# Copyright © 2020 Interplanetary Database Association e.V.,
# Planetmint and IPDB software contributors.
# SPDX-License-Identifier: (Apache-2.0 AND CC-BY-4.0)
# Code is Apache-2.0 and docs are CC-BY-4.0
import multiprocessing
from hashlib import sha3_256

import base58
import base64
import random

from functools import singledispatch

from planetmint import backend
from planetmint.backend.localmongodb.connection import LocalMongoDBConnection
from planetmint.backend.tarantool.connection import TarantoolDBConnection
from planetmint.backend.schema import TABLES
from transactions.common import crypto
from transactions.common.transaction_mode_types import BROADCAST_TX_COMMIT
from transactions.types.assets.create import Create
from transactions.types.elections.vote import Vote
from transactions.types.elections.validator_utils import election_id_to_public_key
from planetmint.abci.tendermint_utils import key_to_base64, merkleroot
from planetmint.abci.rpc import MODE_COMMIT, MODE_LIST


@singledispatch
def flush_db(connection, dbname):
    raise NotImplementedError


@flush_db.register(LocalMongoDBConnection)
def flush_localmongo_db(connection, dbname):
    for t in TABLES:
        getattr(connection.conn[dbname], t).delete_many({})


@flush_db.register(TarantoolDBConnection)
def flush_tarantool_db(connection, dbname):
    connection.connect().call("drop")
    connection.connect().call("init")


def generate_block(planet, test_abci_rpc):
    from transactions.common.crypto import generate_key_pair

    alice = generate_key_pair()
    tx = Create.generate([alice.public_key], [([alice.public_key], 1)], assets=[{"data": None}]).sign(
        [alice.private_key]
    )

    code, message = test_abci_rpc.write_transaction(
        MODE_LIST, test_abci_rpc.tendermint_rpc_endpoint, MODE_COMMIT, tx, BROADCAST_TX_COMMIT
    )
    assert code == 202


def to_inputs(election, i, ed25519_node_keys):
    input0 = election.to_inputs()[i]
    votes = election.outputs[i].amount
    public_key0 = input0.owners_before[0]
    key0 = ed25519_node_keys[public_key0]
    return (input0, votes, key0)


def gen_vote(election, i, ed25519_node_keys):
    (input_i, votes_i, key_i) = to_inputs(election, i, ed25519_node_keys)
    election_pub_key = election_id_to_public_key(election.id)
    return Vote.generate([input_i], [([election_pub_key], votes_i)], election_ids=[election.id]).sign(
        [key_i.private_key]
    )


def generate_validators(powers):
    """Generates an arbitrary number of validators with random public keys.

    The object under the `storage` key is in the format expected by DB.

    The object under the `eleciton` key is in the format expected by
    the upsert validator election.

    `public_key`, `private_key` are in the format used for signing transactions.

    Args:
        powers: A list of intergers representing the voting power to
                assign to the corresponding validators.
    """
    validators = []
    for power in powers:
        kp = crypto.generate_key_pair()
        validators.append(
            {
                "storage": {
                    "public_key": {
                        "value": key_to_base64(base58.b58decode(kp.public_key).hex()),
                        "type": "ed25519-base64",
                    },
                    "voting_power": power,
                },
                "election": {
                    "node_id": f"node-{random.choice(range(100))}",
                    "power": power,
                    "public_key": {
                        "value": base64.b16encode(base58.b58decode(kp.public_key)).decode("utf-8"),
                        "type": "ed25519-base16",
                    },
                },
                "public_key": kp.public_key,
                "private_key": kp.private_key,
            }
        )
    return validators


# NOTE: This works for some but not for all test cases check if this or code base needs fix
def generate_election(b, cls, public_key, private_key, asset_data, voter_keys):
    voters = b.get_recipients_list()
    election = cls.generate([public_key], voters, asset_data, None).sign([private_key])

    votes = [
        Vote.generate([election.to_inputs()[i]], [([election_id_to_public_key(election.id)], power)], [election.id])
        for i, (_, power) in enumerate(voters)
    ]
    for key, v in zip(voter_keys, votes):
        v.sign([key])

    return election, votes


def delete_unspent_outputs(connection, *unspent_outputs):
    """Deletes the given ``unspent_outputs`` (utxos).

    Args:
        *unspent_outputs (:obj:`tuple` of :obj:`dict`): Variable
            length tuple or list of unspent outputs.
    """
    if unspent_outputs:
        return backend.query.delete_unspent_outputs(connection, *unspent_outputs)


def get_utxoset_merkle_root(connection):
    """Returns the merkle root of the utxoset. This implies that
    the utxoset is first put into a merkle tree.

    For now, the merkle tree and its root will be computed each
    time. This obviously is not efficient and a better approach
    that limits the repetition of the same computation when
    unnecesary should be sought. For instance, future optimizations
    could simply re-compute the branches of the tree that were
    affected by a change.

    The transaction hash (id) and output index should be sufficient
    to uniquely identify a utxo, and consequently only that
    information from a utxo record is needed to compute the merkle
    root. Hence, each node of the merkle tree should contain the
    tuple (txid, output_index).

    .. important:: The leaves of the tree will need to be sorted in
        some kind of lexicographical order.

    Returns:
        str: Merkle root in hexadecimal form.
    """
    utxoset = backend.query.get_unspent_outputs(connection)
    # TODO Once ready, use the already pre-computed utxo_hash field.
    # See common/transactions.py for details.
    hashes = [
        sha3_256("{}{}".format(utxo["transaction_id"], utxo["output_index"]).encode()).digest() for utxo in utxoset
    ]
    # TODO Notice the sorted call!
    return merkleroot(sorted(hashes))


def store_unspent_outputs(connection, *unspent_outputs):
    """Store the given ``unspent_outputs`` (utxos).

    Args:
        *unspent_outputs (:obj:`tuple` of :obj:`dict`): Variable
            length tuple or list of unspent outputs.
    """
    if unspent_outputs:
        return backend.query.store_unspent_outputs(connection, *unspent_outputs)


def update_utxoset(connection, transaction):
    """
    Update the UTXO set given ``transaction``. That is, remove
    the outputs that the given ``transaction`` spends, and add the
    outputs that the given ``transaction`` creates.

    Args:
        transaction (:obj:`~planetmint.models.Transaction`): A new
            transaction incoming into the system for which the UTXOF
            set needs to be updated.
    """
    spent_outputs = [spent_output for spent_output in transaction.spent_outputs]
    if spent_outputs:
        delete_unspent_outputs(connection, *spent_outputs)
    store_unspent_outputs(connection, *[utxo._asdict() for utxo in transaction.unspent_outputs])


class ProcessGroup(object):
    def __init__(self, concurrency=None, group=None, target=None, name=None, args=None, kwargs=None, daemon=None):
        self.concurrency = concurrency or multiprocessing.cpu_count()
        self.group = group
        self.target = target
        self.name = name
        self.args = args or ()
        self.kwargs = kwargs or {}
        self.daemon = daemon
        self.processes = []

    def start(self):
        for i in range(self.concurrency):
            proc = multiprocessing.Process(
                group=self.group,
                target=self.target,
                name=self.name,
                args=self.args,
                kwargs=self.kwargs,
                daemon=self.daemon,
            )
            proc.start()
            self.processes.append(proc)