import pymongo
import trafilatura
import trafilatura.feeds
import trafilatura.sitemaps
import trafilatura.spider
import trafilatura.utils
import sys
import courlan

LANGUAGE="sk"
BATCHSIZE=10

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:
            hval += (hval << 3) + cv
            zv = hval >> 31
            hval &= 0x7fffffff
            hval += zv
            hsz += 1
        if c == "\n" and hsz > 0:
            if hsz > 100:
                checksums.append(hval)
                sizes.append(sz)
            sz = 0
            hsz = 0
    if hsz > 100:
        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("*", llink):
        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,ldomain = r
    print(llink,ldomain)
    # domain rules
    if not ldomain.endswith("sk"):
        print("bad domain")
        return None
    if courlan.is_not_crawlable(llink):
        print("not crawlable")
        return None
    return None

def filter_links(links,rules=None):
    out = set()
    for link in links:
        r = is_link_good(link)
        if r is None:
            continue
        # check robots.txt rules
        if rules is not None and not rules.can_fetch("*", r):
            continue
        out.add(llink)
    return out

def sort_links(links,domain):
    for llink in filtered_links:
        doc = get_link_doc(link,"backlink")
        if courlan.is_external(link,domain):
            doc["status"]= "frontlink"
        elif courlan.is_navigation(link):
            doc["status"] = "navigation"
        linkcol.insert_one(doc)

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}

def generic_visit(domain):
    known_links = set(get_visited_links(domain))
    visit_links = []
    visit_links = trafilatura.find_feed_urls(domain)
    if visit_links is None:
        visit_links = trafilatura.sitemap_search(domain)
    if visit_links is None:
        visit_links = trafilatura.focused_crawler(dommain,known_links=known_links)


def fetch_pages(link_batch):
    htmls  = []
    print(link_batch)
    print("zzzzzzzzzz")
    for link in link_batch:
        print("fetching:::::")
        print(link)
        response = trafilatura.fetch_url(link,decode=False)
        htmlstring, homepage = trafilatura.spider.refresh_detection(response.data, link)
        # is there a meta-refresh on the page?
        if homepage is None:  # malformed or malicious content
            response = None
        htmls.append(response)
    return htmls

def fetch_rules(base_url):
    rules = urllib.robotparser.RobotFileParser()
    rules.set_url(base_url + '/robots.txt')
    # exceptions happening here
    try:
        rules.read()
    except Exception as exc:
        LOGGER.error('cannot read robots.txt: %s', exc)
        rules = None
    return rules


def extract_pages(link_batch,responses):
    out = []
    extracted_links = set()
    for link,response in zip(link_batch,responses):
        doc = None
        assert link is not None
        html = None
        response_link = None
        if response is not None:
            html = trafilatura.utils.decode_response(response) 
        if html is not None:
            doc = trafilatura.bare_extraction(html,url=link,with_metadata=True,include_formatting=True,target_language=LANGUAGE)
        out.append((link,response_link,html,doc))
    return out


def index_pages(db,domain,extracted_pages):
    extracted_links = set()
    linkcol = db["links"]
    htmlcol = db["html"]
    contentcol = db["content"]
    for original_link,final_link,html,doc in extracted_pages:
        state = "good"
        if html is None:
            state = "html_error"
        elif doc is None:
            state = "content_error"
        if html is not None:
            htmlcol.insert_one({"url":final_link,"html":html})
        if doc is not None:
            checksums,sizes = calculate_checksums(doc["text"])
            doc["paragraph_checksums"] = checksums
            doc["paragraph_sizes"] = sizes
            # todo extract links
            print(doc)
            contentcol.insert_one(doc)


def extract_links(link_batch,responses,domain,rules,default_status="frontlink"):
    links = {}
    for original_link,response in zip(link_batch,resposnes):
        final_link = response.url
        status = default_status
        link = original_link
        if original_link != final_link:
            links[original_link] = "redirect"
            link = final_link
        if courlan.is_external(link,domain):
            status = "frontlink"
        elif courlan.is_navigation(link):
            status = "navigation"
        links[link] = status
        extracted_links = courlan.extract_links(response.content)
        for link in extracted_links
            if courlan.is_external(link,domain):
                status = "frontlink"
            elif courlan.is_navigation(link):
                status = "navigation"
            links[link] = status
    outlinks = []
    for link,status in links.items():
        if  not is_robot_good(rules):
            continue
        link = is_link_good(link)
        if link is None:
            continue
        outlinks.append((link,status))
    return outlinks

def index_links(db,extracted_links):
    linkcol=db["links"]
    for link,status in extracted_links:
        doc = get_link_doc(link,status)
        linkcol.insert_one(doc)


def get_links(db,domain,status,batch_size=BATCHSIZE):
    linkcol = db["links"]
    res  = linkcol.find({"status":status,"domain":domain},{"url":1},limit=batch_size)
    print(res,domain,status)
    front_links = []
    for doc in res:
        print(doc)
        front_links.append(doc["url"])
    return front_links


def index_front_links(db,filtered_links):
    linkcol = db["links"]
    for link in filtered_links:
        linkcol.insert_one(get_link_doc(link,"frontlink"))


    #visit_links = trafilatura.feeds.find_feed_urls(domain)
    #visit_links = trafilatura.sitemaps.sitemap_search(domain)
    #print(visit_links)
    #for link in visit_links:
    #    content = trafilatura.fetch_url(link,decode=True)
    #    document = trafilatura.bare_extraction(content)
    #    print(content)

def process_links(status,domain,links=[],rules=None):
    links += get_links(db,domain,status)
    responses = fetch_pages(links)
    extracted_pages = extract_pages(links,responses)
    extracted_links = extract_links(links,responses,domain,rules,status)
    index_links(db,extracted_links)
    index_pages(db,domain,extracted_pages)

def simple_visit(start_link):
    start_link,domain = courlan.check_url(start_link)
    myclient = pymongo.MongoClient("mongodb://root:example@localhost:27017/")
    db=myclient["crawler"]
    rules = fetch_robot(domain)
    navigation_links =[start_link]
    print(navigation_links)
    process_links(db,domain,"navigation",navigation_links,rules)
    process_links(db,domain,front_links,rules)
    back_links = get_links(db,domain,"backlink")
    process_links(db,domain,front_links,rules)
    #new_front_links = fetch_front_links(navigation_links)
    print("NEW FRONT LINKS")
    #print(new_front_links)
    #index_front_links(db,new_front_links)
    front_links = get_links(db,domain,"frontlink")
    print("NEW VISIT LINKS")
    visit_links = front_links
    print(visit_links)
    responses = fetch_pages(visit_links)

simple_visit(sys.argv[1])