import concurrent
import concurrent.futures
import dataclasses
import multiprocessing as mp
import os
import re
from abc import ABC, abstractmethod
from enum import Enum
from typing import Any, Dict, List, Optional, Tuple, Union

import numpy as np
import torch
from PIL import Image
from transformers import BaseImageProcessorFast

from sglang.srt.managers.schedule_batch import Modality, MultimodalDataItem
from sglang.srt.utils import encode_video, load_audio, load_image


class MultimodalInputFormat(Enum):
    """Enum for different multimodal input formats."""

    RAW_IMAGES = "raw_images"
    PRECOMPUTED_FEATURES = "precomputed_features"
    PIXEL_VALUES = "pixel_values"
    AUDIO = "audio"


@dataclasses.dataclass
class BaseMultiModalProcessorOutput:
    # input_text, with each frame of video/image represented with a image_token
    input_text: str

    # frames loaded from image and video, in given order
    images: Optional[list[Union[Image.Image, dict]]] = None

    # audios
    audios: Optional[list[Union[np.ndarray, dict]]] = None

    def normalize(self):
        for field_name in ["images", "audios"]:
            field = getattr(self, field_name, None)
            if field is not None and isinstance(field, list) and len(field) == 0:
                setattr(self, field_name, None)


@dataclasses.dataclass
class MultimodalSpecialTokens:
    image_token: Optional[Union[int, str, List[str]]] = None
    video_token: Optional[Union[int, str, List[str]]] = None
    audio_token: Optional[Union[int, str, List[str]]] = None

    def convert_to_str(self, token: Union[str, int], processor) -> str:
        if token is None:
            return token
        if isinstance(token, str):
            return token
        return processor.tokenizer.convert_ids_to_tokens([token])[0]

    def convert_to_strs(self, processor):
        self.image_token = self.convert_to_str(self.image_token, processor)
        self.video_token = self.convert_to_str(self.video_token, processor)
        self.audio_token = self.convert_to_str(self.audio_token, processor)

    image_token_regex: Optional[re.Pattern] = None
    video_token_regex: Optional[re.Pattern] = None
    audio_token_regex: Optional[re.Pattern] = None

    def __post_init__(self):
        if self.image_token_regex is None and self.image_token is not None:
            self.image_token_regex = re.compile(re.escape(self.image_token))
        if self.video_token_regex is None and self.video_token is not None:
            self.video_token_regex = re.compile(re.escape(self.video_token))
        if self.audio_token_regex is None and self.audio_token is not None:
            self.audio_token_regex = re.compile(re.escape(self.audio_token))

    def collect(self) -> re.Pattern:
        tokens = [
            self.image_token_regex,
            self.video_token_regex,
            self.audio_token_regex,
        ]
        patterns = []
        flags = 0
        for t in tokens:
            if t is not None:
                patterns.append(t.pattern)
                flags |= t.flags
        combined = "(" + "|".join(f"(?:{p})" for p in patterns) + ")"
        return re.compile(combined, flags)


class BaseMultimodalProcessor(ABC):
    models = []

    def __init__(self, hf_config, server_args, _processor):
        self.hf_config = hf_config
        self._processor = _processor
        self.arch = hf_config.architectures[0]
        self.server_args = server_args
        # FIXME: not accurate, model and image specific
        self.NUM_TOKEN_PER_FRAME = 330

        self.io_executor = concurrent.futures.ThreadPoolExecutor(
            max_workers=int(os.environ.get("SGLANG_IO_WORKERS", 4))
        )
        self.cpu_executor = concurrent.futures.ProcessPoolExecutor(
            mp_context=mp.get_context("fork"),
            max_workers=int(os.environ.get("SGLANG_CPU_WORKERS", os.cpu_count())),
        )

    def process_mm_data(
        self, input_text, images=None, videos=None, audios=None, **kwargs
    ):
        """
        process multimodal data with transformers AutoProcessor
        """
        if images is not None:
            kwargs["images"] = images
        if videos is not None:
            kwargs["videos"] = videos
        if audios is not None:
            kwargs["audios"] = audios

        processor = self._processor
        if hasattr(processor, "image_processor") and isinstance(
            processor.image_processor, BaseImageProcessorFast
        ):
            kwargs["device"] = "cuda"
        result = processor.__call__(
            text=[input_text],
            padding=True,
            return_tensors="pt",
            **kwargs,
        )
        if "pixel_values" in result and isinstance(
            result["pixel_values"], torch.Tensor
        ):
            result["pixel_values"] = result["pixel_values"].to("cpu")
        return result

    @abstractmethod
    async def process_mm_data_async(
        self,
        image_data,
        input_text,
        request_obj,
        max_req_input_len,
        **kwargs,
    ) -> Optional[Dict[str, Any]]:
        pass

    def get_estimated_frames_list(self, image_data):
        """
        estimate the total frame count from all visual input
        """
        # Lazy import because decord is not available on some arm platforms.
        from decord import VideoReader, cpu

        # Before processing inputs
        if not image_data or len(image_data) == 0:
            return []
        estimated_frames_list = []
        for image in image_data:
            if isinstance(image, str) and image.startswith("video:"):
                path = image[len("video:") :]
                # Estimate frames for the video
                vr = VideoReader(path, ctx=cpu(0))
                num_frames = len(vr)
            else:
                # For images, each contributes one frame
                num_frames = 1
            estimated_frames_list.append(num_frames)

        return estimated_frames_list

    @staticmethod
    def _load_single_item(
        data, is_video, is_audio, frame_count_limit=None, discard_alpha_channel=True
    ):
        """Static method that can be pickled for multiprocessing"""
        if isinstance(data, dict):
            return data
        try:
            if is_audio:
                return load_audio(data)
            elif is_video:
                path = data[len("video:") :]
                return encode_video(path, frame_count_limit)
            else:
                img, _ = load_image(data)
                return img.convert("RGB") if discard_alpha_channel else img
        except Exception as e:
            raise RuntimeError(f"Error while loading data {data}: {e}")

    def submit_data_loading_tasks(
        self,
        text_parts: List[str],
        multimodal_tokens: MultimodalSpecialTokens,
        image_data: Optional[list] = None,
        audio_data: Optional[list] = None,
        discard_alpha_channel: bool = True,
    ):
        """
        load multimodal data parallelly
        """

        # TODO(mick): load from server_args, env, or sampling_params
        MAX_NUM_FRAMES = 30
        estimated_frames_list = self.get_estimated_frames_list(image_data=image_data)
        total_frame_count = sum(estimated_frames_list)
        # a heuristic value, suggesting the maximum fraction of frames to embed from all visual inputs.
        # e.g., 0.1 suggests that 1 frame out of 10 input frames should be used
        scaling_factor = min(1.0, MAX_NUM_FRAMES / max(1, total_frame_count))

        assert len(image_data) == len(estimated_frames_list)
        # Submit all tasks
        futures = []
        task_info = []
        image_index, audio_index = 0, 0

        for text_part in text_parts:
            if (
                multimodal_tokens.image_token_regex
                and multimodal_tokens.image_token_regex.match(text_part)
            ):
                data = image_data[image_index]
                is_video = isinstance(data, str) and data.startswith("video:")
                estimated_frames = estimated_frames_list[image_index]
                frame_count_limit = max(1, int(estimated_frames * scaling_factor))
                futures.append(
                    self.io_executor.submit(
                        BaseMultimodalProcessor._load_single_item,
                        data,
                        is_video,
                        False,
                        frame_count_limit,
                        discard_alpha_channel,
                    )
                )
                task_info.append((Modality.IMAGE, data, frame_count_limit))
                image_index += 1
            elif (
                multimodal_tokens.audio_token_regex
                and multimodal_tokens.audio_token_regex.match(text_part)
            ):
                data = audio_data[audio_index]
                futures.append(
                    self.io_executor.submit(
                        BaseMultimodalProcessor._load_single_item,
                        data,
                        False,
                        True,
                        None,
                        discard_alpha_channel,
                    )
                )
                task_info.append((Modality.AUDIO, data, None))
                audio_index += 1

        return futures, task_info

    def load_mm_data(
        self,
        prompt: str | List[int],
        multimodal_tokens: MultimodalSpecialTokens,
        max_req_input_len: int,
        image_data: Optional[list] = None,
        audio_data: Optional[list] = None,
        return_text: Optional[bool] = True,
        discard_alpha_channel: bool = True,
    ) -> BaseMultiModalProcessorOutput:
        """
        Each frame of video/image will be replaced by a single image token

        Args:
            multimodal_tokens (list[str]): list of special token which denoting a single multimodal data
                e.g. image token or audio token
            discard_alpha_channel: if True, discards the alpha channel in the returned images

        """
        if not return_text:
            raise NotImplementedError()
        if image_data is None:
            image_data = []

        multimodal_tokens.convert_to_strs(self._processor)
        multimodal_tokens_pattern = multimodal_tokens.collect()

        if isinstance(prompt, list) and return_text:
            assert len(prompt) and isinstance(prompt[0], int)
            prompt = self._processor.tokenizer.decode(prompt)
        else:
            prompt = prompt

        assert isinstance(prompt, str)
        # split text into list of normal text and special tokens
        text_parts = re.split(multimodal_tokens_pattern, prompt)

        futures, task_info = self.submit_data_loading_tasks(
            text_parts=text_parts,
            multimodal_tokens=multimodal_tokens,
            image_data=image_data,
            audio_data=audio_data,
            discard_alpha_channel=discard_alpha_channel,
        )
        # Process results
        images, audios = [], []
        new_text = ""
        task_ptr = 0

        for text_part in text_parts:
            if multimodal_tokens_pattern.match(text_part):
                task_type, data, frame_limit = task_info[task_ptr]
                result = futures[task_ptr].result()
                task_ptr += 1

                if task_type == Modality.IMAGE:
                    # If data is already processed it will be a
                    # dictionary. In this case we want to keep the
                    # expanded tokens in text_part. Otherwise, we will
                    # call the processor code, so keep only a single image
                    # token.
                    mm_tokens = (
                        text_part
                        if isinstance(data, dict)
                        else multimodal_tokens.image_token
                    )
                    frames = [result] if not isinstance(result, list) else result
                    if frames:
                        images += frames
                        new_text += mm_tokens * len(frames)
                elif task_type == Modality.AUDIO:
                    # audio
                    mm_tokens = (
                        text_part
                        if isinstance(data, dict)
                        else multimodal_tokens.audio_token
                    )
                    audios.append(result)
                    new_text += mm_tokens
                # TODO: handle video
            else:
                new_text += text_part

        out = BaseMultiModalProcessorOutput(
            input_text=new_text,
            images=images,
            audios=audios,
        )
        out.normalize()
        return out

    @staticmethod
    def get_mm_items_offset(
        input_ids: torch.Tensor, mm_token_id: int
    ) -> List[Tuple[int, int]]:
        """
        Get a set of range for mm_items from input_ids
        Example:
            input_ids = [1, 2, 3, 3, 3, 4, 3, 3]
            mm_token_id = 3
            return result = [(2,4),(6,7)]
        """
        mask = input_ids == mm_token_id

        start_positions = (mask & ~torch.roll(mask, 1)).nonzero(as_tuple=True)[0]
        end_positions = (mask & ~torch.roll(mask, -1)).nonzero(as_tuple=True)[0]

        return list(zip(start_positions.tolist(), end_positions.tolist()))

    @staticmethod
    def get_mm_items_offset_by_pair(
        input_ids: torch.Tensor, mm_start_id: int, mm_end_id: int
    ) -> List[Tuple[int, int]]:
        indices_start = (input_ids == mm_start_id).nonzero(as_tuple=True)[0] + 1
        indices_end = (input_ids == mm_end_id).nonzero(as_tuple=True)[0] - 1

        return list(zip(indices_start.tolist(), indices_end.tolist()))

    @staticmethod
    def _extract_processor_features(
        items: List[dict], attr_name: str
    ) -> Optional[torch.Tensor]:
        """
        Helper function to concat extracted attributes from processor output.
        """
        values = [value for item in items if (value := item.get(attr_name)) is not None]
        return torch.cat(values) if values else None

    # When we assume that all the items have the same attributes
    def _extract_processor_features_from_all_attributes(
        self, items: List[dict]
    ) -> dict:
        values = {}
        # Verify all items have the same keys
        first_keys = set(items[0].keys())
        for item in items[1:]:
            if set(item.keys()) != first_keys:
                raise ValueError(
                    f"All items must have the same attributes. "
                    f"First item has {first_keys}, but found {set(item.keys())}"
                )

        # Process each attribute
        for k, v in items[0].items():
            if isinstance(v, list):
                values[k] = self._extract_processor_features(items, k)
            else:
                # Verify all items have the same value for non-list attributes
                for item in items[1:]:
                    if item[k] != v:
                        raise ValueError(
                            f"All items must have the same value for attribute {k}. "
                            f"First item has {v}, but found {item[k]}"
                        )
                values[k] = v
        return values

    def process_and_combine_mm_data(
        self, base_output: BaseMultiModalProcessorOutput
    ) -> Tuple[Optional[MultimodalDataItem], torch.Tensor]:
        """
        Process multimodal data and return the combined multimodal item and input_ids.
        Handles all three input formats at the same abstraction level.

        Returns:
            Tuple of (combined_mm_item, input_ids)
        """

        def tokenize_text(input_text: str) -> torch.Tensor:
            """Tokenize input text."""
            return self._processor.tokenizer(
                input_text,
                return_tensors="pt",
                add_special_tokens=True,
            ).input_ids.flatten()

        def categorize_mm_inputs(mm_inputs: List) -> MultimodalInputFormat:
            """Categorize multimodal inputs and validate consistency."""
            try:
                has_image = False
                has_pixel_values = False
                has_precomputed_features = False
                has_audio = False

                for mm_input in mm_inputs:
                    if isinstance(mm_input, Image.Image):
                        has_image = True
                    elif isinstance(mm_input, np.ndarray):
                        has_audio = True
                    elif isinstance(mm_input, dict):
                        if mm_input.get("precomputed_features", None) is not None:
                            has_precomputed_features = True
                        elif mm_input.get("pixel_values", None) is not None:
                            has_pixel_values = True
                        else:
                            raise ValueError(
                                f"Invalid multimodal input: {mm_input}, expected dict with pixel_values or precomputed_features"
                            )
                    else:
                        raise ValueError(
                            f"Invalid multimodal input: {mm_input}, expected Image.Image or dict"
                        )

                # Validate format consistency
                format_count = sum(
                    [has_image, has_pixel_values, has_precomputed_features, has_audio]
                )
                if format_count > 1:
                    raise ValueError(
                        "Unsupported: mixture of multimodal input formats. "
                        f"Found formats: image={has_image}, pixel_values={has_pixel_values}, "
                        f"precomputed_features={has_precomputed_features}, audio={has_audio}"
                    )

                if has_image:
                    return MultimodalInputFormat.RAW_IMAGES
                elif has_precomputed_features:
                    return MultimodalInputFormat.PRECOMPUTED_FEATURES
                elif has_pixel_values:
                    return MultimodalInputFormat.PIXEL_VALUES
                elif has_audio:
                    return MultimodalInputFormat.AUDIO
                else:
                    raise ValueError("No valid multimodal input format found")
            except Exception as e:
                raise ValueError(f"Failed to categorize inputs: {e}")

        def process_raw_images(
            base_output: BaseMultiModalProcessorOutput,
        ) -> Tuple[MultimodalDataItem, torch.Tensor]:
            """Process raw Image.Image objects using transformers processor."""
            ret = self.process_mm_data(
                input_text=base_output.input_text,
                images=base_output.images,
            )
            combined_mm_item = MultimodalDataItem(modality=Modality.IMAGE)

            # Copy all fields from processor output except input_ids
            for key, value in ret.items():
                if key != "input_ids" and hasattr(combined_mm_item, key):
                    setattr(combined_mm_item, key, value)

            input_ids = ret["input_ids"].flatten()
            return combined_mm_item, input_ids

        def process_precomputed_features(
            base_output: BaseMultiModalProcessorOutput,
        ) -> Tuple[MultimodalDataItem, torch.Tensor]:
            """Process inputs with precomputed features."""
            combined_mm_item = MultimodalDataItem(modality=Modality.IMAGE)
            combined_mm_item.precomputed_features = self._extract_processor_features(
                base_output.images, "precomputed_features"
            )
            input_ids = tokenize_text(base_output.input_text)
            return combined_mm_item, input_ids

        def process_pixel_values(
            base_output: BaseMultiModalProcessorOutput,
        ) -> Tuple[MultimodalDataItem, torch.Tensor]:
            """Process inputs with pixel values."""
            values = self._extract_processor_features_from_all_attributes(
                base_output.images
            )
            combined_mm_item = MultimodalDataItem.from_dict(values)
            input_ids = tokenize_text(base_output.input_text)
            return combined_mm_item, input_ids

        def process_audio(
            base_output: BaseMultiModalProcessorOutput,
        ) -> Tuple[MultimodalDataItem, torch.Tensor]:
            """Process inputs with audio."""
            ret = self.process_mm_data(
                input_text=base_output.input_text,
                audio=base_output.audios,  # Note: "audio" is for gemma3n only
            )
            combined_mm_item = MultimodalDataItem(modality=Modality.AUDIO)
            for key, value in ret.items():
                if key != "input_ids" and hasattr(combined_mm_item, key):
                    setattr(combined_mm_item, key, value)
            input_ids = ret["input_ids"].flatten()
            return combined_mm_item, input_ids

        def finalize_mm_item(
            combined_mm_item: MultimodalDataItem, input_ids: torch.Tensor
        ) -> MultimodalDataItem:
            """Apply common post-processing to the multimodal item."""
            if combined_mm_item.modality in [Modality.IMAGE, Modality.MULTI_IMAGES]:
                combined_mm_item.image_offsets = self.get_mm_items_offset(
                    input_ids=input_ids,
                    mm_token_id=self.IM_TOKEN_ID,
                )
            elif combined_mm_item.modality == Modality.AUDIO:
                combined_mm_item.audio_offsets = self.get_mm_items_offset(
                    input_ids=input_ids,
                    mm_token_id=self.AUDIO_TOKEN_ID,
                )
            elif combined_mm_item.modality == Modality.VIDEO:
                combined_mm_item.video_offsets = self.get_mm_items_offset(
                    input_ids=input_ids,
                    mm_token_id=self.VIDEO_TOKEN_ID,
                )
            else:
                raise ValueError(f"Unknown modality: {combined_mm_item.modality}")
            return combined_mm_item

        # Main logic - determine input type and handle text-only case
        mm_inputs = base_output.images or base_output.audios
        if not mm_inputs:
            input_ids = tokenize_text(base_output.input_text)
            return None, input_ids

        # Categorize input formats
        input_format = categorize_mm_inputs(mm_inputs)

        # Process based on format
        if input_format == MultimodalInputFormat.RAW_IMAGES:
            combined_mm_item, input_ids = process_raw_images(base_output)
        elif input_format == MultimodalInputFormat.PRECOMPUTED_FEATURES:
            combined_mm_item, input_ids = process_precomputed_features(base_output)
        elif input_format == MultimodalInputFormat.PIXEL_VALUES:
            combined_mm_item, input_ids = process_pixel_values(base_output)
        elif input_format == MultimodalInputFormat.AUDIO:
            combined_mm_item, input_ids = process_audio(base_output)
        else:
            raise ValueError(f"Unknown input format: {input_format}")

        # Finalize with common processing
        combined_mm_item = finalize_mm_item(combined_mm_item, input_ids)
        return combined_mm_item, input_ids
