"""
OpenAI-compatible embedding adapter.

Works with both OpenAI (``/v1/embeddings``) and OpenRouter
(``/api/v1/embeddings``) since they share the same API format.
The *provider* parameter determines the default base URL and
API key environment variable.
"""

import time
from typing import Optional, Dict, Any

from markitect.llm.embedding_adapter import EmbeddingAdapter
from markitect.llm.config import resolve_api_key, find_project_root
from markitect.llm._http import post_json
from markitect.llm.exceptions import (
    LLMConfigurationError,
    LLMAPIError,
    LLMRateLimitError,
)

_DEFAULT_MODEL = "text-embedding-3-small"

_PROVIDER_DEFAULTS: Dict[str, Dict[str, str]] = {
    "openai": {
        "api_base": "https://api.openai.com/v1",
        "env_var": "OPENAI_API_KEY",
    },
    "openrouter": {
        "api_base": "https://openrouter.ai/api/v1",
        "env_var": "OPENROUTER_API_KEY",
    },
}


class OpenAICompatibleEmbeddingAdapter(EmbeddingAdapter):
    """Embedding adapter for OpenAI-compatible endpoints.

    A single class handles both OpenAI and OpenRouter because they
    expose the same ``/embeddings`` endpoint format.
    """

    def __init__(
        self,
        model: Optional[str] = None,
        api_key: Optional[str] = None,
        api_base: Optional[str] = None,
        provider: str = "openai",
        max_retries: int = 3,
    ):
        if provider not in _PROVIDER_DEFAULTS:
            known = ", ".join(sorted(_PROVIDER_DEFAULTS))
            raise LLMConfigurationError(
                f"Unknown embedding provider {provider!r}. Choose from: {known}",
                context={"provider": provider},
            )

        defaults = _PROVIDER_DEFAULTS[provider]
        self._model = model or _DEFAULT_MODEL
        self._api_base = (api_base or defaults["api_base"]).rstrip("/")
        self._max_retries = max_retries
        self._provider = provider

        # Resolve API key
        env_var = defaults["env_var"]
        root = find_project_root()
        key_file_paths = [root / f"apikey-{provider}.txt"] if root else []
        self._api_key = resolve_api_key(
            explicit=api_key,
            env_var=env_var,
            key_file_paths=key_file_paths,
        )

    def embed(self, texts: list[str]) -> list[list[float]]:
        """Embed texts via the OpenAI-compatible ``/embeddings`` endpoint.

        Raises:
            LLMConfigurationError: If no API key is configured.
            LLMAPIError: On HTTP errors after retries are exhausted.
        """
        if not self._api_key:
            raise LLMConfigurationError(
                "No API key configured for embedding adapter",
                context={"provider": self._provider},
            )

        url = f"{self._api_base}/embeddings"
        payload: Dict[str, Any] = {
            "model": self._model,
            "input": texts,
        }
        headers = {"Authorization": f"Bearer {self._api_key}"}

        data = self._post_with_retries(url, payload, headers)

        # Response: {"data": [{"embedding": [...], "index": 0}, ...]}
        # Sort by index to guarantee input order.
        items = sorted(data["data"], key=lambda d: d["index"])
        return [item["embedding"] for item in items]

    def validate(self) -> bool:
        """Return ``True`` if an API key is available."""
        return self._api_key is not None

    def _post_with_retries(
        self,
        url: str,
        payload: Dict[str, Any],
        headers: Dict[str, str],
    ) -> Dict[str, Any]:
        last_exc: Optional[Exception] = None
        for attempt in range(self._max_retries + 1):
            try:
                return post_json(url, payload, headers)
            except LLMRateLimitError as exc:
                last_exc = exc
                if attempt < self._max_retries:
                    time.sleep(2 ** attempt)
            except LLMAPIError as exc:
                if exc.status_code >= 500 and attempt < self._max_retries:
                    last_exc = exc
                    time.sleep(2 ** attempt)
                else:
                    raise
        raise last_exc  # type: ignore[misc]