"""Bounded UTF-8 JSON boundary, rejecting duplicate keys and non-finite values."""
import json

MAX_JSON_BYTES = 1_048_576
MAX_JSON_DEPTH = 32


def _pairs(pairs):
    result = {}
    for key, value in pairs:
        if key in result:
            raise ValueError("Duplicate JSON key")
        result[key] = value
    return result


def _constant(value):
    raise ValueError("Non-finite JSON number")


def _float(value):
    import math
    parsed = float(value)
    if not math.isfinite(parsed):
        raise ValueError("Non-finite JSON number")
    return parsed


def _integer(value):
    # Cross-runtime bound, independent of Python's changing int conversion cap.
    if len(value.lstrip("-")) > 128:
        raise ValueError("JSON integer exceeds 128 digits")
    return int(value)


def _check_text(text):
    if not isinstance(text, str) or len(text) > MAX_JSON_BYTES:
        raise ValueError("JSON input must be bounded UTF-8 text")
    try:
        if len(text.encode("utf-8", errors="strict")) > MAX_JSON_BYTES:
            raise ValueError("JSON input too large")
    except UnicodeEncodeError as exc:
        raise ValueError("Invalid Unicode scalar value") from exc
    # Limit nesting before asking a recursive JSON decoder to allocate objects.
    depth = 0
    quoted = escaped = False
    for ch in text:
        if quoted:
            if escaped:
                escaped = False
            elif ch == "\\":
                escaped = True
            elif ch == '"':
                quoted = False
        elif ch == '"':
            quoted = True
        elif ch in "[{":
            depth += 1
            if depth > MAX_JSON_DEPTH:
                raise ValueError("JSON nesting too deep")
        elif ch in "]}":
            depth -= 1


def strict_loads(text):
    _check_text(text)
    try:
        value = json.loads(text, object_pairs_hook=_pairs, parse_constant=_constant, parse_float=_float, parse_int=_integer)
        # Escaped surrogate pairs are decoded normally; lone surrogates fail.
        stack = [value]
        while stack:
            item = stack.pop()
            if isinstance(item, str):
                item.encode("utf-8", errors="strict")
            elif isinstance(item, dict):
                stack.extend(item.keys())
                stack.extend(item.values())
            elif isinstance(item, list):
                stack.extend(item)
        return value
    except (UnicodeError, RecursionError) as exc:
        raise ValueError("Invalid JSON Unicode or nesting") from exc


def strict_dumps(value):
    return json.dumps(value, ensure_ascii=True, sort_keys=True, indent=2, allow_nan=False)