import re

from .math_round_div import round_div
from .money_amount import Money, money
from .retail_sales_tax_us_data import STATE_RATES, STATE_RATES_HISTORY
from .retail_sales_tax_us_types import UsSalesTax

_ISO_DATE = re.compile(r"[0-9]{4}-[0-9]{2}-[0-9]{2}")


def _state_rate(state: str, on_date: str) -> int:
    if not any(r.state == state for r in STATE_RATES):
        raise ValueError('unknown US state "%s"' % (state,))
    best = None
    for r in STATE_RATES:
        if r.state != state or on_date < r.valid_from or (r.valid_to is not None and on_date > r.valid_to):
            continue
        if best is None or r.valid_from > best.valid_from:
            best = r
    if best is not None:
        return best.rate_per_million
    if STATE_RATES_HISTORY != "full":
        earliest = None
        for r in STATE_RATES:
            if r.state == state and (earliest is None or r.valid_from < earliest):
                earliest = r.valid_from
        if earliest is not None and on_date < earliest:
            raise ValueError(
                "no sales tax rate for %s on %s: this build was installed with history=%s, "
                "so it only carries rates from %s. Reinstall with history=full for older sales."
                % (state, on_date, STATE_RATES_HISTORY, earliest)
            )
    raise ValueError("no sales tax rate for %s on %s" % (state, on_date))


def sales_tax_us(amount: Money, state: str, local_rate_per_million: int, on_date: str) -> UsSalesTax:
    """US sales tax: the state's base rate on the date of sale plus the
    caller's local rate, applied once and rounded half up to the cent.
    """
    if not isinstance(on_date, str) or not _ISO_DATE.fullmatch(on_date):
        raise ValueError('onDate must be an ISO date (YYYY-MM-DD), received "%s"' % (on_date,))
    if amount.currency != "USD":
        raise ValueError("US sales tax is charged in USD, received %s" % amount.currency)
    if (
        isinstance(local_rate_per_million, bool)
        or not isinstance(local_rate_per_million, int)
        or local_rate_per_million < 0
        or local_rate_per_million >= 1000000
    ):
        raise ValueError("localRatePerMillion must be from 0 to 999999, received %r" % (local_rate_per_million,))
    state_rate_per_million = _state_rate(state, on_date)
    combined = state_rate_per_million + local_rate_per_million
    tax = money(round_div(amount.minor * combined, 1000000, "half-up"), "USD")
    return UsSalesTax(
        state=state,
        state_rate_per_million=state_rate_per_million,
        local_rate_per_million=local_rate_per_million,
        combined_rate_per_million=combined,
        taxable=amount,
        tax=tax,
        total=money(amount.minor + tax.minor, "USD"),
    )