import csv, random, sys
import pytest
from base64 import b64decode
sys.path.append("multiformats")
from unsignedvarint import *
def test_examples():
    with open("../../spec/multiformats/unsigned-varint-examples.csv") as examples:
        for [input, output] in csv.reader(examples):
            assert(encode(int(input)) == b64decode(output))
            assert(decode(encode(int(input))) == int(input))
def test_random():
    for example in [random.randint(0, PRACTICAL_MAX) for i in range(1000)]:
        assert(decode(encode(example)) == example)
def test_errors():
    # Empty bytes can't be decoded
    with pytest.raises(Exception):
        decode(bytes([]))
    # Negative numbers don't get encoded
    with pytest.raises(AssertionError):
        encode(-1)
    # Leading nulls error
    with pytest.raises(AssertionError):
        decode(bytes([0, 0, 0]))
    # PRACTICAL_MAX_BYTES is tipping point:
    decode(bytes([255, 255, 255, 255, 255, 255, 255, 255, 127]))
    with pytest.raises(AssertionError):
        decode(bytes([255, 255, 255, 255, 255, 255, 255, 255, 255, 1]))
    # PRACTICAL_MAX is tipping point:
    encode(PRACTICAL_MAX)
    with pytest.raises(AssertionError):
        encode(PRACTICAL_MAX + 1)

[metadata]
name = multiformats
version = 0.0.1
[options]
packages = find_namespace:
[options.extras_require]
testing =
	setuptools
	pytest
	pytest-cov
[tool:pytest]
testpaths = test
[coverage:run]
branch = True
[coverage:report]
show_missing = True
skip_covered = True

[build-system]
requires = ["setuptools"]
build-backend = "setuptools.build_meta"

from typing import *
PRACTICAL_MAX_BYTES = 9
PRACTICAL_MAX = 2 ** (7 * PRACTICAL_MAX_BYTES) - 1
UnsignedVarint = NewType("UnsignedVarint", bytes)
def _encode(i: int) -> UnsignedVarint:
    assert(i >= 0)
    if i > 127:
        r = (bytes([(i % 128) + 128]) + encode (i // 128))
    else:
        r = bytes([i])
    return UnsignedVarint(r)
def encode(i: int) -> UnsignedVarint:
    assert(i <= PRACTICAL_MAX)
    return _encode(i)
def _decode(b: List[int]) -> int:
    match b:
        case []:
            raise Exception("Expected at least 1 byte")
        case [c, *t]:
            if c >= 128:
                assert(len(t) > 0)
                return (c - 128) + 128 * _decode(t)
            else:
                assert(len(t) == 0)
                return c
def decode(b: UnsignedVarint) -> int:
    assert(len(b) <= PRACTICAL_MAX_BYTES)
    return _decode(list(b))