###
# Copyright (c) 2019, James Lu <james@overdrivenetworks.com>
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###

"""
accountsdb: Provides storage for user-specific data via Supybot accounts, ident@host, or nicks.
"""

import pickle
import os

from supybot import ircdb, log, conf, registry

MODES = ["accounts", "identhost", "nicks"]
DEFAULT_MODE = MODES[0]

class _AccountsDBAddressConfig(registry.OnlySomeStrings):
    validStrings = MODES

CONFIG_OPTION_NAME = "DBAddressingMode"
CONFIG_OPTION = _AccountsDBAddressConfig(DEFAULT_MODE, """Sets the DB addressing mode.
    This requires reloading the plugin to take effect. Valid settings include accounts
    (save users by Supybot accounts and ident@host if not registered), identhost
    (save users by ident@host), and nicks (save users by nicks).
    When changing addressing modes, existing keys will be left intact, but migration between
    addressing modes is NOT supported.""")

class AccountsDB():
    """
    Abstraction to map users to third-party account names.

    This stores users by their bot account first, falling back to their
    ident@host if they are not logged in.
    """

    def __init__(self, plugin_name, filename, addressing_mode=DEFAULT_MODE, case_sensitive=False):
        """
        Loads the existing database, creating a new one in memory if none
        exists.
        """
        self.db = {}
        self._plugin_name = plugin_name
        self.filename = conf.supybot.directories.data.dirize(filename)
        self.case_sensitive = case_sensitive

        self.addressing_mode = addressing_mode

        try:
            with open(self.filename, 'rb') as f:
               self.db = pickle.load(f)
        except Exception as e:
            log.debug('%s: Unable to load database, creating '
                      'a new one: %s', self._plugin_name, e)
        else:
            if not case_sensitive:
                for key, val in self.db.copy().items():
                    if not key.islower():
                        log.debug('%s: case-shifting key %s to %s', self._plugin_name, key, key.lower())
                        self.db[key.lower()] = val
                        del self.db[key]

    def flush(self):
        """Exports the database to a file."""
        tmp_filename = self.filename + '.tmp'
        try:
            with open(tmp_filename, 'wb') as f:
                pickle.dump(self.db, f, 2)
            os.rename(tmp_filename, self.filename)
        except Exception as e:
            log.exception('%s: Unable to write database: %s', self._plugin_name, e)

    def _get_key(self, prefix):
        nick, identhost = prefix.split('!', 1)

        if self.addressing_mode == "accounts":
            try:  # Try to first look up the caller as a bot account.
                userobj = ircdb.users.getUser(prefix)
                return userobj.name
            except KeyError:  # If that fails, store them by nick@host.
                return identhost
        elif self.addressing_mode == "identhost":
            return identhost
        elif self.addressing_mode == "nicks":
            return nick
        else:
            raise ValueError("Unknown addressing mode %r" % self.addressing_mode)

    def set(self, prefix, newId):
        """Sets a user ID given the user's prefix."""
        user = self._get_key(prefix)

        if not self.case_sensitive:
            user = user.lower()
        self.db[user] = newId

    def get(self, prefix):
        """Sets a user ID given the user's prefix."""

        user = self._get_key(prefix)
        log.debug('%s: looking up prefix %s; got user %s', self._plugin_name, prefix, user)

        if not self.case_sensitive:
            user = user.lower()
        # Automatically returns None if entry does not exist
        return self.db.get(user)