# Copyright (c) 2006 The Regents of The University of Michigan
# All rights reserved.
#
# 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 holders 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 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

import os, sys

config_path = os.path.dirname(os.path.abspath(__file__))
config_root = os.path.dirname(config_path)


class PathSearchFunc:
    _sys_paths = None
    environment_variable = "M5_PATH"

    def __init__(self, subdirs, sys_paths=None):
        if isinstance(subdirs, str):
            subdirs = [subdirs]
        self._subdir = os.path.join(*subdirs)
        if sys_paths:
            self._sys_paths = sys_paths

    def __call__(self, filename):
        if os.sep in filename:
            return filename
        else:
            if self._sys_paths is None:
                try:
                    paths = os.environ[self.environment_variable].split(":")
                except KeyError:
                    paths = ["/dist/m5/system", "/n/poolfs/z/dist/m5/system"]

                # expand '~' and '~user' in paths
                paths = list(map(os.path.expanduser, paths))

                # filter out non-existent directories
                paths = list(filter(os.path.isdir, paths))

                if not paths:
                    raise OSError(
                        "Can't find system files directory, "
                        "check your {} environment variable".format(
                            self.environment_variable
                        )
                    )

                self._sys_paths = list(paths)

            filepath = os.path.join(self._subdir, filename)
            paths = (os.path.join(p, filepath) for p in self._sys_paths)
            try:
                return next(p for p in paths if os.path.exists(p))
            except StopIteration:
                raise OSError(
                    f"Can't find file '{filepath}' on {self.environment_variable}."
                )


disk = PathSearchFunc("disks")
binary = PathSearchFunc("binaries")
script = PathSearchFunc("boot", sys_paths=[config_root])