# Copyright (c) 2021, NVIDIA CORPORATION.  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 pynini
from nemo_text_processing.text_normalization.en.graph_utils import (
    NEMO_NOT_QUOTE,
    GraphFst,
    delete_preserve_order,
    insert_space,
)
from pynini.lib import pynutil


class FractionFst(GraphFst):
    """
    Finite state transducer for verbalizing fraction
        e.g. tokens { fraction { integer: "huszonhárom" numerator: "négy" denominator: "hatod" } } ->
        huszonhárom négy hatod

    Args:
        deterministic: if True will provide a single transduction option,
            for False multiple transduction are generated (used for audio-based normalization)
    """

    def __init__(self, deterministic: bool = True, lm: bool = False):
        super().__init__(name="fraction", kind="verbalize", deterministic=deterministic)

        optional_sign = pynini.closure(pynini.cross("negative: \"true\"", "mínusz "), 0, 1)

        integer = pynutil.delete("integer_part: \"") + pynini.closure(NEMO_NOT_QUOTE) + pynutil.delete("\" ")

        numerator = pynutil.delete("numerator: \"") + pynini.closure(NEMO_NOT_QUOTE) + pynutil.delete("\" ")

        denominator = pynutil.delete("denominator: \"") + pynini.closure(NEMO_NOT_QUOTE) + pynutil.delete("\"")

        graph = numerator + insert_space + denominator
        if not deterministic:
            graph |= numerator + denominator

        conjunction = pynutil.insert("és ")
        if not deterministic and not lm:
            conjunction = pynini.closure(conjunction, 0, 1)

        integer = pynini.closure(optional_sign + integer + insert_space + conjunction, 0, 1)

        graph = integer + graph + delete_preserve_order

        self.graph = graph
        delete_tokens = self.delete_tokens(self.graph)
        self.fst = delete_tokens.optimize()
