import pymongo
import pymongo.errors
import trafilatura
import trafilatura.feeds
import trafilatura.sitemaps
import trafilatura.spider
import trafilatura.utils
import trafilatura.external
import sys
import courlan
import urllib
from datetime import datetime
import click
import logging as LOGGER
import os
import pprint
import re
import time
import collections
import math
import json

LANGUAGE= os.getenv("SUCKER_LANGUAGE","sk")
DOMAIN = os.getenv("SUCKER_DOMAIN","sk")
BATCHSIZE=os.getenv("SUCKER_BATCHSIZE",10)
CONNECTION=os.getenv("SUCKER_CONNECTION","mongodb://root:example@localhost:27017/")
DBNAME=os.getenv("SUCKER_DBNAME","crawler")
MINFILESIZE=300
MAXFILESIZE=10000000
MINTEXTSIZE=200
CHECK_PARAGRAPH_SIZE=150
TEXT_TRASH_SIZE=200
TEXT_TRASH_RATIO=0.6

def put_queue(db,channel,message):
    queuecol = db["queue"]
    queuecol.insert_one({"channel":channel,"message":message,"created_at":datetime.utcnow(),"started_at":None})

def reserve_queue(db,channel,message):
    queuecol = db["queue"]
    r = queuecol.find_one_and_delete({"channel":channel},sort={"created_at":-1})

def delete_queue(db,channel):
    queuecol = db["queue"]
    pass

def calculate_checksums(text):
    """
    @return fingerprints of a paragraphs in text. Paragraphs are separated by a blank line
    """
    checksums = []
    sizes = []
    hval = 0
    hsz = 0
    sz = 0
    for c in text:
        cv = ord(c)
        sz += 1
        if cv > 64:  # ignore non-ascii
            hval += (hval << 3) + cv
            zv = hval >> 31
            hval &= 0x7fffffff
            hval += zv
            hsz += 1
        if c == "\n" and hsz > 0:
            if hsz > CHECK_PARAGRAPH_SIZE:
                checksums.append(hval)
                sizes.append(sz)
            sz = 0
            hsz = 0
    if hsz > CHECK_PARAGRAPH_SIZE:
        checksums.append(hval)
        sizes.append(sz)
    return checksums, sizes

def is_robot_good(link,rules):
    # check robots.txt rules
    if rules is not None and not rules.can_fetch("*", link):
        return False
    return True

def is_link_good(link):
    r = courlan.check_url(link,strict=True,language=LANGUAGE)
    if r is None:
        return None
    llink,lhostname = r
    #print(llink,lhostname)
    # hostname rules
    if not lhostname.endswith(DOMAIN):
        LOGGER.debug("bad hostname")
        return None
    if courlan.is_not_crawlable(llink):
        LOGGER.debug("not crawlable")
        return None
    return llink

def get_link_doc(link,status="frontlink"):
    r  = courlan.check_url(link)
    assert r is not None
    link,host = r
    domain = courlan.extract_domain(link)
    return {"url":link,"host":host,"domain":domain,"status":status,"created_at":datetime.utcnow()}


def fetch_pages(link_batch):
    htmls  = []
    #print(link_batch)
    #print("zzzzzzzzzz")
    for link in link_batch:
        print("fetching:::::")
        print(link)
        final_link = link
        response = trafilatura.fetch_url(link,decode=False)
        time.sleep(2)
        html = None
        if response is not None :
            good = True
            if response.status != 200:
                good = False
                LOGGER.error('not a 200 response: %s for URL %s', response.status, url)
            elif response.data is None or len(response.data) < MINFILESIZE:
                LOGGER.error('too small/incorrect for URL %s', link)
                good = False
            # raise error instead?
            elif len(response.data) > MAXFILESIZE:
                good = False
                LOGGER.error('too large: length %s for URL %s', len(response.data), link)
            if good:
                html = trafilatura.utils.decode_response(response) 
                final_link = response.url
            if html is not None:
                html, final_link = trafilatura.spider.refresh_detection(html, final_link)
                # is there a meta-refresh on the page?
                if final_link is None:  # malformed or malicious content
                    html = None
        htmls.append((final_link,html))
    return htmls

def fetch_robot(base_url):
    try:
        rawrules = trafilatura.fetch_url("https://"+ base_url + "/robots.txt")
        #print(rawrules)
        rules = urllib.robotparser.RobotFileParser()
        rules.parse(rawrules.split("\n"))
        LOGGER.info('got robots')
    except Exception as exc:
        LOGGER.error('cannot read robots.txt: %s', exc)
        rules = None
    # exceptions happening here
    return rules


def extract_pages(link_batch,responses):
    out = []
    for original_link,(final_link,html) in zip(link_batch,responses):
        doc = None
        assert original_link is not None
        if html is not None:
            doc = trafilatura.bare_extraction(html,url=final_link,with_metadata=True,include_formatting=False,target_language=LANGUAGE,favor_precision=True)
            if doc is not None:
                if not "text" in doc or len(doc["text"]) < MINTEXTSIZE:
                    # text too small
                    doc = None

        out.append((original_link,final_link,html,doc))
    return out


def index_pages(db,hostname,extracted_pages):
    linkcol = db["links"]
    htmlcol = db["html"]
    contentcol = db["content"]
    checkcol = db["check"]
    links = []
    for original_link,final_link,html,doc in extracted_pages:
        state = "good"
        link = original_link
        if original_link != final_link:
            linkcol.update_one({"url":original_link},{"$set":{"status":"redirect"}})
            link = final_link
        if html is None:
            state = "html_error"
        elif doc is None:
            state = "content_error"
        if doc is not None:
            text = doc["text"]
            checksums,sizes = calculate_checksums(text)
            doc["text_size"] = len(text)
            doc["paragraph_checksums"] = checksums
            doc["paragraph_sizes"] = sizes
            goodsz = sum(sizes)
            # Not enough larger paragraphs
            if len(text) < TEXT_TRASH_SIZE or goodsz/len(text) < TEXT_TRASH_RATIO:
                state = "trash"
            end_sentence_marker = re.compile("\w[\.]")
            sentences = 0
            for item in re.finditer(end_sentence_marker,text):
                t = item.group(0)
                if t[0].islower():
                    sentences += 1
            doc["sentences"] = sentences
        # check copy
        if state == "good":
            copysz = len(text) - goodsz
            for chs,paragraph_size in zip(doc["paragraph_checksums"],doc["paragraph_sizes"]):
                # index paragraph checksums
                nd = checkcol.find_one({"_id":chs})
                if nd is not None:
                    copysz += paragraph_size
            if (copysz / len(text)) > TEXT_TRASH_RATIO:
                state = "copy"
            print(copysz)
        if state == "good":
            htdoc = get_link_doc(link,state)
            htdoc["html"] = html
            htdoc["html_size"] = len(html)
            # can be revisited - upsert
            del htdoc["url"]
            htmlcol.update_one({"url":link},{"$set":htdoc},upsert=True)
            doc.update(get_link_doc(link,"good"))
            # todo extract links
            print(doc)
            del doc["url"]
            contentcol.update_one({"url":link},{"$set":doc},upsert=True)
            for chs in doc["paragraph_checksums"]:
                try:
                    checkcol.insert_one({"_id":chs})
                except pymongo.errors.DuplicateKeyError as err:
                    pass
        linkcol.update_one({"url":original_link},{"$set":{"status":state}})


def extract_links(link_batch,responses,hostname,rules,default_status="frontlink"):
    links = {}
    badrobot = 0
    for original_link,(final_link,html) in zip(link_batch,responses):
        status = default_status
        external_links = courlan.extract_links(html,final_link,external_bool=True,language=LANGUAGE)
        for link in external_links:
            links[link] = "frontlink"
        internal_links = courlan.extract_links(html,final_link,external_bool=False,language=LANGUAGE)
        #print(extracted_links)
        for link in internal_links:
            if not is_robot_good(link,rules):
                badrobot += 1
                continue
            status = str(default_status)
            #print(link,status)
            links[link] = status
    outlinks = []
    badlink = 0
    for link,status in links.items():
        link = is_link_good(link)
        if link is None:
            badlink += 1
            continue
        outlinks.append((link,status))
    print(f"{len(links)} total links, {badrobot} badrobot {badlink} badlinks")
    return outlinks

def index_links(db,extracted_links):
    linkcol=db["links"]
    for link,status in extracted_links:
        if not is_link_good(link):
            continue
        doc = get_link_doc(link,status)
        try:
            linkcol.insert_one(doc)
        except pymongo.errors.DuplicateKeyError as ex:
            pass

def get_link_features(link):
    a, urlpath = courlan.get_host_and_path(link)
    features = re.split("[/?&]",urlpath)
    #features = re.split("[/?-_=]",urlpath)
    res = []
    for feature in features:
        if len(feature) < 1:
            continue
        if feature.isdigit():
            feature = "<NUM>"
        res.append(feature)
    if len(res) < 2:
        return None
    res = res[:-1]
    print(res)
    return res

class LinkClassifier:
    def __init__(self):

        self.goodcounter = collections.Counter()
        self.badcounter = collections.Counter()
        self.good_count = 0
        self.bad_count = 0
        self.alpha = 0.001

    def train(self,db,hostname):
        linkcol = db["links"]
        res = linkcol.find({"host":hostname,"status": {"$not":{"$in":["frontlink","backlink"]}}})
        testset = []
        for i,item in enumerate(res):
            link = item["url"]
            state = item["status"]
            cl = 0
            if state == "good":
                cl = 1
            print(cl,state,link)
            if i % 10 == 1:
                testset.append((link,cl))
                continue
            features = get_link_features(link)
            if features is None:
                continue
            lf = len(features)
            if state == "good":
                for feature in features:
                    self.good_count += 1
                    self.goodcounter[feature] += 1
            else:
                for feature in features:
                    self.bad_count += 1
                    self.badcounter[feature] += 1
        self.bdictsize = len(self.badcounter)
        self.gdictsize = len(self.goodcounter)
        # eval
        gg = 0
        for l,cl in testset:
            pcp = self.classify(l)
            r = 0
            if pcp > 0:
                r = 1
            if r == cl:
                gg += 1
            else:
                print("MISS",l,cl,pcp)
        print("Accuracy:")
        print(len(testset))
        print(gg / len(testset))

    def classify(self,link):
        features = get_link_features(link)
        res = 0
        gp = math.log(self.good_count) - math.log(self.good_count + self.bad_count)
        bp = math.log(self.bad_count) - math.log(self.good_count + self.bad_count)
        if features is None:
            return math.exp(gp) - math.exp(bp)
        gcc = math.log(self.gdictsize * self.alpha + self.good_count)
        bcc = math.log(self.bdictsize * self.alpha + self.bad_count)
        goodprob = 0
        badprob = 0
        for feature in features:
            g = math.log((self.goodcounter[feature] + self.alpha)) - gcc 
            goodprob += g
            b = math.log(self.badcounter[feature] + self.alpha) - bcc
            badprob += b
            print(feature,g,b)
        if (goodprob + gp)  > (badprob + bp):
        #if goodprob > badprob:
            res = 1
        pa = math.exp(goodprob + gp)
        pb = math.exp(badprob + bp)
        return pa - pb



def get_links(db,hostname,status,batch_size):
    linkcol = db["links"]
    # count downloaded links
    res = linkcol.aggregate([
        { "$match": { "status": {"$not":{"$in":["frontlink","backlink"]}},"host":hostname } },
        {"$group":{"_id":None,
                   "count":{"$count":{}},
                   }
         },
    ])
    links = set()
    out = list(res)
    if len(out) == 0:
        return list()
    if out[0]["count"] < 200:
    #res  = linkcol.find({"status":status,"host":hostname},{"url":1},limit=batch_size)
        # get random links
        res = linkcol.aggregate([
            { "$match": { "status": status,"host":hostname } },
            { "$sample": { "size": batch_size } }
        ])
        for i,doc in enumerate(res):
            #print(">>>>>" + status)
            #print(doc);
            links.add(doc["url"])
            if i >= batch_size:
                break
    else:
        cl = LinkClassifier()
        cl.train(db,hostname)
        res = linkcol.aggregate([
            { "$match": { "status": status,"host":hostname } },
            { "$sample": { "size": batch_size * 100 } }
        ])
        outlinks = []
        for i,doc in enumerate(res):
            #print(">>>>>" + status)
            #print(doc);
            link = doc["url"]
            outlinks.append((doc["url"],cl.classify(link)))
        outlinks = sorted(outlinks, key=lambda x: x[1],reverse=True)
        links = [l[0] for l in outlinks[0:batch_size]]
        # todo remove very bad links from database
    return list(links)


def fetch_sitemap_links(start_link):
    out = []
    navigation_links = trafilatura.sitemaps.sitemap_search(start_link,target_lang=LANGUAGE)
    for link in navigation_links:
        out.append((link,"frontlink"))
    return out

def process_links(db,hostname,status,links=[],rules=None,batch_size=BATCHSIZE):
    #print(links)
    responses = fetch_pages(links)
    #print(responses)
    extracted_pages = extract_pages(links,responses)
    #print(extracted_pages)
    extracted_links = extract_links(links,responses,hostname,rules,status)
    #print(extracted_links)
    index_links(db,extracted_links)
    index_pages(db,hostname,extracted_pages)


def link_summary(db,hostname):
    linkcol = db["links"]
    #res = linkcol.distinct("hostname",{"hostname":hostname})
    
    # count links
    res = linkcol.aggregate([
        {"$match":{"host":hostname}},
        {"$group":{"_id":"$status","count":{"$sum":1}}},
    ])
    badcount = 0
    goodcount = 0
    out = ["good","frontlink","backlink"]
    info = {}
    for item in res:
        if item["_id"] not in out:
            badcount += item["count"]
        if item["_id"] == "good":
            goodcount = item["count"]
        info[item["_id"]] = item["count"]
    good_prob = goodcount / (goodcount + badcount)
    info["good_prob"] = good_prob
    info["bad_documents"] = badcount
    print(">>>Domain Content")
    contentcol = db["content"]
    res = contentcol.aggregate([
        {"$match":{"host":hostname}},
        #{"$project": {"textsum":{"$sum":"$text_size"}}}
        {"$group":{"_id":None,
                   "text_size_sum":{"$sum":"$text_size"},
                   }
         },
    ])
    text_size = 0
    for item in res:
        text_size = item["text_size_sum"]
    good_document_characters = 0
    if goodcount > 0:
        good_document_characters = text_size / goodcount
    fetch_average_characters = text_size / (goodcount +  badcount)
    info["total_good_characters"] = text_size
    info["average_good_characters"] = good_document_characters
    info["average_fetch_characters"] = fetch_average_characters
    domaincol = db["domain"]
    if goodcount + badcount > 100: 
        cl = LinkClassifier()
        cl.train(db,hostname)
        res = linkcol.aggregate([
            { "$match": { "status": "backlink","host":hostname } },
            { "$sample": { "size": BATCHSIZE * 100 } }
        ])
        predicted_good = 0
        predicted_bad = 0
        for item in res:
            cll = cl.classify(item["url"])
            if cll > 0:
                predicted_good += 1
            else:
                predicted_bad += 1
        predicted_good_prob = 0
        if predicted_good + predicted_bad > 0:
            predicted_good_prob = predicted_good / (predicted_good + predicted_bad)
        info["predicted_good_prob"] = predicted_good_prob
    print(info)
    domaincol.update_one({"host":hostname},{"$set":info},upsert=True)

def domain_summary(db,hostname):
    linkcol = db["links"]
    #res = linkcol.distinct("hostname",{"hostname":hostname})
    
    # count links
    res = linkcol.aggregate([
        {"$group":{"_id":"$hostname","text_size_sum":{"$sum":"$text_size"}}},
    ])
    for item in res:
        print(item)

@click.group()
def cli():
    pass

@cli.command()
def createdb():
    myclient = pymongo.MongoClient(CONNECTION)
    db=myclient[DBNAME]
    linkcol = db["links"]
    linkcol.create_index("url",unique=True)
    linkcol.create_index("host")
    contentcol = db["content"]
    contentcol.create_index("url",unique=True)
    #contentcol.create_index({"paragraph_checksums":1})
    contentcol.create_index("host")
    htmlcol = db["html"]
    htmlcol.create_index("url",unique=True)
    domaincol = db["domains"]
    domaincol.create_index("host",unique=True)

@cli.command()
@click.argument("link")
def parseurl(link):
    link,hostname = courlan.check_url(link)
    rawrules = trafilatura.fetch_url("https://"+ hostname + "/robots.txt")
    print(rawrules)
    rules = urllib.robotparser.RobotFileParser()
    rules.parse(rawrules.split("\n"))
    print(rules.can_fetch("*",link))
    print(rules.site_maps())
    print(rules.crawl_delay("*"))
    html = trafilatura.fetch_url(link,decode=True)
    doc = trafilatura.bare_extraction(html)
    import pprint
    pprint.pprint(doc)

@cli.command()
@click.argument("link")
def externaldomains(link):
    html = trafilatura.fetch_url(link,decode=True)
    external_links = courlan.extract_links(html,link,external_bool=True,language=LANGUAGE)
    domains = set()
    for l in external_links:
        r = courlan.check_url(l)
        if r is None:
            pass
        link,domain = r
        domains.add(domain)
    for d in domains:
        print(d)

@cli.command()
@click.argument("start_link")
def classify(start_link):
    myclient = pymongo.MongoClient(CONNECTION)
    db=myclient[DBNAME]
    start_link,hostname = courlan.check_url(start_link)
    cl = LinkClassifier()
    cl.train(db,hostname)

@cli.command()
@click.argument("start_link")
def visit(start_link):
    myclient = pymongo.MongoClient(CONNECTION)
    db=myclient[DBNAME]
    start_link,hostname = courlan.check_url(start_link)
    batch_size = BATCHSIZE

    print("Getting  frontlinks")
    links = get_links(db,hostname,"frontlink",batch_size)
    print(f"Got {len(links)} frontlinks")
    if len(links) < batch_size:
        print("Fetching sitemap links")
        sitemap_links = fetch_sitemap_links(start_link)
        index_links(db,sitemap_links)
        links = get_links(db,hostname,"frontlink",batch_size)
    links.insert(0,start_link)
    if len(links) < batch_size:
        back_links = get_links(db,hostname,"backlink",batch_size - len(links))
        links += back_links

    print("Processing links")
    rules = fetch_robot(hostname)
    responses = fetch_pages(links)
    extracted_pages = extract_pages(links,responses)
    extracted_links = extract_links(links,responses,hostname,rules,"backlink")
    index_links(db,extracted_links)
    index_pages(db,hostname,extracted_pages)
    link_summary(db,hostname)

if __name__ == "__main__":
    cli()