from typing import Sequence

from .charts_scale_linear_scale import interpolate, pair
from .math_ln import ln
from .math_round_float import round_float


def log_scale(domain: Sequence[float], range: Sequence[float], value: float, clamp: bool) -> float:
    """Where value lands on a logarithmic axis: equal ratios take equal lengths.

    The base cancels out, so there is none to pass. ln is math.ln, not
    math.log, so every language lands on the same double.
    """
    d0, d1 = pair(domain, "domain")
    r0, r1 = pair(range, "range")
    if not (d0 > 0) or not (d1 > 0):
        raise ValueError(f"log scale domain must be positive; got [{d0}, {d1}]")
    if d0 == d1:
        raise ValueError(f"domain has no width: both ends are {d0}")
    if not (value > 0):
        raise ValueError(f"value must be positive for a log scale; got {value}")
    l0 = ln(d0)
    t = (ln(value) - l0) / (ln(d1) - l0)
    if clamp:
        t = max(0.0, min(1.0, t))
    return round_float(interpolate(r0, r1, t), 6)