"""Tiny, dependency-free helpers (stdlib only)."""
from __future__ import annotations
import json
import urllib.request
import urllib.error
from datetime import datetime, timezone


class HttpError(Exception):
    def __init__(self, status: int, url: str, body: str = ""):
        super().__init__(f"HTTP {status} for {url}")
        self.status, self.url, self.body = status, url, body


def default_get(url: str, headers: dict | None = None, timeout: int = 15):
    """Return (status, text). The single network primitive — injected in tests."""
    req = urllib.request.Request(url, headers=headers or {})
    try:
        with urllib.request.urlopen(req, timeout=timeout) as r:
            return getattr(r, "status", r.getcode()), r.read().decode("utf-8")
    except urllib.error.HTTPError as e:
        return e.code, e.read().decode("utf-8", "replace")


def get_json(url: str, headers: dict | None = None, getter=default_get):
    status, body = getter(url, headers)
    if status != 200:
        raise HttpError(status, url, body)
    return json.loads(body)


def dig(data, path: str):
    """Read a dotted path out of nested dicts: dig(d, 'a.b') -> d['a']['b'] or None."""
    cur = data
    for part in path.split("."):
        if isinstance(cur, dict):
            cur = cur.get(part)
        else:
            return None
    return cur


def utcnow() -> str:
    return datetime.now(timezone.utc).isoformat(timespec="seconds")


def fmt(v) -> str:
    if v is None:
        return "—"  # em dash
    try:
        f = float(v)
        return str(int(f)) if f.is_integer() else str(round(f, 2))
    except (TypeError, ValueError):
        return str(v)