"""
Provider factory.

This is the ONLY module the rest of the application should import to talk
to an LLM. It picks the concrete provider based on config.LLM_PROVIDER and
exposes a single generate(prompt) function. Swapping providers is a
config change only.
"""

import config
from logs.logger import get_logger

logger = get_logger(__name__)

_PROVIDER_SINGLETON = None


def _build_provider():
    provider_name = config.LLM_PROVIDER.lower()

    if provider_name == "local":
        from llm.local_provider import LocalMistralProvider

        return LocalMistralProvider()

    if provider_name == "groq":
        from llm.groq_provider import GroqProvider

        return GroqProvider()

    if provider_name == "openai":
        from llm.openai_provider import OpenAIProvider

        return OpenAIProvider()

    raise ValueError(
        f"Unknown LLM_PROVIDER={provider_name!r} in config.py. "
        "Expected one of: 'local', 'groq', 'openai'."
    )


def get_provider():
    """Module-level singleton so the local model (if used) loads only once."""
    global _PROVIDER_SINGLETON
    if _PROVIDER_SINGLETON is None:
        _PROVIDER_SINGLETON = _build_provider()
        logger.info("LLM provider initialized: %s", _PROVIDER_SINGLETON.name())
    return _PROVIDER_SINGLETON


def generate(prompt: str, stream: bool = False):
    """
    The single entrypoint the rest of the app (Flask routes, agents,
    evaluation) should call. Never import a provider class directly outside
    of this module.
    """
    provider = get_provider()
    return provider.generate(prompt, stream=stream)


def reset_provider():
    """Mainly for tests: force re-reading config.LLM_PROVIDER on next call."""
    global _PROVIDER_SINGLETON
    _PROVIDER_SINGLETON = None