import json
import pathlib
from functools import lru_cache
from importlib.metadata import version as package_version
from jinja2.sandbox import ImmutableSandboxedEnvironment
from packaging import version
from pydantic import BaseModel
from typing import Optional, Dict

# Small replication of AutoTokenizer's chat template system for efficiency

class PromptTemplate(BaseModel):
    name: str
    template: str

def get_prompt_from_template(messages, 
                             prompt_template: PromptTemplate, 
                             add_generation_prompt: bool,
                             special_tokens: Optional[Dict[str, str]] = None):
    if version.parse(package_version("jinja2")) < version.parse("3.0.0"):
        raise ImportError(
            "Parsing these chat completion messages requires jinja2 3.0.0 or greater. "
            f"Current version: {version('jinja2')}\n"
            "Please upgrade jinja by running the following command: "
            "pip install --upgrade jinja2"
        )

    compiled_template = _compile_template(prompt_template.template)
    return compiled_template.render(
        messages = messages,
        add_generation_prompt = add_generation_prompt,
        **special_tokens,
    )

# Inspired from https://github.com/huggingface/transformers/blob/main/src/transformers/tokenization_utils_base.py#L1761
@lru_cache
def _compile_template(template: str):
    jinja_env = ImmutableSandboxedEnvironment(trim_blocks = True, lstrip_blocks = True)
    jinja_template = jinja_env.from_string(template)
    return jinja_template

# Find a matching template name from a model path
def find_template_from_model(model_path: pathlib.Path):
    model_name = model_path.name
    template_directory = pathlib.Path("templates")
    for filepath in template_directory.glob("*.jinja"):
        template_name = filepath.stem.lower()

        # Check if the template name is present in the model name
        if template_name in model_name.lower():
            return template_name

# Get a template from a jinja file
def get_template_from_file(prompt_template_name: str):
    template_path = pathlib.Path(f"templates/{prompt_template_name}.jinja")
    if template_path.exists():
        with open(template_path, "r", encoding = "utf8") as raw_template:
            return PromptTemplate(
                name = prompt_template_name,
                template = raw_template.read()
            )

    return None


# Get a template from a JSON file
# Requires a key and template name
def get_template_from_model_json(json_path: pathlib.Path, key: str, name: str):
    if json_path.exists():
        with open(json_path, "r", encoding = "utf8") as config_file:
            model_config = json.load(config_file)
            chat_template = model_config.get(key)
            if chat_template:
                return PromptTemplate(
                    name = name,
                    template = chat_template
                )

    return None