Module src.communicatorutils.downloadblocks

"""
    Onionr - Private P2P Communication

    Download blocks using the communicator instance
"""
from typing import TYPE_CHECKING
if TYPE_CHECKING:
    from communicator import OnionrCommunicatorDaemon

from gevent import spawn

import onionrexceptions
import logger
import onionrpeers
import communicator
from communicator import peeraction
from communicator import onlinepeers
from onionrutils import blockmetadata
from onionrutils import validatemetadata
from coredb import blockmetadb
from onionrutils.localcommand import local_command
import onionrcrypto
import onionrstorage
from onionrblocks import onionrblacklist
from onionrblocks import storagecounter
from . import shoulddownload
"""
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.
"""


def download_blocks_from_communicator(comm_inst: "OnionrCommunicatorDaemon"):
    """Use communicator instance to download blocks in the comms's queue"""
    blacklist = onionrblacklist.OnionrBlackList()
    storage_counter = storagecounter.StorageCounter()
    LOG_SKIP_COUNT = 50 # for how many iterations we skip logging the counter
    count: int = 0
    metadata_validation_result: bool = False
    # Iterate the block queue in the communicator
    for blockHash in list(comm_inst.blockQueue):
        count += 1

        triedQueuePeers = [] # List of peers we've tried for a block
        try:
            blockPeers = list(comm_inst.blockQueue[blockHash])
        except KeyError:
            blockPeers = []
        removeFromQueue = True

        if not shoulddownload.should_download(comm_inst, blockHash):
            continue

        if comm_inst.shutdown or not comm_inst.isOnline or storage_counter.is_full():
            # Exit loop if shutting down or offline, or disk allocation reached
            break
        # Do not download blocks being downloaded
        if blockHash in comm_inst.currentDownloading:
            continue

        if len(comm_inst.onlinePeers) == 0:
            break

        comm_inst.currentDownloading.append(blockHash) # So we can avoid concurrent downloading in other threads of same block
        if len(blockPeers) == 0:
            try:
                peerUsed = onlinepeers.pick_online_peer(comm_inst)
            except onionrexceptions.OnlinePeerNeeded:
                continue
        else:
            blockPeers = onionrcrypto.cryptoutils.random_shuffle(blockPeers)
            peerUsed = blockPeers.pop(0)

        if not comm_inst.shutdown and peerUsed.strip() != '':
            logger.info("Attempting to download %s from %s..." % (blockHash[:12], peerUsed))
        content = peeraction.peer_action(comm_inst, peerUsed, 'getdata/' + blockHash, max_resp_size=3000000) # block content from random peer (includes metadata)

        if content is not False and len(content) > 0:
            try:
                content = content.encode()
            except AttributeError:
                pass

            realHash = onionrcrypto.hashers.sha3_hash(content)
            try:
                realHash = realHash.decode() # bytes on some versions for some reason
            except AttributeError:
                pass
            if realHash == blockHash:
                #content = content.decode() # decode here because sha3Hash needs bytes above
                metas = blockmetadata.get_block_metadata_from_data(content) # returns tuple(metadata, meta), meta is also in metadata
                metadata = metas[0]
                try:
                    metadata_validation_result = \
                        validatemetadata.validate_metadata(metadata, metas[2])
                except onionrexceptions.DataExists:
                    metadata_validation_result = False
                if metadata_validation_result: # check if metadata is valid, and verify nonce
                    if onionrcrypto.cryptoutils.verify_POW(content): # check if POW is enough/correct
                        logger.info('Attempting to save block %s...' % blockHash[:12])
                        try:
                            onionrstorage.set_data(content)
                        except onionrexceptions.DataExists:
                            logger.warn('Data is already set for %s ' % (blockHash,))
                        except onionrexceptions.DiskAllocationReached:
                            logger.error('Reached disk allocation allowance, cannot save block %s.' % (blockHash,))
                            removeFromQueue = False
                        else:
                            blockmetadb.add_to_block_DB(blockHash, dataSaved=True) # add block to meta db
                            spawn(
                                local_command,
                                f'/daemon-event/upload_event',
                                post=True,
                                is_json=True,
                                postData={'block': blockHash}
                            )

                            blockmetadata.process_block_metadata(blockHash) # caches block metadata values to block database
                    else:
                        logger.warn('POW failed for block %s.' % (blockHash,))
                else:
                    if blacklist.inBlacklist(realHash):
                        logger.warn('Block %s is blacklisted.' % (realHash,))
                    else:
                        logger.warn('Metadata for block %s is invalid.' % (blockHash,))
                        blacklist.addToDB(blockHash)
            else:
                # if block didn't meet expected hash
                tempHash = onionrcrypto.hashers.sha3_hash(content) # lazy hack, TODO use var
                try:
                    tempHash = tempHash.decode()
                except AttributeError:
                    pass
                # Punish peer for sharing invalid block (not always malicious, but is bad regardless)
                onionrpeers.PeerProfiles(peerUsed).addScore(-50)
                if tempHash != 'ed55e34cb828232d6c14da0479709bfa10a0923dca2b380496e6b2ed4f7a0253':
                    # Dumb hack for 404 response from peer. Don't log it if 404 since its likely not malicious or a critical error.
                    logger.warn(
                        'Block hash validation failed for ' +
                        blockHash + ' got ' + tempHash)
                else:
                    removeFromQueue = False # Don't remove from queue if 404
            if removeFromQueue:
                try:
                    del comm_inst.blockQueue[blockHash] # remove from block queue both if success or false
                    if count == LOG_SKIP_COUNT:
                        logger.info('%s blocks remaining in queue' %
                        [len(comm_inst.blockQueue)], terminal=True)
                        count = 0
                except KeyError:
                    pass
        comm_inst.currentDownloading.remove(blockHash)
    comm_inst.decrementThreadCount('getBlocks')