"""SCons.Variables

This file defines the Variables class that is used to add user-friendly
customizable variables to an SCons build.
"""

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__revision__ = "__FILE__ __REVISION__ __DATE__ __DEVELOPER__"

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=True):
        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="", default=None, validator=None, converter=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 = key[1:]
        else:
            option.key     = key
            option.aliases = [ 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 list(option.aliases) + [ option.key ]:
            if alias in self.unknown:
                del self.unknown[alias]

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

    def Add(self, key, help="", default=None, validator=None, converter=None, **kw):
        """Add an option.

        Args:
          key: the name of the variable, or a list or tuple of arguments
          help: optional help text for the options (Default value = "")
          default: optional default value for option (Default value = None)
          validator: optional function called to validate the option's value
            (Default value = None)
          converter: optional function to be called to convert the option's
            value before putting it in the environment. (Default value = None)
          \*\*kw: keyword args, unused.

        """
        if SCons.Util.is_List(key) or isinstance(key, tuple):
            self._do_add(*key)
            return

        if not SCons.Util.is_String(key) or \
            not SCons.Environment.is_valid_construction_var(key):
                raise SCons.Errors.UserError("Illegal Variables.Add() key `%s'" % str(key))

        self._do_add(key, help, default, validator, converter)

    def AddVariables(self, *optlist):
        """
        Add 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):
        """
        Update an environment with the option variables.

        env - the environment to update.
        """

        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, 'r') 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 list(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

        # Call the convert functions:
        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))


        # Finally validate the values:
        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):
        """
        Returns any options in the specified arguments lists that
        were not known, declared options in this object.
        """
        return self.unknown

    def Save(self, filename, env):
        """
        Saves all the options in the given file.  This file can
        then be used to load the options next run.  This can be used
        to create an option cache file.

        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:
            fh = open(filename, 'w')

            try:
                # Make an assignment in the file for each option
                # within the environment that was assigned a value
                # other than the default.
                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:
                            defaultVal = option.converter(defaultVal)

                        if str(env.subst('${%s}' % option.key)) != str(defaultVal):
                            fh.write('%s = %s\n' % (option.key, repr(value)))
                    except KeyError:
                        pass
            finally:
                fh.close()

        except IOError as x:
            raise SCons.Errors.UserError('Error writing options to file: %s\n%s' % (filename, x))

    def GenerateHelpText(self, env, sort=None):
        """
        Generate the help text for the options.

        env - an environment that is used to get the current values
              of the options.
        cmp - Either a function as follows: The specific sort function should 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, self=self, env=env):
            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, options) if _f]

        return ''.join(lines)

    format  = '\n%s: %s\n    default: %s\n    actual: %s\n'
    format_ = '\n%s: %s\n    default: %s\n    actual: %s\n    aliases: %s\n'

    def FormatVariableHelpText(self, env, key, help, default, actual, aliases=[]):
        # Don't display the key name itself as an alias.
        aliases = [a for a in aliases if a != key]
        if len(aliases)==0:
            return self.format % (key, help, default, actual)
        else:
            return self.format_ % (key, help, default, actual, aliases)

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