# Copyright 2015 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================

"""Generic entry point script."""

import errno as _errno
import sys as _sys

from . import flags


def _usage(shorthelp):
    """Writes __main__'s docstring to stdout with some help text.

    Args:
      shorthelp: bool, if True, prints only flags from the main module,
          rather than all flags.
    """
    doc = _sys.modules["__main__"].__doc__
    if not doc:
        doc = "\nUSAGE: %s [flags]\n" % _sys.argv[0]
        doc = flags.text_wrap(doc, indent="       ", firstline_indent="")
    else:
        # Replace all '%s' with sys.argv[0], and all '%%' with '%'.
        num_specifiers = doc.count("%") - 2 * doc.count("%%")
        try:
            doc %= (_sys.argv[0],) * num_specifiers
        except (OverflowError, TypeError, ValueError):
            # Just display the docstring as-is.
            pass
    if shorthelp:
        flag_str = flags.FLAGS.main_module_help()
    else:
        flag_str = str(flags.FLAGS)
    try:
        _sys.stdout.write(doc)
        if flag_str:
            _sys.stdout.write("\nflags:\n")
            _sys.stdout.write(flag_str)
        _sys.stdout.write("\n")
    except IOError as e:
        # We avoid printing a huge backtrace if we get EPIPE, because
        # "foo.par --help | less" is a frequent use case.
        if e.errno != _errno.EPIPE:
            raise


class _HelpFlag(flags.BooleanFlag):
    """Special boolean flag that displays usage and raises SystemExit."""

    NAME = "help"
    SHORT_NAME = "h"

    def __init__(self):
        super().__init__(
            self.NAME, False, "show this help", short_name=self.SHORT_NAME
        )

    def parse(self, arg):
        if arg:
            _usage(shorthelp=True)
            print()
            print("Try --helpfull to get a list of all flags.")
            _sys.exit(1)


class _HelpshortFlag(_HelpFlag):
    """--helpshort is an alias for --help."""

    NAME = "helpshort"
    SHORT_NAME = None


class _HelpfullFlag(flags.BooleanFlag):
    """Display help for flags in main module and all dependent modules."""

    def __init__(self):
        super().__init__("helpfull", False, "show full help")

    def parse(self, arg):
        if arg:
            _usage(shorthelp=False)
            _sys.exit(1)


_define_help_flags_called = False


def _define_help_flags():
    global _define_help_flags_called
    if not _define_help_flags_called:
        flags.DEFINE_flag(_HelpFlag())
        flags.DEFINE_flag(_HelpfullFlag())
        flags.DEFINE_flag(_HelpshortFlag())
        _define_help_flags_called = True


# @tf_export('app.run')
def run(main=None, argv=None):
    """Runs the program with an optional 'main' function and 'argv' list."""

    # Define help flags.
    _define_help_flags()

    # Parse known flags.
    argv = flags.FLAGS(_sys.argv if argv is None else argv, known_only=True)

    main = main or _sys.modules["__main__"].main

    # Call the main function, passing through any arguments
    # to the final program.
    _sys.exit(main(argv))
