import asyncio
import json
from contextlib import asynccontextmanager
from typing import AsyncIterator

import aiohttp
from botocore.auth import SigV4Auth
from botocore.awsrequest import AWSRequest

from vsp.llm.bedrock.bedrock_model import AnthropicModel, BedrockModel, get_bedrock_model_rate_limit
from vsp.llm.bedrock.bedrock_rate_limiter import BedrockRateLimiter
from vsp.llm.llm_service import LLMService
from vsp.shared import aws_clients, config, logger_factory

logger = logger_factory.get_logger(__name__)


class AsyncBedrockService(LLMService):
    """
    An asynchronous service class for making calls to the AWS Bedrock API.

    This class handles authentication, rate limiting, and API interactions
    when using AWS Bedrock's language models.
    """

    def __init__(self, model: BedrockModel, max_concurrency: int = 10):
        """
        Initialize the AsyncBedrockService.

        Args:
            model (BedrockModel): The Bedrock model to use for API calls.
            max_concurrency (int): Maximum number of concurrent API calls. Defaults to 10.
        """
        bedrock_client = aws_clients.get_bedrock_client()
        self._session: aiohttp.ClientSession | None = None
        self._credentials = bedrock_client._get_credentials()
        self._region = config.get_aws_region()
        self._semaphore = asyncio.Semaphore(max_concurrency)
        self._model = model
        self._rate_limiter = BedrockRateLimiter(
            rate=max(get_bedrock_model_rate_limit(model).requests_per_minute - 10, 1), per=60.0
        )

    @asynccontextmanager
    async def __call__(self) -> AsyncIterator["AsyncBedrockService"]:
        self._session = aiohttp.ClientSession()
        try:
            yield self
        finally:
            if self._session:
                await self._session.close()

    async def invoke(
        self,
        user_prompt: str | None = None,
        system_prompt: str | None = None,
        partial_assistant_prompt: str | None = None,
        max_tokens: int = 1000,
        temperature: float = 0.0,
    ) -> str | None:
        """
        Invoke the Bedrock API with the given prompts and parameters.

        This method handles rate limiting and makes the API call.

        Args:
            user_prompt (str | None): The main prompt from the user.
            system_prompt (str | None): A system message to set the context.
            partial_assistant_prompt (str | None): A partial response from the assistant.
            max_tokens (int): Maximum number of tokens in the response.
            temperature (float): Sampling temperature for response generation.

        Returns:
            str | None: The generated response from the Bedrock API, or None if no response.

        Raises:
            ValueError: If the model is not an Anthropic model or if no prompts are provided.
            Exception: For any errors encountered during the API call.
        """
        # Verify that the model is an Anthropic model
        if not isinstance(self._model, AnthropicModel):
            raise ValueError(f"Model {self._model} is not an Anthropic model")

        # Verify that user prompt, system prompt, and partial assistant prompt are not all None
        if not any([user_prompt, system_prompt, partial_assistant_prompt]):
            raise ValueError("At least one of user_prompt, system_prompt, or partial_assistant_prompt must be provided")

        async with self._semaphore:  # Use semaphore to limit concurrency
            await self._rate_limiter.acquire()  # rate limit first
            url = f"https://bedrock-runtime.{self._region}.amazonaws.com/model/{self._model.value}/invoke"
            if user_prompt:
                messages = [{"role": "user", "content": user_prompt}]
            if partial_assistant_prompt:
                messages.append({"role": "assistant", "content": partial_assistant_prompt})

            body = {
                "anthropic_version": "bedrock-2023-05-31",
                "max_tokens": max_tokens,
                "messages": messages,
                "temperature": temperature,
            }

            if system_prompt:
                body["system"] = system_prompt

            body_json = json.dumps(body)

            headers = {
                "Content-Type": "application/json",
                "Accept": "application/json",
            }

            request = AWSRequest(method="POST", url=url, data=body_json, headers=headers)
            SigV4Auth(self._credentials, "bedrock", self._region).add_auth(request)

            if self._session is None:
                raise RuntimeError("Session is not initialized")

            async with self._session.post(url, data=body_json, headers=dict(request.headers)) as response:
                logger.info("Bedrock API called", url=response.url)
                if response.status != 200:
                    raise Exception(f"Bedrock API error: {response.status} {await response.text()}")

                response_body = await response.json()

                if "content" not in response_body:
                    raise Exception(f"Content not found in Bedrock response: {response_body}")

                text = str(response_body["content"][0]["text"])
                if partial_assistant_prompt:
                    text = f"{partial_assistant_prompt}{text}"

                # Extract token usage information
                input_tokens = response_body.get("usage", {}).get("input_tokens", 0)
                output_tokens = response_body.get("usage", {}).get("output_tokens", 0)

                # Log token usage
                logger.info("Token usage", input_tokens=input_tokens, output_tokens=output_tokens)

                return text