#!/usr/local/bin/python2.7
# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
from __future__ import (unicode_literals, division, absolute_import,
                        print_function)

__license__   = 'GPL v3'
__copyright__ = '2011, Kovid Goyal <kovid@kovidgoyal.net>'
__docformat__ = 'restructuredtext en'

import time, hashlib
from urllib import urlencode
from functools import partial
from Queue import Queue, Empty

from lxml import etree

from calibre.ebooks.metadata import check_isbn
from calibre.ebooks.metadata.sources.base import Source
from calibre.ebooks.metadata.book.base import Metadata
from calibre.ebooks.chardet import xml_to_unicode
from calibre.utils.date import parse_date, utcnow
from calibre.utils.cleantext import clean_ascii_chars
from calibre.utils.localization import canonicalize_lang
from calibre import as_unicode

NAMESPACES = {
              'openSearch':'http://a9.com/-/spec/opensearchrss/1.0/',
              'atom' : 'http://www.w3.org/2005/Atom',
              'dc'   : 'http://purl.org/dc/terms',
              'gd'   : 'http://schemas.google.com/g/2005'
            }
XPath = partial(etree.XPath, namespaces=NAMESPACES)

total_results  = XPath('//openSearch:totalResults')
start_index    = XPath('//openSearch:startIndex')
items_per_page = XPath('//openSearch:itemsPerPage')
entry          = XPath('//atom:entry')
entry_id       = XPath('descendant::atom:id')
creator        = XPath('descendant::dc:creator')
identifier     = XPath('descendant::dc:identifier')
title          = XPath('descendant::dc:title')
date           = XPath('descendant::dc:date')
publisher      = XPath('descendant::dc:publisher')
subject        = XPath('descendant::dc:subject')
description    = XPath('descendant::dc:description')
language       = XPath('descendant::dc:language')
rating         = XPath('descendant::gd:rating[@average]')

def get_details(browser, url, timeout): # {{{
    try:
        raw = browser.open_novisit(url, timeout=timeout).read()
    except Exception as e:
        gc = getattr(e, 'getcode', lambda : -1)
        if gc() != 403:
            raise
        # Google is throttling us, wait a little
        time.sleep(2)
        raw = browser.open_novisit(url, timeout=timeout).read()

    return raw
# }}}

def to_metadata(browser, log, entry_, timeout): # {{{

    def get_text(extra, x):
        try:
            ans = x(extra)
            if ans:
                ans = ans[0].text
                if ans and ans.strip():
                    return ans.strip()
        except:
            log.exception('Programming error:')
        return None


    id_url = entry_id(entry_)[0].text
    google_id = id_url.split('/')[-1]
    title_ = ': '.join([x.text for x in title(entry_)]).strip()
    authors = [x.text.strip() for x in creator(entry_) if x.text]
    if not authors:
        authors = [_('Unknown')]
    if not id_url or not title:
        # Silently discard this entry
        return None

    mi = Metadata(title_, authors)
    mi.identifiers = {'google':google_id}
    try:
        raw = get_details(browser, id_url, timeout)
        feed = etree.fromstring(xml_to_unicode(clean_ascii_chars(raw),
            strip_encoding_pats=True)[0])
        extra = entry(feed)[0]
    except:
        log.exception('Failed to get additional details for', mi.title)
        return mi

    mi.comments = get_text(extra, description)
    lang = canonicalize_lang(get_text(extra, language))
    if lang:
        mi.language = lang
    mi.publisher = get_text(extra, publisher)

    # ISBN
    isbns = []
    for x in identifier(extra):
        t = str(x.text).strip()
        if t[:5].upper() in ('ISBN:', 'LCCN:', 'OCLC:'):
            if t[:5].upper() == 'ISBN:':
                t = check_isbn(t[5:])
                if t:
                    isbns.append(t)
    if isbns:
        mi.isbn = sorted(isbns, key=len)[-1]
    mi.all_isbns = isbns

    # Tags
    try:
        btags = [x.text for x in subject(extra) if x.text]
        tags = []
        for t in btags:
            atags = [y.strip() for y in t.split('/')]
            for tag in atags:
                if tag not in tags:
                    tags.append(tag)
    except:
        log.exception('Failed to parse tags:')
        tags = []
    if tags:
        mi.tags = [x.replace(',', ';') for x in tags]

    # pubdate
    pubdate = get_text(extra, date)
    if pubdate:
        try:
            default = utcnow().replace(day=15)
            mi.pubdate = parse_date(pubdate, assume_utc=True, default=default)
        except:
            log.error('Failed to parse pubdate %r'%pubdate)

    # Ratings
    for x in rating(extra):
        try:
            mi.rating = float(x.get('average'))
            if mi.rating > 5:
                mi.rating /= 2
        except:
            log.exception('Failed to parse rating')

    # Cover
    mi.has_google_cover = None
    for x in extra.xpath(
            '//*[@href and @rel="http://schemas.google.com/books/2008/thumbnail"]'):
        mi.has_google_cover = x.get('href')
        break

    return mi
# }}}

class GoogleBooks(Source):

    name = 'Google'
    description = _('Downloads metadata and covers from Google Books')

    capabilities = frozenset(['identify', 'cover'])
    touched_fields = frozenset(['title', 'authors', 'tags', 'pubdate',
        'comments', 'publisher', 'identifier:isbn', 'rating',
        'identifier:google', 'languages'])
    supports_gzip_transfer_encoding = True
    cached_cover_url_is_reliable = False

    GOOGLE_COVER = 'http://books.google.com/books?id=%s&printsec=frontcover&img=1'

    DUMMY_IMAGE_MD5 = frozenset(['0de4383ebad0adad5eeb8975cd796657'])

    def get_book_url(self, identifiers): # {{{
        goog = identifiers.get('google', None)
        if goog is not None:
            return ('google', goog, 'http://books.google.com/books?id=%s'%goog)
    # }}}

    def create_query(self, log, title=None, authors=None, identifiers={}): # {{{
        BASE_URL = 'http://books.google.com/books/feeds/volumes?'
        isbn = check_isbn(identifiers.get('isbn', None))
        q = ''
        if isbn is not None:
            q += 'isbn:'+isbn
        elif title or authors:
            def build_term(prefix, parts):
                return ' '.join('in'+prefix + ':' + x for x in parts)
            title_tokens = list(self.get_title_tokens(title))
            if title_tokens:
                q += build_term('title', title_tokens)
            author_tokens = self.get_author_tokens(authors,
                    only_first_author=True)
            if author_tokens:
                q += ('+' if q else '') + build_term('author',
                        author_tokens)

        if isinstance(q, unicode):
            q = q.encode('utf-8')
        if not q:
            return None
        return BASE_URL+urlencode({
            'q':q,
            'max-results':20,
            'start-index':1,
            'min-viewability':'none',
            })
    # }}}

    def download_cover(self, log, result_queue, abort, # {{{
            title=None, authors=None, identifiers={}, timeout=30):
        cached_url = self.get_cached_cover_url(identifiers)
        if cached_url is None:
            log.info('No cached cover found, running identify')
            rq = Queue()
            self.identify(log, rq, abort, title=title, authors=authors,
                    identifiers=identifiers)
            if abort.is_set():
                return
            results = []
            while True:
                try:
                    results.append(rq.get_nowait())
                except Empty:
                    break
            results.sort(key=self.identify_results_keygen(
                title=title, authors=authors, identifiers=identifiers))
            for mi in results:
                cached_url = self.get_cached_cover_url(mi.identifiers)
                if cached_url is not None:
                    break
        if cached_url is None:
            log.info('No cover found')
            return

        if abort.is_set():
            return
        br = self.browser
        log('Downloading cover from:', cached_url)
        try:
            cdata = br.open_novisit(cached_url, timeout=timeout).read()
            if cdata:
                if hashlib.md5(cdata).hexdigest() in self.DUMMY_IMAGE_MD5:
                    log.warning('Google returned a dummy image, ignoring')
                else:
                    result_queue.put((self, cdata))
        except:
            log.exception('Failed to download cover from:', cached_url)

    # }}}

    def get_cached_cover_url(self, identifiers): # {{{
        url = None
        goog = identifiers.get('google', None)
        if goog is None:
            isbn = identifiers.get('isbn', None)
            if isbn is not None:
                goog = self.cached_isbn_to_identifier(isbn)
        if goog is not None:
            url = self.cached_identifier_to_cover_url(goog)

        return url
    # }}}

    def get_all_details(self, br, log, entries, abort, # {{{
            result_queue, timeout):
        for relevance, i in enumerate(entries):
            try:
                ans = to_metadata(br, log, i, timeout)
                if isinstance(ans, Metadata):
                    ans.source_relevance = relevance
                    goog = ans.identifiers['google']
                    for isbn in getattr(ans, 'all_isbns', []):
                        self.cache_isbn_to_identifier(isbn, goog)
                    if ans.has_google_cover:
                        self.cache_identifier_to_cover_url(goog,
                                self.GOOGLE_COVER%goog)
                    self.clean_downloaded_metadata(ans)
                    result_queue.put(ans)
            except:
                log.exception(
                    'Failed to get metadata for identify entry:',
                    etree.tostring(i))
            if abort.is_set():
                break
    # }}}

    def identify(self, log, result_queue, abort, title=None, authors=None, # {{{
            identifiers={}, timeout=30):
        query = self.create_query(log, title=title, authors=authors,
                identifiers=identifiers)
        if not query:
            log.error('Insufficient metadata to construct query')
            return
        br = self.browser
        try:
            raw = br.open_novisit(query, timeout=timeout).read()
        except Exception as e:
            log.exception('Failed to make identify query: %r'%query)
            return as_unicode(e)

        try:
            parser = etree.XMLParser(recover=True, no_network=True)
            feed = etree.fromstring(xml_to_unicode(clean_ascii_chars(raw),
                strip_encoding_pats=True)[0], parser=parser)
            entries = entry(feed)
        except Exception as e:
            log.exception('Failed to parse identify results')
            return as_unicode(e)

        if not entries and identifiers and title and authors and \
                not abort.is_set():
            return self.identify(log, result_queue, abort, title=title,
                    authors=authors, timeout=timeout)

        # There is no point running these queries in threads as google
        # throttles requests returning 403 Forbidden errors
        self.get_all_details(br, log, entries, abort, result_queue, timeout)

        return None
    # }}}

if __name__ == '__main__': # tests {{{
    # To run these test use: calibre-debug -e src/calibre/ebooks/metadata/sources/google.py
    from calibre.ebooks.metadata.sources.test import (test_identify_plugin,
            title_test, authors_test)
    test_identify_plugin(GoogleBooks.name,
        [


            (
                {'identifiers':{'isbn': '0743273567'}, 'title':'Great Gatsby',
                    'authors':['Fitzgerald']},
                [title_test('The great gatsby', exact=True),
                    authors_test(['Francis Scott Fitzgerald'])]
            ),

            (
                {'title': 'Flatland', 'authors':['Abbott']},
                [title_test('Flatland', exact=False)]
            ),
    ])
# }}}

