#!/usr/bin/env python3
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import pyparsing as pp
import json
import re
from helper import _set_up_py_parsing_nicer_debug_output
_set_up_py_parsing_nicer_debug_output(pp)


class QMakeSpecificJSONParser:
    def __init__(self, *, debug: bool = False) -> None:
        self.debug = debug
        self.grammar = self.create_py_parsing_grammar()

    def create_py_parsing_grammar(self):
        # Keep around all whitespace.
        pp.ParserElement.setDefaultWhitespaceChars('')

        def add_element(name: str, value: pp.ParserElement):
            nonlocal self
            if self.debug:
                value.setName(name)
                value.setDebug()
            return value

        # Our grammar is pretty simple. We want to remove all newlines
        # inside quoted strings, to make the quoted strings JSON
        # compliant. So our grammar should skip to the first quote while
        # keeping everything before it as-is, process the quoted string
        # skip to the next quote, and repeat that until the end of the
        # file.

        EOF = add_element('EOF', pp.StringEnd())
        SkipToQuote = add_element('SkipToQuote', pp.SkipTo('"'))
        SkipToEOF = add_element('SkipToEOF', pp.SkipTo(EOF))

        def remove_newlines_and_whitespace_in_quoted_string(tokens):
            first_string = tokens[0]
            replaced_string = re.sub(r'\n[ ]*', ' ', first_string)
            return replaced_string

        QuotedString = add_element('QuotedString', pp.QuotedString(quoteChar='"',
                                                                   multiline=True,
                                                                   unquoteResults=False))
        QuotedString.setParseAction(remove_newlines_and_whitespace_in_quoted_string)

        QuotedTerm = add_element('QuotedTerm', pp.Optional(SkipToQuote) + QuotedString)
        Grammar = add_element('Grammar', pp.OneOrMore(QuotedTerm) + SkipToEOF)

        return Grammar

    def parse_file_using_py_parsing(self, file: str):
        print('Pre processing "{}" using py parsing to remove incorrect newlines.'.format(file))
        try:
            with open(file, 'r') as file_fd:
                contents = file_fd.read()

            parser_result = self.grammar.parseString(contents, parseAll=True)
            token_list = parser_result.asList()
            joined_string = ''.join(token_list)

            return joined_string
        except pp.ParseException as pe:
            print(pe.line)
            print(' '*(pe.col-1) + '^')
            print(pe)
            raise pe

    def parse(self, file: str):
        pre_processed_string = self.parse_file_using_py_parsing(file)
        print('Parsing "{}" using json.loads().'.format(file))
        json_parsed = json.loads(pre_processed_string)
        return json_parsed