# Copyright 2023-2024 SGLang Team
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================

import logging
from typing import Iterable, Optional, Tuple

import torch
from torch import nn
from transformers import PretrainedConfig

from sglang.srt.distributed import get_tensor_model_parallel_world_size
from sglang.srt.eplb.expert_distribution import get_global_expert_distribution_recorder
from sglang.srt.layers.communicator import (
    LayerCommunicator,
    LayerScatterModes,
    enable_moe_dense_fully_dp,
)
from sglang.srt.layers.dp_attention import (
    get_attention_tp_rank,
    is_dp_attention_enabled,
)
from sglang.srt.layers.layernorm import RMSNorm
from sglang.srt.layers.logits_processor import LogitsProcessor
from sglang.srt.layers.quantization.base_config import QuantizationConfig
from sglang.srt.layers.vocab_parallel_embedding import (
    ParallelLMHead,
    VocabParallelEmbedding,
)
from sglang.srt.model_executor.forward_batch_info import ForwardBatch
from sglang.srt.model_loader.weight_utils import default_weight_loader
from sglang.srt.models.mimo_v2_flash import (
    MiMoV2Attention,
    MiMoV2FlashForCausalLM,
    MiMoV2MLP,
)
from sglang.srt.server_args import get_global_server_args
from sglang.srt.utils import add_prefix

MiMoV2FlashConfig = None

logger = logging.getLogger(__name__)


class MiMoV2MTPLayer(nn.Module):
    def __init__(
        self,
        config: MiMoV2FlashConfig,
        layer_id: int = 0,
        quant_config: Optional[QuantizationConfig] = None,
        prefix: str = "",
    ) -> None:
        super().__init__()
        self.config = config
        self.hidden_size = config.hidden_size

        rope_theta = getattr(config, "rope_theta", 1000000)
        rope_scaling = getattr(config, "rope_scaling", None)
        max_position_embeddings = getattr(config, "max_position_embeddings", 32768)

        self.self_attn = MiMoV2Attention(
            hidden_size=self.hidden_size,
            num_heads=config.swa_num_attention_heads,
            num_kv_heads=config.swa_num_key_value_heads,
            head_dim=config.swa_head_dim,
            v_head_dim=getattr(config, "swa_v_head_dim", None),
            v_scale=getattr(config, "attention_value_scale", None),
            sliding_window_size=config.sliding_window_size,
            attention_bias=config.attention_bias,
            attention_sink_bias=getattr(config, "add_swa_attention_sink_bias", False),
            layer_id=layer_id,
            rope_theta=getattr(config, "swa_rope_theta", rope_theta),
            rope_scaling=rope_scaling,
            max_position_embeddings=max_position_embeddings,
            quant_config=quant_config,
            partial_rotary_factor=getattr(config, "partial_rotary_factor", 1.0),
            prefix=add_prefix("self_attn", prefix),
        )
        self.is_layer_sparse = False
        is_previous_layer_sparse = True
        is_next_layer_sparse = False

        if enable_moe_dense_fully_dp():
            mlp_tp_rank, mlp_tp_size = 0, 1
        else:
            mlp_tp_rank, mlp_tp_size = None, None
        self.mlp = MiMoV2MLP(
            hidden_size=self.hidden_size,
            intermediate_size=config.intermediate_size,
            hidden_act=config.hidden_act,
            quant_config=quant_config,
            prefix=add_prefix("mlp", prefix),
            tp_rank=mlp_tp_rank,
            tp_size=mlp_tp_size,
        )
        self.input_layernorm = RMSNorm(config.hidden_size, eps=config.layernorm_epsilon)
        self.post_attention_layernorm = RMSNorm(
            config.hidden_size, eps=config.layernorm_epsilon
        )
        self.layer_scatter_modes = LayerScatterModes.init_new(
            layer_id=layer_id,
            num_layers=1,
            is_layer_sparse=self.is_layer_sparse,
            is_previous_layer_sparse=is_previous_layer_sparse,
            is_next_layer_sparse=is_next_layer_sparse,
        )
        self.layer_communicator = LayerCommunicator(
            layer_scatter_modes=self.layer_scatter_modes,
            input_layernorm=self.input_layernorm,
            post_attention_layernorm=self.post_attention_layernorm,
        )

    def forward(
        self,
        positions: torch.Tensor,
        hidden_states: torch.Tensor,
        forward_batch: ForwardBatch,
        residual: Optional[torch.Tensor],
    ) -> Tuple[torch.Tensor, torch.Tensor]:

        hidden_states, residual = self.layer_communicator.prepare_attn(
            hidden_states, residual, forward_batch
        )

        if hidden_states.shape[0] != 0:
            hidden_states = self.self_attn(
                positions=positions,
                hidden_states=hidden_states,
                forward_batch=forward_batch,
            )

        hidden_states, residual = self.layer_communicator.prepare_mlp(
            hidden_states, residual, forward_batch
        )
        with get_global_expert_distribution_recorder().disable_this_region():
            hidden_states = self.mlp(hidden_states)
        hidden_states, residual = self.layer_communicator.postprocess_layer(
            hidden_states, residual, forward_batch
        )

        return hidden_states, residual


class MiMoV2ModelNextN(nn.Module):
    def __init__(
        self,
        config: PretrainedConfig,
        quant_config: Optional[QuantizationConfig] = None,
        prefix: str = "",
    ) -> None:
        super().__init__()

        self.vocab_size = config.vocab_size

        self.embed_tokens = VocabParallelEmbedding(
            config.vocab_size,
            config.hidden_size,
            use_attn_tp_group=is_dp_attention_enabled(),
            prefix=add_prefix("embed_tokens", prefix),
        )

        self.enorm = RMSNorm(config.hidden_size, eps=config.layernorm_epsilon)
        self.hnorm = RMSNorm(config.hidden_size, eps=config.layernorm_epsilon)

        self.eh_proj = nn.Linear(2 * config.hidden_size, config.hidden_size, bias=False)

        self.mtp_block = MiMoV2MTPLayer(
            config,
            0,
            quant_config=quant_config,
            prefix=add_prefix("decoder", prefix),
        )
        self.final_layernorm = RMSNorm(config.hidden_size, eps=config.layernorm_epsilon)

    def forward(
        self,
        input_ids: torch.Tensor,
        positions: torch.Tensor,
        forward_batch: ForwardBatch,
        input_embeds: torch.Tensor = None,
    ) -> torch.Tensor:
        if input_embeds is None:
            hidden_states = self.embed_tokens(input_ids)
        else:
            hidden_states = input_embeds
        if hidden_states.shape[0] > 0:
            hidden_states = self.eh_proj(
                torch.cat(
                    (
                        self.enorm(hidden_states),
                        self.hnorm(forward_batch.spec_info.hidden_states),
                    ),
                    dim=-1,
                )
            )
        hidden_states, residual = self.mtp_block(
            positions=positions,
            hidden_states=hidden_states,
            forward_batch=forward_batch,
            residual=None,
        )
        hidden_states_before_norm = None
        if not forward_batch.forward_mode.is_idle():
            if forward_batch.return_hidden_states_before_norm:
                hidden_states_before_norm = (
                    hidden_states if residual is None else hidden_states + residual
                )
            if residual is not None:
                hidden_states, _ = self.final_layernorm(hidden_states, residual)
            else:
                hidden_states = self.final_layernorm(hidden_states)

        return hidden_states, hidden_states_before_norm


class MiMoV2MTP(MiMoV2FlashForCausalLM):

    def __init__(
        self,
        config: PretrainedConfig,
        quant_config: Optional[QuantizationConfig] = None,
        draft_model_idx: Optional[int] = None,
        prefix: str = "",
    ) -> None:
        nn.Module.__init__(self)
        self.config = config
        self.tp_size = get_tensor_model_parallel_world_size()
        self.quant_config = quant_config

        self.model = MiMoV2ModelNextN(
            config, quant_config, prefix=add_prefix("model", prefix)
        )
        self.lm_head = ParallelLMHead(
            config.vocab_size,
            config.hidden_size,
            quant_config=quant_config,
            prefix=add_prefix("lm_head", prefix),
            use_attn_tp_group=get_global_server_args().enable_dp_lm_head,
        )
        self.logits_processor = LogitsProcessor(config)

    @torch.no_grad()
    def forward(
        self,
        input_ids: torch.Tensor,
        positions: torch.Tensor,
        forward_batch: ForwardBatch,
    ) -> torch.Tensor:
        hidden_states, hidden_states_before_norm = self.model(
            input_ids, positions, forward_batch
        )
        return self.logits_processor(
            input_ids,
            hidden_states,
            self.lm_head,
            forward_batch,
            hidden_states_before_norm=hidden_states_before_norm,
        )

    def load_weights(self, weights: Iterable[Tuple[str, torch.Tensor]], is_nextn=False):
        stacked_params_mapping = [
            # (param_name, shard_name, shard_id)
            ("qkv_proj", "q_proj", "q"),
            ("qkv_proj", "k_proj", "k"),
            ("qkv_proj", "v_proj", "v"),
            ("gate_up_proj", "gate_proj", 0),
            ("gate_up_proj", "up_proj", 1),
        ]

        params_dict = dict(self.named_parameters())
        for name, loaded_weight in weights:
            if "rotary_emb.inv_freq" in name or "projector" in name:
                continue
            if "rotary_emb.cos_cached" in name or "rotary_emb.sin_cached" in name:
                # Models trained using ColossalAI may include these tensors in
                # the checkpoint. Skip them.
                continue
            if self.config.tie_word_embeddings and "lm_head.weight" in name:
                continue
            if name.startswith("model.vision_tower") and name not in params_dict:
                continue
            name = self.map_model_name_to_mtp_param_name(name)

            for param_name, weight_name, shard_id in stacked_params_mapping:

                if weight_name not in name:
                    continue
                if "mtp_block" not in name:
                    break
                name = name.replace(weight_name, param_name)
                # Skip loading extra bias for GPTQ models.
                if name.endswith(".bias") and name not in params_dict:
                    continue
                param = params_dict[name]
                weight_loader = param.weight_loader
                weight_loader(param, loaded_weight, shard_id)
                break
            else:
                # Skip loading extra bias for GPTQ models.
                if name.endswith(".bias") and name not in params_dict:
                    continue

                if "mtp_block" not in name and (
                    "embed_tokens" not in name
                    and "lm_head" not in name
                    and "enorm" not in name
                    and "hnorm" not in name
                    and "eh_proj" not in name
                    and "final_layernorm" not in name
                ):
                    continue
                if name in params_dict.keys():
                    param = params_dict[name]
                    if "attention_sink_bias" in name:
                        start = get_attention_tp_rank() * param.numel()
                        param.data.copy_(loaded_weight[start : start + param.numel()])
                    else:
                        weight_loader = getattr(
                            param, "weight_loader", default_weight_loader
                        )
                        weight_loader(param, loaded_weight)
                else:
                    logger.warning(f"Parameter {name} not found in params_dict")

    def map_model_name_to_mtp_param_name(self, name: str) -> str:
        import re

        if "pre_mlp_layernorm" in name:
            name = name.replace("pre_mlp_layernorm", "post_attention_layernorm")

        name_without_prefix = [
            "enorm",
            "hnorm",
            "eh_proj",
            "final_layernorm",
        ]
        pattern = r"model.mtp.layers.(\d+)."
        group = re.match(pattern, name)
        if group is not None:
            for sub_name in name_without_prefix:
                if sub_name in name:
                    name = name.replace(group.group(), "model.")
                    return name
            name = name.replace(group.group(), "model.mtp_block.")
        return name

    def get_embed_and_head(self):
        return self.model.embed_tokens.weight, self.lm_head.weight

    def set_embed_and_head(self, embed, head):
        del self.model.embed_tokens.weight
        del self.lm_head.weight
        self.model.embed_tokens.weight = embed
        self.lm_head.weight = head
        torch.cuda.empty_cache()
        torch.cuda.synchronize()


EntryClass = MiMoV2MTP