# Copyright (c) 2021, NVIDIA CORPORATION & AFFILIATES.  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.inverse_text_normalization.fr.graph_utils import (
    NEMO_NOT_QUOTE,
    GraphFst,
    delete_space,
    insert_space,
)
from pynini.lib import pynutil


class FractionFst(GraphFst):
    """
    Finite state transducer for verbalizing fraction
        e.g. fraction { integer_part: "1" numerator: "2" denominator: "3" } } -> 1 2/3

    """

    def __init__(self):
        super().__init__(name="fraction", kind="verbalize")
        optional_sign = pynini.closure(pynini.cross("negative: \"true\"", "-") + delete_space, 0, 1)
        integer = (
            pynutil.delete("integer_part: \"")
            + pynini.closure(NEMO_NOT_QUOTE, 1)
            + pynutil.delete("\"")
            + insert_space
        )
        numerator = pynutil.delete("numerator: \"") + pynini.closure(NEMO_NOT_QUOTE, 1) + pynutil.delete("\"")

        denominator = (
            pynutil.insert('/')
            + pynutil.delete("denominator: \"")
            + pynini.closure(NEMO_NOT_QUOTE, 1)
            + pynutil.delete("\"")
        )

        graph = (pynini.closure(integer + delete_space, 0, 1) + numerator + delete_space + denominator).optimize()
        self.numbers = graph
        delete_tokens = self.delete_tokens(optional_sign + graph)
        self.fst = delete_tokens.optimize()
