epicyon/content.py

__filename__ = "content.py"
__author__ = "Bob Mottram"
__license__ = "AGPL3+"
__version__ = "1.0.0"
__maintainer__ = "Bob Mottram"
__email__ = "bob@freedombone.net"
__status__ = "Production"

import os
import time
import commentjson
import email.parser
from shutil import copyfile

def replaceEmojiFromTags(content: str,tag: [],messageType: str) -> str:
    """Uses the tags to replace :emoji: with html image markup
    """
    for tagItem in tag:
        if not tagItem.get('type'):
            continue
        if tagItem['type']!='Emoji':
            continue
        if not tagItem.get('name'):
            continue
        if not tagItem.get('icon'):
            continue
        if not tagItem['icon'].get('url'):
            continue
        if tagItem['name'] not in content:
            continue
        htmlClass='emoji'
        if messageType=='post header':
            htmlClass='emojiheader'            
        if messageType=='profile':
            htmlClass='emojiprofile'
        emojiHtml="<img src=\""+tagItem['icon']['url']+"\" alt=\""+tagItem['name'].replace(':','')+"\" align=\"middle\" class=\""+htmlClass+"\"/>"
        content=content.replace(tagItem['name'],emojiHtml)
    return content

def addMusicTag(content: str,tag: str) -> str:
    """If a music link is found then ensure that the post is tagged appropriately
    """
    if '#' not in tag:
        tag='#'+tag
    if tag in content:
        return content
    musicSites=['soundcloud.com','bandcamp.com']
    musicSiteFound=False
    for site in musicSites:
        if site+'/' in content:
            musicSiteFound=True
            break
    if not musicSiteFound:
        return content
    return ':music: '+content+' '+tag+' '

def addWebLinks(content: str) -> str:
    """Adds markup for web links
    """
    if not ('https://' in content or 'http://' in content):
        return content

    maxLinkLength=40
    words=content.replace('\n',' --linebreak-- ').split(' ')
    replaceDict={}
    for w in words:
        if w.startswith('https://') or \
           w.startswith('http://') or \
           w.startswith('dat://'):
            if w.endswith('.') or w.endswith(';'):
                w=w[:-1]
            markup='<a href="'+w+'" rel="nofollow noopener" target="_blank">'
            if w.startswith('https://'):
                markup+='<span class="invisible">https://</span>'
            elif w.startswith('http://'):
                markup+='<span class="invisible">http://</span>'
            elif w.startswith('dat://'):
                markup+='<span class="invisible">dat://</span>'
            linkText=w.replace('https://','').replace('http://','').replace('dat://','')
            # prevent links from becoming too long
            if len(linkText)>maxLinkLength:
                markup+='<span class="ellipsis">'+linkText[:maxLinkLength]+'</span>'
                markup+='<span class="invisible">'+linkText[maxLinkLength:]+'</span></a>'
            else:
                markup+='<span class="ellipsis">'+linkText+'</span></a>'
            replaceDict[w]=markup
    for url,markup in replaceDict.items():
        content=content.replace(url,markup)
    content=content.replace(' --linebreak-- ','<br>')
    return content

def validHashTag(hashtag: str) -> bool:
    """Returns true if the give hashtag contains valid characters
    """
    validChars = set('0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ')
    if set(hashtag).issubset(validChars):
        return True
    return False

def addHashTags(wordStr: str,httpPrefix: str,domain: str,replaceHashTags: {},postHashtags: {}) -> bool:
    """Detects hashtags and adds them to the replacements dict
    Also updates the hashtags list to be added to the post
    """
    if replaceHashTags.get(wordStr):
       return True
    hashtag=wordStr[1:]
    if not validHashTag(hashtag):
        return False
    hashtagUrl=httpPrefix+"://"+domain+"/tags/"+hashtag
    postHashtags[hashtag]= {
        'href': hashtagUrl,
        'name': '#'+hashtag,
        'type': 'Hashtag'
    }
    replaceHashTags[wordStr]= \
        "<a href=\""+hashtagUrl+"\" class=\"mention hashtag\" rel=\"tag\">#<span>"+hashtag+"</span></a>"
    return True

def loadEmojiDict(emojiDataFilename: str,emojiDict: {}) -> None:
    """Creates an emoji dictionary based on emoji/emoji-data.txt
    """
    if not os.path.isfile(emojiDataFilename):
        return
    with open (emojiDataFilename, "r") as fileHandler:
        for line in fileHandler:
            if len(line)<5:
                continue
            if line.startswith('#'):
                continue
            if '; Emoji' not in line:
                continue
            if ')' not in line:
                continue
            emojiUnicode=line.split(' ')[0]
            if len(emojiUnicode)<4:
                continue
            if '..' in emojiUnicode:
                emojiUnicode=emojiUnicode.split('..')[0]
            emojiName=line.split(')',1)[1].strip().replace('\n','').replace(' ','').replace('-','')
            if '..' in emojiName:
                emojiName=emojiName.split('..')[0]
            emojiDict[emojiName.lower()]=emojiUnicode

def addEmoji(baseDir: str,wordStr: str,httpPrefix: str,domain: str,replaceEmoji: {},postTags: {},emojiDict: {}) -> bool:
    """Detects Emoji and adds them to the replacements dict
    Also updates the tags list to be added to the post
    """
    if not wordStr.startswith(':'):
        return False
    if not wordStr.endswith(':'):
        return False
    if len(wordStr)<3:
        return False
    if replaceEmoji.get(wordStr):
       return True
    # remove leading and trailing : characters
    emoji=wordStr[1:]
    emoji=emoji[:-1]
    # is the text of the emoji valid?
    if not validHashTag(emoji):
        return False
    if not emojiDict.get(emoji):
        return False
    emojiFilename=baseDir+'/emoji/'+emojiDict[emoji]+'.png'
    if not os.path.isfile(emojiFilename):
        return False
    emojiUrl=httpPrefix+"://"+domain+"/emoji/"+emojiDict[emoji]+'.png'
    postTags[emoji]= {
        'icon': {
            'mediaType': 'image/png',
            'type': 'Image',
            'url': emojiUrl
        },
        'name': ':'+emoji+':',
        'type': 'Emoji'
    }
    return True

def addMention(wordStr: str,httpPrefix: str,following: str,replaceMentions: {},recipients: [],tags: {}) -> bool:
    """Detects mentions and adds them to the replacements dict and recipients list
    """
    possibleHandle=wordStr[1:]
    # @nick
    if following and '@' not in possibleHandle:
        # fall back to a best effort match against the following list
        # if no domain was specified. eg. @nick
        possibleNickname=possibleHandle
        for follow in following:
            if follow.startswith(possibleNickname+'@'):
                replaceDomain=follow.replace('\n','').split('@')[1]
                recipientActor=httpPrefix+"://"+replaceDomain+"/users/"+possibleNickname
                if recipientActor not in recipients:
                    recipients.append(recipientActor)
                tags[wordStr]={
                    'href': recipientActor,
                    'name': wordStr,
                    'type': 'Mention'
                }
                replaceMentions[wordStr]="<span class=\"h-card\"><a href=\""+httpPrefix+"://"+replaceDomain+"/@"+possibleNickname+"\" class=\"u-url mention\">@<span>"+possibleNickname+"</span></a></span>"
                return True
        return False
    possibleNickname=None
    possibleDomain=None
    if '@' not in possibleHandle:
        return False
    possibleNickname=possibleHandle.split('@')[0]
    if not possibleNickname:
        return False
    possibleDomain=possibleHandle.split('@')[1].strip('\n')
    if not possibleDomain:
        return False
    if following:
        for follow in following:
            if follow.replace('\n','')!=possibleHandle:
                continue
            recipientActor=httpPrefix+"://"+possibleDomain+"/users/"+possibleNickname
            if recipientActor not in recipients:
                recipients.append(recipientActor)
            tags[wordStr]={
                'href': recipientActor,
                'name': wordStr,
                'type': 'Mention'
            }
            replaceMentions[wordStr]="<span class=\"h-card\"><a href=\""+httpPrefix+"://"+possibleDomain+"/@"+possibleNickname+"\" class=\"u-url mention\">@<span>"+possibleNickname+"</span></a></span>"
            return True
    # @nick@domain
    if not (possibleDomain=='localhost' or '.' in possibleDomain):
        return False        
    recipientActor=httpPrefix+"://"+possibleDomain+"/users/"+possibleNickname
    if recipientActor not in recipients:
        recipients.append(recipientActor)
    tags[wordStr]={
        'href': recipientActor,
        'name': wordStr,
        'type': 'Mention'
    }
    replaceMentions[wordStr]="<span class=\"h-card\"><a href=\""+httpPrefix+"://"+possibleDomain+"/@"+possibleNickname+"\" class=\"u-url mention\">@<span>"+possibleNickname+"</span></a></span>"
    return True

def removeLongWords(content: str,maxWordLength: int,longWordsList: []) -> str:
    """Breaks up long words so that on mobile screens this doesn't disrupt the layout
    """
    words=content.split(' ')
    if not longWordsList:
        longWordsList=[]
        for wordStr in words:
            if len(wordStr)>maxWordLength:
                if wordStr not in longWordsList:
                    longWordsList.append(wordStr)
    for wordStr in longWordsList:
        if wordStr.startswith('<'):
            continue
        if '=\"' in wordStr:
            continue
        if '@' in wordStr:
            if '@@' not in wordStr:
                continue
        if 'https:' in wordStr:
            continue
        elif 'http:' in wordStr:
            continue
        elif 'dat:' in wordStr:
            continue
        if '<' in wordStr:
            wordStr=wordStr.split('<',1)[0]
        if '/' in wordStr:
            continue
        if len(wordStr[maxWordLength:])<maxWordLength:
            content= \
                content.replace(wordStr, \
                                wordStr[:maxWordLength]+'\n'+ \
                                wordStr[maxWordLength:])
        else:
            content= \
                content.replace(wordStr, \
                                wordStr[:maxWordLength])
    return content

def addHtmlTags(baseDir: str,httpPrefix: str, \
                nickname: str,domain: str,content: str, \
                recipients: [],hashtags: {},isJsonContent=False) -> str:
    """ Replaces plaintext mentions such as @nick@domain into html
    by matching against known following accounts
    """
    if content.startswith('<p>'):
        return content
    maxWordLength=40
    content=content.replace('\n',' --linebreak-- ')
    content=addMusicTag(content,'nowplaying')
    words=content.replace(',',' ').replace(';',' ').split(' ')
    
    # remove . for words which are not mentions
    wordCtr=0
    newWords=[]
    for wordIndex in range(0,len(words)):
        wordStr=words[wordIndex]
        if wordStr.endswith('.'):
            if not wordStr.startswith('@'):
                wordStr=wordStr[:-1]
        if wordStr.startswith('.'):
            wordStr=wordStr[1:]
        newWords.append(wordStr)
    words=newWords

    replaceMentions={}
    replaceHashTags={}
    replaceEmoji={}
    emojiDict={}
    originalDomain=domain
    if ':' in domain:
        domain=domain.split(':')[0]
    followingFilename=baseDir+'/accounts/'+nickname+'@'+domain+'/following.txt'

    # read the following list so that we can detect just @nick
    # in addition to @nick@domain
    following=None
    if '@' in words:
        if os.path.isfile(followingFilename):
            with open(followingFilename, "r") as f:
                following = f.readlines()

    # extract mentions and tags from words
    longWordsList=[]
    for wordStr in words:
        wordLen=len(wordStr)
        if wordLen>2:
            if wordLen>maxWordLength:
                longWordsList.append(wordStr)
            firstChar=wordStr[0]
            if firstChar=='@':
                if addMention(wordStr,httpPrefix,following,replaceMentions,recipients,hashtags):
                    continue
            elif firstChar=='#':
                if addHashTags(wordStr,httpPrefix,originalDomain,replaceHashTags,hashtags):
                    continue
            elif ':' in wordStr:
                #print('TAG: emoji located - '+wordStr)
                wordStr2=wordStr.split(':')[1]
                if not emojiDict:
                    # emoji.json is generated so that it can be customized and the changes
                    # will be retained even if default_emoji.json is subsequently updated                    
                    if not os.path.isfile(baseDir+'/emoji/emoji.json'):
                        copyfile(baseDir+'/emoji/default_emoji.json',baseDir+'/emoji/emoji.json')
                emojiDictCtr=0
                while not emojiDict and emojiDictCtr<5:
                    if emojiDictCtr>0:
                        print('Retry emoji load '+baseDir+'/emoji/emoji.json')
                    try:
                        with open(baseDir+'/emoji/emoji.json', 'r') as fp:
                            emojiDict=commentjson.load(fp)
                            if emojiDictCtr>0:
                                print('emojiDict loaded on try '+str(emojiDictCtr))
                            break
                    except:
                        print('WARN: commentjson exception addHtmlTags')
                        print('Failed to load emoji (try '+str(emojiDictCtr)+'): '+baseDir+'/emoji/emoji.json')
                        time.sleep(1)
                        emojiDictCtr+=1

                #print('TAG: looking up emoji for :'+wordStr2+':')
                addEmoji(baseDir,':'+wordStr2+':',httpPrefix,originalDomain,replaceEmoji,hashtags,emojiDict)

    # replace words with their html versions
    for wordStr,replaceStr in replaceMentions.items():
        content=content.replace(wordStr,replaceStr)
    for wordStr,replaceStr in replaceHashTags.items():
        content=content.replace(wordStr,replaceStr)
    if not isJsonContent:
        for wordStr,replaceStr in replaceEmoji.items():
            content=content.replace(wordStr,replaceStr)

    content=addWebLinks(content)
    if longWordsList:
        content=removeLongWords(content,maxWordLength,longWordsList)
    content=content.replace(' --linebreak-- ','</p><p>')
    return '<p>'+content+'</p>'
                
def getMentionsFromHtml(htmlText: str,matchStr="<span class=\"h-card\"><a href=\"") -> []:
    """Extracts mentioned actors from the given html content string
    """
    mentions=[]
    if matchStr not in htmlText:
        return mentions
    mentionsList=htmlText.split(matchStr)
    for mentionStr in mentionsList:
        if '"' not in mentionStr:
            continue
        actorStr=mentionStr.split('"')[0]
        if actorStr.startswith('http') or \
           actorStr.startswith('dat:'):
            if actorStr not in mentions:
                mentions.append(actorStr)
    return mentions

def extractMediaInFormPOST(postBytes,boundary,name: str):
    """Extracts the binary encoding for image/video/audio within a http form POST
    Returns the media bytes and the remaining bytes
    """
    imageStartBoundary=b'Content-Disposition: form-data; name="'+name.encode('utf8', 'ignore')+b'";'
    imageStartLocation=postBytes.find(imageStartBoundary)
    if imageStartLocation==-1:
        return None,postBytes

    # bytes after the start boundary appears
    mediaBytes=postBytes[imageStartLocation:]

    # look for the next boundary
    imageEndBoundary=boundary.encode('utf8', 'ignore')
    imageEndLocation=mediaBytes.find(imageEndBoundary)
    if imageEndLocation==-1:
        # no ending boundary
        return mediaBytes,postBytes[:imageStartLocation]

    # remaining bytes after the end of the image
    remainder=mediaBytes[imageEndLocation:]

    # remove bytes after the end boundary
    mediaBytes=mediaBytes[:imageEndLocation]

    # return the media and the before+after bytes
    return mediaBytes,postBytes[:imageStartLocation]+remainder

def saveMediaInFormPOST(mediaBytes,baseDir: str, \
                        nickname: str,domain: str,debug: bool, \
                        filenameBase=None) -> (str,str):
    """Saves the given media bytes extracted from http form POST
    Returns the filename and attachment type
    """
    if not mediaBytes:
        if debug:
            print('DEBUG: No media found within POST')
        return None,None

    mediaLocation=-1
    searchStr=''
    filename=None
    
    # directly search the binary array for the beginning
    # of an image
    extensionList= {
        'png': 'image/png',
        'jpeg': 'image/jpeg',
        'gif': 'image/gif',
        'mp4': 'video/mp4',
        'ogv': 'video/ogv',
        'mp3': 'audio/mpeg',
        'ogg': 'audio/ogg'
    }
    for extension,contentType in extensionList.items():
        searchStr=b'Content-Type: '+contentType.encode('utf8', 'ignore')
        mediaLocation=mediaBytes.find(searchStr)
        if not filenameBase:
            filenameBase= \
                baseDir+'/accounts/'+ \
                nickname+'@'+domain+'/upload'
        if mediaLocation>-1:
            mediaFound=True
            if extension=='jpeg':
                extension='jpg'
            elif extension=='mpeg':
                extension='mp3'
            filename=filenameBase+'.'+extension
            attachmentMediaType= \
                searchStr.decode().split('/')[0].replace('Content-Type: ','')
            break

    if not filename:
        return None,None

    # locate the beginning of the image, after any
    # carriage returns
    startPos=mediaLocation+len(searchStr)
    for offset in range(1,8):
        if mediaBytes[startPos+offset]!=10:
            if mediaBytes[startPos+offset]!=13:
                startPos+=offset
                break

    fd = open(filename, 'wb')
    fd.write(mediaBytes[startPos:])
    fd.close()
    return filename,attachmentMediaType

def extractTextFieldsInPOST(postBytes,boundary) -> {}:
    """Returns a dictionary containing the text fields of a http form POST
    The boundary argument comes from the http header
    """    
    msg = email.parser.BytesParser().parsebytes(postBytes)
    messageFields=msg.get_payload(decode=True).decode('utf-8').split(boundary)
    fields={}
    # examine each section of the POST, separated by the boundary
    for f in messageFields:
        if f=='--':
            continue
        if ' name="' not in f:
            continue                    
        postStr=f.split(' name="',1)[1]
        if '"' not in postStr:
            continue
        postKey=postStr.split('"',1)[0]
        postValueStr=postStr.split('"',1)[1]
        if ';' in postValueStr:
            continue
        if '\r\n' not in postValueStr:
            continue
        postLines=postValueStr.split('\r\n')                                    
        postValue=''
        if len(postLines)>2:
            for line in range(2,len(postLines)-1):
                if line>2:
                    postValue+='\n'
                postValue+=postLines[line]
        fields[postKey]=postValue
    return fields