services/utils/fal_service.py

from __future__ import annotations

import os
from typing import Any, Mapping

from services.exceptions import GenerationError

try:
    import fal_client  # type: ignore[import-not-found]
except ModuleNotFoundError:  # pragma: no cover
    fal_client = None  # type: ignore[assignment]

# Fal text uses the OpenRouter "any LLM" router endpoint
DEFAULT_FAL_TEXT_MODEL = os.getenv("FAL_TEXT_MODEL", "openrouter/router")

# Default image model: nano banana as main image backend
DEFAULT_FAL_IMAGE_MODEL = os.getenv("FAL_IMAGE_MODEL", "fal-ai/nano-banana")


def _ensure_fal_client(api_key: str | None = None) -> Any:
    if fal_client is None:
        raise GenerationError(
            "The 'fal-client' package is required to use the fal.ai backends."
        )

    if api_key:
        # fal_client uses the FAL_KEY environment variable for authentication
        os.environ.setdefault("FAL_KEY", api_key)

    return fal_client


def run_fal(
        model: str,
        arguments: Mapping[str, Any],
        api_key: str | None = None,
) -> dict[str, Any]:
    """Run a fal.ai model synchronously and return the raw response."""
    client = _ensure_fal_client(api_key)

    # Check if FAL_KEY is set
    if not os.getenv("FAL_KEY"):
        raise GenerationError(
            "FAL_KEY environment variable is not set. "
            "Please set it in your .env file or environment. "
            "Get your API key from https://fal.ai/dashboard"
        )
    
    try:
        result = client.run(model, arguments=dict(arguments))
    except Exception as exc:  # pragma: no cover
        # Include the original error message for better debugging
        error_msg = str(exc) if str(exc) else type(exc).__name__
        raise GenerationError(
            f"fal.ai request to {model!r} failed: {error_msg}"
        ) from exc

    if not isinstance(result, dict):
        raise GenerationError(
            f"fal.ai model {model!r} returned an unexpected response type "
            f"{type(result).__name__}."
        )

    return result