# 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,
    NEMO_SIGMA,
    GraphFst,
    delete_space,
    insert_space,
)
from pynini.lib import pynutil


class DecimalFst(GraphFst):
    """
    Finite state transducer for verbalizing decimal, e.g.
        decimal { negative: "true" integer_part: "twelve" fractional_part: "five o o six" quantity: "billion" } -> minus twelve point five o o six billion

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

    def __init__(self, cardinal, deterministic: bool = True):
        super().__init__(name="decimal", kind="verbalize", deterministic=deterministic)
        self.optional_sign = pynini.cross("negative: \"true\"", "minus ")
        if not deterministic:
            self.optional_sign |= pynini.cross("negative: \"true\"", "negative ")
        self.optional_sign = pynini.closure(self.optional_sign + delete_space, 0, 1)
        self.integer = pynutil.delete("integer_part:") + cardinal.integer
        self.optional_integer = pynini.closure(self.integer + delete_space + insert_space, 0, 1)
        self.fractional_default = (
            pynutil.delete("fractional_part:")
            + delete_space
            + pynutil.delete("\"")
            + pynini.closure(NEMO_NOT_QUOTE, 1)
            + pynutil.delete("\"")
        )

        self.fractional = pynutil.insert("point ") + self.fractional_default

        self.quantity = (
            delete_space
            + insert_space
            + pynutil.delete("quantity:")
            + delete_space
            + pynutil.delete("\"")
            + pynini.closure(NEMO_NOT_QUOTE, 1)
            + pynutil.delete("\"")
        )
        self.optional_quantity = pynini.closure(self.quantity, 0, 1)

        graph = self.optional_sign + (
            self.integer
            | (self.integer + self.quantity)
            | (self.optional_integer + self.fractional + self.optional_quantity)
        )

        self.numbers = graph
        delete_tokens = self.delete_tokens(graph)
        if not deterministic:
            delete_tokens |= pynini.compose(
                delete_tokens,
                NEMO_SIGMA
                + (
                    pynini.cross(" point five", " and a half")
                    | pynini.cross("zero point five", "half")
                    | pynini.cross(" point two five", " and a quarter")
                    | pynini.cross("zero point two five", "quarter")
                ),
            ).optimize()
        self.fst = delete_tokens.optimize()
