#!/usr/bin/env python
# -*- coding: utf-8 -*-

# Mitter, a simple client for Twitter
# Copyright (C) 2007, 2008  The Mitter Contributors
#
# 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 logging
import os.path

from mitterlib.network.networkbase import NetworkData
from mitterlib import module_search

_log = logging.getLogger('mitterlib.network.Networks')

# List of files that are not networks
SKIPPABLES = ('__init__.py', 'networkbase.py')

"""The network manager, besides managing the other networks and their options,
have the following options:

*timeout*
  Timeout for requests, in seconds. This value is (or should) be used to all
  networks. Default value is '120'.

*save_count*
  Number of operations till the configuration file is saved again.  Most
  networks will save their status in the config file, but not request it to be
  saved immediately (nor should they, 'cause they can save a weird state in
  case the next network causes Mitter to crash or something related.) A value
  of 0 means the Network Manager will save the config file after each round of
  requests to all networks (failing or succeding); for devices that use flash
  drives as storage, it's recommended some large value (since those devices
  have a defined number of writes as lifetime.) Default is '5'.
"""

#--------------------------------------------------------------------
# Helper functions
#--------------------------------------------------------------------

def _import_name(module):
    """Based on the name of the module, return the proper "import"
    statement."""
    (name, _) = os.path.splitext(module)
    return 'mitterlib.network.%s' % (name)


#--------------------------------------------------------------------
# Exceptions
#--------------------------------------------------------------------

class NetworksError(Exception):
    """Basic Networks exception."""
    pass


class NetworksNoSuchNetworkError(NetworksError):
    """The request network does not exists."""

    def __init__(self, network):
        self._network = network

    def __str__(self):
        return 'Unknown network %s' % (self._network)
    pass


class NetworksNoNetworkSetupError(NetworksError):
    """There are no networks set up."""
    pass


class NetworksErrorLoadingNetwork(NetworksError):
    """Error loadig one of the networks."""

    def __init__(self, network, exception):
        self._network = network
        self._exception = str(exception)

    def __str__(self):
        return "Couldn't load %s (%s)" % (self._network, self._exception)


class Networks(object):
    """Network transparency layer: Keeps a list of available networks and send
    requests to all those who have been setup."""

    def __init__(self, options):
        self._networks = {}
        self._options = options
        self._operations = 0
        self.options()

    @property
    def networks(self):
        if self._networks:
            return self._networks

        for module_name in module_search(__file__, SKIPPABLES):
            import_name = _import_name(module_name)
            module = __import__(import_name, fromlist=[import_name])
            connection = module.Connection(self._options)
            self._networks[connection.SHORTCUT] = connection

        return self._networks

    def _targets(self, shortcut):
        """Select a network based on the shortcut. If the shortcut is None,
        returns all available network shortcuts."""
        if shortcut:
            if not shortcut in self.networks:
                raise NetworksNoSuchNetworkError(shortcut)
            else:
                targets = [shortcut]
        else:
            targets = self.networks

        setup = False
        for target in targets:
            if self.networks[target].is_setup():
                setup = True
                yield target

        if not setup:
            raise NetworksNoNetworkSetupError
        return

    def _save(self):
        """Check the number of operations and, if it above the minimum value,
        save the config file."""
        max_count = self._options['Network_Manager']['save_count']
        _log.debug('Operations %d, max %d', self._operations, max_count)
        if self._operations > max_count:
            self._options.save()
            self._operations = 0
            _log.debug('Config file saved')
        return

    def settings(self):
        """Return a dictionary with the options that the interfaces need to
        setup."""
        result = []
        for shortcut in self.networks:
            settings = {
                'shortcut': shortcut,
                'name': self.networks[shortcut].NAMESPACE,
                'options': self.networks[shortcut].AUTH,
            }
            result.append(settings)
        return result

    def options(self):
        for shortcut in self.networks:
            conn = self.networks[shortcut]
            conn.options(self._options)

        # add Networks own options
        self._options.add_group('Network_Manager', 'Network Manager')
        self._options.add_option(
                '--timeout',
                group='Network_Manager',
                option='timeout',
                help='Timeout for requests in all networks.',
                type='int',
                metavar='SECONDS',
                default=120)
        self._options.add_option(
                group='Network_Manager',
                option='save_count',
                help='Number of network operations till the config file ' \
                        'is saved',
                type='int',
                metavar='OPERATIONS',
                default=5,
                is_cmd_option=False)
        return

    def name(self, shortcut):
        """Return the name of a network based on the shortcut."""
        try:
            name = self.networks[shortcut].NAMESPACE
        except KeyError:
            raise NetworksNoSuchNetworkError(shortcut)
        return name

    # This is basically a copy of all methods available in NetworkBase, with
    # the additional parameter "network" (to request data from just one
    # source)
    def messages(self, network=None):
        """Return a list of NetworkData objects for the main "timeline" (the
        default list presented to the user.)"""
        result = []
        for shortcut in self._targets(network):
            for message in self.networks[shortcut].messages():
                message.network = shortcut
                result.append(message)
            self._operations += 1
            # don't check the operations count inside the loop; if Mitter
            # fails, all the last messages can still be retrieved ('cause the
            # config file wasn't saved yet.)
        self._save()
        return result

    def update(self, status, reply_to=None, network=None):
        """Update the user status. Must return the id for the new status."""
        if reply_to and isinstance(reply_to, NetworkData):
            # If you pass a NetworkData object, we get the proper network
            network = reply_to.network

        results = []
        for shortcut in self._targets(network):
            results.append(self.networks[shortcut].update(status, reply_to))
            self._operations += 1
        self._save()
        return results

    def reply_prefix(self, message):
        """Return the prefix to be used in the reply for that message."""
        assert(isinstance(message, NetworkData))
        return self.networks[message.network].reply_prefix(message)

    def repost(self, message):
        """Repost a message in the user's timeline. The network used is
        the same in the message."""
        assert(isinstance(message, NetworkData))
        self.networks[message.network].repost(message)
        self._operations += 1
        self._save()
        return

    def favourite(self, message):
        """Change the favourite status of the message."""
        assert(isinstance(message, NetworkData))
        self.networks[message.network].favourite(message)
        self._operations += 1
        self._save()
        return

    def delete_message(self, message, network=None):
        """Delete an update. Message can be a NetworkData object, in which
        case network is not necessary; otherwise a network must be
        provided."""
        if isinstance(message, NetworkData):
            network = message.network

        self.networks[network].delete_message(message)
        self._operations += 1
        self._save()
        return

    def message(self, message_id, network):
        """Return a single NetworkData object for a specified message."""
        # TODO: This should probably be named parent() and receive a
        # NetworkData. Still returns a single NetworkData object.
        if not network in self.networks:
            raise NetworksNoSuchNetworkError(network)

        data = self.networks[network].message(message_id)
        data.network = network
        self._operations += 1
        self._save()
        return data

    def link(self, message):
        """Returns a link directly to the message."""
        assert(isinstance(message, NetworkData))
        return self.networks[message.network].link(message)

    def replies(self, network=None):
        """Return a list of NetworkData objects for the replies for the user
        messages."""
        result = []
        for shortcut in self._targets(network):
            for message in self.networks[shortcut].replies():
                message.network = shortcut
                result.append(message)
            self._operations += 1
        self._save()
        return result

    def available_requests(self, network=None):
        """Return a dictionary with the available requests the user can
        make to each network before getting capped."""
        result = {}
        for shortcut in self._targets(network):
            requests = self.networks[shortcut].available_requests()
            result[shortcut] = requests
        return result

    def can_delete(self, message):
        """Return True if the message can be deleted; False otherwise."""
        assert(isinstance(message, NetworkData))
        return self.networks[message.network].can_delete(message)

    def can_reply(self, message):
        """Return True if the message can be replied; False otherwise."""
        assert(isinstance(message, NetworkData))
        return self.networks[message.network].can_reply(message)

    def can_repost(self, message):
        """Return True if the message can be resposted; False otherwise."""
        assert(isinstance(message, NetworkData))
        return self.networks[message.network].can_repost(message)

    def can_favourite(self, message):
        """Return True if the message can be favourited/unfavourited; False
        otherwise."""
        assert(isinstance(message, NetworkData))
        return self.networks[message.network].can_favourite(message)

    # TODO: Function to return a regexp for usernames