"""LLM Client with dual-provider routing (HuggingFace + Anthropic)."""

import logging
import time
from typing import Optional

from config import (
    LLM_PROVIDER, LLM_MODEL, HF_TOKEN, ANTHROPIC_API_KEY,
    MAX_RETRIES, RETRY_DELAY, REQUEST_TIMEOUT,
)

logger = logging.getLogger(__name__)


class LLMClient:
    """Dual-provider LLM client. Routes to HuggingFace or Anthropic based on LLM_PROVIDER."""

    def __init__(self):
        self.provider = LLM_PROVIDER.lower().strip()
        self.model = LLM_MODEL
        self._client = None
        self._init_provider()

    def _init_provider(self):
        if self.provider == "anthropic":
            if not ANTHROPIC_API_KEY:
                logger.warning("ANTHROPIC_API_KEY not set. LLM calls will fail.")
                return
            try:
                import anthropic
                self._client = anthropic.Anthropic(api_key=ANTHROPIC_API_KEY)
                logger.info(f"LLMClient initialized: Anthropic / {self.model}")
            except ImportError:
                logger.error("anthropic package not installed. Run: pip install anthropic")
            except Exception as e:
                logger.error(f"Failed to initialize Anthropic client: {e}")
        else:  # default: huggingface
            if not HF_TOKEN:
                logger.warning("HF_TOKEN not set. LLM calls will fail.")
                return
            try:
                from huggingface_hub import InferenceClient
                self._client = InferenceClient(token=HF_TOKEN, timeout=REQUEST_TIMEOUT)
                logger.info(f"LLMClient initialized: HuggingFace / {self.model}")
            except ImportError:
                logger.error("huggingface_hub not installed. Run: pip install huggingface_hub")
            except Exception as e:
                logger.error(f"Failed to initialize HF InferenceClient: {e}")

    def is_configured(self) -> bool:
        return self._client is not None

    def generate(self, prompt: str, max_new_tokens: int = 1024) -> Optional[str]:
        """Generate a response with retry logic. Returns None on failure."""
        if not self._client:
            return None

        last_err = None
        for attempt in range(MAX_RETRIES):
            try:
                if self.provider == "anthropic":
                    result = self._call_anthropic(prompt, max_new_tokens)
                else:
                    result = self._call_huggingface(prompt, max_new_tokens)
                if result:
                    return result
                logger.warning("Empty response from LLM")
            except Exception as e:
                last_err = e
                msg = str(e).lower()
                logger.warning(f"LLM call failed (attempt {attempt + 1}/{MAX_RETRIES}): {e}")
                if "401" in msg or "unauthorized" in msg or "invalid" in msg:
                    break  # don't retry auth errors
                if attempt < MAX_RETRIES - 1:
                    time.sleep(RETRY_DELAY)

        logger.error(f"LLM generation failed after {MAX_RETRIES} attempts. Last error: {last_err}")
        return None

    def _call_huggingface(self, prompt: str, max_new_tokens: int) -> Optional[str]:
        response = self._client.chat_completion(
            model=self.model,
            messages=[{"role": "user", "content": prompt}],
            max_tokens=max_new_tokens,
            temperature=0.7,
            top_p=0.9,
        )
        if hasattr(response, "choices") and response.choices:
            content = response.choices[0].message.content
            return content.strip() if content else None
        return None

    def _call_anthropic(self, prompt: str, max_new_tokens: int) -> Optional[str]:
        response = self._client.messages.create(
            model=self.model,
            max_tokens=max_new_tokens,
            messages=[{"role": "user", "content": prompt}],
        )
        if response.content and len(response.content) > 0:
            return response.content[0].text.strip()
        return None


_llm_client: Optional[LLMClient] = None


def get_llm_client() -> LLMClient:
    global _llm_client
    if _llm_client is None:
        _llm_client = LLMClient()
    return _llm_client