# Copyright (c) 2021, NVIDIA CORPORATION.  All rights reserved.
# Copyright 2015 and onwards Google, Inc.
#
# 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.

from nemo_text_processing.inverse_text_normalization.vi.graph_utils import GraphFst, delete_space
from nemo_text_processing.inverse_text_normalization.vi.utils import get_abs_path

try:
    import pynini
    from pynini.lib import pynutil

    PYNINI_AVAILABLE = True
except (ModuleNotFoundError, ImportError):
    PYNINI_AVAILABLE = False


class TelephoneFst(GraphFst):
    """
    Finite state transducer for classifying telephone numbers, e.g.
        một hai ba một hai ba năm sáu bảy tám -> { number_part: "1231235678" }
    """

    def __init__(self):
        super().__init__(name="telephone", kind="classify")
        graph_zero = pynini.string_file(get_abs_path("data/numbers/zero.tsv"))
        graph_digit = pynini.string_file(get_abs_path("data/numbers/digit.tsv"))
        digit = graph_digit | graph_zero
        last_digit = digit | pynini.cross("mốt", "1") | pynini.cross("tư", "4") | pynini.cross("lăm", "5")

        graph_number_part = pynini.closure(digit + delete_space, 2) + last_digit
        number_part = pynutil.insert("number_part: \"") + graph_number_part + pynutil.insert("\"")

        graph = number_part
        final_graph = self.add_tokens(graph)
        self.fst = final_graph.optimize()
