from typing import List, Optional, Sequence

from .math_round_div import round_div
from .stats_percentile import percentile
from .net_latency_summary_types import LatencySummary


def summarise_latency(samples_us: Sequence[Optional[int]]) -> LatencySummary:
    """Summarise a run of probes the way ping does, in whole microseconds.

    Integer microseconds rather than float milliseconds, so every language
    gives the same answer and a vector can compare exactly. A lost probe counts
    towards loss and is skipped (not a break) when measuring jitter.
    """
    if isinstance(samples_us, (str, bytes)) or not isinstance(samples_us, (list, tuple)):
        raise TypeError("samplesUs must be a list")
    if len(samples_us) == 0:
        raise ValueError("samplesUs must not be empty")
    got: List[int] = []
    for s in samples_us:
        if s is None:
            continue
        if isinstance(s, bool) or not (isinstance(s, int) or (isinstance(s, float) and s.is_integer())):
            raise TypeError("each sample must be a whole number of microseconds or null, received %r" % (s,))
        s = int(s)
        if s < 0:
            raise ValueError("samples must not be negative, received %d" % s)
        got.append(s)
    sent = len(samples_us)
    received = len(got)
    lost = sent - received
    loss = round_div(lost * 10000, sent, "half-up")
    if received == 0:
        return LatencySummary(sent=sent, received=received, lost=lost, loss_basis_points=loss,
                              min_us=None, avg_us=None, max_us=None, p95_us=None, jitter_us=None)
    jitter = None
    if received >= 2:
        diffs = sum(abs(got[i] - got[i - 1]) for i in range(1, received))
        jitter = round_div(diffs, received - 1, "half-up")
    # Nearest-rank returns a sample that was really seen, so it is a whole number.
    p95 = int(percentile([float(v) for v in got], 95, "nearest-rank", 0))
    return LatencySummary(
        sent=sent,
        received=received,
        lost=lost,
        loss_basis_points=loss,
        min_us=min(got),
        avg_us=round_div(sum(got), received, "half-up"),
        max_us=max(got),
        p95_us=p95,
        jitter_us=jitter,
    )