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#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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#
#     http://www.apache.org/licenses/LICENSE-2.0
#
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import pynini
from pynini.lib import pynutil

from nemo_text_processing.text_normalization.en.graph_utils import NEMO_NOT_QUOTE, NEMO_SPACE, GraphFst, delete_space


class FractionFst(GraphFst):
    """
    Finite state transducer for verbalizing fractions
        e.g. fraction { numerator: "8" denominator: "3" } -> "8/3"
    """

    def __init__(self):
        super().__init__(name="fraction", kind="verbalize")

        optional_negative = pynutil.delete("negative: \"") + pynini.cross("True", "-") + pynutil.delete("\"")
        optional_negative = pynini.closure(optional_negative + delete_space, 0, 1)

        integer_part = pynutil.delete("integer_part: \"") + pynini.closure(NEMO_NOT_QUOTE) + pynutil.delete("\"")
        optional_integer_part = pynini.closure(integer_part + NEMO_SPACE, 0, 1)

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

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

        graph = (
            optional_negative + optional_integer_part + numerator + delete_space + pynutil.insert("/") + denominator
        )

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