from typing import Union

import torch
import torch.distributed as dist
import torch.nn as nn
from transformers.tokenization_utils_base import BatchEncoding
from transformers.utils import logging

from colossalai.cluster import ProcessGroupMesh
from colossalai.pipeline.schedule.generate import GenerateSchedule
from colossalai.pipeline.stage_manager import PipelineStageManager
from colossalai.shardformer import ShardConfig, ShardFormer
from colossalai.shardformer.policies.base_policy import Policy

from ..kv_cache import MemoryManager
from .microbatch_manager import MicroBatchManager
from .policies import model_policy_map

PP_AXIS, TP_AXIS = 0, 1

_supported_models = [
    "LlamaForCausalLM",
    "BloomForCausalLM",
    "LlamaGPTQForCausalLM",
    "SmoothLlamaForCausalLM",
    "ChatGLMForConditionalGeneration",
]


class CaiInferEngine:
    """
    CaiInferEngine is a class that handles the pipeline parallel inference.

    Args:
        tp_size (int): the size of tensor parallelism.
        pp_size (int): the size of pipeline parallelism.
        model (`nn.Module`): the model not in pipeline style, and will be modified with `ShardFormer`.
        model_policy (`colossalai.shardformer.policies.base_policy.Policy`): the policy to shardformer model.
        micro_batch_size (int): the micro batch size.
        micro_batch_buffer_size (int): the buffer size for micro batch. Normally, it should be the same as the number of pipeline stages.
        max_batch_size (int): the maximum batch size.
        max_input_len (int): the maximum input length.
        max_output_len (int): the maximum output length.

    Example:

    ```python
    from colossalai.inference import InferEngine
    from colossalai.inference.pipeline.policies import LlamaModelInferPolicy
    import colossalai
    from transformers import LlamaForCausalLM, LlamaTokenizer

    colossalai.launch_from_torch(config={})

    model = LlamaForCausalLM.from_pretrained("your_path_to_model")
    tokenizer = LlamaTokenizer.from_pretrained("/home/lczyh/share/models/llama-7b-hf")
    # assume the model is infered with 2 pipeline stages
    inferengine = CaiInferEngine(pp_size=2, model=model, model_policy=LlamaModelInferPolicy())

    input = ["Introduce a landmark in China ","Introduce a landmark in China "]
    data = tokenizer(input, return_tensors='pt')
    output = inferengine.inference([data.to('cuda').data])

    ```

    """

    def __init__(
        self,
        tp_size: int = 1,
        pp_size: int = 1,
        dtype: str = "fp16",
        model: nn.Module = None,
        model_policy: Policy = None,
        micro_batch_size: int = 1,
        micro_batch_buffer_size: int = None,
        max_batch_size: int = 4,
        max_input_len: int = 32,
        max_output_len: int = 32,
        quant: str = None,
        verbose: bool = False,
        # TODO: implement early_stopping, and various gerneration options
        early_stopping: bool = False,
        do_sample: bool = False,
        num_beams: int = 1,
    ) -> None:
        if quant == "gptq":
            from ..quant.gptq import GPTQManager

            self.gptq_manager = GPTQManager(model.quantize_config, max_input_len=max_input_len)
            model = model.model
        elif quant == "smoothquant":
            model = model.model

        assert model.__class__.__name__ in _supported_models, f"Model {model.__class__.__name__} is not supported."
        assert (
            tp_size * pp_size == dist.get_world_size()
        ), f"TP size({tp_size}) * PP size({pp_size}) should be equal to the global world size ({dist.get_world_size()})"
        assert model, "Model should be provided."
        assert dtype in ["fp16", "fp32", "bf16"], "dtype should be one of 'fp16', 'fp32', 'bf16'"

        assert max_batch_size <= 64, "Max batch size exceeds the constraint"
        assert max_input_len + max_output_len <= 4096, "Max length exceeds the constraint"
        assert quant in ["smoothquant", "gptq", None], "quant should be one of 'smoothquant', 'gptq'"
        self.pp_size = pp_size
        self.tp_size = tp_size
        self.quant = quant

        logger = logging.get_logger(__name__)
        if quant == "smoothquant" and dtype != "fp32":
            dtype = "fp32"
            logger.warning_once("Warning: smoothquant only support fp32 and int8 mix precision. set dtype to fp32")

        if dtype == "fp16":
            self.dtype = torch.float16
            model.half()
        elif dtype == "bf16":
            self.dtype = torch.bfloat16
            model.to(torch.bfloat16)
        else:
            self.dtype = torch.float32

        if model_policy is None:
            model_policy = model_policy_map[model.config.model_type]()

        # Init pg mesh
        pg_mesh = ProcessGroupMesh(pp_size, tp_size)

        stage_manager = PipelineStageManager(pg_mesh, PP_AXIS, True)
        self.cache_manager_list = [
            self._init_manager(model, max_batch_size, max_input_len, max_output_len)
            for _ in range(micro_batch_buffer_size or pp_size)
        ]
        self.mb_manager = MicroBatchManager(
            stage_manager.stage,
            micro_batch_size,
            micro_batch_buffer_size or pp_size,
            max_input_len,
            max_output_len,
            self.cache_manager_list,
        )
        self.verbose = verbose
        self.schedule = GenerateSchedule(stage_manager, self.mb_manager, verbose)

        self.model = self._shardformer(model, model_policy, stage_manager, pg_mesh.get_group_along_axis(TP_AXIS))
        if quant == "gptq":
            self.gptq_manager.post_init_gptq_buffer(self.model)

    def generate(self, input_list: Union[BatchEncoding, dict]):
        """
        Args:
            input_list (list): a list of input data, each element is a `BatchEncoding` or `dict`.

        Returns:
            out (list): a list of output data, each element is a list of token.
            timestamp (float): the time cost of the inference, only return when verbose is `True`.
        """
        assert isinstance(
            input_list, (BatchEncoding, dict)
        ), f"Only accept BatchEncoding or dict as input, but get {input_list.__class__.__name__}."
        if isinstance(input_list, BatchEncoding):
            input_list = input_list.data
        out, timestamp = self.schedule.generate_step(self.model, iter([input_list]))
        if self.verbose:
            return out, timestamp
        else:
            return out

    def _shardformer(self, model, model_policy, stage_manager, tp_group):
        shardconfig = ShardConfig(
            tensor_parallel_process_group=tp_group,
            pipeline_stage_manager=stage_manager,
            enable_tensor_parallelism=(self.tp_size > 1),
            enable_fused_normalization=False,
            enable_all_optimization=False,
            enable_flash_attention=False,
            enable_jit_fused=False,
            enable_sequence_parallelism=False,
            extra_kwargs={"quant": self.quant},
        )
        shardformer = ShardFormer(shard_config=shardconfig)
        shard_model, _ = shardformer.optimize(model, model_policy)
        return shard_model.cuda()

    def _init_manager(self, model, max_batch_size: int, max_input_len: int, max_output_len: int) -> None:
        max_total_token_num = max_batch_size * (max_input_len + max_output_len)
        if model.config.model_type == "llama":
            head_dim = model.config.hidden_size // model.config.num_attention_heads
            head_num = model.config.num_key_value_heads // self.tp_size
            num_hidden_layers = (
                model.config.num_hidden_layers
                if hasattr(model.config, "num_hidden_layers")
                else model.config.num_layers
            )
            layer_num = num_hidden_layers // self.pp_size
        elif model.config.model_type == "bloom":
            head_dim = model.config.hidden_size // model.config.n_head
            head_num = model.config.n_head // self.tp_size
            num_hidden_layers = model.config.n_layer
            layer_num = num_hidden_layers // self.pp_size
        elif model.config.model_type == "chatglm":
            head_dim = model.config.hidden_size // model.config.num_attention_heads
            if model.config.multi_query_attention:
                head_num = model.config.multi_query_group_num // self.tp_size
            else:
                head_num = model.config.num_attention_heads // self.tp_size
            num_hidden_layers = model.config.num_layers
            layer_num = num_hidden_layers // self.pp_size
        else:
            raise NotImplementedError("Only support llama, bloom and chatglm model.")

        if self.quant == "smoothquant":
            cache_manager = MemoryManager(max_total_token_num, torch.int8, head_num, head_dim, layer_num)
        else:
            cache_manager = MemoryManager(max_total_token_num, self.dtype, head_num, head_dim, layer_num)
        return cache_manager
