"""HTTP client for the Cube.js API of Indicateurs Territoriaux."""

import asyncio
import os
from typing import Any, Literal

import httpx
from dotenv import load_dotenv

load_dotenv()

_MAX_ATTEMPTS = 3
_BACKOFF_SECONDS = (0.5, 1.0, 2.0)
_RETRYABLE_STATUS = frozenset({502, 503, 504})


class CubeJsClientError(Exception):
    """Base exception for Cube.js client errors."""

    pass


class AuthenticationError(CubeJsClientError):
    """Raised when authentication fails (401)."""

    pass


class BadRequestError(CubeJsClientError):
    """Raised when the request is malformed (400)."""

    pass


class CubeJsClient:
    """HTTP client for the Cube.js REST API.
    
    This client handles authentication and provides methods to interact
    with the Indicateurs Territoriaux API endpoints.
    """

    def __init__(
        self,
        base_url: str | None = None,
        token: str | None = None,
        timeout: float = 30.0,
    ):
        """Initialize the Cube.js client.
        
        Args:
            base_url: Base URL of the API. Defaults to env var INDICATEURS_TE_BASE_URL.
            token: JWT authentication token. Defaults to env var INDICATEURS_TE_TOKEN.
            timeout: Request timeout in seconds.
        """
        self.base_url = (
            base_url
            or os.getenv("INDICATEURS_TE_BASE_URL")
            or "https://api.indicateurs.ecologie.gouv.fr"
        )
        self.token = token or os.getenv("INDICATEURS_TE_TOKEN")
        
        if not self.token:
            raise ValueError(
                "No API token provided. Set INDICATEURS_TE_TOKEN environment variable "
                "or pass token parameter."
            )
        
        self.timeout = timeout
        self._client: httpx.AsyncClient | None = None

    @property
    def headers(self) -> dict[str, str]:
        """HTTP headers for API requests."""
        return {
            "Authorization": f"Bearer {self.token}",
            "Content-Type": "application/json",
        }

    async def _get_client(self) -> httpx.AsyncClient:
        """Get or create the async HTTP client."""
        if self._client is None or self._client.is_closed:
            self._client = httpx.AsyncClient(
                base_url=self.base_url,
                headers=self.headers,
                timeout=self.timeout,
            )
        return self._client

    async def close(self) -> None:
        """Close the HTTP client."""
        if self._client is not None and not self._client.is_closed:
            await self._client.aclose()
            self._client = None

    async def _handle_response(self, response: httpx.Response) -> dict[str, Any]:
        """Handle API response and raise appropriate errors.
        
        Args:
            response: The HTTP response object.
            
        Returns:
            Parsed JSON response.
            
        Raises:
            AuthenticationError: If the token is invalid or expired (401).
            BadRequestError: If the request is malformed (400).
            CubeJsClientError: For other HTTP errors.
        """
        if response.status_code == 401:
            raise AuthenticationError(
                "Authentication failed. Your API token may be invalid or expired. "
                "Please check your INDICATEURS_TE_TOKEN environment variable."
            )
        
        if response.status_code == 400:
            try:
                error_detail = response.json()
            except Exception:
                error_detail = response.text
            raise BadRequestError(
                f"Bad request to API. Details: {error_detail}"
            )
        
        if response.status_code >= 400:
            raise CubeJsClientError(
                f"API request failed with status {response.status_code}: {response.text}"
            )
        
        return response.json()

    async def _request(
        self,
        method: Literal["GET", "POST"],
        path: str,
        **kwargs: Any,
    ) -> dict[str, Any]:
        client = await self._get_client()

        for attempt in range(_MAX_ATTEMPTS):
            try:
                response = await client.request(method, path, **kwargs)
            except httpx.TimeoutException as e:
                if attempt < _MAX_ATTEMPTS - 1:
                    await asyncio.sleep(_BACKOFF_SECONDS[attempt])
                    continue
                raise CubeJsClientError(
                    f"Indicators API did not respond within {self.timeout}s"
                ) from e
            except httpx.ConnectError as e:
                if attempt < _MAX_ATTEMPTS - 1:
                    await asyncio.sleep(_BACKOFF_SECONDS[attempt])
                    continue
                raise CubeJsClientError("Indicators API unreachable") from e
            except httpx.HTTPError as e:
                if attempt < _MAX_ATTEMPTS - 1:
                    await asyncio.sleep(_BACKOFF_SECONDS[attempt])
                    continue
                raise CubeJsClientError(f"Indicators API network error: {e}") from e

            if (
                response.status_code in _RETRYABLE_STATUS
                and attempt < _MAX_ATTEMPTS - 1
            ):
                await asyncio.sleep(_BACKOFF_SECONDS[attempt])
                continue

            return await self._handle_response(response)

        raise CubeJsClientError("Indicators API unavailable")

    async def get_meta(self) -> dict[str, Any]:
        """Fetch the API schema metadata.
        
        Returns the complete schema including all cubes, their measures,
        dimensions, and available filters.
        
        Returns:
            Dict containing the API metadata with 'cubes' key.
            
        Raises:
            AuthenticationError: If authentication fails.
            CubeJsClientError: For other API errors.
        """
        return await self._request("GET", "/cubejs-api/v1/meta")

    async def load(self, query: dict[str, Any]) -> dict[str, Any]:
        """Execute a data query against the Cube.js API.
        
        Args:
            query: The Cube.js query object containing measures, dimensions,
                   filters, and other query parameters.
                   
        Returns:
            Dict containing the query results with 'data' key.
            
        Raises:
            AuthenticationError: If authentication fails.
            BadRequestError: If the query is malformed.
            CubeJsClientError: For other API errors.
            
        Example:
            >>> query = {
            ...     "measures": ["indicateur_metadata.count"],
            ...     "dimensions": ["indicateur_metadata.id", "indicateur_metadata.libelle"],
            ...     "limit": 10
            ... }
            >>> result = await client.load(query)
        """
        return await self._request(
            "POST",
            "/cubejs-api/v1/load",
            json={"query": query},
        )

    async def load_indicators_metadata(
        self,
        dimensions: list[str] | None = None,
        filters: list[dict[str, Any]] | None = None,
        limit: int = 500,
    ) -> list[dict[str, Any]]:
        """Load indicator metadata from the indicateur_metadata cube.
        
        Convenience method for querying the indicator metadata cube.
        
        Args:
            dimensions: List of dimensions to fetch. Defaults to basic info.
            filters: Optional list of filters to apply.
            limit: Maximum number of results.
            
        Returns:
            List of indicator metadata records.
        """
        if dimensions is None:
            dimensions = [
                "indicateur_metadata.id",
                "indicateur_metadata.libelle",
                "indicateur_metadata.unite",
                "indicateur_metadata.description",
                "indicateur_metadata.mailles_disponibles",
                "indicateur_metadata.thematique_fnv",
                "indicateur_metadata.annees_disponibles",
            ]
        
        query: dict[str, Any] = {
            "dimensions": dimensions,
            "limit": limit,
        }
        
        if filters:
            query["filters"] = filters
        
        result = await self.load(query)
        return result.get("data", [])

    # Dimensions souhaitées pour les sources ; seules celles réellement exposées par
    # /meta sont demandées (l'API refuse toute dimension inconnue, ex. « libelle »).
    SOURCE_DIMENSIONS_WANTED = (
        "id_indicateur",
        "nom_source",
        "libelle",
        "libelle_source",
        "description",
        "producteur_source",
        "distributeur_source",
        "license_source",
        "licence_source",
        "lien_page",
        "annees_disponibles_source",
        "maille_mini_disponible",
        "couverture_geographique",
        "date_derniere_extraction",
    )

    async def load_sources_metadata(
        self,
        indicator_id: int | None = None,
        limit: int = 100,
        available_dimensions: list[str] | None = None,
    ) -> list[dict[str, Any]]:
        """Load source metadata from the indicateur_x_source_metadata cube.
        
        Args:
            indicator_id: Optional indicator ID to filter sources.
            limit: Maximum number of results.
            available_dimensions: Full dimension names of the cube as listed by /meta.
                When given, only wanted dimensions that actually exist are requested.
            
        Returns:
            List of source metadata records.
        """
        cube = "indicateur_x_source_metadata"
        wanted = [f"{cube}.{d}" for d in self.SOURCE_DIMENSIONS_WANTED]
        if available_dimensions is not None:
            existing = set(available_dimensions)
            dimensions = [d for d in wanted if d in existing]
        else:
            dimensions = wanted
        if f"{cube}.id_indicateur" not in dimensions:
            return []
        
        query: dict[str, Any] = {
            "dimensions": dimensions,
            "limit": limit,
        }
        
        if indicator_id is not None:
            query["filters"] = [
                {
                    "member": "indicateur_x_source_metadata.id_indicateur",
                    "operator": "equals",
                    "values": [str(indicator_id)],
                }
            ]
        
        result = await self.load(query)
        return result.get("data", [])

    async def search_indicators_by_libelle(
        self,
        search_term: str,
        limit: int = 50,
    ) -> list[dict[str, Any]]:
        """Search indicators by keyword in libelle using contains filter.
        
        This uses Cube.js contains operator for server-side filtering.
        Note: Limited to single term, for multi-term use client-side filtering.
        
        Args:
            search_term: Term to search for in indicator libelle.
            limit: Maximum number of results.
            
        Returns:
            List of matching indicator metadata records.
        """
        query: dict[str, Any] = {
            "dimensions": [
                "indicateur_metadata.id",
                "indicateur_metadata.libelle",
                "indicateur_metadata.description",
                "indicateur_metadata.unite",
                "indicateur_metadata.mailles_disponibles",
                "indicateur_metadata.thematique_fnv",
            ],
            "filters": [
                {
                    "member": "indicateur_metadata.libelle",
                    "operator": "contains",
                    "values": [search_term],
                }
            ],
            "limit": limit,
        }
        
        result = await self.load(query)
        return result.get("data", [])


    async def find_territories(
        self,
        cube_name: str,
        geocode_dim: str,
        libelle_dim: str,
        name: str,
        limit: int = 20,
    ) -> list[dict[str, Any]]:
        """Find territories whose name contains `name` (case-insensitive, Cube.js `contains`).
        
        Args:
            cube_name: A data cube that carries the geographic dimensions.
            geocode_dim: Short dimension name (e.g. "geocode_epci").
            libelle_dim: Short dimension name (e.g. "libelle_epci").
            name: Text to search in the territory label.
            limit: Maximum number of distinct territories.
            
        Returns:
            List of rows with the two full dimension names as keys.
        """
        query: dict[str, Any] = {
            "dimensions": [f"{cube_name}.{geocode_dim}", f"{cube_name}.{libelle_dim}"],
            "filters": [
                {
                    "member": f"{cube_name}.{libelle_dim}",
                    "operator": "contains",
                    "values": [name],
                }
            ],
            "limit": limit,
        }
        result = await self.load(query)
        return result.get("data", [])


# Singleton instance for the application
_client_instance: CubeJsClient | None = None


def get_client() -> CubeJsClient:
    """Get or create the singleton CubeJsClient instance.
    
    Returns:
        The shared CubeJsClient instance.
    """
    global _client_instance
    if _client_instance is None:
        _client_instance = CubeJsClient()
    return _client_instance


async def close_client() -> None:
    """Close the singleton client instance."""
    global _client_instance
    if _client_instance is not None:
        await _client_instance.close()
        _client_instance = None