#!/usr/bin/env python3

# Copyright (c) Facebook, Inc. and its affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.

import logging
import os
import shutil
from typing import List, Optional


logger = logging.getLogger(__file__)


try:
    from fvcore.common.file_io import PathManager as FVCorePathManager

    try:
        # [FB only - for now] AWS PathHandler for PathManager
        from .fb_pathhandlers import S3PathHandler

        FVCorePathManager.register_handler(S3PathHandler())
    except KeyError:
        logging.warning("S3PathHandler already registered.")
    except ImportError:
        logging.debug(
            "S3PathHandler couldn't be imported. Either missing fb-only files, or boto3 module."
        )

except ImportError:
    FVCorePathManager = None


class PathManager:
    """
    Wrapper for insulating OSS I/O (using Python builtin operations) from
    fvcore's PathManager abstraction (for transparently handling various
    internal backends).
    """

    @staticmethod
    def open(
        path: str,
        mode: str = "r",
        buffering: int = -1,
        encoding: Optional[str] = None,
        errors: Optional[str] = None,
        newline: Optional[str] = None,
    ):
        if FVCorePathManager:
            return FVCorePathManager.open(
                path=path,
                mode=mode,
                buffering=buffering,
                encoding=encoding,
                errors=errors,
                newline=newline,
            )
        return open(
            path,
            mode=mode,
            buffering=buffering,
            encoding=encoding,
            errors=errors,
            newline=newline,
        )

    @staticmethod
    def copy(src_path: str, dst_path: str, overwrite: bool = False) -> bool:
        if FVCorePathManager:
            return FVCorePathManager.copy(
                src_path=src_path, dst_path=dst_path, overwrite=overwrite
            )
        return shutil.copyfile(src_path, dst_path)

    @staticmethod
    def get_local_path(path: str, **kwargs) -> str:
        if FVCorePathManager:
            return FVCorePathManager.get_local_path(path, **kwargs)
        return path

    @staticmethod
    def exists(path: str) -> bool:
        if FVCorePathManager:
            return FVCorePathManager.exists(path)
        return os.path.exists(path)

    @staticmethod
    def isfile(path: str) -> bool:
        if FVCorePathManager:
            return FVCorePathManager.isfile(path)
        return os.path.isfile(path)

    @staticmethod
    def ls(path: str) -> List[str]:
        if FVCorePathManager:
            return FVCorePathManager.ls(path)
        return os.listdir(path)

    @staticmethod
    def mkdirs(path: str) -> None:
        if FVCorePathManager:
            return FVCorePathManager.mkdirs(path)
        os.makedirs(path, exist_ok=True)

    @staticmethod
    def rm(path: str) -> None:
        if FVCorePathManager:
            return FVCorePathManager.rm(path)
        os.remove(path)

    @staticmethod
    def chmod(path: str, mode: int) -> None:
        if not PathManager.path_requires_pathmanager(path):
            os.chmod(path, mode)

    @staticmethod
    def register_handler(handler) -> None:
        if FVCorePathManager:
            return FVCorePathManager.register_handler(handler=handler)

    @staticmethod
    def copy_from_local(
        local_path: str, dst_path: str, overwrite: bool = False, **kwargs
    ) -> None:
        if FVCorePathManager:
            return FVCorePathManager.copy_from_local(
                local_path=local_path, dst_path=dst_path, overwrite=overwrite, **kwargs
            )
        return shutil.copyfile(local_path, dst_path)

    @staticmethod
    def path_requires_pathmanager(path: str) -> bool:
        """Do we require PathManager to access given path?"""
        if FVCorePathManager:
            for p in FVCorePathManager._path_handlers.keys():
                if path.startswith(p):
                    return True
        return False

    @staticmethod
    def supports_rename(path: str) -> bool:
        # PathManager doesn't yet support renames
        return not PathManager.path_requires_pathmanager(path)

    @staticmethod
    def rename(src: str, dst: str):
        os.rename(src, dst)