#!/usr/bin/env python3
'''
    Onionr - P2P Microblogging Platform & Social network.

    This file contains both the OnionrCommunicate class for communcating with peers
    and code to operate as a daemon, getting commands from the command queue database (see core.Core.daemonQueue)
'''
'''
    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/>.
'''
import sys, os, core, config, json, onionrblockapi as block, requests, time, logger, threading, onionrplugins as plugins, base64
import onionrexceptions
from defusedxml import minidom

class OnionrCommunicatorDaemon:
    def __init__(self, debug, developmentMode):
        logger.warn('New (unstable) communicator is being used.')

        # list of timer instances
        self.timers = []

        # initalize core with Tor socks port being 3rd argument
        self.proxyPort = sys.argv[2]
        self._core = core.Core(torPort=self.proxyPort)

        # intalize NIST beacon salt and time
        self.nistSaltTimestamp = 0
        self.powSalt = 0

        # loop time.sleep delay in seconds
        self.delay = 1

        # time app started running for info/statistics purposes
        self.startTime = self._core._utils.getEpoch()

        # lists of connected peers and peers we know we can't reach currently
        self.onlinePeers = []
        self.offlinePeers = []

        # amount of threads running by name, used to prevent too many
        self.threadCounts = {}
        
        # set true when shutdown command recieved
        self.shutdown = False

        # list of new blocks to download, added to when new block lists are fetched from peers
        self.blockQueue = []
        
        # Clear the daemon queue for any dead messages
        if os.path.exists(self._core.queueDB):
            self._core.clearDaemonQueue()

        # Loads in and starts the enabled plugins
        plugins.reload()

        # Print nice header thing :)
        if config.get('general.display_header', True):
            self.header()

        if debug or developmentMode:
            OnionrCommunicatorTimers(self, self.heartbeat, 10)
        
        # Initalize peer online list
        self.getOnlinePeers()

        # Set timers, function reference, seconds
        OnionrCommunicatorTimers(self, self.daemonCommands, 5)
        OnionrCommunicatorTimers(self, self.detectAPICrash, 5)
        OnionrCommunicatorTimers(self, self.getOnlinePeers, 60)
        OnionrCommunicatorTimers(self, self.lookupBlocks, 7)
        OnionrCommunicatorTimers(self, self.getBlocks, 10)
        OnionrCommunicatorTimers(self, self.clearOfflinePeer, 120)
        OnionrCommunicatorTimers(self, self.lookupKeys, 125)
        OnionrCommunicatorTimers(self, self.lookupAdders, 600)

        # Main daemon loop, mainly for calling timers, don't do any complex operations here to avoid locking
        while not self.shutdown:
            for i in self.timers:
                i.processTimer()
            time.sleep(self.delay)
        logger.info('Goodbye.')
    
    def lookupKeys(self):
        '''Lookup new keys'''
        logger.info('LOOKING UP NEW KEYS')
        tryAmount = 1
        for i in range(tryAmount):
            # Download new key list from random online peers
            peer = self.pickOnlinePeer()
            newKeys = self.peerAction(peer, action='kex')
            self._core._utils.mergeKeys(newKeys)
        
        self.decrementThreadCount('lookupKeys')
        return
    
    def lookupAdders(self):
        '''Lookup new peer addresses'''
        logger.info('LOOKING UP NEW ADDRESSES')
        tryAmount = 1
        for i in range(tryAmount):
            # Download new peer address list from random online peers
            peer = self.pickOnlinePeer()
            newAdders = self.peerAction(peer, action='pex')
            self._core._utils.mergeAdders(newAdders)
        
        self.decrementThreadCount('lookupKeys')

    def lookupBlocks(self):
        '''Lookup new blocks & add them to download queue'''
        logger.info('LOOKING UP NEW BLOCKS')
        tryAmount = 2
        newBlocks = ''
        for i in range(tryAmount):
            peer = self.pickOnlinePeer() # select random online peer
            newDBHash = self.peerAction(peer, 'getDBHash') # get their db hash
            if newDBHash == False:
                continue # if request failed, restart loop (peer is added to offline peers automatically)
            if newDBHash != self._core.getAddressInfo(peer, 'DBHash'):
                self._core.setAddressInfo(peer, 'DBHash', newDBHash)
                newBlocks = self.peerAction(peer, 'getBlockHashes')
                if newBlocks != False:
                    # if request was a success
                    for i in newBlocks.split('\n'):
                        if self._core._utils.validateHash(i):
                            # if newline seperated string is valid hash
                            if not os.path.exists('data/blocks/' + i + '.db'):
                                # if block does not exist on disk and is not already in block queue
                                if i not in self.blockQueue:
                                    self.blockQueue.append(i)
        self.decrementThreadCount('lookupBlocks')
        return

    def getBlocks(self):
        '''download new blocks in queue'''
        for blockHash in self.blockQueue:
            logger.info("ATTEMPTING TO DOWNLOAD " + blockHash)
            content = self.peerAction(self.pickOnlinePeer(), 'getData', data=blockHash) # block content from random peer (includes metadata)
            if content != False:
                try:
                    content = content.encode()
                except AttributeError:
                    pass
                content = base64.b64decode(content) # content is base64 encoded in transport
                if self._core._crypto.sha3Hash(content) == blockHash:
                    content = content.decode() # decode here because sha3Hash needs bytes above
                    metas = self._core._utils.getBlockMetadataFromData(content) # returns tuple(metadata, meta), meta is also in metadata
                    metadata = metas[0]
                    meta = metas[1]
                    if self._core._utils.validateMetadata(metadata): # check if metadata is valid
                        if self._core._crypto.verifyPow(metas[2], metadata): # check if POW is enough/correct
                            logger.info('Block passed proof, saving.')
                            self._core.setData(content)
                            self._core.addToBlockDB(blockHash, dataSaved=True)
                        else:
                            logger.warn('POW failed for block ' + blockHash)
                    else:
                        logger.warn('Metadata for ' + blockHash + ' is invalid.')
                else:
                    # if block didn't meet expected hash
                    logger.warn('Block hash validation failed for ' + blockHash + ' got ' + self._core._crypto.sha3Hash(content))
                self.blockQueue.remove(blockHash) # remove from block queue both if success or false
        self.decrementThreadCount('getBlocks')
        return

    def pickOnlinePeer(self):
        '''randomly picks peer from pool without bias (using secrets module)'''
        retData = ''
        while True:
            peerLength = len(self.onlinePeers)
            if peerLength <= 0:
                break
            try:
                # get a random online peer, securely. May get stuck in loop if network is lost or if all peers in pool magically disconnect at once
                retData = self.onlinePeers[self._core._crypto.secrets.randbelow(peerLength)]
            except IndexError:
                pass
            else:
                break
        return retData

    def decrementThreadCount(self, threadName):
        '''Decrement amount of a thread name if more than zero, called when a function meant to be run in a thread ends'''
        try:
            if self.threadCounts[threadName] > 0:
                self.threadCounts[threadName] -= 1
        except KeyError:
            pass
    
    def clearOfflinePeer(self):
        '''Removes the longest offline peer to retry later'''
        try:
            removed = self.offlinePeers.pop(0)
        except IndexError:
            pass
        else:
            logger.debug('removed ' + removed + ' from offline list to try them again.')
        self.decrementThreadCount('clearOfflinePeer')

    def getOnlinePeers(self):
        '''Manages the self.onlinePeers attribute list, connects to more peers if we have none connected'''

        logger.info('Refreshing peer pool.')
        maxPeers = 4
        needed = maxPeers - len(self.onlinePeers)

        for i in range(needed):
            if len(self.onlinePeers) == 0:
                self.connectNewPeer(useBootstrap=True)
        self.decrementThreadCount('getOnlinePeers')

    def addBootstrapListToPeerList(self, peerList):
        '''Add the bootstrap list to the peer list (no duplicates)'''
        for i in self._core.bootstrapList:
            if i not in peerList:
                peerList.append(i)

    def connectNewPeer(self, peer='', useBootstrap=False):
        '''Adds a new random online peer to self.onlinePeers'''
        retData = False
        tried = self.offlinePeers
        if peer != '':
            if self._core._utils.validateID(peer):
                peerList = [peer]
            else:
                raise onionrexceptions.InvalidAddress('Will not attempt connection test to invalid address')
        else:
            peerList = self._core.listAdders()

        if len(peerList) == 0 or useBootstrap:
            # Avoid duplicating bootstrap addresses in peerList
            self.addBootstrapListToPeerList(peerList)

        for address in peerList:
            if len(address) == 0 or address in tried or address in self.onlinePeers:
                continue
            if self.peerAction(address, 'ping') == 'pong!':
                logger.info('Connected to ' + address)
                self.onlinePeers.append(address)
                retData = address
                break
            else:
                tried.append(address)
                logger.debug('Failed to connect to ' + address)
        else:
            if len(self.onlinePeers) == 0:
                logger.warn('Could not connect to any peer')
        return retData
          
    def printOnlinePeers(self):
        '''logs online peer list'''
        if len(self.onlinePeers) == 0:
            logger.warn('No online peers')
            return
        for i in self.onlinePeers:
            logger.info(self.onlinePeers[i])

    def peerAction(self, peer, action, data=''):
        '''Perform a get request to a peer'''
        if len(peer) == 0:
            return False
        logger.info('Performing ' + action + ' with ' + peer + ' on port ' + str(self.proxyPort))
        url = 'http://' + peer + '/public/?action=' + action
        if len(data) > 0:
            url += '&data=' + data
        retData = self._core._utils.doGetRequest(url, port=self.proxyPort)
        # if request failed, (error), mark peer offline
        if retData == False:
            try:
                self.onlinePeers.remove(peer)
                self.getOnlinePeers() # Will only add a new peer to pool if needed
            except ValueError:
                pass
        return retData

    def heartbeat(self):
        '''Show a heartbeat debug message'''
        currentTime = self._core._utils.getEpoch() - self.startTime
        logger.debug('heartbeat, running seconds: ' + str(currentTime))
        self.decrementThreadCount('heartbeat')

    def daemonCommands(self):
        '''process daemon commands from daemonQueue'''
        cmd = self._core.daemonQueue()

        if cmd is not False:
            if cmd[0] == 'shutdown':
                self.shutdown = True
            elif cmd[0] == 'announceNode':
                self.announce(cmd[1])
            elif cmd[0] == 'runCheck':
                logger.debug('Status check; looks good.')
                open('data/.runcheck', 'w+').close()
            elif cmd[0] == 'connectedPeers':
                self.printOnlinePeers()
            elif cmd[0] == 'kex':
                self.timers['lookupKeys'].count = (self.timers['lookupKeys'].frequency - 1)
            else:
                logger.info('Recieved daemonQueue command:' + cmd[0])
        self.decrementThreadCount('daemonCommands')

    def announce(self, peer):
        '''Announce to peers our address'''
        announceCount = 0
        announceAmount = 2
        for peer in self._core.listAdders():
            announceCount += 1
            if self.peerAction(peer, 'announce', self._core.hsAdder) == 'Success':
                logger.info('Successfully introduced node to ' + peer)
                break
            else:
                if announceCount == announceAmount:
                    logger.warn('Could not introduce node. Try again soon')
                    break

    def detectAPICrash(self):
        '''exit if the api server crashes/stops'''
        if self._core._utils.localCommand('ping', silent=False) != 'pong':
            for i in range(5):
                if self._core._utils.localCommand('ping') == 'pong':
                    break # break for loop
                time.sleep(1)
            else:
                # This executes if the api is NOT detected to be running
                logger.error('Daemon detected API crash (or otherwise unable to reach API after long time), stopping...')
                self.shutdown = True
        self.decrementThreadCount('detectAPICrash')

    def header(self, message = logger.colors.fg.pink + logger.colors.bold + 'Onionr' + logger.colors.reset + logger.colors.fg.pink + ' has started.'):
        if os.path.exists('static-data/header.txt'):
            with open('static-data/header.txt', 'rb') as file:
                # only to stdout, not file or log or anything
                print(file.read().decode().replace('P', logger.colors.fg.pink).replace('W', logger.colors.reset + logger.colors.bold).replace('G', logger.colors.fg.green).replace('\n', logger.colors.reset + '\n'))
                logger.info(logger.colors.fg.lightgreen + '-> ' + str(message) + logger.colors.reset + logger.colors.fg.lightgreen + ' <-\n')

class OnionrCommunicatorTimers:
    def __init__(self, daemonInstance, timerFunction, frequency, makeThread=True, threadAmount=1, maxThreads=5):
        self.timerFunction = timerFunction
        self.frequency = frequency
        self.threadAmount = threadAmount
        self.makeThread = makeThread
        self.daemonInstance = daemonInstance
        self.maxThreads = maxThreads
        self._core = self.daemonInstance._core

        self.daemonInstance.timers.append(self)
        self.count = 0

    def processTimer(self):
        # mark how many instances of a thread we have (decremented at thread end)
        self.count += 1
        try:
            self.daemonInstance.threadCounts[self.timerFunction.__name__]
        except KeyError:
            self.daemonInstance.threadCounts[self.timerFunction.__name__] = 0
        # execute thread if it is time
        if self.count == self.frequency:
            if self.makeThread:
                for i in range(self.threadAmount):
                    if self.daemonInstance.threadCounts[self.timerFunction.__name__] >= self.maxThreads:
                        logger.warn(self.timerFunction.__name__ + ' has too many current threads to start anymore.')
                    else:
                        self.daemonInstance.threadCounts[self.timerFunction.__name__] += 1
                        newThread = threading.Thread(target=self.timerFunction)
                        newThread.start()
            else:
                self.timerFunction()
            self.count = 0

shouldRun = False
debug = True
developmentMode = False
if config.get('general.dev_mode', True):
    developmentMode = True
try:
    if sys.argv[1] == 'run':
        shouldRun = True
except IndexError:
    pass
if shouldRun:
    try:
        OnionrCommunicatorDaemon(debug, developmentMode)
    except KeyboardInterrupt:
        sys.exit(1)
        pass
    except Exception as e:
        logger.error('Error occured in Communicator', error = e, timestamp = False)