import re
from collections import defaultdict
from operator import itemgetter
from threading import RLock
from urlparse import urlparse, unquote
from searx.engines import engines

CONTENT_LEN_IGNORED_CHARS_REGEX = re.compile('[,;:!?\./\\\\ ()-_]', re.M | re.U)
WHITESPACE_REGEX = re.compile('( |\t|\n)+', re.M | re.U)


# return the meaningful length of the content for a result
def result_content_len(content):
    if isinstance(content, basestring):
        return len(CONTENT_LEN_IGNORED_CHARS_REGEX.sub('', content))
    else:
        return 0


def compare_urls(url_a, url_b):
    if url_a.netloc != url_b.netloc or url_a.query != url_b.query:
        return False

    # remove / from the end of the url if required
    path_a = url_a.path[:-1]\
        if url_a.path.endswith('/')\
        else url_a.path
    path_b = url_b.path[:-1]\
        if url_b.path.endswith('/')\
        else url_b.path

    return unquote(path_a) == unquote(path_b)


def merge_two_infoboxes(infobox1, infobox2):
    if 'urls' in infobox2:
        urls1 = infobox1.get('urls', None)
        if urls1 is None:
            urls1 = []
            infobox1['urls'] = urls1

        urlSet = set()
        for url in infobox1.get('urls', []):
            urlSet.add(url.get('url', None))

        for url in infobox2.get('urls', []):
            if url.get('url', None) not in urlSet:
                urls1.append(url)

    if 'img_src' in infobox2:
        img1 = infobox1.get('img_src', None)
        img2 = infobox2.get('img_src')
        if img1 is None:
            infobox1['img_src'] = img2

    if 'attributes' in infobox2:
        attributes1 = infobox1.get('attributes', None)
        if attributes1 is None:
            attributes1 = []
            infobox1['attributes'] = attributes1

        attributeSet = set()
        for attribute in infobox1.get('attributes', []):
            if attribute.get('label', None) not in attributeSet:
                attributeSet.add(attribute.get('label', None))

        for attribute in infobox2.get('attributes', []):
            attributes1.append(attribute)

    if 'content' in infobox2:
        content1 = infobox1.get('content', None)
        content2 = infobox2.get('content', '')
        if content1 is not None:
            if result_content_len(content2) > result_content_len(content1):
                infobox1['content'] = content2
        else:
            infobox1['content'] = content2


def result_score(result):
    weight = 1.0

    for result_engine in result['engines']:
        if hasattr(engines[result_engine], 'weight'):
            weight *= float(engines[result_engine].weight)

    occurences = len(result['positions'])

    return sum((occurences * weight) / position for position in result['positions'])


class ResultContainer(object):
    """docstring for ResultContainer"""
    def __init__(self):
        super(ResultContainer, self).__init__()
        self.results = defaultdict(list)
        self._merged_results = []
        self.infoboxes = []
        self._infobox_ids = {}
        self.suggestions = set()
        self.answers = set()

    def extend(self, engine_name, results):
        for result in list(results):
            if 'suggestion' in result:
                self.suggestions.add(result['suggestion'])
                results.remove(result)
            elif 'answer' in result:
                self.answers.add(result['answer'])
                results.remove(result)
            elif 'infobox' in result:
                self._merge_infobox(result)
                results.remove(result)

        with RLock():
            engines[engine_name].stats['search_count'] += 1
            engines[engine_name].stats['result_count'] += len(results)

        if not results:
            return

        self.results[engine_name].extend(results)

        for i, result in enumerate(results):
            try:
                result['url'] = result['url'].decode('utf-8')
            except:
                pass
            position = i + 1
            self._merge_result(result, position)

    def _merge_infobox(self, infobox):
        add_infobox = True
        infobox_id = infobox.get('id', None)
        if infobox_id is not None:
            existingIndex = self._infobox_ids.get(infobox_id, None)
            if existingIndex is not None:
                merge_two_infoboxes(self.infoboxes[existingIndex], infobox)
                add_infobox = False

        if add_infobox:
            self.infoboxes.append(infobox)
            self._infobox_ids[infobox_id] = len(self.infoboxes) - 1

    def _merge_result(self, result, position):
        result['parsed_url'] = urlparse(result['url'])

        # if the result has no scheme, use http as default
        if not result['parsed_url'].scheme:
            result['parsed_url'] = result['parsed_url']._replace(scheme="http")
            result['url'] = result['parsed_url'].geturl()

        result['host'] = result['parsed_url'].netloc

        if result['host'].startswith('www.'):
            result['host'] = result['host'].replace('www.', '', 1)

        result['engines'] = [result['engine']]

        # strip multiple spaces and cariage returns from content
        if result.get('content'):
            result['content'] = WHITESPACE_REGEX.sub(' ', result['content'])

        # check for duplicates
        duplicated = False
        for merged_result in self._merged_results:
            if compare_urls(result['parsed_url'], merged_result['parsed_url'])\
               and result.get('template') == merged_result.get('template'):
                duplicated = merged_result
                break

        # merge duplicates together
        if duplicated:
            # using content with more text
            if result_content_len(result.get('content', '')) >\
                    result_content_len(duplicated.get('content', '')):
                duplicated['content'] = result['content']

            # add the new position
            duplicated['positions'].append(position)

            # add engine to list of result-engines
            duplicated['engines'].append(result['engine'])

            # using https if possible
            if duplicated['parsed_url'].scheme != 'https' and result['parsed_url'].scheme == 'https':
                duplicated['url'] = result['parsed_url'].geturl()
                duplicated['parsed_url'] = result['parsed_url']

        # if there is no duplicate found, append result
        else:
            result['positions'] = [position]
            with RLock():
                self._merged_results.append(result)

    def get_ordered_results(self):
        for result in self._merged_results:
            score = result_score(result)
            result['score'] = score
            with RLock():
                for result_engine in result['engines']:
                    engines[result_engine].stats['score_count'] += score

        results = sorted(self._merged_results, key=itemgetter('score'), reverse=True)

        # pass 2 : group results by category and template
        gresults = []
        categoryPositions = {}

        for i, res in enumerate(results):
            # FIXME : handle more than one category per engine
            category = engines[res['engine']].categories[0] + ':' + ''\
                if 'template' not in res\
                else res['template']

            current = None if category not in categoryPositions\
                else categoryPositions[category]

            # group with previous results using the same category
            # if the group can accept more result and is not too far
            # from the current position
            if current is not None and (current['count'] > 0)\
                    and (len(gresults) - current['index'] < 20):
                # group with the previous results using
                # the same category with this one
                index = current['index']
                gresults.insert(index, res)

                # update every index after the current one
                # (including the current one)
                for k in categoryPositions:
                    v = categoryPositions[k]['index']
                    if v >= index:
                        categoryPositions[k]['index'] = v + 1

                # update this category
                current['count'] -= 1

            else:
                # same category
                gresults.append(res)

                # update categoryIndex
                categoryPositions[category] = {'index': len(gresults), 'count': 8}

        # return gresults
        return gresults

    def results_length(self):
        return len(self._merged_results)
