# Copyright (c) Meta Platforms, Inc. and affiliates.
# All rights reserved.
#
# This source code is licensed under the BSD-style license found in the
# LICENSE file in the root directory of this source tree.

import io
from pathlib import Path

from typing import Union

from torch import Tensor
from torchcodec import _core as core

ERROR_REPORTING_INSTRUCTIONS = """
This should never happen. Please report an issue following the steps in
https://github.com/pytorch/torchcodec/issues/new?assignees=&labels=&projects=&template=bug-report.yml.
"""


def create_decoder(
    *,
    source: Union[str, Path, io.RawIOBase, io.BufferedReader, bytes, Tensor],
    seek_mode: str,
) -> Tensor:
    if isinstance(source, str):
        return core.create_from_file(source, seek_mode)
    elif isinstance(source, Path):
        return core.create_from_file(str(source), seek_mode)
    elif isinstance(source, io.RawIOBase) or isinstance(source, io.BufferedReader):
        return core.create_from_file_like(source, seek_mode)
    elif isinstance(source, bytes):
        return core.create_from_bytes(source, seek_mode)
    elif isinstance(source, Tensor):
        return core.create_from_tensor(source, seek_mode)
    elif isinstance(source, io.TextIOBase):
        raise TypeError(
            "source is for reading text, likely from open(..., 'r'). Try with 'rb' for binary reading?"
        )
    elif hasattr(source, "read") and hasattr(source, "seek"):
        # This check must be after checking for text-based reading. Also placing
        # it last in general to be defensive: hasattr is a blunt instrument. We
        # could use the inspect module to check for methods with the right
        # signature.
        return core.create_from_file_like(source, seek_mode)

    raise TypeError(
        f"Unknown source type: {type(source)}. "
        "Supported types are str, Path, bytes, Tensor and file-like objects with "
        "read(self, size: int) -> bytes and "
        "seek(self, offset: int, whence: int) -> int methods."
    )