import dataclasses
from enum import auto, Enum
from typing import List, Any

import torch
from PIL import Image
from transformers import StoppingCriteria, StoppingCriteriaList

from imagebind.models.image_bind import ModalityType


class SeparatorStyle(Enum):
    """Different separator style."""
    SINGLE = auto()
    TWO = auto()


@dataclasses.dataclass
class Conversation:
    """A class that keeps all conversation history."""
    system: str
    roles: List[str]
    messages: List[List[str]]
    offset: int
    # system_img: List[Image.Image] = []
    sep_style: SeparatorStyle = SeparatorStyle.SINGLE
    sep: str = "###"
    sep2: str = None

    skip_next: bool = False
    conv_id: Any = None

    def get_prompt(self):
        if self.sep_style == SeparatorStyle.SINGLE:
            ret = self.system + self.sep
            for role, message in self.messages:
                if message:
                    ret += role + ": " + message + self.sep
                else:
                    ret += role + ":"
            return ret
        elif self.sep_style == SeparatorStyle.TWO:
            seps = [self.sep, self.sep2]
            ret = self.system + seps[0]
            for i, (role, message) in enumerate(self.messages):
                if message:
                    ret += role + ": " + message + seps[i % 2]
                else:
                    ret += role + ":"
            return ret
        else:
            raise ValueError(f"Invalid style: {self.sep_style}")

    def append_message(self, role, message):
        self.messages.append([role, message])

    def to_gradio_chatbot(self):
        ret = []
        for i, (role, msg) in enumerate(self.messages[self.offset:]):
            if i % 2 == 0:
                ret.append([msg, None])
            else:
                ret[-1][-1] = msg
        return ret

    def copy(self):
        return Conversation(
            system=self.system,
            # system_img=self.system_img,
            roles=self.roles,
            messages=[[x, y] for x, y in self.messages],
            offset=self.offset,
            sep_style=self.sep_style,
            sep=self.sep,
            sep2=self.sep2,
            conv_id=self.conv_id)

    def dict(self):
        return {
            "system": self.system,
            # "system_img": self.system_img,
            "roles": self.roles,
            "messages": self.messages,
            "offset": self.offset,
            "sep": self.sep,
            "sep2": self.sep2,
            "conv_id": self.conv_id,
        }


class StoppingCriteriaSub(StoppingCriteria):

    def __init__(self, stops=[], encounters=1):
        super().__init__()
        self.stops = stops

    def __call__(self, input_ids: torch.LongTensor, scores: torch.FloatTensor):
        for stop in self.stops:
            if torch.all((stop == input_ids[0][-len(stop):])).item():
                return True

        return False


CONV_VISION = Conversation(
    system="Give the following image: <Vision>ImageContent</Vision>. "
           "You will be able to see the image once I provide it to you. Please answer my questions.",
    roles=("Human", "Assistant"),
    messages=[],
    offset=2,
    sep_style=SeparatorStyle.SINGLE,
    sep="###",
)

# TODO: If needed and possible, rewrite this file and re-organize the definition of components.


class Chat:
    def __init__(self, model, vis_processor, device='cuda:0'):
        self.device = device
        self.model = model
        self.vis_processor = vis_processor
        stop_words_ids = [torch.tensor([835]).to(self.device),
                          torch.tensor([2277, 29937]).to(self.device)]  # '###' can be encoded in two different ways.
        self.stopping_criteria = StoppingCriteriaList([StoppingCriteriaSub(stops=stop_words_ids)])

    def ask(self, text, conv):
        # NOTE: the hard code for postfix is removed.
        # TODO: Need to be compatible with more modalities.
        end_token = '</Vision>'
        if len(conv.messages) > 0 and conv.messages[-1][0] == conv.roles[0] \
                and conv.messages[-1][1][-len(end_token):] == end_token:  # last message is image.
            conv.messages[-1][1] = ' '.join([conv.messages[-1][1], text])
        else:
            conv.append_message(conv.roles[0], text)

    def answer(self, conv, img_list, max_new_tokens=300, num_beams=1, min_length=1, top_p=0.9,
               repetition_penalty=1.0, length_penalty=1, temperature=1.0, max_length=2000):
        # Generate an answer written by LLaMA
        conv.append_message(conv.roles[1], None)
        embs = self.get_context_emb(conv, img_list)

        current_max_len = embs.shape[1] + max_new_tokens
        if current_max_len - max_length > 0:
            print('Warning: The number of tokens in current conversation exceeds the max length. '
                  'The model will not see the contexts outside the range.')
        begin_idx = max(0, current_max_len - max_length)

        embs = embs[:, begin_idx:]

        outputs = self.model.llama_model.generate(
            inputs_embeds=embs,
            max_new_tokens=max_new_tokens,
            stopping_criteria=self.stopping_criteria,
            num_beams=num_beams,
            do_sample=True,
            min_length=min_length,
            top_p=top_p,
            repetition_penalty=repetition_penalty,
            length_penalty=length_penalty,
            temperature=temperature,
        )
        output_token = outputs[0]
        if output_token[0] == 0:  # the model might output a unknown token <unk> at the beginning. remove it
            output_token = output_token[1:]
        if output_token[0] == 1:  # some users find that there is a start token <s> at the beginning. remove it
            output_token = output_token[1:]
        output_text = self.model.llama_tokenizer.decode(output_token, add_special_tokens=False)
        output_text = output_text.split('###')[0]  # remove the stop sign '###'
        output_text = output_text.split('Assistant:')[-1].strip()
        conv.messages[-1][1] = output_text
        return output_text, output_token.cpu().numpy()

    def upload_img(self, image, conv, img_list):
        # Upload Image, Encode Image and Create a new message from human.
        if isinstance(image, str):  # is a image path
            raw_image = Image.open(image).convert('RGB')
            image = self.vis_processor(raw_image).unsqueeze(0).to(self.device)
        elif isinstance(image, Image.Image):
            raw_image = image
            image = self.vis_processor(raw_image).unsqueeze(0).to(self.device)
        elif isinstance(image, torch.Tensor):
            if len(image.shape) == 3:
                image = image.unsqueeze(0)
            image = image.to(self.device)

        all_embeddings = self.model.encode_inputs({ModalityType.VISION: image})
        image_emb = all_embeddings[ModalityType.VISION]
        img_list.append(image_emb)
        conv.append_message(conv.roles[0], "<Vision><VisionHere></Vision>")
        msg = "Received."
        # self.conv.append_message(self.conv.roles[1], msg)
        return msg

    def get_context_emb(self, conv, img_list):
        # Insert the image embeddings into the prompts and queries. Note that the img_list: List[Tensor]
        prompt = conv.get_prompt()
        prompt_segs = prompt.split('<VisionHere>')
        assert len(prompt_segs) == len(img_list) + 1, "Unmatched numbers of image placeholders and images."
        seg_tokens = [
            self.model.llama_tokenizer(
                seg, return_tensors="pt", add_special_tokens=i == 0).to(self.device).input_ids
            # only add bos to the first seg
            for i, seg in enumerate(prompt_segs)
        ]
        seg_embs = [self.model.llama_model.model.embed_tokens(seg_t) for seg_t in seg_tokens]
        mixed_embs = [emb for pair in zip(seg_embs[:-1], img_list) for emb in pair] + [seg_embs[-1]]
        mixed_embs = torch.cat(mixed_embs, dim=1)
        return mixed_embs