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import struct
from binascii import a2b_hex, b2a_hex
from typing import Union, Dict, List

import web3


def make_w3(gateway_config=None):
    """
    Create a Web3 instance configured and ready-to-use gateway to the blockchain.

    :param gateway_config: Blockchain gateway configuration.
    :type gateway_config: dict

    :return: Configured Web3 instance.
    :rtype: :class:`web3.Web3`
    """
    if gateway_config is None or gateway_config['type'] == 'auto':
        w3 = web3.Web3()

    elif gateway_config['type'] == 'user':
        request_kwargs = gateway_config.get('http_options', {})
        w3 = web3.Web3(web3.Web3.HTTPProvider(gateway_config['http'], request_kwargs=request_kwargs))

    elif gateway_config['type'] == 'infura':
        request_kwargs = gateway_config.get('http_options', {})
        project_id = gateway_config['key']
        # project_secret = gateway_config['secret']

        http_url = 'https://{}.infura.io/v3/{}'.format(gateway_config['network'], project_id)
        w3 = web3.Web3(web3.Web3.HTTPProvider(http_url, request_kwargs=request_kwargs))

        # https://web3py.readthedocs.io/en/stable/middleware.html#geth-style-proof-of-authority
        if gateway_config.get('network', None) == 'rinkeby':
            # This middleware is required to connect to geth --dev or the Rinkeby public network.
            from web3.middleware import geth_poa_middleware

            # inject the poa compatibility middleware to the innermost layer
            w3.middleware_onion.inject(geth_poa_middleware, layer=0)

    # FIXME
    elif gateway_config['type'] == 'cloudflare':
        # https://developers.cloudflare.com/web3/ethereum-gateway/reference/supported-networks/
        raise NotImplementedError()

    # FIXME
    elif gateway_config['type'] == 'zksync':
        # https://v2-docs.zksync.io/dev/testnet/important-links.html
        raise NotImplementedError()

    else:
        raise RuntimeError('invalid blockchain gateway type "{}"'.format(gateway_config['type']))

    return w3


def unpack_uint128(data):
    assert data is None or type(data) == bytes, 'data must by bytes, was {}'.format(type(data))
    if data and type(data) == bytes:
        assert len(data) == 16, 'data must be bytes[16], but was bytes[{}]'.format(len(data))

    if data:
        return web3.Web3.toInt(data)
    else:
        return 0


def pack_uint128(value):
    assert value is None or (type(value) == int and value >= 0 and value < 2**128)

    if value:
        data = web3.Web3.toBytes(value)
        return b'\x00' * (16 - len(data)) + data
    else:
        return b'\x00' * 16


def unpack_uint256(data):
    assert data is None or type(data) == bytes, 'data must by bytes, was {}'.format(type(data))
    if data and type(data) == bytes:
        assert len(data) == 32, 'data must be bytes[32], but was bytes[{}]'.format(len(data))

    if data:
        return int(web3.Web3.toInt(data))
    else:
        return 0


def pack_uint256(value):
    assert value is None or (type(value) == int and value >= 0 and value < 2**256), 'value must be uint256, but was {}'.format(value)

    if value:
        data = web3.Web3.toBytes(value)
        return b'\x00' * (32 - len(data)) + data
    else:
        return b'\x00' * 32


def pack_ethadr(value: Union[bytes, str], return_dict: bool = False) -> Union[List[int], Dict[str, int]]:
    """

    :param value:
    :param return_dict:
    :return:
    """
    if type(value) == str:
        if value.startswith('0x'):
            value_bytes = a2b_hex(value[2:])
        else:
            value_bytes = a2b_hex(value)
    elif type(value) == bytes:
        value_bytes = value
    else:
        assert False, 'invalid type {} for value'.format(type(value))
    assert len(value_bytes) == 20

    w = []
    for i in range(5):
        w.append(struct.unpack('<I', value_bytes[0 + i * 4:4 + i * 4])[0])

    if return_dict:
        packed_value = {'w0': w[0], 'w1': w[1], 'w2': w[2], 'w3': w[3], 'w4': w[4]}
    else:
        packed_value = w

    return packed_value


def unpack_ethadr(packed_value: Union[List[int], Dict[str, int]], return_str=False) -> Union[bytes, str]:
    """

    :param packed_value:
    :param return_str:
    :return:
    """
    w = []
    if type(packed_value) == dict:
        for i in range(5):
            w.append(struct.pack('<I', packed_value['w{}'.format(i)]))
    elif type(packed_value) == list:
        for i in range(5):
            w.append(struct.pack('<I', packed_value[i]))
    else:
        assert False, 'should not arrive here'

    if return_str:
        return web3.Web3.toChecksumAddress('0x' + b2a_hex(b''.join(w)).decode())
    else:
        return b''.join(w)