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

import logging
from typing import AsyncIterator

import torch
from sglang.srt.parser.conversation import chat_templates
from transformers import AutoImageProcessor, AutoModel, AutoTokenizer

import dynamo.nixl_connect as connect
from dynamo._core import Client, Component, Context
from dynamo.runtime import DistributedRuntime
from dynamo.sglang.args import Config
from dynamo.sglang.multimodal_utils import ImageLoader, encode_image_embeddings
from dynamo.sglang.protocol import SglangMultimodalRequest
from dynamo.sglang.request_handlers.handler_base import BaseWorkerHandler

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


class MultimodalEncodeWorkerHandler(BaseWorkerHandler):
    """
    Handler for multimodal encode worker component that processes images/videos
    and forwards them to the downstream worker.
    """

    def __init__(
        self,
        component: Component,
        config: Config,
        pd_worker_client: Client,
    ) -> None:
        super().__init__(component, engine=None, config=config)
        self.pd_worker_client = pd_worker_client
        self.model = config.server_args.model_path
        self.served_model_name = config.server_args.served_model_name

        self.image_loader = ImageLoader(cache_size=CACHE_SIZE_MAXIMUM)

        self.image_processor = AutoImageProcessor.from_pretrained(
            self.model, trust_remote_code=True
        )
        self.vision_model = AutoModel.from_pretrained(
            self.model,
            device_map="auto",
            torch_dtype=torch.float16,
            trust_remote_code=True,
        )

        # Load tokenizer to convert image token string to integer ID
        self.tokenizer = AutoTokenizer.from_pretrained(
            self.model, trust_remote_code=True
        )

        # Get image token string and handle it properly
        image_token_str = (
            chat_templates[getattr(config.server_args, "chat_template")]
            .copy()
            .image_token
        )

        # For Qwen2.5-VL, the image token might be multiple tokens
        if image_token_str == "<|vision_start|><|image_pad|><|vision_end|>":
            # These are likely the individual special tokens for Qwen2.5-VL
            image_pad_id = self.tokenizer.convert_tokens_to_ids("<|image_pad|>")

            # Use the image_pad token as the main image token
            self.image_token_id = image_pad_id
        else:
            # Fallback for other models
            self.image_token_id = self.tokenizer.convert_tokens_to_ids(image_token_str)

        self.min_workers = 1

    def cleanup(self):
        pass

    async def generate(
        self, request: SglangMultimodalRequest, context: Context
    ) -> AsyncIterator[str]:
        """
        Generate precomputed embeddings for multimodal input.

        Args:
            request: Multimodal request with image/video data.
            context: Context object for cancellation handling.
        """
        if not isinstance(request, SglangMultimodalRequest):
            if isinstance(request, str):
                request = SglangMultimodalRequest.model_validate_json(request)
            else:
                request = SglangMultimodalRequest.model_validate(request)

        # The following steps encode the requested image for SGLang:
        # 1. Open the image from the provided URL.
        # 2. Process the image using the processor (which handles tokenization).
        # 3. Extract input_ids and image data from processed result.
        # 4. Run the image through the vision model to get precomputed embeddings.
        # 5. Create SGLang-specific multimodal data format.
        # 6. Create a descriptor for the embeddings and send to downstream worker.

        try:
            if not request.multimodal_input.image_url:
                raise ValueError("image_url is required for the encode worker.")

            image = await self.image_loader.load_image(
                request.multimodal_input.image_url
            )

            image_embeds = self.image_processor(images=image, return_tensors="pt")
            precomputed_embeddings = encode_image_embeddings(
                model_name=self.served_model_name,
                image_embeds=image_embeds,
                vision_encoder=self.vision_model,
                projector=None,
            )

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

            # Store the image data info in the request for downstream
            request.image_grid_thw = image_grid_thw
            request.embeddings_shape = tuple(precomputed_embeddings.shape)

            # Replace the single image token with multiple image tokens based on embedding shape
            image_token_id_index = request.request.token_ids.index(self.image_token_id)

            num_image_tokens = precomputed_embeddings.shape[
                1
            ]  # Number of image patches
            # Replace single image token with multiple image tokens
            request.request.token_ids = (
                request.request.token_ids[:image_token_id_index]
                + [self.image_token_id] * num_image_tokens
                + request.request.token_ids[
                    image_token_id_index + 1 :
                ]  # Skip the original token
            )

            # Create descriptor for the multimodal data
            descriptor = connect.Descriptor(precomputed_embeddings)

            with await self._connector.create_readable(descriptor) as readable:
                request.serialized_request = readable.metadata()

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

                # Get the response generator from downstream worker
                response_generator = await self.pd_worker_client.round_robin(
                    request.model_dump_json()
                )
                await readable.wait_for_completion()

                async for response in response_generator:
                    yield response.data() if hasattr(response, "data") else str(
                        response
                    )

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

    async def async_init(self, runtime: DistributedRuntime):
        logger.info("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("Startup completed.")
