"""Gemini File API uploader implementation."""

from __future__ import annotations

import asyncio
from datetime import datetime, timezone
import io
import logging
import os
from pathlib import Path
import random
import time
from typing import Any

from crewai_files.core.constants import (
    BACKOFF_BASE_DELAY,
    BACKOFF_JITTER_FACTOR,
    BACKOFF_MAX_DELAY,
    GEMINI_FILE_TTL,
)
from crewai_files.core.sources import FilePath
from crewai_files.core.types import FileInput
from crewai_files.processing.exceptions import (
    PermanentUploadError,
    TransientUploadError,
    classify_upload_error,
)
from crewai_files.uploaders.base import FileUploader, UploadResult


logger = logging.getLogger(__name__)


def _compute_backoff_delay(attempt: int) -> float:
    """Compute exponential backoff delay with jitter.

    Args:
        attempt: The current attempt number (0-indexed).

    Returns:
        Delay in seconds with jitter applied.
    """
    delay: float = min(BACKOFF_BASE_DELAY * (2**attempt), BACKOFF_MAX_DELAY)
    jitter: float = random.uniform(0, delay * BACKOFF_JITTER_FACTOR)  # noqa: S311
    return float(delay + jitter)


def _classify_gemini_error(e: Exception, filename: str | None) -> Exception:
    """Classify a Gemini exception as transient or permanent upload error.

    Checks Gemini-specific error message patterns first, then falls back
    to generic status code classification.

    Args:
        e: The exception to classify.
        filename: The filename for error context.

    Returns:
        A TransientUploadError or PermanentUploadError wrapping the original.
    """
    error_msg = str(e).lower()

    if "quota" in error_msg or "rate" in error_msg or "limit" in error_msg:
        return TransientUploadError(f"Rate limit error: {e}", file_name=filename)
    if "auth" in error_msg or "permission" in error_msg or "denied" in error_msg:
        return PermanentUploadError(
            f"Authentication/permission error: {e}", file_name=filename
        )
    if "invalid" in error_msg or "unsupported" in error_msg:
        return PermanentUploadError(f"Invalid request: {e}", file_name=filename)

    return classify_upload_error(e, filename)


def _get_file_path(file: FileInput) -> Path | None:
    """Get the filesystem path if file source is FilePath.

    Args:
        file: The file input to check.

    Returns:
        Path if source is FilePath, None otherwise.
    """
    source = file._file_source
    if isinstance(source, FilePath):
        return source.path
    return None


class GeminiFileUploader(FileUploader):
    """Uploader for Google Gemini File API.

    Uses the google-genai SDK to upload files. Files are stored for 48 hours.
    """

    def __init__(
        self,
        api_key: str | None = None,
        client: Any = None,
    ) -> None:
        """Initialize the Gemini uploader.

        Args:
            api_key: Optional Google API key. If not provided, uses
                GOOGLE_API_KEY environment variable.
            client: Optional pre-instantiated Gemini client.
        """
        self._api_key = api_key or os.environ.get("GOOGLE_API_KEY")
        self._client: Any = client

    @property
    def provider_name(self) -> str:
        """Return the provider name."""
        return "gemini"

    def _get_client(self) -> Any:
        """Get or create the Gemini client."""
        if self._client is None:
            try:
                from google import genai

                self._client = genai.Client(api_key=self._api_key)
            except ImportError as e:
                raise ImportError(
                    "google-genai is required for Gemini file uploads. "
                    "Install with: pip install google-genai"
                ) from e
        return self._client

    def upload(self, file: FileInput, purpose: str | None = None) -> UploadResult:
        """Upload a file to Gemini.

        For FilePath sources, passes the path directly to the SDK which handles
        streaming internally via resumable uploads, avoiding memory overhead.

        Args:
            file: The file to upload.
            purpose: Optional purpose/description (used as display name).

        Returns:
            UploadResult with the file URI and metadata.

        Raises:
            TransientUploadError: For retryable errors (network, rate limits).
            PermanentUploadError: For non-retryable errors (auth, validation).
        """
        try:
            client = self._get_client()
            display_name = purpose or file.filename

            file_path = _get_file_path(file)
            if file_path is not None:
                file_size = file_path.stat().st_size
                logger.info(
                    f"Uploading file '{file.filename}' to Gemini via path "
                    f"({file_size} bytes, streaming)"
                )
                uploaded_file = client.files.upload(
                    file=file_path,
                    config={
                        "display_name": display_name,
                        "mime_type": file.content_type,
                    },
                )
            else:
                content = file.read()
                file_data = io.BytesIO(content)
                file_data.name = file.filename

                logger.info(
                    f"Uploading file '{file.filename}' to Gemini ({len(content)} bytes)"
                )

                uploaded_file = client.files.upload(
                    file=file_data,
                    config={
                        "display_name": display_name,
                        "mime_type": file.content_type,
                    },
                )

            if file.content_type.startswith("video/"):
                if not self.wait_for_processing(uploaded_file.name):
                    raise PermanentUploadError(
                        f"Video processing failed for {file.filename}",
                        file_name=file.filename,
                    )

            expires_at = datetime.now(timezone.utc) + GEMINI_FILE_TTL

            logger.info(
                f"Uploaded to Gemini: {uploaded_file.name} (URI: {uploaded_file.uri})"
            )

            return UploadResult(
                file_id=uploaded_file.name,
                file_uri=uploaded_file.uri,
                content_type=file.content_type,
                expires_at=expires_at,
                provider=self.provider_name,
            )
        except ImportError:
            raise
        except (TransientUploadError, PermanentUploadError):
            raise
        except Exception as e:
            raise _classify_gemini_error(e, file.filename) from e

    async def aupload(
        self, file: FileInput, purpose: str | None = None
    ) -> UploadResult:
        """Async upload a file to Gemini using native async client.

        For FilePath sources, passes the path directly to the SDK which handles
        streaming internally via resumable uploads, avoiding memory overhead.

        Args:
            file: The file to upload.
            purpose: Optional purpose/description (used as display name).

        Returns:
            UploadResult with the file URI and metadata.

        Raises:
            TransientUploadError: For retryable errors (network, rate limits).
            PermanentUploadError: For non-retryable errors (auth, validation).
        """
        try:
            client = self._get_client()
            display_name = purpose or file.filename

            file_path = _get_file_path(file)
            if file_path is not None:
                file_size = file_path.stat().st_size
                logger.info(
                    f"Uploading file '{file.filename}' to Gemini via path "
                    f"({file_size} bytes, streaming)"
                )
                uploaded_file = await client.aio.files.upload(
                    file=file_path,
                    config={
                        "display_name": display_name,
                        "mime_type": file.content_type,
                    },
                )
            else:
                content = await file.aread()
                file_data = io.BytesIO(content)
                file_data.name = file.filename

                logger.info(
                    f"Uploading file '{file.filename}' to Gemini ({len(content)} bytes)"
                )

                uploaded_file = await client.aio.files.upload(
                    file=file_data,
                    config={
                        "display_name": display_name,
                        "mime_type": file.content_type,
                    },
                )

            if file.content_type.startswith("video/"):
                if not await self.await_for_processing(uploaded_file.name):
                    raise PermanentUploadError(
                        f"Video processing failed for {file.filename}",
                        file_name=file.filename,
                    )

            expires_at = datetime.now(timezone.utc) + GEMINI_FILE_TTL

            logger.info(
                f"Uploaded to Gemini: {uploaded_file.name} (URI: {uploaded_file.uri})"
            )

            return UploadResult(
                file_id=uploaded_file.name,
                file_uri=uploaded_file.uri,
                content_type=file.content_type,
                expires_at=expires_at,
                provider=self.provider_name,
            )
        except ImportError:
            raise
        except (TransientUploadError, PermanentUploadError):
            raise
        except Exception as e:
            raise _classify_gemini_error(e, file.filename) from e

    def delete(self, file_id: str) -> bool:
        """Delete an uploaded file from Gemini.

        Args:
            file_id: The file name/ID to delete.

        Returns:
            True if deletion was successful, False otherwise.
        """
        try:
            client = self._get_client()
            client.files.delete(name=file_id)
            logger.info(f"Deleted Gemini file: {file_id}")
            return True
        except Exception as e:
            logger.warning(f"Failed to delete Gemini file {file_id}: {e}")
            return False

    async def adelete(self, file_id: str) -> bool:
        """Async delete an uploaded file from Gemini.

        Args:
            file_id: The file name/ID to delete.

        Returns:
            True if deletion was successful, False otherwise.
        """
        try:
            client = self._get_client()
            await client.aio.files.delete(name=file_id)
            logger.info(f"Deleted Gemini file: {file_id}")
            return True
        except Exception as e:
            logger.warning(f"Failed to delete Gemini file {file_id}: {e}")
            return False

    def get_file_info(self, file_id: str) -> dict[str, Any] | None:
        """Get information about an uploaded file.

        Args:
            file_id: The file name/ID.

        Returns:
            Dictionary with file information, or None if not found.
        """
        try:
            client = self._get_client()
            file_info = client.files.get(name=file_id)
            return {
                "name": file_info.name,
                "uri": file_info.uri,
                "display_name": file_info.display_name,
                "mime_type": file_info.mime_type,
                "size_bytes": file_info.size_bytes,
                "state": str(file_info.state),
                "create_time": file_info.create_time,
                "expiration_time": file_info.expiration_time,
            }
        except Exception as e:
            logger.debug(f"Failed to get Gemini file info for {file_id}: {e}")
            return None

    def list_files(self) -> list[dict[str, Any]]:
        """List all uploaded files.

        Returns:
            List of dictionaries with file information.
        """
        try:
            client = self._get_client()
            files = client.files.list()
            return [
                {
                    "name": f.name,
                    "uri": f.uri,
                    "display_name": f.display_name,
                    "mime_type": f.mime_type,
                    "size_bytes": f.size_bytes,
                    "state": str(f.state),
                }
                for f in files
            ]
        except Exception as e:
            logger.warning(f"Failed to list Gemini files: {e}")
            return []

    def wait_for_processing(self, file_id: str, timeout_seconds: int = 300) -> bool:
        """Wait for a file to finish processing with exponential backoff.

        Some files (especially videos) need time to process after upload.

        Args:
            file_id: The file name/ID.
            timeout_seconds: Maximum time to wait.

        Returns:
            True if processing completed, False if timed out or failed.
        """
        try:
            from google.genai.types import FileState
        except ImportError:
            return True

        client = self._get_client()
        start_time = time.time()
        attempt = 0

        while time.time() - start_time < timeout_seconds:
            file_info = client.files.get(name=file_id)

            if file_info.state == FileState.ACTIVE:
                return True
            if file_info.state == FileState.FAILED:
                logger.error(f"Gemini file processing failed: {file_id}")
                return False

            time.sleep(_compute_backoff_delay(attempt))
            attempt += 1

        logger.warning(f"Timed out waiting for Gemini file processing: {file_id}")
        return False

    async def await_for_processing(
        self, file_id: str, timeout_seconds: int = 300
    ) -> bool:
        """Async wait for a file to finish processing with exponential backoff.

        Some files (especially videos) need time to process after upload.

        Args:
            file_id: The file name/ID.
            timeout_seconds: Maximum time to wait.

        Returns:
            True if processing completed, False if timed out or failed.
        """
        try:
            from google.genai.types import FileState
        except ImportError:
            return True

        client = self._get_client()
        start_time = time.time()
        attempt = 0

        while time.time() - start_time < timeout_seconds:
            file_info = await client.aio.files.get(name=file_id)

            if file_info.state == FileState.ACTIVE:
                return True
            if file_info.state == FileState.FAILED:
                logger.error(f"Gemini file processing failed: {file_id}")
                return False

            await asyncio.sleep(_compute_backoff_delay(attempt))
            attempt += 1

        logger.warning(f"Timed out waiting for Gemini file processing: {file_id}")
        return False