import os
from dataclasses import asdict
from typing import Any, Generator

import cohere
from loguru import logger as log

from .abstract import AbstractGenerator
from .prompt import ANSWER_INSTRUCTION, Prompt


class Cohere(metaclass=AbstractGenerator):
    def __init__(self) -> None:
        self.client = cohere.Client(os.environ["COHERE_API_KEY"])

    def rerank(self, prompt: Prompt):
        response = self.client.rerank(
            model="rerank-english-v3.0",
            query=prompt.query,
            documents=[d.text for d in prompt.documents],
            top_n=3,
        )
        ranking = list(
            filter(lambda x: x.relevance_score > 0.5, response.results)
        )
        prompt.documents = [prompt.documents[r.index] for r in ranking]
        return prompt

    def generate(self, prompt: Prompt) -> Generator[Any, Any, Any]:
        log.debug("Generating answer from cohere...")
        if prompt.documents:
            prompt = self.rerank(prompt)
        query = f"{prompt.query}\n\n{ANSWER_INSTRUCTION}"
        for event in self.client.chat_stream(
            message=query,
            documents=[asdict(d) for d in prompt.documents],
            prompt_truncation="AUTO",
        ):
            if event.event_type == "text-generation":
                yield event.text
            elif event.event_type == "citation-generation":
                yield event.citations
            elif event.event_type == "stream-end":
                yield event.finish_reason