# 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 pynini.lib import pynutil

from nemo_text_processing.text_normalization.en.graph_utils import (
    NEMO_CHAR,
    GraphFst,
    delete_extra_space,
    delete_space,
)


class MeasureFst(GraphFst):
    """
    Finite state transducer for verbalizing measure, e.g.
        measure { cardinal { negative: "true" integer: "12" } units: "kg" } -> -12 kg

    Args:
        decimal: DecimalFst
        cardinal: CardinalFst
    """

    def __init__(self, decimal: GraphFst, cardinal: GraphFst, fraction: GraphFst):
        super().__init__(name="measure", kind="verbalize")
        optional_sign = pynini.closure(pynini.cross("negative: \"true\"", "-"), 0, 1)
        unit = (
            pynutil.delete("units:")
            + delete_space
            + pynutil.delete("\"")
            + pynini.closure(NEMO_CHAR - " ", 1)
            + pynutil.delete("\"")
            + delete_space
        )
        graph_decimal = (
            pynutil.delete("decimal {")
            + delete_space
            + optional_sign
            + delete_space
            + decimal.numbers
            + delete_space
            + pynutil.delete("}")
        )
        graph_cardinal = (
            pynutil.delete("cardinal {")
            + delete_space
            + optional_sign
            + delete_space
            + cardinal.numbers
            + delete_space
            + pynutil.delete("}")
        )
        graph_fraction = fraction.fst + delete_space + pynutil.insert(" ") + unit
        graph_fraction |= graph_cardinal + delete_extra_space + fraction.fst + delete_extra_space + unit

        graph_math = pynutil.delete("units: \"math\"") + delete_space + cardinal.fst
        graph = (graph_cardinal | graph_decimal) + delete_space + pynutil.insert(" ") + unit
        graph |= graph_fraction
        graph |= graph_math

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