from typing import Sequence

from .math_round_div import round_div
from .monitor_status_code_summary_types import StatusCodeSummary


def summarise_status_codes(statuses: Sequence[int]) -> StatusCodeSummary:
    """HTTP status codes counted by class, with the server error rate (5xx) and
    the client error rate (4xx) kept apart: only 5xx is the server's failure."""
    counts = [0, 0, 0, 0, 0]
    for s in statuses:
        if not isinstance(s, int) or isinstance(s, bool):
            raise ValueError("status code must be a whole number")
        if s < 100 or s > 599:
            raise ValueError("status code must be 100 to 599, received %d" % s)
        counts[s // 100 - 1] += 1
    total = len(statuses)

    def rate(n: int) -> int:
        return 0 if total == 0 else round_div(n * 10000, total, "half-up")

    return StatusCodeSummary(
        total=total,
        informational=counts[0],
        success=counts[1],
        redirect=counts[2],
        client_error=counts[3],
        server_error=counts[4],
        error_rate_basis_points=rate(counts[4]),
        client_error_rate_basis_points=rate(counts[3]),
    )