# coding=utf-8
import json
import os
from dataclasses import asdict, dataclass
from pathlib import Path
from typing import Any, Dict, List, Optional, Type, TypeVar, Union

from huggingface_hub import ModelHubMixin, hf_hub_download

# Generic variable that is either ModelHubMixin or a subclass thereof
T = TypeVar("T", bound="ModelHubMixin")

TEMPLATE_FILENAME = "dialogue_template.json"
IGNORE_INDEX = -100


@dataclass
class DialogueTemplate(ModelHubMixin):
    """Converts all turns of a dialogue between a user and assistant to a standardized format."""

    system: str
    messages: List[Dict[str, str]] = None
    system_token: str = "<|system|>"
    user_token: str = "<|user|>"
    assistant_token: str = "<|assistant|>"
    end_token: str = "<|end|>"

    def __post_init__(self):
        """Ensure that messages is never None."""
        if self.messages is None:
            self.messages = []

    def get_training_prompt(self) -> str:
        if len(self.messages) == 0:
            raise ValueError("Dialogue template must have at least one message.")
        prompt = self.system_token + "\n" + self.system + self.end_token + "\n"
        for message in self.messages:
            if message["role"] == "user":
                prompt += self.user_token + "\n" + message["content"] + self.end_token + "\n"
            else:
                prompt += self.assistant_token + "\n" + message["content"] + self.end_token + "\n"
        return prompt

    def get_inference_prompt(self) -> str:
        if len(self.messages) == 0:
            raise ValueError("Dialogue template must have at least one message.")
        prompt = self.system_token + "\n" + self.system + self.end_token + "\n"
        for message in self.messages:
            if message["role"] == "user":
                prompt += self.user_token + "\n" + message["content"] + self.end_token + "\n"
            else:
                prompt += self.assistant_token + "\n" + message["content"] + self.end_token + "\n"
        prompt += self.assistant_token + "\n"
        return prompt

    def get_dialogue(self):
        if len(self.messages) == 0:
            raise ValueError("Dialogue template must have at least one message.")
        prompt = ""
        for message in self.messages:
            if message["role"] == "user":
                prompt += "\n\nHuman: " + message["content"]
            else:
                prompt += "\n\nAssistant: " + message["content"]
        return prompt

    def get_special_tokens(self) -> List[str]:
        return [self.system_token, self.user_token, self.assistant_token, self.end_token]

    def copy(self):
        return DialogueTemplate(
            system=self.system,
            messages=self.messages,
            system_token=self.system_token,
            user_token=self.user_token,
            assistant_token=self.assistant_token,
            end_token=self.end_token,
        )

    def to_dict(self) -> Dict[str, Any]:
        return {k: v for k, v in asdict(self).items()}

    @classmethod
    def from_dict(cls, data):
        return DialogueTemplate(
            system=data.get("system", ""),
            messages=data.get("messages", None),
            system_token=data.get("system_token", "<|system|>"),
            user_token=data.get("user_token", "<|user|>"),
            assistant_token=data.get("assistant_token", "<|assistant|>"),
            end_token=data.get("end_token", "<|end|>"),
        )

    def _save_pretrained(self, save_directory: Union[str, Path]) -> None:
        save_directory = Path(save_directory)
        save_directory.mkdir(exist_ok=True)
        with open(save_directory / "dialogue_template.json", "w") as f:
            json.dump(self.to_dict(), f, indent=2)

    @classmethod
    def _from_pretrained(
        cls: Type[T],
        *,
        model_id: str,
        revision: Optional[str],
        cache_dir: Optional[Union[str, Path]],
        force_download: bool,
        proxies: Optional[Dict],
        resume_download: bool,
        local_files_only: bool,
        token: Optional[Union[str, bool]],
        **model_kwargs,
    ) -> T:
        """Loads the dialogue template from a local directory or the Huggingface Hub."""
        if os.path.isdir(model_id):
            print("Loading dialogue template from local directory")
            template_file = os.path.join(model_id, TEMPLATE_FILENAME)
        else:
            template_file = hf_hub_download(
                repo_id=model_id,
                filename=TEMPLATE_FILENAME,
                revision=revision or "main",
                cache_dir=cache_dir,
                force_download=force_download,
                proxies=proxies,
                resume_download=resume_download,
                token=token,
                local_files_only=local_files_only,
            )
        with open(template_file, "r") as f:
            data = json.load(f)
        return cls.from_dict(data=data)


# Default template
default_template = DialogueTemplate(
    system="Below is a dialogue between a human user and an AI assistant. The assistant is happy to help with almost anything, and will do its best to understand exactly what is needed.",
)

# Supporting other templates
no_system_template = DialogueTemplate(system="")
alpaca_template = DialogueTemplate(
    system="Below is an instruction that describes a task. Write a response that appropriately completes the request.",
    user_token="### Instruction:",
    assistant_token="### Response:",
)

SUPPORTED_DIALOGUE_TEMPLATES = {
    "default": default_template,
    "no_system": no_system_template,
    "alpaca": alpaca_template,
}


def get_dialogue_template(template: str) -> DialogueTemplate:
    if template not in SUPPORTED_DIALOGUE_TEMPLATES:
        raise ValueError(f"Template {template} is not supported!")
    return SUPPORTED_DIALOGUE_TEMPLATES[template].copy()


def prepare_dialogue(example, dialogue_template, is_train=True):
    if "messages" in example and example["messages"] is not None:
        dialogue_template.messages = example["messages"]
    elif "prompt" in example and "completion" in example:
        dialogue_template.messages = [
            {"role": "user", "content": example["prompt"]},
            {"role": "assistant", "content": example["completion"]},
        ]
    elif "prompt" in example:
        dialogue_template.messages = [{"role": "user", "content": example["prompt"]}]
    else:
        raise ValueError(
            f"Could not format example as dialogue! Require either `messages` or `[prompt, completion]` or `[prompt]` keys but found {list(example.keys())}"
        )
    if is_train:
        example["text"] = dialogue_template.get_training_prompt()
    else:
        example["text"] = dialogue_template.get_inference_prompt()
    return example