# BSD 3-Clause License
#
# - Copyright (c) 2008-Present, IPython Development Team
# - Copyright (c) 2001-2007, Fernando Perez <fernando.perez@colorado.edu>
# - Copyright (c) 2001, Janko Hauser <jhauser@zscout.de>
# - Copyright (c) 2001, Nathaniel Gray <n8gray@caltech.edu>
#
# All rights reserved.
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# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice, this
#   list of conditions and the following disclaimer.

# * Redistributions in binary form must reproduce the above copyright notice,
#   this list of conditions and the following disclaimer in the documentation
#   and/or other materials provided with the distribution.

# * Neither the name of the copyright holder nor the names of its
#   contributors may be used to endorse or promote products derived from
#   this software without specific prior written permission.

# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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# Code modified from IPython (BSD license)
# Source: https://github.com/ipython/ipython/blob/master/IPython/utils/syspathcontext.py#L42

import sys

from streamlit import util


class modified_sys_path:
    """A context for prepending a directory to sys.path for a second."""

    def __init__(self, main_script_path: str):
        self._main_script_path = main_script_path
        self._added_path = False

    def __repr__(self) -> str:
        return util.repr_(self)

    def __enter__(self):
        if self._main_script_path not in sys.path:
            sys.path.insert(0, self._main_script_path)
            self._added_path = True

    def __exit__(self, type, value, traceback):
        if self._added_path:
            try:
                sys.path.remove(self._main_script_path)
            except ValueError:
                # It's already removed.
                pass

        # Returning False causes any exceptions to be re-raised.
        return False