#
# Copyright 2018-2019 Espressif Systems (Shanghai) PTE LTD
#
# 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.
#

import kconfiglib
from pyparsing import (Combine, Group, Literal, Optional, Word, alphanums, hexnums, infixNotation, nums, oneOf,
                       opAssoc, printables, quotedString, removeQuotes)


class SDKConfig:
    """
    Encapsulates an sdkconfig file. Defines grammar of a configuration entry, and enables
    evaluation of logical expressions involving those entries.
    """

    # A configuration entry is in the form CONFIG=VALUE. Definitions of components of that grammar
    IDENTIFIER = Word(alphanums.upper() + '_')

    HEX = Combine('0x' + Word(hexnums)).setParseAction(lambda t:int(t[0], 16))
    DECIMAL = Combine(Optional(Literal('+') | Literal('-')) + Word(nums)).setParseAction(lambda t:int(t[0]))
    LITERAL = Word(printables.replace(':', ''))
    QUOTED_LITERAL = quotedString.setParseAction(removeQuotes)

    VALUE = HEX | DECIMAL | LITERAL | QUOTED_LITERAL

    # Operators supported by the expression evaluation
    OPERATOR = oneOf(['=', '!=', '>', '<', '<=', '>='])

    def __init__(self, kconfig_file, sdkconfig_file):
        self.config = kconfiglib.Kconfig(kconfig_file)
        self.config.load_config(sdkconfig_file)

    def evaluate_expression(self, expression):
        result = self.config.eval_string(expression)

        if result == 0:  # n
            return False
        elif result == 2:  # y
            return True
        else:  # m
            raise Exception('unsupported config expression result')

    @staticmethod
    def get_expression_grammar():
        identifier = SDKConfig.IDENTIFIER.setResultsName('identifier')
        operator = SDKConfig.OPERATOR.setResultsName('operator')
        value = SDKConfig.VALUE.setResultsName('value')

        test_binary = identifier + operator + value
        test_single = identifier

        test = test_binary | test_single

        condition = Group(Optional('(').suppress() + test + Optional(')').suppress())

        grammar = infixNotation(condition, [
                                ('!', 1, opAssoc.RIGHT),
                                ('&&', 2, opAssoc.LEFT),
                                ('||',  2, opAssoc.LEFT)])

        return grammar