epicyon/utils.py

__filename__ = "utils.py"
__author__ = "Bob Mottram"
__license__ = "AGPL3+"
__version__ = "1.2.0"
__maintainer__ = "Bob Mottram"
__email__ = "bob@freedombone.net"
__status__ = "Production"

import os
import time
import shutil
import datetime
import json
import idna
from pprint import pprint
from calendar import monthrange
from followingCalendar import addPersonToCalendar
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes

# posts containing these strings will always get screened out,
# both incoming and outgoing.
# Could include dubious clacks or admin dogwhistles
invalidCharacters = (
    '卐', '卍', '࿕', '࿖', '࿗', '࿘'
)


def isFeaturedWriter(baseDir: str, nickname: str, domain: str) -> bool:
    """Is the given account a featured writer, appearing in the features
    timeline on news instances?
    """
    featuresBlockedFilename = \
        baseDir + '/accounts/' + \
        nickname + '@' + domain + '/.nofeatures'
    return not os.path.isfile(featuresBlockedFilename)


def refreshNewswire(baseDir: str):
    """Causes the newswire to be updates after a change to user accounts
    """
    refreshNewswireFilename = baseDir + '/accounts/.refresh_newswire'
    if os.path.isfile(refreshNewswireFilename):
        return
    refreshFile = open(refreshNewswireFilename, 'w+')
    refreshFile.write('\n')
    refreshFile.close()


def getSHA256(msg: str):
    """Returns a SHA256 hash of the given string
    """
    digest = hashes.Hash(hashes.SHA256(), backend=default_backend())
    digest.update(msg)
    return digest.finalize()


def _localNetworkHost(host: str) -> bool:
    """Returns true if the given host is on the local network
    """
    if host.startswith('localhost') or \
       host.startswith('192.') or \
       host.startswith('127.') or \
       host.startswith('10.'):
        return True
    return False


def decodedHost(host: str) -> str:
    """Convert hostname to internationalized domain
    https://en.wikipedia.org/wiki/Internationalized_domain_name
    """
    if ':' not in host:
        # eg. mydomain:8000
        if not _localNetworkHost(host):
            if not host.endswith('.onion'):
                if not host.endswith('.i2p'):
                    return idna.decode(host)
    return host


def getLockedAccount(actorJson: {}) -> bool:
    """Returns whether the given account requires follower approval
    """
    if not actorJson.get('manuallyApprovesFollowers'):
        return False
    if actorJson['manuallyApprovesFollowers'] is True:
        return True
    return False


def hasUsersPath(pathStr: str) -> bool:
    """Whether there is a /users/ path (or equivalent) in the given string
    """
    usersList = ('users', 'accounts', 'channel', 'profile', 'u')
    for usersStr in usersList:
        if '/' + usersStr + '/' in pathStr:
            return True
    return False


def validPostDate(published: str, maxAgeDays=7) -> bool:
    """Returns true if the published date is recent and is not in the future
    """
    baselineTime = datetime.datetime(1970, 1, 1)

    daysDiff = datetime.datetime.utcnow() - baselineTime
    nowDaysSinceEpoch = daysDiff.days

    try:
        postTimeObject = \
            datetime.datetime.strptime(published, "%Y-%m-%dT%H:%M:%SZ")
    except BaseException:
        return False

    daysDiff = postTimeObject - baselineTime
    postDaysSinceEpoch = daysDiff.days

    if postDaysSinceEpoch > nowDaysSinceEpoch:
        print("Inbox post has a published date in the future!")
        return False

    if nowDaysSinceEpoch - postDaysSinceEpoch >= maxAgeDays:
        print("Inbox post is not recent enough")
        return False
    return True


def getFullDomain(domain: str, port: int) -> str:
    """Returns the full domain name, including port number
    """
    if not port:
        return domain
    if ':' in domain:
        return domain
    if port == 80 or port == 443:
        return domain
    return domain + ':' + str(port)


def isDormant(baseDir: str, nickname: str, domain: str, actor: str,
              dormantMonths=3) -> bool:
    """Is the given followed actor dormant, from the standpoint
    of the given account
    """
    lastSeenFilename = \
        baseDir + '/accounts/' + nickname + '@' + domain + \
        '/lastseen/' + actor.replace('/', '#') + '.txt'

    if not os.path.isfile(lastSeenFilename):
        return False

    with open(lastSeenFilename, 'r') as lastSeenFile:
        daysSinceEpochStr = lastSeenFile.read()
        daysSinceEpoch = int(daysSinceEpochStr)
        currTime = datetime.datetime.utcnow()
        currDaysSinceEpoch = (currTime - datetime.datetime(1970, 1, 1)).days
        timeDiffMonths = \
            int((currDaysSinceEpoch - daysSinceEpoch) / 30)
        if timeDiffMonths >= dormantMonths:
            return True
    return False


def isEditor(baseDir: str, nickname: str) -> bool:
    """Returns true if the given nickname is an editor
    """
    editorsFile = baseDir + '/accounts/editors.txt'

    if not os.path.isfile(editorsFile):
        adminName = getConfigParam(baseDir, 'admin')
        if not adminName:
            return False
        if adminName == nickname:
            return True
        return False

    with open(editorsFile, "r") as f:
        lines = f.readlines()
        if len(lines) == 0:
            adminName = getConfigParam(baseDir, 'admin')
            if not adminName:
                return False
            if adminName == nickname:
                return True
        for editor in lines:
            editor = editor.strip('\n').strip('\r')
            if editor == nickname:
                return True
    return False


def getImageExtensions() -> []:
    """Returns a list of the possible image file extensions
    """
    return ('png', 'jpg', 'jpeg', 'gif', 'webp', 'avif', 'svg')


def getVideoExtensions() -> []:
    """Returns a list of the possible video file extensions
    """
    return ('mp4', 'webm', 'ogv')


def getAudioExtensions() -> []:
    """Returns a list of the possible audio file extensions
    """
    return ('mp3', 'ogg')


def getMediaExtensions() -> []:
    """Returns a list of the possible media file extensions
    """
    return getImageExtensions() + getVideoExtensions() + getAudioExtensions()


def getImageFormats() -> str:
    """Returns a string of permissable image formats
    used when selecting an image for a new post
    """
    imageExt = getImageExtensions()

    imageFormats = ''
    for ext in imageExt:
        if imageFormats:
            imageFormats += ', '
        imageFormats += '.' + ext
    return imageFormats


def getMediaFormats() -> str:
    """Returns a string of permissable media formats
    used when selecting an attachment for a new post
    """
    mediaExt = getMediaExtensions()

    mediaFormats = ''
    for ext in mediaExt:
        if mediaFormats:
            mediaFormats += ', '
        mediaFormats += '.' + ext
    return mediaFormats


def removeHtml(content: str) -> str:
    """Removes html links from the given content.
    Used to ensure that profile descriptions don't contain dubious content
    """
    if '<' not in content:
        return content
    removing = False
    content = content.replace('<q>', '"').replace('</q>', '"')
    result = ''
    for ch in content:
        if ch == '<':
            removing = True
        elif ch == '>':
            removing = False
        elif not removing:
            result += ch
    return result


def firstParagraphFromString(content: str) -> str:
    """Get the first paragraph from a blog post
    to be used as a summary in the newswire feed
    """
    if '<p>' not in content or '</p>' not in content:
        return removeHtml(content)
    paragraph = content.split('<p>')[1]
    if '</p>' in paragraph:
        paragraph = paragraph.split('</p>')[0]
    return removeHtml(paragraph)


def isSystemAccount(nickname: str) -> bool:
    """Returns true if the given nickname is a system account
    """
    if nickname == 'news' or nickname == 'inbox':
        return True
    return False


def _createConfig(baseDir: str) -> None:
    """Creates a configuration file
    """
    configFilename = baseDir + '/config.json'
    if os.path.isfile(configFilename):
        return
    configJson = {
    }
    saveJson(configJson, configFilename)


def setConfigParam(baseDir: str, variableName: str, variableValue) -> None:
    """Sets a configuration value
    """
    _createConfig(baseDir)
    configFilename = baseDir + '/config.json'
    configJson = {}
    if os.path.isfile(configFilename):
        configJson = loadJson(configFilename)
    configJson[variableName] = variableValue
    saveJson(configJson, configFilename)


def getConfigParam(baseDir: str, variableName: str):
    """Gets a configuration value
    """
    _createConfig(baseDir)
    configFilename = baseDir + '/config.json'
    configJson = loadJson(configFilename)
    if configJson:
        if variableName in configJson:
            return configJson[variableName]
    return None


def isSuspended(baseDir: str, nickname: str) -> bool:
    """Returns true if the given nickname is suspended
    """
    adminNickname = getConfigParam(baseDir, 'admin')
    if not adminNickname:
        return False
    if nickname == adminNickname:
        return False

    suspendedFilename = baseDir + '/accounts/suspended.txt'
    if os.path.isfile(suspendedFilename):
        with open(suspendedFilename, "r") as f:
            lines = f.readlines()
        for suspended in lines:
            if suspended.strip('\n').strip('\r') == nickname:
                return True
    return False


def getFollowersList(baseDir: str,
                     nickname: str, domain: str,
                     followFile='following.txt') -> []:
    """Returns a list of followers for the given account
    """
    filename = \
        baseDir + '/accounts/' + nickname + '@' + domain + '/' + followFile

    if not os.path.isfile(filename):
        return []

    with open(filename, "r") as f:
        lines = f.readlines()
        for i in range(len(lines)):
            lines[i] = lines[i].strip()
        return lines
    return []


def getFollowersOfPerson(baseDir: str,
                         nickname: str, domain: str,
                         followFile='following.txt') -> []:
    """Returns a list containing the followers of the given person
    Used by the shared inbox to know who to send incoming mail to
    """
    followers = []
    if ':' in domain:
        domain = domain.split(':')[0]
    handle = nickname + '@' + domain
    if not os.path.isdir(baseDir + '/accounts/' + handle):
        return followers
    for subdir, dirs, files in os.walk(baseDir + '/accounts'):
        for account in dirs:
            filename = os.path.join(subdir, account) + '/' + followFile
            if account == handle or account.startswith('inbox@'):
                continue
            if not os.path.isfile(filename):
                continue
            with open(filename, 'r') as followingfile:
                for followingHandle in followingfile:
                    followingHandle2 = followingHandle.replace('\n', '')
                    followingHandle2 = followingHandle2.replace('\r', '')
                    if followingHandle2 == handle:
                        if account not in followers:
                            followers.append(account)
                        break
        break
    return followers


def removeIdEnding(idStr: str) -> str:
    """Removes endings such as /activity and /undo
    """
    if idStr.endswith('/activity'):
        idStr = idStr[:-len('/activity')]
    elif idStr.endswith('/undo'):
        idStr = idStr[:-len('/undo')]
    elif idStr.endswith('/event'):
        idStr = idStr[:-len('/event')]
    elif idStr.endswith('/replies'):
        idStr = idStr[:-len('/replies')]
    return idStr


def getProtocolPrefixes() -> []:
    """Returns a list of valid prefixes
    """
    return ('https://', 'http://', 'ftp://',
            'dat://', 'i2p://', 'gnunet://',
            'hyper://', 'gemini://', 'gopher://')


def getLinkPrefixes() -> []:
    """Returns a list of valid web link prefixes
    """
    return ('https://', 'http://', 'ftp://',
            'dat://', 'i2p://', 'gnunet://',
            'hyper://', 'gemini://', 'gopher://', 'briar:')


def removeAvatarFromCache(baseDir: str, actorStr: str) -> None:
    """Removes any existing avatar entries from the cache
    This avoids duplicate entries with differing extensions
    """
    avatarFilenameExtensions = getImageExtensions()
    for extension in avatarFilenameExtensions:
        avatarFilename = \
            baseDir + '/cache/avatars/' + actorStr + '.' + extension
        if os.path.isfile(avatarFilename):
            os.remove(avatarFilename)


def saveJson(jsonObject: {}, filename: str) -> bool:
    """Saves json to a file
    """
    tries = 0
    while tries < 5:
        try:
            with open(filename, 'w+') as fp:
                fp.write(json.dumps(jsonObject))
                return True
        except BaseException:
            print('WARN: saveJson ' + str(tries))
            time.sleep(1)
            tries += 1
    return False


def loadJson(filename: str, delaySec=2, maxTries=5) -> {}:
    """Makes a few attempts to load a json formatted file
    """
    jsonObject = None
    tries = 0
    while tries < maxTries:
        try:
            with open(filename, 'r') as fp:
                data = fp.read()
                jsonObject = json.loads(data)
                break
        except BaseException:
            print('WARN: loadJson exception')
            if delaySec > 0:
                time.sleep(delaySec)
            tries += 1
    return jsonObject


def loadJsonOnionify(filename: str, domain: str, onionDomain: str,
                     delaySec=2) -> {}:
    """Makes a few attempts to load a json formatted file
    This also converts the domain name to the onion domain
    """
    jsonObject = None
    tries = 0
    while tries < 5:
        try:
            with open(filename, 'r') as fp:
                data = fp.read()
                if data:
                    data = data.replace(domain, onionDomain)
                    data = data.replace('https:', 'http:')
                    print('*****data: ' + data)
                jsonObject = json.loads(data)
                break
        except BaseException:
            print('WARN: loadJson exception')
            if delaySec > 0:
                time.sleep(delaySec)
            tries += 1
    return jsonObject


def getStatusNumber(publishedStr=None) -> (str, str):
    """Returns the status number and published date
    """
    if not publishedStr:
        currTime = datetime.datetime.utcnow()
    else:
        currTime = \
            datetime.datetime.strptime(publishedStr, '%Y-%m-%dT%H:%M:%SZ')
    daysSinceEpoch = (currTime - datetime.datetime(1970, 1, 1)).days
    # status is the number of seconds since epoch
    statusNumber = \
        str(((daysSinceEpoch * 24 * 60 * 60) +
             (currTime.hour * 60 * 60) +
             (currTime.minute * 60) +
             currTime.second) * 1000 +
            int(currTime.microsecond / 1000))
    # See https://github.com/tootsuite/mastodon/blob/
    # 995f8b389a66ab76ec92d9a240de376f1fc13a38/lib/mastodon/snowflake.rb
    # use the leftover microseconds as the sequence number
    sequenceId = currTime.microsecond % 1000
    # shift by 16bits "sequence data"
    statusNumber = str((int(statusNumber) << 16) + sequenceId)
    published = currTime.strftime("%Y-%m-%dT%H:%M:%SZ")
    return statusNumber, published


def evilIncarnate() -> []:
    return ('gab.com', 'gabfed.com', 'spinster.xyz',
            'kiwifarms.cc', 'djitter.com')


def isEvil(domain: str) -> bool:
    # https://www.youtube.com/watch?v=5qw1hcevmdU
    if not isinstance(domain, str):
        print('WARN: Malformed domain ' + str(domain))
        return True
    # if a domain contains any of these strings then it is
    # declaring itself to be hostile
    evilEmporium = (
        'nazi', 'extremis', 'extreemis', 'gendercritic',
        'kiwifarm', 'illegal', 'raplst', 'rapist',
        'antivax', 'plandemic'
    )
    for hostileStr in evilEmporium:
        if hostileStr in domain:
            return True
    evilDomains = evilIncarnate()
    for concentratedEvil in evilDomains:
        if domain.endswith(concentratedEvil):
            return True
    return False


def containsInvalidChars(jsonStr: str) -> bool:
    """Does the given json string contain invalid characters?
    """
    for isInvalid in invalidCharacters:
        if isInvalid in jsonStr:
            return True
    return False


def removeInvalidChars(text: str) -> str:
    """Removes any invalid characters from a string
    """
    for isInvalid in invalidCharacters:
        if isInvalid not in text:
            continue
        text = text.replace(isInvalid, '')
    return text


def createPersonDir(nickname: str, domain: str, baseDir: str,
                    dirname: str) -> str:
    """Create a directory for a person
    """
    handle = nickname + '@' + domain
    if not os.path.isdir(baseDir + '/accounts/' + handle):
        os.mkdir(baseDir + '/accounts/' + handle)
    boxDir = baseDir + '/accounts/' + handle + '/' + dirname
    if not os.path.isdir(boxDir):
        os.mkdir(boxDir)
    return boxDir


def createOutboxDir(nickname: str, domain: str, baseDir: str) -> str:
    """Create an outbox for a person
    """
    return createPersonDir(nickname, domain, baseDir, 'outbox')


def createInboxQueueDir(nickname: str, domain: str, baseDir: str) -> str:
    """Create an inbox queue and returns the feed filename and directory
    """
    return createPersonDir(nickname, domain, baseDir, 'queue')


def domainPermitted(domain: str, federationList: []):
    if len(federationList) == 0:
        return True
    if ':' in domain:
        domain = domain.split(':')[0]
    if domain in federationList:
        return True
    return False


def urlPermitted(url: str, federationList: []):
    if isEvil(url):
        return False
    if not federationList:
        return True
    for domain in federationList:
        if domain in url:
            return True
    return False


def getLocalNetworkAddresses() -> []:
    """Returns patterns for local network address detection
    """
    return ('localhost', '127.0.', '192.168', '10.0.')


def dangerousMarkup(content: str, allowLocalNetworkAccess: bool) -> bool:
    """Returns true if the given content contains dangerous html markup
    """
    if '<' not in content:
        return False
    if '>' not in content:
        return False
    contentSections = content.split('<')
    invalidPartials = ()
    if not allowLocalNetworkAccess:
        invalidPartials = getLocalNetworkAddresses()
    invalidStrings = ('script', 'canvas', 'style', 'abbr',
                      'frame', 'iframe', 'html', 'body',
                      'hr', 'allow-popups', 'allow-scripts')
    for markup in contentSections:
        if '>' not in markup:
            continue
        markup = markup.split('>')[0].strip()
        for partialMatch in invalidPartials:
            if partialMatch in markup:
                return True
        if ' ' not in markup:
            for badStr in invalidStrings:
                if badStr in markup:
                    return True
        else:
            for badStr in invalidStrings:
                if badStr + ' ' in markup:
                    return True
    return False


def getDisplayName(baseDir: str, actor: str, personCache: {}) -> str:
    """Returns the display name for the given actor
    """
    if '/statuses/' in actor:
        actor = actor.split('/statuses/')[0]
    if not personCache.get(actor):
        return None
    nameFound = None
    if personCache[actor].get('actor'):
        if personCache[actor]['actor'].get('name'):
            nameFound = personCache[actor]['actor']['name']
    else:
        # Try to obtain from the cached actors
        cachedActorFilename = \
            baseDir + '/cache/actors/' + (actor.replace('/', '#')) + '.json'
        if os.path.isfile(cachedActorFilename):
            actorJson = loadJson(cachedActorFilename, 1)
            if actorJson:
                if actorJson.get('name'):
                    nameFound = actorJson['name']
    if nameFound:
        if dangerousMarkup(nameFound, False):
            nameFound = "*ADVERSARY*"
    return nameFound


def getNicknameFromActor(actor: str) -> str:
    """Returns the nickname from an actor url
    """
    if actor.startswith('@'):
        actor = actor[1:]
    if '/users/' not in actor:
        if '/profile/' in actor:
            nickStr = actor.split('/profile/')[1].replace('@', '')
            if '/' not in nickStr:
                return nickStr
            else:
                return nickStr.split('/')[0]
        elif '/channel/' in actor:
            nickStr = actor.split('/channel/')[1].replace('@', '')
            if '/' not in nickStr:
                return nickStr
            else:
                return nickStr.split('/')[0]
        elif '/accounts/' in actor:
            nickStr = actor.split('/accounts/')[1].replace('@', '')
            if '/' not in nickStr:
                return nickStr
            else:
                return nickStr.split('/')[0]
        elif '/u/' in actor:
            nickStr = actor.split('/u/')[1].replace('@', '')
            if '/' not in nickStr:
                return nickStr
            else:
                return nickStr.split('/')[0]
        elif '/@' in actor:
            # https://domain/@nick
            nickStr = actor.split('/@')[1]
            if '/' in nickStr:
                nickStr = nickStr.split('/')[0]
            return nickStr
        elif '@' in actor:
            nickStr = actor.split('@')[0]
            return nickStr
        return None
    nickStr = actor.split('/users/')[1].replace('@', '')
    if '/' not in nickStr:
        return nickStr
    else:
        return nickStr.split('/')[0]


def getDomainFromActor(actor: str) -> (str, int):
    """Returns the domain name from an actor url
    """
    if actor.startswith('@'):
        actor = actor[1:]
    port = None
    prefixes = getProtocolPrefixes()
    if '/profile/' in actor:
        domain = actor.split('/profile/')[0]
        for prefix in prefixes:
            domain = domain.replace(prefix, '')
    elif '/accounts/' in actor:
        domain = actor.split('/accounts/')[0]
        for prefix in prefixes:
            domain = domain.replace(prefix, '')
    elif '/channel/' in actor:
        domain = actor.split('/channel/')[0]
        for prefix in prefixes:
            domain = domain.replace(prefix, '')
    elif '/users/' in actor:
        domain = actor.split('/users/')[0]
        for prefix in prefixes:
            domain = domain.replace(prefix, '')
    elif '/u/' in actor:
        domain = actor.split('/u/')[0]
        for prefix in prefixes:
            domain = domain.replace(prefix, '')
    elif '/@' in actor:
        domain = actor.split('/@')[0]
        for prefix in prefixes:
            domain = domain.replace(prefix, '')
    elif '@' in actor:
        domain = actor.split('@')[1].strip()
    else:
        domain = actor
        for prefix in prefixes:
            domain = domain.replace(prefix, '')
        if '/' in actor:
            domain = domain.split('/')[0]
    if ':' in domain:
        portStr = domain.split(':')[1]
        if not portStr.isdigit():
            return None, None
        port = int(portStr)
        domain = domain.split(':')[0]
    return domain, port


def _setDefaultPetName(baseDir: str, nickname: str, domain: str,
                       followNickname: str, followDomain: str) -> None:
    """Sets a default petname
    This helps especially when using onion or i2p address
    """
    if ':' in domain:
        domain = domain.split(':')[0]
    userPath = baseDir + '/accounts/' + nickname + '@' + domain
    petnamesFilename = userPath + '/petnames.txt'

    petnameLookupEntry = followNickname + ' ' + \
        followNickname + '@' + followDomain + '\n'
    if not os.path.isfile(petnamesFilename):
        # if there is no existing petnames lookup file
        with open(petnamesFilename, 'w+') as petnamesFile:
            petnamesFile.write(petnameLookupEntry)
        return

    with open(petnamesFilename, 'r') as petnamesFile:
        petnamesStr = petnamesFile.read()
        if petnamesStr:
            petnamesList = petnamesStr.split('\n')
            for pet in petnamesList:
                if pet.startswith(followNickname + ' '):
                    # petname already exists
                    return
    # petname doesn't already exist
    with open(petnamesFilename, 'a+') as petnamesFile:
        petnamesFile.write(petnameLookupEntry)


def followPerson(baseDir: str, nickname: str, domain: str,
                 followNickname: str, followDomain: str,
                 federationList: [], debug: bool,
                 followFile='following.txt') -> bool:
    """Adds a person to the follow list
    """
    followDomainStrLower = followDomain.lower().replace('\n', '')
    if not domainPermitted(followDomainStrLower,
                           federationList):
        if debug:
            print('DEBUG: follow of domain ' +
                  followDomain + ' not permitted')
        return False
    if debug:
        print('DEBUG: follow of domain ' + followDomain)

    if ':' in domain:
        handle = nickname + '@' + domain.split(':')[0]
    else:
        handle = nickname + '@' + domain

    if not os.path.isdir(baseDir + '/accounts/' + handle):
        print('WARN: account for ' + handle + ' does not exist')
        return False

    if ':' in followDomain:
        handleToFollow = followNickname + '@' + followDomain.split(':')[0]
    else:
        handleToFollow = followNickname + '@' + followDomain

    # was this person previously unfollowed?
    unfollowedFilename = baseDir + '/accounts/' + handle + '/unfollowed.txt'
    if os.path.isfile(unfollowedFilename):
        if handleToFollow in open(unfollowedFilename).read():
            # remove them from the unfollowed file
            newLines = ''
            with open(unfollowedFilename, "r") as f:
                lines = f.readlines()
                for line in lines:
                    if handleToFollow not in line:
                        newLines += line
            with open(unfollowedFilename, 'w+') as f:
                f.write(newLines)

    if not os.path.isdir(baseDir + '/accounts'):
        os.mkdir(baseDir + '/accounts')
    handleToFollow = followNickname + '@' + followDomain
    filename = baseDir + '/accounts/' + handle + '/' + followFile
    if os.path.isfile(filename):
        if handleToFollow in open(filename).read():
            if debug:
                print('DEBUG: follow already exists')
            return True
        # prepend to follow file
        try:
            with open(filename, 'r+') as f:
                content = f.read()
                if handleToFollow + '\n' not in content:
                    f.seek(0, 0)
                    f.write(handleToFollow + '\n' + content)
                    print('DEBUG: follow added')
        except Exception as e:
            print('WARN: Failed to write entry to follow file ' +
                  filename + ' ' + str(e))
    else:
        # first follow
        if debug:
            print('DEBUG: ' + handle +
                  ' creating new following file to follow ' + handleToFollow +
                  ', filename is ' + filename)
        with open(filename, 'w+') as f:
            f.write(handleToFollow + '\n')

    if followFile.endswith('following.txt'):
        # Default to adding new follows to the calendar.
        # Possibly this could be made optional
        # if following a person add them to the list of
        # calendar follows
        print('DEBUG: adding ' +
              followNickname + '@' + followDomain + ' to calendar of ' +
              nickname + '@' + domain)
        addPersonToCalendar(baseDir, nickname, domain,
                            followNickname, followDomain)
        # add a default petname
        _setDefaultPetName(baseDir, nickname, domain,
                           followNickname, followDomain)
    return True


def votesOnNewswireItem(status: []) -> int:
    """Returns the number of votes on a newswire item
    """
    totalVotes = 0
    for line in status:
        if 'vote:' in line:
            totalVotes += 1
    return totalVotes


def locateNewsVotes(baseDir: str, domain: str,
                    postUrl: str) -> str:
    """Returns the votes filename for a news post
    within the news user account
    """
    postUrl = \
        postUrl.strip().replace('\n', '').replace('\r', '')

    # if this post in the shared inbox?
    postUrl = removeIdEnding(postUrl.strip()).replace('/', '#')

    if postUrl.endswith('.json'):
        postUrl = postUrl + '.votes'
    else:
        postUrl = postUrl + '.json.votes'

    accountDir = baseDir + '/accounts/news@' + domain + '/'
    postFilename = accountDir + 'outbox/' + postUrl
    if os.path.isfile(postFilename):
        return postFilename

    return None


def locateNewsArrival(baseDir: str, domain: str,
                      postUrl: str) -> str:
    """Returns the arrival time for a news post
    within the news user account
    """
    postUrl = \
        postUrl.strip().replace('\n', '').replace('\r', '')

    # if this post in the shared inbox?
    postUrl = removeIdEnding(postUrl.strip()).replace('/', '#')

    if postUrl.endswith('.json'):
        postUrl = postUrl + '.arrived'
    else:
        postUrl = postUrl + '.json.arrived'

    accountDir = baseDir + '/accounts/news@' + domain + '/'
    postFilename = accountDir + 'outbox/' + postUrl
    if os.path.isfile(postFilename):
        with open(postFilename, 'r') as arrivalFile:
            arrival = arrivalFile.read()
            if arrival:
                arrivalDate = \
                    datetime.datetime.strptime(arrival,
                                               "%Y-%m-%dT%H:%M:%SZ")
                return arrivalDate

    return None


def clearFromPostCaches(baseDir: str, recentPostsCache: {},
                        postId: str) -> None:
    """Clears cached html for the given post, so that edits
    to news will appear
    """
    filename = '/postcache/' + postId + '.html'
    for subdir, dirs, files in os.walk(baseDir + '/accounts'):
        for acct in dirs:
            if '@' not in acct:
                continue
            if 'inbox@' in acct:
                continue
            cacheDir = os.path.join(baseDir + '/accounts', acct)
            postFilename = cacheDir + filename
            if os.path.isfile(postFilename):
                try:
                    os.remove(postFilename)
                except BaseException:
                    print('WARN: clearFromPostCaches file not removed ' +
                          postFilename)
                    pass
            # if the post is in the recent posts cache then remove it
            if recentPostsCache.get('index'):
                if postId in recentPostsCache['index']:
                    recentPostsCache['index'].remove(postId)
            if recentPostsCache.get('json'):
                if recentPostsCache['json'].get(postId):
                    del recentPostsCache['json'][postId]
            if recentPostsCache.get('html'):
                if recentPostsCache['html'].get(postId):
                    del recentPostsCache['html'][postId]
        break


def locatePost(baseDir: str, nickname: str, domain: str,
               postUrl: str, replies=False) -> str:
    """Returns the filename for the given status post url
    """
    if not replies:
        extension = 'json'
    else:
        extension = 'replies'

    # if this post in the shared inbox?
    postUrl = removeIdEnding(postUrl.strip()).replace('/', '#')

    # add the extension
    postUrl = postUrl + '.' + extension

    # search boxes
    boxes = ('inbox', 'outbox', 'tlblogs', 'tlevents')
    accountDir = baseDir + '/accounts/' + nickname + '@' + domain + '/'
    for boxName in boxes:
        postFilename = accountDir + boxName + '/' + postUrl
        if os.path.isfile(postFilename):
            return postFilename

    # check news posts
    accountDir = baseDir + '/accounts/news' + '@' + domain + '/'
    postFilename = accountDir + 'outbox/' + postUrl
    if os.path.isfile(postFilename):
        return postFilename

    # is it in the announce cache?
    postFilename = baseDir + '/cache/announce/' + nickname + '/' + postUrl
    if os.path.isfile(postFilename):
        return postFilename

    # print('WARN: unable to locate ' + nickname + ' ' + postUrl)
    return None


def _removeAttachment(baseDir: str, httpPrefix: str, domain: str,
                      postJson: {}):
    if not postJson.get('attachment'):
        return
    if not postJson['attachment'][0].get('url'):
        return
#    if port:
#        if port != 80 and port != 443:
#            if ':' not in domain:
#                domain = domain + ':' + str(port)
    attachmentUrl = postJson['attachment'][0]['url']
    if not attachmentUrl:
        return
    mediaFilename = baseDir + '/' + \
        attachmentUrl.replace(httpPrefix + '://' + domain + '/', '')
    if os.path.isfile(mediaFilename):
        os.remove(mediaFilename)
    etagFilename = mediaFilename + '.etag'
    if os.path.isfile(etagFilename):
        os.remove(etagFilename)
    postJson['attachment'] = []


def removeModerationPostFromIndex(baseDir: str, postUrl: str,
                                  debug: bool) -> None:
    """Removes a url from the moderation index
    """
    moderationIndexFile = baseDir + '/accounts/moderation.txt'
    if not os.path.isfile(moderationIndexFile):
        return
    postId = removeIdEnding(postUrl)
    if postId in open(moderationIndexFile).read():
        with open(moderationIndexFile, "r") as f:
            lines = f.readlines()
            with open(moderationIndexFile, "w+") as f:
                for line in lines:
                    if line.strip("\n").strip("\r") != postId:
                        f.write(line)
                    else:
                        if debug:
                            print('DEBUG: removed ' + postId +
                                  ' from moderation index')


def _isReplyToBlogPost(baseDir: str, nickname: str, domain: str,
                       postJsonObject: str):
    """Is the given post a reply to a blog post?
    """
    if not postJsonObject.get('object'):
        return False
    if not isinstance(postJsonObject['object'], dict):
        return False
    if not postJsonObject['object'].get('inReplyTo'):
        return False
    if not isinstance(postJsonObject['object']['inReplyTo'], str):
        return False
    blogsIndexFilename = baseDir + '/accounts/' + \
        nickname + '@' + domain + '/tlblogs.index'
    if not os.path.isfile(blogsIndexFilename):
        return False
    postId = removeIdEnding(postJsonObject['object']['inReplyTo'])
    postId = postId.replace('/', '#')
    if postId in open(blogsIndexFilename).read():
        return True
    return False


def deletePost(baseDir: str, httpPrefix: str,
               nickname: str, domain: str, postFilename: str,
               debug: bool, recentPostsCache: {}) -> None:
    """Recursively deletes a post and its replies and attachments
    """
    postJsonObject = loadJson(postFilename, 1)
    if postJsonObject:
        # don't allow deletion of bookmarked posts
        bookmarksIndexFilename = \
            baseDir + '/accounts/' + nickname + '@' + domain + \
            '/bookmarks.index'
        if os.path.isfile(bookmarksIndexFilename):
            bookmarkIndex = postFilename.split('/')[-1] + '\n'
            if bookmarkIndex in open(bookmarksIndexFilename).read():
                return

        # don't remove replies to blog posts
        if _isReplyToBlogPost(baseDir, nickname, domain,
                              postJsonObject):
            return

        # remove from recent posts cache in memory
        if recentPostsCache:
            postId = \
                removeIdEnding(postJsonObject['id']).replace('/', '#')
            if recentPostsCache.get('index'):
                if postId in recentPostsCache['index']:
                    recentPostsCache['index'].remove(postId)
            if recentPostsCache.get('json'):
                if recentPostsCache['json'].get(postId):
                    del recentPostsCache['json'][postId]
            if recentPostsCache.get('html'):
                if recentPostsCache['html'].get(postId):
                    del recentPostsCache['html'][postId]

        # remove any attachment
        _removeAttachment(baseDir, httpPrefix, domain, postJsonObject)

        extensions = ('votes', 'arrived', 'muted')
        for ext in extensions:
            extFilename = postFilename + '.' + ext
            if os.path.isfile(extFilename):
                os.remove(extFilename)

        # remove cached html version of the post
        cachedPostFilename = \
            getCachedPostFilename(baseDir, nickname, domain, postJsonObject)
        if cachedPostFilename:
            if os.path.isfile(cachedPostFilename):
                os.remove(cachedPostFilename)
        # removePostFromCache(postJsonObject,recentPostsCache)

        hasObject = False
        if postJsonObject.get('object'):
            hasObject = True

        # remove from moderation index file
        if hasObject:
            if isinstance(postJsonObject['object'], dict):
                if postJsonObject['object'].get('moderationStatus'):
                    if postJsonObject.get('id'):
                        postId = removeIdEnding(postJsonObject['id'])
                        removeModerationPostFromIndex(baseDir, postId, debug)

        # remove any hashtags index entries
        removeHashtagIndex = False
        if hasObject:
            if hasObject and isinstance(postJsonObject['object'], dict):
                if postJsonObject['object'].get('content'):
                    if '#' in postJsonObject['object']['content']:
                        removeHashtagIndex = True
        if removeHashtagIndex:
            if postJsonObject['object'].get('id') and \
               postJsonObject['object'].get('tag'):
                # get the id of the post
                postId = removeIdEnding(postJsonObject['object']['id'])
                for tag in postJsonObject['object']['tag']:
                    if tag['type'] != 'Hashtag':
                        continue
                    if not tag.get('name'):
                        continue
                    # find the index file for this tag
                    tagIndexFilename = \
                        baseDir + '/tags/' + tag['name'][1:] + '.txt'
                    if not os.path.isfile(tagIndexFilename):
                        continue
                    # remove postId from the tag index file
                    lines = None
                    with open(tagIndexFilename, "r") as f:
                        lines = f.readlines()
                    if lines:
                        newlines = ''
                        for fileLine in lines:
                            if postId in fileLine:
                                continue
                            newlines += fileLine
                        if not newlines.strip():
                            # if there are no lines then remove the
                            # hashtag file
                            os.remove(tagIndexFilename)
                        else:
                            with open(tagIndexFilename, "w+") as f:
                                f.write(newlines)

    # remove any replies
    repliesFilename = postFilename.replace('.json', '.replies')
    if os.path.isfile(repliesFilename):
        if debug:
            print('DEBUG: removing replies to ' + postFilename)
        with open(repliesFilename, 'r') as f:
            for replyId in f:
                replyFile = locatePost(baseDir, nickname, domain, replyId)
                if replyFile:
                    if os.path.isfile(replyFile):
                        deletePost(baseDir, httpPrefix,
                                   nickname, domain, replyFile, debug,
                                   recentPostsCache)
        # remove the replies file
        os.remove(repliesFilename)
    # finally, remove the post itself
    os.remove(postFilename)


def isValidLanguage(text: str) -> bool:
    """Returns true if the given text contains a valid
    natural language string
    """
    naturalLanguages = {
        "Latin": [65, 866],
        "Cyrillic": [1024, 1274],
        "Greek": [880, 1280],
        "isArmenian": [1328, 1424],
        "isHebrew": [1424, 1536],
        "Arabic": [1536, 1792],
        "Syriac": [1792, 1872],
        "Thaan": [1920, 1984],
        "Devanagari": [2304, 2432],
        "Bengali": [2432, 2560],
        "Gurmukhi": [2560, 2688],
        "Gujarati": [2688, 2816],
        "Oriya": [2816, 2944],
        "Tamil": [2944, 3072],
        "Telugu": [3072, 3200],
        "Kannada": [3200, 3328],
        "Malayalam": [3328, 3456],
        "Sinhala": [3456, 3584],
        "Thai": [3584, 3712],
        "Lao": [3712, 3840],
        "Tibetan": [3840, 4096],
        "Myanmar": [4096, 4256],
        "Georgian": [4256, 4352],
        "HangulJamo": [4352, 4608],
        "Cherokee": [5024, 5120],
        "UCAS": [5120, 5760],
        "Ogham": [5760, 5792],
        "Runic": [5792, 5888],
        "Khmer": [6016, 6144],
        "Mongolian": [6144, 6320]
    }
    for langName, langRange in naturalLanguages.items():
        okLang = True
        for ch in text:
            if ch.isdigit():
                continue
            if ord(ch) not in range(langRange[0], langRange[1]):
                okLang = False
                break
        if okLang:
            return True
    return False


def _isReservedName(nickname: str) -> bool:
    """Is the given nickname reserved for some special function?
    """
    reservedNames = ('inbox', 'dm', 'outbox', 'following',
                     'public', 'followers', 'category',
                     'channel', 'calendar',
                     'tlreplies', 'tlmedia', 'tlblogs',
                     'tlevents', 'tlblogs', 'tlfeatures',
                     'moderation', 'moderationaction',
                     'activity', 'undo', 'pinned',
                     'reply', 'replies', 'question', 'like',
                     'likes', 'users', 'statuses', 'tags',
                     'accounts', 'channels', 'profile', 'u',
                     'updates', 'repeat', 'announce',
                     'shares', 'fonts', 'icons', 'avatars',
                     'welcome')
    if nickname in reservedNames:
        return True
    return False


def validNickname(domain: str, nickname: str) -> bool:
    """Is the given nickname valid?
    """
    if not isValidLanguage(nickname):
        return False
    forbiddenChars = ('.', ' ', '/', '?', ':', ';', '@', '#')
    for c in forbiddenChars:
        if c in nickname:
            return False
    # this should only apply for the shared inbox
    if nickname == domain:
        return False
    if _isReservedName(nickname):
        return False
    return True


def noOfAccounts(baseDir: str) -> bool:
    """Returns the number of accounts on the system
    """
    accountCtr = 0
    for subdir, dirs, files in os.walk(baseDir + '/accounts'):
        for account in dirs:
            if '@' in account:
                if not account.startswith('inbox@'):
                    accountCtr += 1
        break
    return accountCtr


def noOfActiveAccountsMonthly(baseDir: str, months: int) -> bool:
    """Returns the number of accounts on the system this month
    """
    accountCtr = 0
    currTime = int(time.time())
    monthSeconds = int(60*60*24*30*months)
    for subdir, dirs, files in os.walk(baseDir + '/accounts'):
        for account in dirs:
            if '@' in account:
                if not account.startswith('inbox@'):
                    lastUsedFilename = \
                        baseDir + '/accounts/' + account + '/.lastUsed'
                    if os.path.isfile(lastUsedFilename):
                        with open(lastUsedFilename, 'r') as lastUsedFile:
                            lastUsed = lastUsedFile.read()
                            if lastUsed.isdigit():
                                timeDiff = (currTime - int(lastUsed))
                                if timeDiff < monthSeconds:
                                    accountCtr += 1
        break
    return accountCtr


def isPublicPostFromUrl(baseDir: str, nickname: str, domain: str,
                        postUrl: str) -> bool:
    """Returns whether the given url is a public post
    """
    postFilename = locatePost(baseDir, nickname, domain, postUrl)
    if not postFilename:
        return False
    postJsonObject = loadJson(postFilename, 1)
    if not postJsonObject:
        return False
    return isPublicPost(postJsonObject)


def isPublicPost(postJsonObject: {}) -> bool:
    """Returns true if the given post is public
    """
    if not postJsonObject.get('type'):
        return False
    if postJsonObject['type'] != 'Create':
        return False
    if not postJsonObject.get('object'):
        return False
    if not isinstance(postJsonObject['object'], dict):
        return False
    if not postJsonObject['object'].get('to'):
        return False
    for recipient in postJsonObject['object']['to']:
        if recipient.endswith('#Public'):
            return True
    return False


def copytree(src: str, dst: str, symlinks=False, ignore=None):
    """Copy a directory
    """
    for item in os.listdir(src):
        s = os.path.join(src, item)
        d = os.path.join(dst, item)
        if os.path.isdir(s):
            shutil.copytree(s, d, symlinks, ignore)
        else:
            shutil.copy2(s, d)


def getCachedPostDirectory(baseDir: str, nickname: str, domain: str) -> str:
    """Returns the directory where the html post cache exists
    """
    htmlPostCacheDir = baseDir + '/accounts/' + \
        nickname + '@' + domain + '/postcache'
    return htmlPostCacheDir


def getCachedPostFilename(baseDir: str, nickname: str, domain: str,
                          postJsonObject: {}) -> str:
    """Returns the html cache filename for the given post
    """
    cachedPostDir = getCachedPostDirectory(baseDir, nickname, domain)
    if not os.path.isdir(cachedPostDir):
        # print('ERROR: invalid html cache directory '+cachedPostDir)
        return None
    if '@' not in cachedPostDir:
        # print('ERROR: invalid html cache directory '+cachedPostDir)
        return None
    cachedPostId = removeIdEnding(postJsonObject['id'])
    cachedPostFilename = cachedPostDir + '/' + cachedPostId.replace('/', '#')
    return cachedPostFilename + '.html'


def removePostFromCache(postJsonObject: {}, recentPostsCache: {}):
    """ if the post exists in the recent posts cache then remove it
    """
    if not postJsonObject.get('id'):
        return

    if not recentPostsCache.get('index'):
        return

    postId = postJsonObject['id']
    if '#' in postId:
        postId = postId.split('#', 1)[0]
    postId = removeIdEnding(postId).replace('/', '#')
    if postId not in recentPostsCache['index']:
        return

    if recentPostsCache['json'].get(postId):
        del recentPostsCache['json'][postId]
    if recentPostsCache['html'].get(postId):
        del recentPostsCache['html'][postId]
    recentPostsCache['index'].remove(postId)


def updateRecentPostsCache(recentPostsCache: {}, maxRecentPosts: int,
                           postJsonObject: {}, htmlStr: str) -> None:
    """Store recent posts in memory so that they can be quickly recalled
    """
    if not postJsonObject.get('id'):
        return
    postId = postJsonObject['id']
    if '#' in postId:
        postId = postId.split('#', 1)[0]
    postId = removeIdEnding(postId).replace('/', '#')
    if recentPostsCache.get('index'):
        if postId in recentPostsCache['index']:
            return
        recentPostsCache['index'].append(postId)
        postJsonObject['muted'] = False
        recentPostsCache['json'][postId] = json.dumps(postJsonObject)
        recentPostsCache['html'][postId] = htmlStr

        while len(recentPostsCache['html'].items()) > maxRecentPosts:
            postId = recentPostsCache['index'][0]
            recentPostsCache['index'].pop(0)
            del recentPostsCache['json'][postId]
            del recentPostsCache['html'][postId]
    else:
        recentPostsCache['index'] = [postId]
        recentPostsCache['json'] = {}
        recentPostsCache['html'] = {}
        recentPostsCache['json'][postId] = json.dumps(postJsonObject)
        recentPostsCache['html'][postId] = htmlStr


def fileLastModified(filename: str) -> str:
    """Returns the date when a file was last modified
    """
    t = os.path.getmtime(filename)
    modifiedTime = datetime.datetime.fromtimestamp(t)
    return modifiedTime.strftime("%Y-%m-%dT%H:%M:%SZ")


def getCSS(baseDir: str, cssFilename: str, cssCache: {}) -> str:
    """Retrieves the css for a given file, or from a cache
    """
    # does the css file exist?
    if not os.path.isfile(cssFilename):
        return None

    lastModified = fileLastModified(cssFilename)

    # has this already been loaded into the cache?
    if cssCache.get(cssFilename):
        if cssCache[cssFilename][0] == lastModified:
            # file hasn't changed, so return the version in the cache
            return cssCache[cssFilename][1]

    with open(cssFilename, 'r') as fpCSS:
        css = fpCSS.read()
        if cssCache.get(cssFilename):
            # alter the cache contents
            cssCache[cssFilename][0] = lastModified
            cssCache[cssFilename][1] = css
        else:
            # add entry to the cache
            cssCache[cssFilename] = [lastModified, css]
        return css

    return None


def daysInMonth(year: int, monthNumber: int) -> int:
    """Returns the number of days in the month
    """
    if monthNumber < 1 or monthNumber > 12:
        return None
    daysRange = monthrange(year, monthNumber)
    return daysRange[1]


def mergeDicts(dict1: {}, dict2: {}) -> {}:
    """Merges two dictionaries
    """
    res = {**dict1, **dict2}
    return res


def isEventPost(messageJson: {}) -> bool:
    """Is the given post a mobilizon-type event activity?
    See https://framagit.org/framasoft/mobilizon/-/blob/
    master/lib/federation/activity_stream/converter/event.ex
    """
    if not messageJson.get('id'):
        return False
    if not messageJson.get('actor'):
        return False
    if not messageJson.get('object'):
        return False
    if not isinstance(messageJson['object'], dict):
        return False
    if not messageJson['object'].get('type'):
        return False
    if messageJson['object']['type'] != 'Event':
        return False
    print('Event arriving')
    if not messageJson['object'].get('startTime'):
        print('No event start time')
        return False
    if not messageJson['object'].get('actor'):
        print('No event actor')
        return False
    if not messageJson['object'].get('content'):
        print('No event content')
        return False
    if not messageJson['object'].get('name'):
        print('No event name')
        return False
    if not messageJson['object'].get('uuid'):
        print('No event UUID')
        return False
    print('Event detected')
    return True


def isBlogPost(postJsonObject: {}) -> bool:
    """Is the given post a blog post?
    """
    if postJsonObject['type'] != 'Create':
        return False
    if not postJsonObject.get('object'):
        return False
    if not isinstance(postJsonObject['object'], dict):
        return False
    if not postJsonObject['object'].get('type'):
        return False
    if not postJsonObject['object'].get('content'):
        return False
    if postJsonObject['object']['type'] != 'Article':
        return False
    return True


def isNewsPost(postJsonObject: {}) -> bool:
    """Is the given post a blog post?
    """
    return postJsonObject.get('news')


def searchBoxPosts(baseDir: str, nickname: str, domain: str,
                   searchStr: str, maxResults: int,
                   boxName='outbox') -> []:
    """Search your posts and return a list of the filenames
    containing matching strings
    """
    path = baseDir + '/accounts/' + nickname + '@' + domain + '/' + boxName
    if not os.path.isdir(path):
        return []
    searchStr = searchStr.lower().strip()

    if '+' in searchStr:
        searchWords = searchStr.split('+')
        for index in range(len(searchWords)):
            searchWords[index] = searchWords[index].strip()
        print('SEARCH: ' + str(searchWords))
    else:
        searchWords = [searchStr]

    res = []
    for root, dirs, fnames in os.walk(path):
        for fname in fnames:
            filePath = os.path.join(root, fname)
            with open(filePath, 'r') as postFile:
                data = postFile.read().lower()

                notFound = False
                for keyword in searchWords:
                    if keyword not in data:
                        notFound = True
                        break
                if notFound:
                    continue

                res.append(filePath)
                if len(res) >= maxResults:
                    return res
        break
    return res


def getFileCaseInsensitive(path: str) -> str:
    """Returns a case specific filename given a case insensitive version of it
    """
    if os.path.isfile(path):
        return path
    if path != path.lower():
        if os.path.isfile(path.lower()):
            return path.lower()
    # directory, filename = os.path.split(path)
    # directory, filename = (directory or '.'), filename.lower()
    # for f in os.listdir(directory):
    #     if f.lower() == filename:
    #         newpath = os.path.join(directory, f)
    #         if os.path.isfile(newpath):
    #             return newpath
    return None


def undoLikesCollectionEntry(recentPostsCache: {},
                             baseDir: str, postFilename: str, objectUrl: str,
                             actor: str, domain: str, debug: bool) -> None:
    """Undoes a like for a particular actor
    """
    postJsonObject = loadJson(postFilename)
    if postJsonObject:
        # remove any cached version of this post so that the
        # like icon is changed
        nickname = getNicknameFromActor(actor)
        cachedPostFilename = getCachedPostFilename(baseDir, nickname,
                                                   domain, postJsonObject)
        if cachedPostFilename:
            if os.path.isfile(cachedPostFilename):
                os.remove(cachedPostFilename)
        removePostFromCache(postJsonObject, recentPostsCache)

        if not postJsonObject.get('type'):
            return
        if postJsonObject['type'] != 'Create':
            return
        if not postJsonObject.get('object'):
            if debug:
                pprint(postJsonObject)
                print('DEBUG: post '+objectUrl+' has no object')
            return
        if not isinstance(postJsonObject['object'], dict):
            return
        if not postJsonObject['object'].get('likes'):
            return
        if not isinstance(postJsonObject['object']['likes'], dict):
            return
        if not postJsonObject['object']['likes'].get('items'):
            return
        totalItems = 0
        if postJsonObject['object']['likes'].get('totalItems'):
            totalItems = postJsonObject['object']['likes']['totalItems']
        itemFound = False
        for likeItem in postJsonObject['object']['likes']['items']:
            if likeItem.get('actor'):
                if likeItem['actor'] == actor:
                    if debug:
                        print('DEBUG: like was removed for ' + actor)
                    postJsonObject['object']['likes']['items'].remove(likeItem)
                    itemFound = True
                    break
        if itemFound:
            if totalItems == 1:
                if debug:
                    print('DEBUG: likes was removed from post')
                del postJsonObject['object']['likes']
            else:
                itlen = len(postJsonObject['object']['likes']['items'])
                postJsonObject['object']['likes']['totalItems'] = itlen

            saveJson(postJsonObject, postFilename)


def updateLikesCollection(recentPostsCache: {},
                          baseDir: str, postFilename: str,
                          objectUrl: str,
                          actor: str, domain: str, debug: bool) -> None:
    """Updates the likes collection within a post
    """
    postJsonObject = loadJson(postFilename)
    if not postJsonObject:
        return
    # remove any cached version of this post so that the
    # like icon is changed
    nickname = getNicknameFromActor(actor)
    cachedPostFilename = getCachedPostFilename(baseDir, nickname,
                                               domain, postJsonObject)
    if cachedPostFilename:
        if os.path.isfile(cachedPostFilename):
            os.remove(cachedPostFilename)
    removePostFromCache(postJsonObject, recentPostsCache)

    if not postJsonObject.get('object'):
        if debug:
            pprint(postJsonObject)
            print('DEBUG: post ' + objectUrl + ' has no object')
        return
    if not isinstance(postJsonObject['object'], dict):
        return
    if not objectUrl.endswith('/likes'):
        objectUrl = objectUrl + '/likes'
    if not postJsonObject['object'].get('likes'):
        if debug:
            print('DEBUG: Adding initial like to ' + objectUrl)
        likesJson = {
            "@context": "https://www.w3.org/ns/activitystreams",
            'id': objectUrl,
            'type': 'Collection',
            "totalItems": 1,
            'items': [{
                'type': 'Like',
                'actor': actor
            }]
        }
        postJsonObject['object']['likes'] = likesJson
    else:
        if not postJsonObject['object']['likes'].get('items'):
            postJsonObject['object']['likes']['items'] = []
        for likeItem in postJsonObject['object']['likes']['items']:
            if likeItem.get('actor'):
                if likeItem['actor'] == actor:
                    # already liked
                    return
        newLike = {
            'type': 'Like',
            'actor': actor
        }
        postJsonObject['object']['likes']['items'].append(newLike)
        itlen = len(postJsonObject['object']['likes']['items'])
        postJsonObject['object']['likes']['totalItems'] = itlen

    if debug:
        print('DEBUG: saving post with likes added')
        pprint(postJsonObject)
    saveJson(postJsonObject, postFilename)


def undoAnnounceCollectionEntry(recentPostsCache: {},
                                baseDir: str, postFilename: str,
                                actor: str, domain: str, debug: bool) -> None:
    """Undoes an announce for a particular actor by removing it from
    the "shares" collection within a post. Note that the "shares"
    collection has no relation to shared items in shares.py. It's
    shares of posts, not shares of physical objects.
    """
    postJsonObject = loadJson(postFilename)
    if postJsonObject:
        # remove any cached version of this announce so that the announce
        # icon is changed
        nickname = getNicknameFromActor(actor)
        cachedPostFilename = getCachedPostFilename(baseDir, nickname, domain,
                                                   postJsonObject)
        if cachedPostFilename:
            if os.path.isfile(cachedPostFilename):
                os.remove(cachedPostFilename)
        removePostFromCache(postJsonObject, recentPostsCache)

        if not postJsonObject.get('type'):
            return
        if postJsonObject['type'] != 'Create':
            return
        if not postJsonObject.get('object'):
            if debug:
                pprint(postJsonObject)
                print('DEBUG: post has no object')
            return
        if not isinstance(postJsonObject['object'], dict):
            return
        if not postJsonObject['object'].get('shares'):
            return
        if not postJsonObject['object']['shares'].get('items'):
            return
        totalItems = 0
        if postJsonObject['object']['shares'].get('totalItems'):
            totalItems = postJsonObject['object']['shares']['totalItems']
        itemFound = False
        for announceItem in postJsonObject['object']['shares']['items']:
            if announceItem.get('actor'):
                if announceItem['actor'] == actor:
                    if debug:
                        print('DEBUG: Announce was removed for ' + actor)
                    anIt = announceItem
                    postJsonObject['object']['shares']['items'].remove(anIt)
                    itemFound = True
                    break
        if itemFound:
            if totalItems == 1:
                if debug:
                    print('DEBUG: shares (announcements) ' +
                          'was removed from post')
                del postJsonObject['object']['shares']
            else:
                itlen = len(postJsonObject['object']['shares']['items'])
                postJsonObject['object']['shares']['totalItems'] = itlen

            saveJson(postJsonObject, postFilename)


def updateAnnounceCollection(recentPostsCache: {},
                             baseDir: str, postFilename: str,
                             actor: str, domain: str, debug: bool) -> None:
    """Updates the announcements collection within a post
    Confusingly this is known as "shares", but isn't the
    same as shared items within shares.py
    It's shares of posts, not shares of physical objects.
    """
    postJsonObject = loadJson(postFilename)
    if postJsonObject:
        # remove any cached version of this announce so that the announce
        # icon is changed
        nickname = getNicknameFromActor(actor)
        cachedPostFilename = getCachedPostFilename(baseDir, nickname, domain,
                                                   postJsonObject)
        if cachedPostFilename:
            if os.path.isfile(cachedPostFilename):
                os.remove(cachedPostFilename)
        removePostFromCache(postJsonObject, recentPostsCache)

        if not postJsonObject.get('object'):
            if debug:
                pprint(postJsonObject)
                print('DEBUG: post ' + postFilename + ' has no object')
            return
        if not isinstance(postJsonObject['object'], dict):
            return
        postUrl = removeIdEnding(postJsonObject['id']) + '/shares'
        if not postJsonObject['object'].get('shares'):
            if debug:
                print('DEBUG: Adding initial shares (announcements) to ' +
                      postUrl)
            announcementsJson = {
                "@context": "https://www.w3.org/ns/activitystreams",
                'id': postUrl,
                'type': 'Collection',
                "totalItems": 1,
                'items': [{
                    'type': 'Announce',
                    'actor': actor
                }]
            }
            postJsonObject['object']['shares'] = announcementsJson
        else:
            if postJsonObject['object']['shares'].get('items'):
                sharesItems = postJsonObject['object']['shares']['items']
                for announceItem in sharesItems:
                    if announceItem.get('actor'):
                        if announceItem['actor'] == actor:
                            return
                newAnnounce = {
                    'type': 'Announce',
                    'actor': actor
                }
                postJsonObject['object']['shares']['items'].append(newAnnounce)
                itlen = len(postJsonObject['object']['shares']['items'])
                postJsonObject['object']['shares']['totalItems'] = itlen
            else:
                if debug:
                    print('DEBUG: shares (announcements) section of post ' +
                          'has no items list')

        if debug:
            print('DEBUG: saving post with shares (announcements) added')
            pprint(postJsonObject)
        saveJson(postJsonObject, postFilename)


def weekDayOfMonthStart(monthNumber: int, year: int) -> int:
    """Gets the day number of the first day of the month
    1=sun, 7=sat
    """
    firstDayOfMonth = datetime.datetime(year, monthNumber, 1, 0, 0)
    return int(firstDayOfMonth.strftime("%w")) + 1


def mediaFileMimeType(filename: str) -> str:
    """Given a media filename return its mime type
    """
    if '.' not in filename:
        return 'image/png'
    extensions = {
        'json': 'application/json',
        'png': 'image/png',
        'jpg': 'image/jpeg',
        'jpeg': 'image/jpeg',
        'gif': 'image/gif',
        'svg': 'image/svg+xml',
        'webp': 'image/webp',
        'avif': 'image/avif',
        'mp3': 'audio/mpeg',
        'ogg': 'audio/ogg',
        'mp4': 'video/mp4',
        'ogv': 'video/ogv'
    }
    fileExt = filename.split('.')[-1]
    if not extensions.get(fileExt):
        return 'image/png'
    return extensions[fileExt]