try:
    import simplejson as json
except ImportError:
    import json  # noqa

from u1db import Document
from u1db.remote.http_target import HTTPSyncTarget
import base64


class LeapDocument(Document):
    """
    LEAP Documents are standard u1db documents with cabability of returning an
    encrypted version of the document json string as well as setting document
    content based on an encrypted version of json string.
    """

    def __init__(self, doc_id=None, rev=None, json='{}', has_conflicts=False,
                 encrypted_json=None):
        super(Document, self).__init__(doc_id, rev, json, has_conflicts)
        if encrypted_json:
            self.set_encrypted_json(encrypted_json)

    def get_encrypted_json(self):
        """
        Returns document's json serialization encrypted with user's public key.
        """
        # TODO: replace for openpgp encryption with users's pub key.
        return base64.b64encode(self.get_json())

    def set_encrypted_json(self):
        """
        Set document's content based on encrypted version of json string.
        """
        # TODO:
        #   - replace for openpgp decryption using user's priv key.
        #   - raise error if unsuccessful.
        return self.set_json(base64.b64decode(self.get_json()))


class LeapSyncTarget(HTTPSyncTarget):

    def _parse_sync_stream(self, data, return_doc_cb, ensure_callback=None):
        parts = data.splitlines()  # one at a time
        if not parts or parts[0] != '[':
            raise BrokenSyncStream
        data = parts[1:-1]
        comma = False
        if data:
            line, comma = utils.check_and_strip_comma(data[0])
            res = json.loads(line)
            if ensure_callback and 'replica_uid' in res:
                ensure_callback(res['replica_uid'])
            for entry in data[1:]:
                if not comma:  # missing in between comma
                    raise BrokenSyncStream
                line, comma = utils.check_and_strip_comma(entry)
                entry = json.loads(line)
                doc = LeapDocument(entry['id'], entry['rev'],
                                   encrypted_json=entry['content'])
                return_doc_cb(doc, entry['gen'], entry['trans_id'])
        if parts[-1] != ']':
            try:
                partdic = json.loads(parts[-1])
            except ValueError:
                pass
            else:
                if isinstance(partdic, dict):
                    self._error(partdic)
            raise BrokenSyncStream
        if not data or comma:  # no entries or bad extra comma
            raise BrokenSyncStream
        return res

    def sync_exchange(self, docs_by_generations, source_replica_uid,
                      last_known_generation, last_known_trans_id,
                      return_doc_cb, ensure_callback=None):
        self._ensure_connection()
        if self._trace_hook:  # for tests
            self._trace_hook('sync_exchange')
        url = '%s/sync-from/%s' % (self._url.path, source_replica_uid)
        self._conn.putrequest('POST', url)
        self._conn.putheader('content-type', 'application/x-u1db-sync-stream')
        for header_name, header_value in self._sign_request('POST', url, {}):
            self._conn.putheader(header_name, header_value)
        entries = ['[']
        size = 1

        def prepare(**dic):
            entry = comma + '\r\n' + json.dumps(dic)
            entries.append(entry)
            return len(entry)

        comma = ''
        size += prepare(
            last_known_generation=last_known_generation,
            last_known_trans_id=last_known_trans_id,
            ensure=ensure_callback is not None)
        comma = ','
        for doc, gen, trans_id in docs_by_generations:
            size += prepare(id=doc.doc_id, rev=doc.rev,
                            content=doc.get_encrypted_json(),
                            gen=gen, trans_id=trans_id)
        entries.append('\r\n]')
        size += len(entries[-1])
        self._conn.putheader('content-length', str(size))
        self._conn.endheaders()
        for entry in entries:
            self._conn.send(entry)
        entries = None
        data, _ = self._response()
        res = self._parse_sync_stream(data, return_doc_cb, ensure_callback)
        data = None
        return res['new_generation'], res['new_transaction_id']