#!/usr/bin/env python3.7
#
# Copyright (C) 2018 The University of Sheffield, UK
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

import sys
import os
import math
import getopt
from multiprocessing import Process, Queue, Manager
from itertools import islice, groupby
from operator import itemgetter
import heapq
import MySQLdb
from MySQLdb import cursors


def unique_justseen(iterable, key=None):
    "List unique elements, preserving order. Remember only the element just seen."
    # unique_justseen('AAAABBBCCDAABBB') --> A B C D A B
    # unique_justseen('ABBCcAD', str.lower) --> A B C A D
    return map(next, map(itemgetter(1), groupby(iterable, key)))


def grouper(it, chunksize):
    while True:
        chunk = list(islice(it, chunksize))
        yield chunk
        if len(chunk) < chunksize:
            break


def execute(q, args=None):
    db = MySQLdb.connect(read_default_file=os.path.expanduser("~/.my.cnf"), cursorclass=cursors.SSDictCursor)
    cursor = db.cursor()
    cursor.execute(q, args)
    return cursor


class MD5Table(Process):
    def __init__(self, out_q, fp_q, query_q):
        super().__init__()

        self.out_q = out_q
        self.fp_q = fp_q
        self.query_q = query_q

        self.table = {}

    def run(self):
        for fps in iter(self.fp_q.get, SimhashTable.STOP):
            for fp_info, _, fp_md5 in fps:
                if fp_md5 not in self.table:
                    self.table[fp_md5] = []
                self.table[fp_md5] += [fp_info]
        for queries in iter(self.query_q.get, SimhashTable.STOP):
            for query_info, _, query_md5 in queries:
                if query_md5 in self.table:
                    for fp_info in self.table[query_md5]:
                        self.out_q.put((query_info, fp_info, -1))
        self.out_q.put(SimhashTable.STOP)


class SimhashTable(Process):
    STOP = "stop"

    def __init__(self, max_dist, splitter, out_q, fp_q, query_q):
        super().__init__()

        self.max_dist = max_dist
        self.out_q = out_q

        self.splitter = splitter
        self.table = {}
        self.fp_q = fp_q
        self.query_q = query_q

    @staticmethod
    def bit_count(n):
        return bin(n).count("1")

    def get_chunk(self, n):
        """Reduces the simhash to a small chunk, given by self.splitters. The chunk will
        then be compared exactly in order to increase performance."""
        sum = 0
        for (s, c) in self.splitter:
            sum <<= c
            sum += (n >> s) & (pow(2, c) - 1)
        return sum

    def _add(self, fp_info, fp_simhash):
        fp_chunk = self.get_chunk(fp_simhash)
        if not fp_chunk in self.table:
            self.table[fp_chunk] = []
        self.table[fp_chunk] += [(fp_info, fp_simhash)]

    def _query(self, query_simhash):
        query_chunk = self.get_chunk(query_simhash)
        if query_chunk in self.table:
            for fp_info, fp_simhash in self.table[query_chunk]:
                diff = SimhashTable.bit_count(query_simhash ^ fp_simhash)
                if diff <= self.max_dist:
                    yield ((fp_info, fp_simhash), diff)

    def run(self):
        for fps in iter(self.fp_q.get, SimhashTable.STOP):
            for fp_info, fp_simhash, _ in fps:
                self._add(fp_info, fp_simhash)
        for queries in iter(self.query_q.get, SimhashTable.STOP):
            for query_info, query_simhash, _ in queries:
                for ((fp_info, fp_simhash), diff) in self._query(query_simhash):
                    self.out_q.put((query_info, fp_info, diff))
        self.out_q.put(SimhashTable.STOP)


class SimhashBucket(Process):
    """Implementation of http://wwwconference.org/www2007/papers/paper215.pdf"""

    def __init__(self, fp_it, query_it, max_dist=3, fp_size=64):
        super().__init__()
        # Each element of splitters describes the key for one table. The first element of the tuple indicates the number
        # of bits that we shift the simhash to the right; the second element indicates how many bits, from the right
        # side, we end up taking. For example, with max_dist=5, we end up with [(0, 11)], [(11, 11)], [(22, 11)],
        # [(33, 11)], [(44, 11)], [(55, 9)]
        if max_dist >= 0 :
            chunksize = math.ceil(fp_size / (max_dist + 1))
            self.splitters = [[(i, min(chunksize, fp_size - i))] for i in range(0, fp_size, chunksize)]
        else:
            self.splitters = []

        self.fp_it = fp_it
        self.query_it = query_it

        self.tables = []
        self.fp_qs = [Queue() for _ in range(len(self.splitters) + 1)]
        self.query_qs = [Queue() for _ in range(len(self.splitters) + 1)]
        self.out_qs = [Queue() for _ in range(len(self.splitters) + 1)]

        self.max_dist = max_dist

        self.fp_store = Manager().list()
        self.query_store = Manager().list()

    @staticmethod
    def broadcast(it, qs, store, chunksize=1):
        for x in grouper(it, chunksize):
            store += [info for info, _, _ in x]
            for q in qs:
                q.put([(len(store) - len(x) + i, simhash, md5) for i, (_, simhash, md5) in enumerate(x)])
        for q in qs:
            q.put(SimhashTable.STOP)

    def run(self):
        self.tables = [SimhashTable(self.max_dist, *args) for args in zip(self.splitters, self.out_qs, self.fp_qs, self.query_qs)] \
            + [MD5Table(self.out_qs[-1], self.fp_qs[-1], self.query_qs[-1])]
        for tbl in self.tables:
            tbl.start()

        SimhashBucket.broadcast(self.fp_it, self.fp_qs, self.fp_store, 100)
        SimhashBucket.broadcast(self.query_it, self.query_qs, self.query_store, 100)

        for i, tbl in enumerate(self.tables):
            tbl.join()

    def __iter__(self):
        for query_i, fp_i, diff in unique_justseen(heapq.merge(*[iter(q.get, SimhashTable.STOP) for q in self.out_qs])):
            yield self.query_store[query_i], self.fp_store[fp_i], diff


def get_cdnjs_simhashes(limit=None):
    for row in execute((
            "select simhash, path, typ, library, version, md5, add_date from "
            "cdnjs where "
            "simhash IS NOT NULL AND path like '%.js' and "
            "HEX(md5) <> 'd41d8cd98f00b204e9800998ecf8427e' and typ = 'NORMALIZED' and add_date is not null "
            "{limit}")
            .format(
                limit=f"limit {limit}" if limit else ""
    )):
        yield row, int(row['simhash']), row['md5']


def get_crxfile_simhashes(extension_limit=None, crxfile_limit=None):
    for row in execute((
            "select extid, crx_etag, path, typ, simhash, md5, lastupdated, name from "
            "(select * from extension_most_recent where downloads >= 100000 {extension_limit}) extension join "
            "(select * from crxfile {crxfile_limit}) crxfile using (crx_etag) "
            "join libdet using (md5, typ) "
            "where simhash is not null and path like '%.js' and typ = 'NORMALIZED'")
            .format(
                extension_limit=f"limit {extension_limit}" if extension_limit else "",
                crxfile_limit=f"limit {crxfile_limit}" if crxfile_limit else ""
    )):
        yield row, int(row['simhash']), row['md5']


def print_help():
    print("""simhashbucket [OPTIONS]""")
    print("""  -h, --help             print this help text""")
    print("""  --limit-cdnjs <N>      only retrieve N rows, default: all""")
    print("""  --limit-extension <N>  only retrieve N rows, default: all""")
    print("""  --limit-crxfile <N>    only retrieve N rows, default: all""")

def parse_args(argv):
    limit_cdnjs = None
    limit_extension = None
    limit_crxfile = None

    try:
        opts, args = getopt.getopt(argv, "h", [
            "limit-cdnjs=", "limit-extension=", "limit-crxfile=", "help"])
    except getopt.GetoptError:
        print_help()
        sys.exit(2)
    try:
        for opt, arg in opts:
            if opt == "--limit-cdnjs":
                limit_cdnjs = int(arg)
            elif opt == "--limit-extension":
                limit_extension = int(arg)
            elif opt == "--limit-crxfile":
                limit_crxfile = int(arg)
            elif opt in ["-h", "--help"]:
                print_help()
                sys.exit(0)
    except ValueError:
        print("Arguments to int options must be an int!", file=sys.stderr)
        print_help()
        sys.exit(2)

    if len(args) != 0:
        print_help()
        sys.exit(2)

    return limit_cdnjs, limit_extension, limit_crxfile


def main(args):
    limit_cdnjs, limit_extension, limit_crxfile = parse_args(args)

    fp_it = get_cdnjs_simhashes(limit_cdnjs)
    query_it = get_crxfile_simhashes(limit_extension, limit_crxfile)

    bucket = SimhashBucket(fp_it, query_it, max_dist=-1)
    bucket.start()
    libraries = {}
    for query_info, fp_info, diff in bucket:
        if diff == -1:
            lib = fp_info["library"]
            t = (fp_info["add_date"], fp_info["version"])
            if lib not in libraries:
                libraries[lib] = {}
            if t not in libraries[lib]:
                libraries[lib][t] = []
            libraries[lib][t] += [(query_info, fp_info)]
            #if fp_info["library"] == "jquery" and fp_info["version"] == "2.1.1":
            #    print(f"{query_info['extid']} ({query_info['crx_etag']}): {query_info['name']} ({query_info['lastupdated']})")

    res = []
    for lib in libraries:
        assigned_MD5s = set()
        for add_date, version in sorted(libraries[lib], key=lambda tup: tup[0], reverse=True):
            md5s = set()
            exts = set()
            for query_info, fp_info in libraries[lib][(add_date, version)]:
                if fp_info["md5"] not in assigned_MD5s:
                    exts.add((query_info["extid"], query_info["crx_etag"]))
                    md5s.add(fp_info["md5"])
            for md5 in md5s:
                assigned_MD5s.add(md5)
            res += [(len(exts), lib, version)]
    for N, lib, version in sorted(res):
        print(f"{lib} (v{version}): {N}")


if __name__ == "__main__":
    main(sys.argv[1:])