# SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0

import asyncio
import logging
import os
import shutil
import tempfile
import time
from dataclasses import dataclass
from typing import AsyncGenerator, AsyncIterator

import safetensors
import torch
from transformers import AutoImageProcessor
from vllm.engine.arg_utils import AsyncEngineArgs
from vllm.inputs import TokensPrompt
from vllm.multimodal.hasher import MultiModalHasher
from vllm.sampling_params import SamplingParams

import dynamo.nixl_connect as connect
from dynamo.runtime import Client, DistributedRuntime

from ..multimodal_utils import (
    ImageLoader,
    VLLMNativeEncoderRequest,
    VLLMNativeEncoderResponse,
    encode_image_embeddings,
    get_encoder_components,
    load_vision_model,
    vLLMMultimodalRequest,
)
from ..multimodal_utils.embedding_cache import EmbeddingCache
from ..multimodal_utils.model import is_qwen_vl_model

logger = logging.getLogger(__name__)

try:
    import cupy as array_module

    if not array_module.cuda.is_available():
        raise ImportError("CUDA is not available.")
    DEVICE = "cuda"
    logger.info("Using cupy for array operations (GPU mode).")
except ImportError as e:
    logger.warning(f"Failed to import cupy, falling back to numpy: {e}.")
    import numpy as array_module

    DEVICE = "cpu"

CACHE_SIZE_MAXIMUM = 8

TRANSFER_LOCAL = int(os.getenv("TRANSFER_LOCAL", 1))


@dataclass
class EmbeddingItem:
    key: str
    image_grid_thw: list
    embeddings_cpu: torch.Tensor


class EncodeWorkerHandler:
    def __init__(
        self,
        engine_args: AsyncEngineArgs,
        pd_worker_client: Client,
    ) -> None:
        self.pd_worker_client = pd_worker_client
        self.engine_args = engine_args
        self.model = self.engine_args.model

        self.image_loader = ImageLoader(cache_size=CACHE_SIZE_MAXIMUM)
        self.image_processor = AutoImageProcessor.from_pretrained(
            self.model, trust_remote_code=True
        )
        self.vision_model = load_vision_model(self.model)
        self.min_workers = 1

        # Get encoder components for the model
        self.vision_encoder, self.projector = get_encoder_components(
            self.model, self.vision_model
        )
        self._connector = None
        self._accumulated_time = 0.0
        self._processed_requests = 0
        self.readables = []
        self.embedding_cache = EmbeddingCache()

        # Use system temp directory for encoder cache files
        self._cache_dir = os.path.join(tempfile.gettempdir(), "encoder_cache")
        os.makedirs(self._cache_dir, exist_ok=True)

    def cleanup(self):
        pass

    async def async_init(self, runtime: DistributedRuntime):
        """Initialize the connector for RDMA transfers"""
        logger.info("Encode worker startup started.")
        # Create and initialize a dynamo connector for this worker.
        # We'll needs this to move data between this worker and remote workers efficiently.
        self._connector = connect.Connector()
        logger.info("Encode worker startup completed.")

    async def generate(
        self, request: vLLMMultimodalRequest, context
    ) -> AsyncIterator[str]:
        logger.debug(f"Got raw request: {request}")
        if not isinstance(request, vLLMMultimodalRequest):
            if isinstance(request, str):
                request = vLLMMultimodalRequest.model_validate_json(request)
            else:
                request = vLLMMultimodalRequest.model_validate(request)
        logger.debug(f"Received encode request: {{ id: {request.request_id} }}.")

        request_id = request.request_id

        # The following steps encode the requested image and provided useful embeddings.
        # 1. Open the image from the provided URL.
        # 2. Process the image using the image processor.
        # 3. Run the image through the vision model's vision tower.
        # 4. Run the results of the vision tower through the multi-modal projector.
        # 5. Create a descriptor for the embeddings.
        # 6. Create a write operation using the serialized request and the descriptor.
        # 7. Await for the write operation to complete.
        # 8. Yield the encode response.

        try:
            time_start = time.perf_counter()
            # Before batch process images, check cache first
            need_encode_indexes = []
            embedding_lists = [None] * len(request.multimodal_inputs)
            for idx in range(len(request.multimodal_inputs)):
                if not request.multimodal_inputs[idx].multimodal_input.image_url:
                    raise ValueError("image_url is required for the encode worker.")

                image_url = request.multimodal_inputs[idx].multimodal_input.image_url
                # see if we have local cache
                embedding_key = self.embedding_cache.generate_hash_key(image_url)
                if self.embedding_cache.has_key(embedding_key):
                    (image_grid_thw, embeddings_cpu) = self.embedding_cache.get(
                        embedding_key
                    )
                    embedding_lists[idx] = EmbeddingItem(
                        embedding_key, image_grid_thw, embeddings_cpu
                    )
                # compute
                else:
                    # keep track of key to avoid recompute of it
                    need_encode_indexes.append((idx, embedding_key))

            # Load and generate image tensors
            image_futures = []
            image_to_load = []
            for idx, _ in need_encode_indexes:
                url = request.multimodal_inputs[idx].multimodal_input.image_url
                image_futures.append(self.image_loader.load_image(url))
                image_to_load.append(url)
            results = await asyncio.gather(*image_futures, return_exceptions=True)
            loaded_images = []
            collective_exceptions = ""
            for i, result in enumerate(results):
                if isinstance(result, Exception):
                    url = image_to_load[i]
                    logger.error(f"Failed to load image from {url[:80]}...: {result}")
                    collective_exceptions += (
                        f"Failed to load image from {url[:80]}...: {result}\n"
                    )
                    continue
                loaded_images.append(result)
            if collective_exceptions:
                raise ValueError(
                    f"Errors occurred during image loading:\n{collective_exceptions}"
                )

            if loaded_images:
                image_embeds = self.image_processor(
                    images=loaded_images, return_tensors="pt"
                )

                # Encode the image embeddings using model-specific encoder
                embeddings = await asyncio.to_thread(
                    encode_image_embeddings,
                    model_name=self.model,
                    image_embeds=image_embeds,
                    vision_encoder=self.vision_encoder,
                    projector=self.projector,
                )

                # [gluo FIXME] This is specific to qwen vision processing..
                # Split concatenated embeddings for each image item.
                if is_qwen_vl_model(self.model):
                    merge_size = self.vision_encoder.spatial_merge_size
                    sizes = (
                        image_embeds["image_grid_thw"].prod(-1)
                        // merge_size
                        // merge_size
                    ).tolist()
                    splitted_embeddings = embeddings.cpu().squeeze(0).split(sizes)
                    logger.debug(
                        f"Splitted embeddings lengths: {[e.shape for e in splitted_embeddings]}"
                    )
                else:
                    # Validated on llava (NOTE need to double check on other models) that the
                    # embeddings already has batch dimension for images, so we can directly
                    # split by batch dimension
                    logger.debug(f"image embedding shape: {embeddings.shape}")
                    splitted_embeddings = embeddings.cpu()

                image_grid_thw = (
                    image_embeds["image_grid_thw"].tolist()
                    if "image_grid_thw" in image_embeds
                    else None
                )

            # fill in the embedding_lists with new computed embeddings and cache them
            for split_idx, (list_idx, key) in enumerate(need_encode_indexes):
                embedding_lists[list_idx] = EmbeddingItem(
                    key,
                    [image_grid_thw[split_idx]] if image_grid_thw else None,
                    splitted_embeddings[split_idx].unsqueeze(0),
                )
                # Cache the computed value for future use
                self.embedding_cache.set(
                    embedding_lists[list_idx].key,
                    (
                        embedding_lists[list_idx].image_grid_thw,
                        embedding_lists[list_idx].embeddings_cpu,
                    ),
                )

            for idx, embedding_item in enumerate(embedding_lists):
                # Update request for transfer metadata
                request.multimodal_inputs[idx].multimodal_input.image_url = None
                request.multimodal_inputs[
                    idx
                ].image_grid_thw = embedding_item.image_grid_thw
                request.multimodal_inputs[idx].embeddings_shape = tuple(
                    embedding_item.embeddings_cpu.shape
                )

                # Prepare transfer
                if TRANSFER_LOCAL:
                    logger.debug(
                        f"ENCODER: saving local safetensors file with key {embedding_item.key}, {embedding_item.embeddings_cpu.numel()} * {embedding_item.embeddings_cpu.element_size()} bytes"
                    )
                    tensors = {"ec_cache": embedding_item.embeddings_cpu}
                    cache_path = os.path.join(
                        self._cache_dir, f"{embedding_item.key}.safetensors"
                    )
                    safetensors.torch.save_file(tensors, cache_path)
                    # [gluo FIXME] need mechanism to clean up local files
                    request.multimodal_inputs[idx].serialized_request = cache_path
                else:
                    descriptor = connect.Descriptor(embedding_item.embeddings_cpu)
                    self.readables.append(
                        await self._connector.create_readable(descriptor)
                    )
                    request.multimodal_inputs[idx].serialized_request = self.readables[
                        -1
                    ].metadata()

            logger.debug(f"Request: {request.model_dump_json()}")

            time_end = time.perf_counter()
            self._accumulated_time += time_end - time_start
            self._processed_requests += 1
            logger.debug(
                f"Encoded image(s) for request {{ id: {request_id} }} in {time_end - time_start:.4f} seconds. "
                f"Average encoding time: {self._accumulated_time / self._processed_requests:.4f} seconds over {self._processed_requests} requests."
            )

            # Yield transformed request back
            yield request.model_dump_json()

        except Exception as e:
            logger.error(f"Error processing request {request_id}: {e}")
            raise


class VLLMEncodeWorkerHandler:
    """
    Handler for vLLM-native encoder worker using ECConnector.
    """

    def __init__(self, runtime, component, engine_client, config):
        """
        Initialize the handler.

        Args:
            runtime: Dynamo distributed runtime
            component: Dynamo component instance
            engine_client: vLLM AsyncLLM instance
            config: Dynamo Config object with CLI arguments
        """
        self.runtime = runtime
        self.component = component
        self.engine_client = engine_client
        self.config = config
        self.temp_dirs = []
        self.image_loader = ImageLoader()

        logger.info(
            f"VLLMNativeEncoderWorkerHandler initialized with "
            f"backend={config.ec_connector_backend}, "
            f"storage_path={config.ec_storage_path}"
        )

    def add_temp_dir(self, temp_dir):
        """Add temporary directory for cleanup."""
        if temp_dir:
            self.temp_dirs.append(temp_dir)

    async def generate(self, request, context) -> AsyncGenerator[str, None]:
        """
        Process encoder request and trigger vLLM encoder execution.

        Args:
            request: VLLMNativeEncoderRequest with multimodal_inputs (list of MultiModalGroup)
            context: Request context from Dynamo runtime

        Yields:
            JSON-encoded VLLMNativeEncoderResponse for each processed item
        """
        # Parse request
        if not isinstance(request, VLLMNativeEncoderRequest):
            if isinstance(request, str):
                request = VLLMNativeEncoderRequest.model_validate_json(request)
            else:
                request = VLLMNativeEncoderRequest.model_validate(request)

        if not request.multimodal_inputs:
            raise ValueError("No multimodal inputs provided in request")

        logger.info(
            f"Processing {len(request.multimodal_inputs)} multimodal item(s) "
            f"for request_id={request.request_id}"
        )

        # Load all images
        # TODO: support video and audio encoding later
        media_list = []
        modality = "image"
        for idx, mm_group in enumerate(request.multimodal_inputs):
            mm_input = mm_group.multimodal_input
            if mm_input.image_url:
                media = await self.image_loader.load_image(mm_input.image_url)
                media_list.append(media)
            elif mm_input.video_url:
                raise NotImplementedError("Video encoding not yet supported")
            else:
                raise ValueError(
                    f"No media URL provided in multimodal_input[{idx}]. "
                    "Specify image_url or video_url."
                )

        # Process all images in one vLLM request
        prompt_dict = TokensPrompt(
            prompt_token_ids=request.token_ids,
            multi_modal_data={"image": media_list},
        )

        try:
            gen = self.engine_client.generate(
                prompt=prompt_dict,
                sampling_params=SamplingParams(max_tokens=1, min_tokens=0),
                request_id=request.request_id,
            )

            # Consume generator to trigger encoder execution
            async for _ in gen:
                pass

            logger.info(
                f"[{request.request_id}] Encoder execution completed for all {len(media_list)} image(s)"
            )

        except Exception as e:
            logger.error(f"[{request.request_id}] Encoder execution failed: {e}")
            raise

        # Compute mm_hash for each image and yield responses
        for idx, media in enumerate(media_list):
            item_request_id = f"{request.request_id}_mm_{idx}"

            try:
                mm_hash = MultiModalHasher.hash_kwargs(
                    model_id=self.config.model, image=media
                )
                logger.debug(f"[{item_request_id}] Computed mm_hash: {mm_hash}")
            except Exception as e:
                logger.error(f"[{item_request_id}] Failed to compute mm_hash: {e}")
                raise

            response = VLLMNativeEncoderResponse(
                request_id=item_request_id,
                mm_hash=mm_hash,
                modality=modality,
                connector_metadata={
                    "ec_connector": self.config.ec_connector_backend,
                    "storage_path": self.config.ec_storage_path,
                },
            )

            logger.debug(f"[{item_request_id}] Returning response: {response}")
            yield response.model_dump_json()

        logger.info(
            f"All {len(request.multimodal_inputs)} multimodal items processed "
            f"for request_id={request.request_id}"
        )

    def cleanup(self):
        """Cleanup resources."""
        logger.info("Cleaning up VLLMNativeEncoderWorkerHandler")

        # Clean up temporary directories
        for temp_dir in self.temp_dirs:
            try:
                shutil.rmtree(temp_dir, ignore_errors=True)
                logger.debug(f"Cleaned up temp directory: {temp_dir}")
            except Exception as e:
                logger.warning(f"Failed to cleanup {temp_dir}: {e}")
