# Copyright 2024 Bytedance Ltd. and/or its affiliates
#
# 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.


from typing import List

from msgspec import field
from packaging import version as vs
from vllm.lora.models import LoRAModel
from vllm.lora.request import LoRARequest
from vllm.lora.utils import get_adapter_absolute_path
from vllm.lora.worker_manager import LRUCacheWorkerLoRAManager

from verl.third_party.vllm import get_version

# To support different vLLM versions, we add the model into SUPPORTED_MOE_MODELS separately to avoid triggering
# unsupported issues.
SUPPORTED_MOE_MODELS = []

try:
    from vllm.model_executor.models.deepseek_v2 import DeepseekV2ForCausalLM, DeepseekV3ForCausalLM

    SUPPORTED_MOE_MODELS.append(DeepseekV2ForCausalLM)
    SUPPORTED_MOE_MODELS.append(DeepseekV3ForCausalLM)
except ImportError:
    pass

try:
    from vllm.model_executor.models.mixtral import MixtralForCausalLM

    SUPPORTED_MOE_MODELS.append(MixtralForCausalLM)
except ImportError:
    pass

try:
    from vllm.model_executor.models.qwen2_moe import Qwen2MoeForCausalLM

    SUPPORTED_MOE_MODELS.append(Qwen2MoeForCausalLM)
except ImportError:
    pass

try:
    from vllm.model_executor.models.qwen3_moe import Qwen3MoeForCausalLM

    SUPPORTED_MOE_MODELS.append(Qwen3MoeForCausalLM)
except ImportError:
    pass

try:
    from vllm.model_executor.models.kimi_vl import KimiVLForConditionalGeneration

    SUPPORTED_MOE_MODELS.append(KimiVLForConditionalGeneration)
except ImportError:
    pass


def patch_vllm_moe_model_weight_loader(model):
    # this is a work around to load the weight of vllm fused moe model
    # it is from a bug from vllm 0.8.2
    # all the weights are supposed to have a weight_loader, but the moe weights
    # do not have a weight_loader, so we need to patch it
    # (True, 'model.embed_tokens.weight')
    # (True, 'model.layers.0.self_attn.qkv_proj.weight')
    # (True, 'model.layers.0.self_attn.qkv_proj.bias')
    # (True, 'model.layers.0.self_attn.o_proj.weight')
    # (True, 'model.layers.0.mlp.gate.weight')
    # (True, 'model.layers.0.mlp.shared_expert.gate_up_proj.weight')
    # (True, 'model.layers.0.mlp.shared_expert.down_proj.weight')
    # (False, 'model.layers.0.mlp.shared_expert_gate.weight')   use default
    # (False, 'model.layers.0.input_layernorm.weight')          use default
    # (False, 'model.layers.0.post_attention_layernorm.weight') use default
    # (False, 'model.layers.0.mlp.experts.w13_weight')          use mlp.experts.weight_loader
    # (False, 'model.layers.0.mlp.experts.w2_weight')          use mlp.experts.weight_loader

    # Define MLP attribute mapping for different model types
    MLP_ATTR_MAPPING = {
        MixtralForCausalLM: "block_sparse_moe",
    }
    DEFAULT_MLP_ATTR = "mlp"

    if not isinstance(model, tuple(SUPPORTED_MOE_MODELS)):
        return

    model = getattr(model, "model", None) or getattr(model, "language_model", None)
    if model is None:
        raise ValueError("The provided model does not have a valid 'model' or 'language_model' attribute.")

    for layer in model.layers:
        mlp_attr = MLP_ATTR_MAPPING.get(type(model), DEFAULT_MLP_ATTR)
        mlp = getattr(layer, mlp_attr)

        param_dict = dict(mlp.named_parameters())
        for name, param in param_dict.items():
            if "w13_weight" in name or "w2_weight" in name:
                param.weight_loader = mlp.experts.weight_loader


class TensorLoRARequest(LoRARequest):
    peft_config: dict = field(default=None)
    lora_tensors: dict = field(default=None)


class VLLMHijack:
    @staticmethod
    def hijack():
        def hijack__load_adapter(self, lora_request: TensorLoRARequest) -> LoRAModel:
            """
            based on vllm.lora.worker_manager.WorkerLoRAManager._load_adapter, support load adapter with lora tensors

            Reason:
            VLLM does not support adding LoRA from tensors directly. It only supports adding LoRA via file paths.
            To synchronize the LoRA tensors of the actor model, we need to find a workaround to enable VLLM to
            load memory-based LoRA tensors.
            """
            try:
                supported_lora_modules = self._adapter_manager.supported_lora_modules
                packed_modules_mapping = self._adapter_manager.packed_modules_mapping
                expected_lora_modules: List[str] = []
                for module in supported_lora_modules:
                    if module in packed_modules_mapping:
                        expected_lora_modules.extend(packed_modules_mapping[module])
                    else:
                        expected_lora_modules.append(module)

                expected_lora_modules = list(set(expected_lora_modules))

                lora_tensors = None
                from vllm.lora.peft_helper import PEFTHelper

                if isinstance(lora_request, TensorLoRARequest):
                    peft_config = lora_request.peft_config
                    lora_tensors = lora_request.lora_tensors
                    peft_helper = PEFTHelper.from_dict(peft_config)
                else:
                    lora_path = get_adapter_absolute_path(lora_request.lora_path)

                    peft_helper = PEFTHelper.from_local_dir(lora_path, self.max_position_embeddings)

                # Validates the LoRA configuration against requirements before
                # loading weights, throwing an exception if validation fails.
                peft_helper.validate_legal(self.lora_config)

                # For some models like Qwen2VL, we need to use hf_to_vllm_mapper
                # to ensure correct loading of lora weights.
                model = self._adapter_manager.model
                hf_to_vllm_mapper = None
                if hasattr(model, "hf_to_vllm_mapper") and model.hf_to_vllm_mapper is not None:
                    hf_to_vllm_mapper = model.hf_to_vllm_mapper

                if isinstance(lora_request, TensorLoRARequest):
                    lora = self._lora_model_cls.from_lora_tensors(
                        lora_model_id=lora_request.lora_int_id,
                        tensors=lora_tensors,
                        peft_helper=peft_helper,
                        device="cpu",
                        dtype=self.lora_config.lora_dtype,
                        embeddings=None,
                        target_embedding_padding=self.vocab_size + self.lora_config.lora_extra_vocab_size,
                        embedding_modules=self.embedding_modules,
                        embedding_padding_modules=self.embedding_padding_modules,
                        weights_mapper=hf_to_vllm_mapper,
                    )
                else:
                    lora = self._lora_model_cls.from_local_checkpoint(
                        lora_path,
                        expected_lora_modules,
                        peft_helper=peft_helper,
                        lora_model_id=lora_request.lora_int_id,
                        device="cpu",
                        dtype=self.lora_config.lora_dtype,
                        target_embedding_padding=self.vocab_size + self.lora_config.lora_extra_vocab_size,
                        embedding_modules=self.embedding_modules,
                        embedding_padding_modules=self.embedding_padding_modules,
                        weights_mapper=hf_to_vllm_mapper,
                    )
            except Exception as e:
                raise e

            if lora.extra_vocab_size > self.lora_config.lora_extra_vocab_size:
                raise ValueError(
                    f"LoRA added vocab size {lora.extra_vocab_size} is greater than lora_extra_vocab_size "
                    f"{self.lora_config.lora_extra_vocab_size}."
                )
            return lora

        def do_hijack(target_cls, target_method_name, hooking_method):
            setattr(target_cls, target_method_name, hooking_method)

        do_hijack(LRUCacheWorkerLoRAManager, "_load_adapter", hijack__load_adapter)


def is_version_ge(pkg: str = "vllm", minver: str = "0.7.3"):
    """check if the package version is greater than or equal to the minimum version"""
    return vs.parse(get_version(pkg)) >= vs.parse(minver)
