():
                            torch.cuda.synchronize()
                            self.timestamps[self.mb_manager.idx].append(time.time())
                        assert (
                            "logits" in logits
                        ), f"When first stage in GENERATE phase, the ouput should have attribute `logits`, but has {logits.keys()}"
                        new_token = self._get_token_id(logits["logits"])
                        self.mb_manager.step(new_token)
                        # If the current micro batch is not DONE, go through blocks
                        if self.mb_manager.cur_state in (Status.GENERATE, Status.COOLDOWN):
                            inputs_dict = self._prepare_inputs_for_new_token(new_token)
                            interval_inputs = {"infer_state": self.mb_manager.cur_infer_state}
                            output_dict = model_forward(model, inputs_dict, interval_inputs)
                    else:
                        assert hidden_states is not None, "When not first stage, the hidden states should not be None"
                        # inputs_dict = self._prepare_inputs_for_interval_stage()
                        inputs_dict = None
                        if self.mb_manager.cur_state is Status.PREFILL:
                            inputs_dict = self.load_micro_batch()
                            self.mb_manager.add_description(inputs_dict)
                        interval_inputs = {
                            "hidden_states": hidden_states["hidden_states"],
                            "infer_state": self.mb_manager.cur_infer_state,
                        }
                        output_dict = model_forward(model, inputs_dict, interval_inputs)

                # Current microbatch is not DONE, send hidden_state to next stage
                if not self.stage_manager.is_first_stage() or self.mb_manager.cur_state in (
                    Status.GENERATE,
                    Status.COOLDOWN,
                ):
                    self.comm.send_forward({"hidden_states": output_dict["hidden_states"]})

                self.mb_manager.next()

            # All microbatch in current round is DONE
            if self.stage_manager.is_first_stage():
                output_sequence.extend(self.mb_manager.export_new_tokens())
            self.mb_manager.clear()
            if self.verbose and self.stage_manager.is_first_stage():
                whole_timestamp.extend(self.timestamps)

        return output_sequence, whole_timestamp
