from typing import Sequence

from .charts_scale_linear_scale import interpolate, pair
from .dates_days_between import days_between
from .math_round_float import round_float


def time_scale(domain: Sequence[str], range: Sequence[float], value: str, clamp: bool) -> float:
    """Where an ISO date lands on the range, linearly by calendar days.

    Days are counted with dates.days-between, never through datetime, so no
    time zone can move a point by a day.
    """
    if len(domain) != 2:
        raise ValueError(f"domain must have exactly 2 values, [from, to]; got {len(domain)}")
    r0, r1 = pair(range, "range")
    span = days_between(domain[0], domain[1])
    if span == 0:
        raise ValueError(f"domain has no width: both ends are {domain[0]}")
    t = days_between(domain[0], value) / span
    if clamp:
        t = max(0.0, min(1.0, t))
    return round_float(interpolate(r0, r1, t), 6)