# -*- coding: utf-8 -*-
# ------------------------------------------------------------
# Gestiona el cache del servidor torrent:
# Guarda los .torrent generado
# Guarda los .resume de cada torrent
# ------------------------------------------------------------
import base64
import os.path
import re

try:
    from python_libtorrent import get_libtorrent

    lt = get_libtorrent()
except Exception, e:
    import libtorrent as lt


class Cache(object):
    CACHE_DIR = '.cache'

    def __init__(self, path):

        if not os.path.isdir(path):
            os.makedirs(path)
        self.path = os.path.join(path, Cache.CACHE_DIR)
        if not os.path.isdir(self.path):
            os.makedirs(self.path)

    def _tname(self, info_hash):
        return os.path.join(self.path, info_hash.upper() + '.torrent')

    def _rname(self, info_hash):
        return os.path.join(self.path, info_hash.upper() + '.resume')

    def save_resume(self, info_hash, data):
        f = open(self._rname(info_hash), 'wb')
        f.write(data)
        f.close()

    def get_resume(self, url=None, info_hash=None):
        if url:
            info_hash = self._index.get(url)
        if not info_hash:
            return
        rname = self._rname(info_hash)
        if os.access(rname, os.R_OK):
            f = open(rname, 'rb')
            v = f.read()
            f.close()
            return v

    def file_complete(self, torrent):
        info_hash = str(torrent.info_hash())
        nt = lt.create_torrent(torrent)
        tname = self._tname(info_hash)
        f = open(tname, 'wb')
        f.write(lt.bencode(nt.generate()))
        f.close()

    def get_torrent(self, url=None, info_hash=None):
        if url:
            info_hash = self._index.get(url)
        if not info_hash:
            return
        tname = self._tname(info_hash)
        if os.access(tname, os.R_OK):
            return tname

    magnet_re = re.compile('xt=urn:btih:([0-9A-Za-z]+)')
    hexa_chars = re.compile('^[0-9A-F]+$')

    @staticmethod
    def hash_from_magnet(m):
        res = Cache.magnet_re.search(m)
        if res:
            ih = res.group(1).upper()
            if len(ih) == 40 and Cache.hexa_chars.match(ih):
                return res.group(1).upper()
            elif len(ih) == 32:
                s = base64.b32decode(ih)
                return "".join("{:02X}".format(ord(c)) for c in s)
            else:
                raise ValueError('Not BT magnet link')

        else:
            raise ValueError('Not BT magnet link')