# Copyright NeMo (https://github.com/NVIDIA/NeMo). 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.

import os
import string
from pathlib import Path
from typing import Dict

import pynini
from pynini import Far
from pynini.export import export
from pynini.lib import byte, pynutil, utf8

FUN_CHAR = utf8.VALID_UTF8_CHAR

FUN_DIGIT = byte.DIGIT
FUN_LOWER = pynini.union(*string.ascii_lowercase).optimize()
FUN_UPPER = pynini.union(*string.ascii_uppercase).optimize()
FUN_ALPHA = pynini.union(FUN_LOWER, FUN_UPPER).optimize()

FUN_SPACE = " "
FUN_WHITE_SPACE = pynini.union(" ", "\t", "\n", "\r", u"\u00A0").optimize()
FUN_NOT_SPACE = pynini.difference(FUN_CHAR, FUN_WHITE_SPACE).optimize()
FUN_NOT_QUOTE = pynini.difference(FUN_CHAR, r'"').optimize()

FUN_PUNCT = pynini.union(*map(pynini.escape, string.punctuation)).optimize()


FUN_SIGMA = pynini.closure(FUN_CHAR)

delete_space = pynutil.delete(pynini.closure(FUN_WHITE_SPACE))
delete_zero_or_one_space = pynutil.delete(pynini.closure(FUN_WHITE_SPACE, 0, 1))
insert_space = pynutil.insert(" ")
delete_extra_space = pynini.cross(pynini.closure(FUN_WHITE_SPACE, 1), " ")


def generator_main(file_name: str, graphs: Dict[str, 'pynini.FstLike']):
    """
    Exports graph as OpenFst finite state archive (FAR) file with given file name and rule name.

    Args:
        file_name: exported file name
        graphs: Mapping of a rule name and Pynini WFST graph to be exported
    """
    exporter = export.Exporter(file_name)
    for rule, graph in graphs.items():
        exporter[rule] = graph.optimize()
    exporter.close()
    print(f'Created {file_name}')


class GraphFst:
    """
    Base class for all grammar fsts.

    Args:
        name: name of grammar class
        kind: either 'classify' or 'verbalize'
        deterministic: if True will provide a single transduction option,
            for False multiple transduction are generated (used for audio-based normalization)
    """

    def __init__(self, name: str, kind: str, deterministic: bool = True):
        self.name = name
        self.kind = kind
        self._fst = None
        self.deterministic = deterministic

        self.far_path = Path(os.path.dirname(__file__) + '/grammars/' + kind + '/' + name + '.far')
        if self.far_exist():
            self._fst = Far(self.far_path, mode="r", arc_type="standard", far_type="default").get_fst()

    def far_exist(self) -> bool:
        """
        Returns true if FAR can be loaded
        """
        return self.far_path.exists()

    @property
    def fst(self) -> 'pynini.FstLike':
        return self._fst

    @fst.setter
    def fst(self, fst):
        self._fst = fst

    def add_tokens(self, fst) -> 'pynini.FstLike':
        """
        Wraps class name around to given fst

        Args:
            fst: input fst

        Returns:
            Fst: fst
        """
        return pynutil.insert(f"{self.name} {{ ") + fst + pynutil.insert(" }")

    def delete_tokens(self, fst) -> 'pynini.FstLike':
        """
        Deletes class name wrap around output of given fst

        Args:
            fst: input fst

        Returns:
            Fst: fst
        """
        res = (
            pynutil.delete(f"{self.name}")
            + delete_space
            + pynutil.delete("{")
            + delete_space
            + fst
            + delete_space
            + pynutil.delete("}")
        )
        return res @ pynini.cdrewrite(pynini.cross(u"\u00A0", " "), "", "", FUN_SIGMA)