# MIT License
#
# Copyright The SCons Foundation
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
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# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

"""Adds user-friendly customizable variables to an SCons build. """

import os.path
import sys
from functools import cmp_to_key

import SCons.Environment
import SCons.Errors
import SCons.Util
import SCons.Warnings

from .BoolVariable import BoolVariable  # okay
from .EnumVariable import EnumVariable  # okay
from .ListVariable import ListVariable  # naja
from .PackageVariable import PackageVariable # naja
from .PathVariable import PathVariable # okay


class Variables:
    """
    Holds all the options, updates the environment with the variables,
    and renders the help text.

    If *is_global* is true, this is a singleton, create only once.

    Args:
      files (optional): List of option configuration files to load
        (backward compatibility). If a single string is passed it is
        automatically placed in a file list (Default value = None)
      args (optional): dictionary to override values set from *files*.
        (Default value = None)
      is_global (optional): global instance? (Default value = True)

    """
    instance = None

    def __init__(self, files=None, args=None, is_global: bool=True) -> None:
        if args is None:
            args = {}
        self.options = []
        self.args = args
        if not SCons.Util.is_List(files):
            if files:
                files = [files,]
            else:
                files = []
        self.files = files
        self.unknown = {}

        # create the singleton instance
        if is_global:
            self = Variables.instance
            if not Variables.instance:
                Variables.instance=self

    def _do_add(self, key, help: str="", default=None, validator=None, converter=None, **kwargs) -> None:

        class Variable:
            pass

        option = Variable()

        # If we get a list or a tuple, we take the first element as the
        # option key and store the remaining in aliases.
        if SCons.Util.is_List(key) or SCons.Util.is_Tuple(key):
            option.key = key[0]
            option.aliases = list(key[1:])
        else:
            option.key = key
            # TODO: normalize to not include key in aliases. Currently breaks tests.
            option.aliases = [key,]
        if not SCons.Environment.is_valid_construction_var(option.key):
            raise SCons.Errors.UserError("Illegal Variables key `%s'" % str(option.key))
        option.help = help
        option.default = default
        option.validator = validator
        option.converter = converter

        self.options.append(option)

        # options might be added after the 'unknown' dict has been set up,
        # so we remove the key and all its aliases from that dict
        for alias in option.aliases + [option.key,]:
            if alias in self.unknown:
                del self.unknown[alias]

    def keys(self) -> list:
        """Returns the keywords for the options."""
        return [o.key for o in self.options]

    def Add(self, key, *args, **kwargs) -> None:
        r""" Adds an option.

        Arguments:
          key: the name of the variable, or a 5-tuple (or list).
            If a tuple, and there are no additional arguments,
            the tuple is unpacked into the four named kwargs from below.
            If a tuple and there are additional arguments, the first word
            of the tuple is taken as the key, and the remainder as aliases.
          *args: optional positional arguments, corresponding to the four
            named kwargs below.

        Keyword Args:
          help: help text for the options (Default value = "")
          default: default value for option (Default value = None)
          validator: function called to validate the option's value
            (Default value = None)
          converter: function to be called to convert the option's
            value before putting it in the environment. (Default value = None)
          **kwargs: arbitrary keyword arguments used by the variable itself.

        """
        if SCons.Util.is_List(key) or SCons.Util.is_Tuple(key):
            if not (len(args) or len(kwargs)):
                return self._do_add(*key)

        return self._do_add(key, *args, **kwargs)

    def AddVariables(self, *optlist) -> None:
        """ Adds a list of options.

        Each list element is a tuple/list of arguments to be passed on
        to the underlying method for adding options.

        Example::

            opt.AddVariables(
                ('debug', '', 0),
                ('CC', 'The C compiler'),
                ('VALIDATE', 'An option for testing validation', 'notset', validator, None),
            )

        """

        for o in optlist:
            self._do_add(*o)

    def Update(self, env, args=None) -> None:
        """ Updates an environment with the option variables.

        Args:
            env: the environment to update.
            args (optional): a dictionary of keys and values to update
                in *env*. If omitted, uses the variables from the commandline.
        """

        values = {}

        # first set the defaults:
        for option in self.options:
            if option.default is not None:
                values[option.key] = option.default

        # next set the value specified in the options file
        for filename in self.files:
            if os.path.exists(filename):
                dir = os.path.split(os.path.abspath(filename))[0]
                if dir:
                    sys.path.insert(0, dir)
                try:
                    values['__name__'] = filename
                    with open(filename) as f:
                        contents = f.read()
                    exec(contents, {}, values)
                finally:
                    if dir:
                        del sys.path[0]
                    del values['__name__']

        # set the values specified on the command line
        if args is None:
            args = self.args

        for arg, value in args.items():
            added = False
            for option in self.options:
                if arg in option.aliases + [option.key,]:
                    values[option.key] = value
                    added = True
            if not added:
                self.unknown[arg] = value

        # put the variables in the environment:
        # (don't copy over variables that are not declared as options)
        for option in self.options:
            try:
                env[option.key] = values[option.key]
            except KeyError:
                pass

        # apply converters
        for option in self.options:
            if option.converter and option.key in values:
                value = env.subst('${%s}'%option.key)
                try:
                    try:
                        env[option.key] = option.converter(value)
                    except TypeError:
                        env[option.key] = option.converter(value, env)
                except ValueError as x:
                    raise SCons.Errors.UserError('Error converting option: %s\n%s'%(option.key, x))


        # apply validators
        for option in self.options:
            if option.validator and option.key in values:
                option.validator(option.key, env.subst('${%s}'%option.key), env)

    def UnknownVariables(self) -> dict:
        """ Returns unknown variables.

        Identifies options that were not known, declared options in this object.
        """
        return self.unknown

    def Save(self, filename, env) -> None:
        """ Save the options to a file.

        Saves all the options which have non-default settings
        to the given file as Python expressions.  This file can
        then be used to load the options for a subsequent run.
        This can be used to create an option cache file.

        Args:
            filename: Name of the file to save into
            env: the environment get the option values from
        """

        # Create the file and write out the header
        try:
            with open(filename, 'w') as fh:
                # Make an assignment in the file for each option
                # within the environment that was assigned a value
                # other than the default. We don't want to save the
                # ones set to default: in case the SConscript settings
                # change you would then pick up old defaults.
                for option in self.options:
                    try:
                        value = env[option.key]
                        try:
                            prepare = value.prepare_to_store
                        except AttributeError:
                            try:
                                eval(repr(value))
                            except KeyboardInterrupt:
                                raise
                            except:
                                # Convert stuff that has a repr() that
                                # cannot be evaluated into a string
                                value = SCons.Util.to_String(value)
                        else:
                            value = prepare()

                        defaultVal = env.subst(SCons.Util.to_String(option.default))
                        if option.converter:
                            try:
                                defaultVal = option.converter(defaultVal)
                            except TypeError:
                                defaultVal = option.converter(defaultVal, env)

                        if str(env.subst('${%s}' % option.key)) != str(defaultVal):
                            fh.write('%s = %s\n' % (option.key, repr(value)))
                    except KeyError:
                        pass
        except OSError as x:
            raise SCons.Errors.UserError('Error writing options to file: %s\n%s' % (filename, x))

    def GenerateHelpText(self, env, sort=None) -> str:
        """ Generates the help text for the options.

        Args:
            env: an environment that is used to get the current values
                of the options.
            sort: Either a comparison function used for sorting
                (must take two arguments and return -1, 0 or 1)
                or a boolean to indicate if it should be sorted.
        """

        if callable(sort):
            options = sorted(self.options, key=cmp_to_key(lambda x, y: sort(x.key, y.key)))
        elif sort is True:
            options = sorted(self.options, key=lambda x: x.key)
        else:
            options = self.options

        def format_opt(opt, self=self, env=env) -> str:
            if opt.key in env:
                actual = env.subst('${%s}' % opt.key)
            else:
                actual = None
            return self.FormatVariableHelpText(env, opt.key, opt.help, opt.default, actual, opt.aliases)

        lines = [_f for _f in map(format_opt, options) if _f]
        return ''.join(lines)

    fmt = '\n%s: %s\n    default: %s\n    actual: %s\n'
    aliasfmt = '\n%s: %s\n    default: %s\n    actual: %s\n    aliases: %s\n'

    def FormatVariableHelpText(self, env, key, help, default, actual, aliases=None) -> str:
        if aliases is None:
            aliases = []
        # Don't display the key name itself as an alias.
        aliases = [a for a in aliases if a != key]
        if aliases:
            return self.aliasfmt % (key, help, default, actual, aliases)
        else:
            return self.fmt % (key, help, default, actual)

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