import os
import pickle
import threading

import state
from bmconfigparser import BMConfigParser

knownNodesLock = threading.Lock()
knownNodes = {}

knownNodesTrimAmount = 2000

# forget a node after rating is this low
knownNodesForgetRating = -0.5


def saveKnownNodes(dirName=None):
    if dirName is None:
        dirName = state.appdata
    with knownNodesLock:
        with open(os.path.join(dirName, 'knownnodes.dat'), 'wb') as output:
            pickle.dump(knownNodes, output)


def increaseRating(peer):
    increaseAmount = 0.1
    maxRating = 1
    with knownNodesLock:
        for stream in knownNodes.keys():
            try:
                knownNodes[stream][peer]["rating"] = min(
                    knownNodes[stream][peer]["rating"] + increaseAmount,
                    maxRating
                )
            except KeyError:
                pass


def decreaseRating(peer):
    decreaseAmount = 0.1
    minRating = -1
    with knownNodesLock:
        for stream in knownNodes.keys():
            try:
                knownNodes[stream][peer]["rating"] = max(
                    knownNodes[stream][peer]["rating"] - decreaseAmount,
                    minRating
                )
            except KeyError:
                pass


def trimKnownNodes(recAddrStream=1):
    if len(knownNodes[recAddrStream]) < \
            BMConfigParser().safeGetInt("knownnodes", "maxnodes"):
        return
    with knownNodesLock:
        oldestList = sorted(
            knownNodes[recAddrStream],
            key=lambda x: x['lastseen']
        )[:knownNodesTrimAmount]
        for oldest in oldestList:
            del knownNodes[recAddrStream][oldest]