from __future__ import annotations

import re
from decimal import Decimal, InvalidOperation, ROUND_HALF_UP

from app.domain import ParsedTransaction, TransactionKind


class ParseError(ValueError):
    pass


_TRANSACTION_RE = re.compile(
    r"^\s*(?P<sign>[+-])?\s*"
    r"(?:(?P<kind>доход|приход|расход|трата)\s+)?"
    r"(?P<amount>\d[\d ]*(?:[,.]\d{1,2})?)\s*"
    r"(?:₽|р\.?|руб(?:лей|ля|ль)?\.?)?\s+"
    r"(?P<description>\S.*)\s*$",
    flags=re.IGNORECASE,
)

_DESCRIPTION_FIRST_RE = re.compile(
    r"^\s*(?P<sign>[+-])\s*(?P<description>зп|зарплата)\s+"
    r"(?P<amount>\d[\d ]*(?:[,.]\d{1,2})?)\s*"
    r"(?:₽|р\.?|руб(?:лей|ля|ль)?\.?)?\s*$",
    flags=re.IGNORECASE,
)

_SALARY_RE = re.compile(r"(?:^|\s)(?:зп|зарплата)(?:$|\s)", flags=re.IGNORECASE)


def parse_transaction(text: str) -> ParsedTransaction:
    match = _TRANSACTION_RE.match(text)
    description_first = False
    if not match:
        match = _DESCRIPTION_FIRST_RE.match(text)
        description_first = match is not None
    if not match:
        raise ParseError("Не удалось распознать сумму и описание")

    raw_amount = match.group("amount").replace(" ", "").replace(",", ".")
    try:
        amount = Decimal(raw_amount)
    except InvalidOperation as exc:
        raise ParseError("Некорректная сумма") from exc
    if amount <= 0:
        raise ParseError("Сумма должна быть больше нуля")

    amount_kopecks = int((amount * 100).quantize(Decimal("1"), rounding=ROUND_HALF_UP))
    description = " ".join(match.group("description").split())
    kind_word = "" if description_first else (match.group("kind") or "").casefold()
    sign = match.group("sign")
    if sign == "-" and kind_word in {"доход", "приход"}:
        raise ParseError("Доход не может быть отрицательным")
    is_salary = _SALARY_RE.search(description) is not None
    kind = (
        TransactionKind.INCOME
        if is_salary or kind_word in {"доход", "приход"}
        else TransactionKind.EXPENSE
    )
    debt_effect = -1 if sign == "-" or kind is TransactionKind.INCOME else 1

    return ParsedTransaction(
        amount_kopecks=amount_kopecks,
        description=description,
        kind=kind,
        debt_effect=debt_effect,
        debt_effect_override=-1 if sign == "-" else None,
    )


def format_money(kopecks: int, *, signed: bool = False) -> str:
    sign = ""
    if signed:
        sign = "+" if kopecks > 0 else ("−" if kopecks < 0 else "")
    absolute = abs(kopecks)
    rubles, cents = divmod(absolute, 100)
    grouped = f"{rubles:,}".replace(",", " ")
    value = f"{grouped},{cents:02d}" if cents else grouped
    return f"{sign}{value} ₽"


_MONEY_ONLY_RE = re.compile(
    r"^\s*(?P<amount>\d[\d ]*(?:[,.]\d{1,2})?)\s*"
    r"(?:₽|р\.?|руб(?:лей|ля|ль)?\.?)?\s*$",
    flags=re.IGNORECASE,
)


def parse_money_amount(text: str) -> int:
    match = _MONEY_ONLY_RE.match(text)
    if not match:
        raise ParseError("Некорректная сумма")
    raw_amount = match.group("amount").replace(" ", "").replace(",", ".")
    try:
        amount = Decimal(raw_amount)
    except InvalidOperation as exc:
        raise ParseError("Некорректная сумма") from exc
    if amount < 0:
        raise ParseError("Сумма не может быть отрицательной")
    return int((amount * 100).quantize(Decimal("1"), rounding=ROUND_HALF_UP))