# SPDX-FileCopyrightText: 2019 Kyubyong Park <kbpark.linguist@gmail.com>
# SPDX-FileContributor: 2025 Enno Hermann
#
# SPDX-License-Identifier: Apache-2.0

"""Adapted from: https://github.com/harmlessman/g2pkk."""

import re

# This is a list of bound nouns preceded by pure Korean numerals.
BOUND_NOUNS = (
    "군데 권 개 그루 닢 대 두 마리 모 모금 뭇 발 발짝 방 번 벌 "
    "보루 살 수 술 시 쌈 움큼 정 짝 채 척 첩 축 켤레 톨 통"
)

# Precompiled regex patterns
_COMMA_RE = re.compile(",")
_BOUND_NOUN_RE = re.compile(r"([\d][\d,]*)([ㄱ-힣]+)/B")


def process_num(num: str, *, sino: bool = True) -> str:
    """Process a string looking like arabic number.

    num: string. Consists of [0-9,]. e.g., 12,345
    sino: boolean. If True, sino-Korean numerals, i.e., 일, 이, .. are considered.
        Otherwise, return pure Korean ones in their modifying forms such as 한, 두, ...

    >>> process_num("123,456,789", sino=True)
    '일억이천삼백사십오만육천칠백팔십구'

    >>> process_num("123,456,789", sino=False)
    '일억이천삼백사십오만육천칠백여든아홉'
    """
    num = _COMMA_RE.sub("", num)

    if num == "0":
        return "영"
    if not sino and num == "20":
        return "스무"

    digits = "123456789"
    names = "일이삼사오육칠팔구"
    digit2name = dict(zip(digits, names, strict=True))

    modifiers = "한 두 세 네 다섯 여섯 일곱 여덟 아홉"
    decimals = "열 스물 서른 마흔 쉰 예순 일흔 여든 아흔"
    digit2mod = dict(zip(digits, modifiers.split(), strict=True))
    digit2dec = dict(zip(digits, decimals.split(), strict=True))

    spelledout: list[str] = []
    for i, digit in enumerate(num):
        i = len(num) - i - 1
        if sino:
            if i == 0:
                name = digit2name.get(digit, "")
            elif i == 1:
                name = digit2name.get(digit, "") + "십"
                name = name.replace("일십", "십")
        elif i == 0:
            name = digit2mod.get(digit, "")
        elif i == 1:
            name = digit2dec.get(digit, "")
        if digit == "0":
            if i % 4 == 0:
                last_three = spelledout[-min(3, len(spelledout)) :]
                if "".join(last_three) == "":
                    spelledout.append("")
                    continue
            else:
                spelledout.append("")
                continue
        if i == 2:
            name = digit2name.get(digit, "") + "백"
            name = name.replace("일백", "백")
        elif i == 3:
            name = digit2name.get(digit, "") + "천"
            name = name.replace("일천", "천")
        elif i == 4:
            name = digit2name.get(digit, "") + "만"
            name = name.replace("일만", "만")
        elif i == 5:
            name = digit2name.get(digit, "") + "십"
            name = name.replace("일십", "십")
        elif i == 6:
            name = digit2name.get(digit, "") + "백"
            name = name.replace("일백", "백")
        elif i == 7:
            name = digit2name.get(digit, "") + "천"
            name = name.replace("일천", "천")
        elif i == 8:
            name = digit2name.get(digit, "") + "억"
        elif i == 9:
            name = digit2name.get(digit, "") + "십"
        elif i == 10:
            name = digit2name.get(digit, "") + "백"
        elif i == 11:
            name = digit2name.get(digit, "") + "천"
        elif i == 12:
            name = digit2name.get(digit, "") + "조"
        elif i == 13:
            name = digit2name.get(digit, "") + "십"
        elif i == 14:
            name = digit2name.get(digit, "") + "백"
        elif i == 15:
            name = digit2name.get(digit, "") + "천"
        spelledout.append(name)

    return "".join(spelledout)


def convert_num(string: str) -> str:
    """Convert a annotated string such that arabic numerals inside are spelled out.

    >>> convert_num("우리 3시/B 10분/B에 만나자.")
    '우리 세시/B 십분/B에 만나자.'

    """
    # Bound Nouns
    tokens = set(_BOUND_NOUN_RE.findall(string))
    for token in tokens:
        num, bn = token
        if bn in BOUND_NOUNS:
            spelledout = process_num(num, sino=False)
        else:
            spelledout = process_num(num, sino=True)
        string = string.replace(f"{num}{bn}/B", f"{spelledout}{bn}/B")

    # digit by digit for remaining digits
    digits = "0123456789"
    names = "영일이삼사오육칠팔구"
    for d, n in zip(digits, names, strict=True):
        string = string.replace(d, n)

    return string