import html
import multiprocessing
import operator
import re
import time
import xml.etree.cElementTree as et
from collections import defaultdict
from datetime import datetime

from mt import mt
import gc

TAG_RE = re.compile(r'<[^>]+>')
TAG_CODE = re.compile(r'<code.+</code>')

printnoln = lambda text: print(text, end='', flush=True)
rprint = lambda text: print('\r' + text)


def dmt(data, progressinterval=1000): return mt(multiprocessing.cpu_count(), data, False, progressinterval)


def cms(): return int(round(time.time() * 1000))


def load(folder):
    users = readUsers(folder + "/Users.xml")
    gc.collect()
    posts = readPosts(folder + "/Posts.xml")
    gc.collect()

    # get first contribution to page:
    firstcontrib = computefirstcontrib(posts)
    sumcontrib = computesumcontrib(posts)

    return users, posts, firstcontrib, sumcontrib


def computesumcontrib(posts):
    x1 = dmt(posts).map(lambda q: q['OwnerUserId'], "calc sum contrib q").getresults()
    x2 = dmt(posts).map(lambda q: [a['OwnerUserId'] for a in q['Answers']], "calc sum contrib a").getresults()
    x3 = dmt(posts).map(lambda q: [c['OwnerUserId'] for a in q['Answers'] for c in a['Comments']] + [c['OwnerUserId'] for c in q['Comments']], "calc sum contrib c").getresults()
    sumcontrib = defaultdict(int)
    for id in x1:
        sumcontrib[id] += 1
    for y in x2:
        for id in y:
            sumcontrib[id] += 1
    for y in x3:
        for id in y:
            sumcontrib[id] += 1
    return sumcontrib


def computefirstcontrib(posts):
    x1 = dmt(posts).map(lambda q: (q['OwnerUserId'], q['CreationDate']), "calc first contrib q").getresults()
    x2 = dmt(posts).map(lambda q: [(a['OwnerUserId'], a['CreationDate']) for a in q['Answers']], "calc first contrib a").getresults()
    firstcontrib = defaultdict(list)
    for (id, date) in x1:
        firstcontrib[id].append(date)
    for y in x2:
        for (id, date) in y:
            firstcontrib[id].append(date)
    firstcontrib = {id: min(ldate) for (id, ldate) in firstcontrib.items()}
    return firstcontrib


def mapuser(item):
    tags = ['Id', 'CreationDate']
    datetags = ['CreationDate']
    user = {tag: getTag(item, tag) for tag in tags}
    for tag in datetags:
        if user[tag] is not None:
            user[tag] = datetime.fromisoformat(user[tag])
        else:
            print("map user: tag " + tag + " is None: " + str(user))
    return user


def mapQuestion(item):
    tags = ['Id', 'CreationDate', 'Body', 'Title', 'OwnerUserId', 'OwnerDisplayName']
    datetags = ['CreationDate']
    question = {tag: getTag(item, tag) for tag in tags}
    for tag in datetags:
        question[tag] = datetime.fromisoformat(question[tag])
    question['Body'] = removetags(html.unescape(question['Body']))
    return question


def mapAnswer(item):
    tags = ['Id', 'ParentId', 'CreationDate', 'Body', 'OwnerUserId']
    datetags = ['CreationDate']
    answer = {tag: getTag(item, tag) for tag in tags}
    for tag in datetags:
        answer[tag] = datetime.fromisoformat(answer[tag])
    answer['Body'] = removetags(html.unescape(answer['Body']))
    return answer


def mapComment(item):
    tags = ['Id', 'ParentId', 'CreationDate', 'Body', 'OwnerUserId']
    datetags = ['CreationDate']
    comment = {tag: getTag(item, tag) for tag in tags}
    for tag in datetags:
        comment[tag] = datetime.fromisoformat(comment[tag])
    comment['Body'] = removetags(html.unescape(comment['Body']))
    return comment


def readUsers(file):
    prefix = "readUsers: "
    printnoln(prefix + "reading xml file ...")

    now = cms()
    items = [elem for event, elem in et.iterparse(file) if elem.tag == "row"]
    rprint(prefix + "reading xml file ... took " + str(cms() - now) + "ms")

    users = dmt(items).map(mapuser, prefix + "mapping users").getresults()

    print(prefix + "done")
    return users


def readPosts(file):
    prefix = "readPosts: "
    printnoln(prefix + "reading xml file ...")

    now = cms()
    items = [elem for event, elem in et.iterparse(file) if elem.tag == "row"]
    rprint(prefix + "reading xml file ... took " + str(cms() - now) + "ms")

    print(prefix + "#posts total: " + str(len(items)))

    questions = readQuestions(items)
    questionids = set(dmt(questions).map(lambda q: q['Id'], prefix + "get question ids").getresults())

    answers = readAnswers(items)
    answerids = set(dmt(answers).map(lambda a: a['Id'], prefix + "get answer ids").getresults())

    comments = readComments(items)

    # filter answers
    answers = dmt(answers).filter(lambda a: a['ParentId'] in questionids, prefix + "filter answers by a.id in q.id").getresults()

    # filter comments
    comments = dmt(comments).filter(lambda c: c['ParentId'] in questionids.union(answerids), prefix + "filter comments by c.id in q.id + a.id").getresults()

    # create question answer mapping
    printnoln(prefix + "create qamapping ...")
    qamapping = {id: [] for id in questionids}
    for a in answers:
        qamapping[a['ParentId']].append(a)
    rprint(prefix + "create qamapping ... done")
    questions = dmt(questions).map(lambda q: setprop(q, 'Answers', qamapping[q['Id']]), prefix + "assign answers to questions").getresults()

    # create comment question comment answer mapping
    printnoln(prefix + "create qacmapping ...")
    qacmapping = {id: [] for id in questionids.union(answerids)}
    for c in comments:
        qacmapping[c['ParentId']].append(c)
    rprint(prefix + "create qacmapping ... done")
    answers = dmt(answers).map(lambda a: setprop(a, 'Comments', qacmapping[a['Id']]), prefix + "assign comments to answers").getresults()
    questions = dmt(questions).map(lambda q: setprop(q, 'Comments', qacmapping[q['Id']]), prefix + "assign comments to questions").getresults()

    # safety check
    countans = dmt(questions).map(lambda q: len(q['Answers']), prefix + "sum answer count") \
        .reduce(operator.add, operator.add, lambda: 0, prefix + "sum answer count").getresults()
    if countans != len(answers):
        print(prefix + "countans != #answer: " + countans + " " + len(answers))
    print(prefix + "done")
    return questions


def readQuestions(items):
    prefix = "readQuestions: "
    questions = dmt(items).filter(lambda item: getTag(item, 'PostTypeId') == "1", prefix + "filter out questions") \
        .map(mapQuestion, prefix + "mapping questions") \
        .filter(lambda q: q['OwnerUserId'] is not None, prefix + "filter out broken questions").getresults()

    print(prefix + "questions read: " + str(len(questions)))
    return questions


def readAnswers(items):
    prefix = "readAnswers: "
    answers = dmt(items).filter(lambda item: getTag(item, 'PostTypeId') == "2", prefix + "filter out answers") \
        .map(mapAnswer, prefix + "mapping answers") \
        .filter(lambda q: q['OwnerUserId'] is not None, prefix + "filter out broken answers").getresults()

    print(prefix + "answers read: " + str(len(answers)))
    return answers


def readComments(items):
    prefix = "readComments: "
    comments = dmt(items).filter(lambda item: getTag(item, 'PostTypeId') == "3", prefix + "filter out comments") \
        .map(mapComment, prefix + "mapping comments") \
        .filter(lambda c: c['OwnerUserId'] is not None, prefix + "filter out broken comments").getresults()

    print(prefix + "comments read: " + str(len(comments)))
    return comments


def getTag(item, tag):
    return item.attrib.get(tag) if tagExists(item, tag) else None


def tagExists(item, tag):
    return tag in item.attrib.keys()


def setprop(dic, key, value):
    dic[key] = value
    return dic


def removetags(text):
    return TAG_RE.sub('', TAG_CODE.sub('', text))