#!/usr/bin/env python
#
# Electrum - lightweight Bitcoin client
# Copyright (C) 2015 Thomas Voegtlin
#
# 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 traceback
import sys
import os
import imp
import pkgutil
import time

from util import *
from i18n import _
from util import profiler, PrintError, DaemonThread
import wallet

class Plugins(DaemonThread):

    @profiler
    def __init__(self, config, is_local, gui_name):
        DaemonThread.__init__(self)
        if is_local:
            find = imp.find_module('plugins')
            plugins = imp.load_module('electrum_plugins', *find)
        else:
            plugins = __import__('electrum_plugins')
        self.pkgpath = os.path.dirname(plugins.__file__)
        self.config = config
        self.hw_wallets = {}
        self.plugins = {}
        self.gui_name = gui_name
        self.descriptions = []
        self.device_manager = DeviceMgr()

        for loader, name, ispkg in pkgutil.iter_modules([self.pkgpath]):
            m = loader.find_module(name).load_module(name)
            d = m.__dict__
            gui_good = gui_name in d.get('available_for', [])
            details = d.get('registers_wallet_type')
            if details:
                self.register_plugin_wallet(name, gui_good, details)
            if not gui_good:
                continue
            self.descriptions.append(d)
            if not d.get('requires_wallet_type') and config.get('use_' + name):
                self.load_plugin(config, name)

    def get(self, name):
        return self.plugins.get(name)

    def count(self):
        return len(self.plugins)

    def load_plugin(self, config, name):
        full_name = 'electrum_plugins.' + name + '.' + self.gui_name
        try:
            p = pkgutil.find_loader(full_name).load_module(full_name)
            plugin = p.Plugin(self, config, name)
            self.add_jobs(plugin.thread_jobs())
            self.plugins[name] = plugin
            self.print_error("loaded", name)
            return plugin
        except Exception:
            self.print_error("cannot initialize plugin", name)
            traceback.print_exc(file=sys.stdout)
            return None

    def close_plugin(self, plugin):
        self.remove_jobs(plugin.thread_jobs())

    def toggle_enabled(self, config, name):
        p = self.get(name)
        config.set_key('use_' + name, p is None, True)
        if p:
            self.plugins.pop(name)
            p.close()
            self.print_error("closed", name)
            return None
        return self.load_plugin(config, name)

    def is_available(self, name, w):
        for d in self.descriptions:
            if d.get('__name__') == name:
                break
        else:
            return False
        deps = d.get('requires', [])
        for dep, s in deps:
            try:
                __import__(dep)
            except ImportError:
                return False
        requires = d.get('requires_wallet_type', [])
        return not requires or w.wallet_type in requires

    def hardware_wallets(self, action):
        wallet_types, descs = [], []
        for name, (gui_good, details) in self.hw_wallets.items():
            if gui_good:
                try:
                    p = self.wallet_plugin_loader(name)
                    if action == 'restore' or p.is_enabled():
                        wallet_types.append(details[1])
                        descs.append(details[2])
                except:
                    self.print_error("cannot load plugin for:", name)
        return wallet_types, descs

    def register_plugin_wallet(self, name, gui_good, details):
        def dynamic_constructor(storage):
            return self.wallet_plugin_loader(name).wallet_class(storage)

        if details[0] == 'hardware':
            self.hw_wallets[name] = (gui_good, details)
        self.print_error("registering wallet %s: %s" %(name, details))
        wallet.wallet_types.append(details + (dynamic_constructor,))

    def wallet_plugin_loader(self, name):
        if not name in self.plugins:
            self.load_plugin(self.config, name)
        return self.plugins[name]

    def run(self):
        jobs = [job for plugin in self.plugins.values()
                for job in plugin.thread_jobs()]
        self.add_jobs(jobs)
        while self.is_running():
            time.sleep(0.1)
            self.run_jobs()
        self.print_error("stopped")


hook_names = set()
hooks = {}

def hook(func):
    hook_names.add(func.func_name)
    return func

def run_hook(name, *args):
    results = []
    f_list = hooks.get(name, [])
    for p, f in f_list:
        if p.is_enabled():
            try:
                r = f(*args)
            except Exception:
                print_error("Plugin error")
                traceback.print_exc(file=sys.stdout)
                r = False
            if r:
                results.append(r)

    if results:
        assert len(results) == 1, results
        return results[0]


class BasePlugin(PrintError):

    def __init__(self, parent, config, name):
        self.parent = parent  # The plugins object
        self.name = name
        self.config = config
        self.wallet = None
        # add self to hooks
        for k in dir(self):
            if k in hook_names:
                l = hooks.get(k, [])
                l.append((self, getattr(self, k)))
                hooks[k] = l

    def diagnostic_name(self):
        return self.name

    def close(self):
        # remove self from hooks
        for k in dir(self):
            if k in hook_names:
                l = hooks.get(k, [])
                l.remove((self, getattr(self, k)))
                hooks[k] = l
        self.parent.close_plugin(self)
        self.on_close()

    def on_close(self):
        pass

    def requires_settings(self):
        return False

    def thread_jobs(self):
        return []

    def is_enabled(self):
        return self.is_available() and self.config.get('use_'+self.name) is True

    def is_available(self):
        return True

    def settings_dialog(self):
        pass


class DeviceMgr(PrintError):
    '''Manages hardware clients.  A client communicates over a hardware
    channel with the device.

    In addition to tracking device HID IDs, the device manager tracks
    hardware wallets and manages wallet pairing.  A HID ID may be
    paired with a wallet when it is confirmed that the hardware device
    matches the wallet, i.e. they have the same master public key.  A
    HID ID can be unpaired if e.g. it is wiped.

    Because of hotplugging, a wallet must request its client
    dynamically each time it is required, rather than caching it
    itself.

    The device manager is shared across plugins, so just one place
    does hardware scans when needed.  By tracking HID IDs, if a device
    is plugged into a different port the wallet is automatically
    re-paired.

    Wallets are informed on connect / disconnect events.  It must
    implement connected(), disconnected() callbacks.  Being connected
    implies a pairing.  Callbacks can happen in any thread context,
    and we do them without holding the lock.

    Confusingly, the HID ID (serial number) reported by the HID system
    doesn't match the device ID reported by the device itself.  We use
    the HID IDs.

    This plugin is thread-safe.  Currently only devices supported by
    hidapi are implemented.

    '''

    def __init__(self):
        super(DeviceMgr, self).__init__()
        # Keyed by wallet.  The value is the hid_id if the wallet has
        # been paired, and None otherwise.
        self.wallets = {}
        # A list of clients.  We create a client for every device present
        # that is of a registered hardware type
        self.clients = []
        # What we recognise.  Keyed by (vendor_id, product_id) pairs,
        # the value is a callback to create a client for those devices
        self.recognised_hardware = {}
        # For synchronization
        self.lock = threading.RLock()

    def register_devices(self, device_pairs, create_client):
        for pair in device_pairs:
            self.recognised_hardware[pair] = create_client

    def unpair(self, hid_id):
        with self.lock:
            wallet = self.wallet_by_hid_id(hid_id)
            if wallet:
                self.wallets[wallet] = None

    def close_client(self, client):
        with self.lock:
            if client in self.clients:
                self.clients.remove(client)
        if client:
            client.close()

    def close_wallet(self, wallet):
        # Remove the wallet from our list; close any client
        with self.lock:
            hid_id = self.wallets.pop(wallet, None)
            self.close_client(self.client_by_hid_id(hid_id))

    def unpaired_clients(self, handler, classinfo):
        '''Returns all unpaired clients of the given type.'''
        self.scan_devices(handler)
        with self.lock:
            return [client for client in self.clients
                    if isinstance(client, classinfo)
                    and not self.wallet_by_hid_id(client.hid_id())]

    def client_by_hid_id(self, hid_id, handler=None):
        '''Like get_client() but when we don't care about wallet pairing.  If
        a device is wiped or in bootloader mode pairing is impossible;
        in such cases we communicate by device ID and not wallet.'''
        if handler:
            self.scan_devices(handler)
        with self.lock:
            for client in self.clients:
                if client.hid_id() == hid_id:
                    return client
            return None

    def wallet_hid_id(self, wallet):
        with self.lock:
            return self.wallets.get(wallet)

    def wallet_by_hid_id(self, hid_id):
        with self.lock:
            for wallet, wallet_hid_id in self.wallets.items():
                if wallet_hid_id == hid_id:
                    return wallet
            return None

    def paired_wallets(self):
        with self.lock:
            return [wallet for (wallet, hid_id) in self.wallets.items()
                    if hid_id is not None]

    def pair_wallet(self, wallet, client):
        assert client in self.clients
        self.print_error("paired:", wallet, client)
        self.wallets[wallet] = client.hid_id()
        wallet.connected()

    def scan_devices(self, handler):
        # All currently supported hardware libraries use hid, so we
        # assume it here.  This can be easily abstracted if necessary.
        # Note this import must be local so those without hardware
        # wallet libraries are not affected.
        import hid

        self.print_error("scanning devices...")

        # First see what's connected that we know about
        devices = {}
        for d in hid.enumerate(0, 0):
            product_key = (d['vendor_id'], d['product_id'])
            create_client = self.recognised_hardware.get(product_key)
            if create_client:
                devices[d['serial_number']] = (create_client, d['path'])

        # Now find out what was disconnected
        with self.lock:
            disconnected = [client for client in self.clients
                            if not client.hid_id() in devices]

        # Close disconnected clients after informing their wallets
        for client in disconnected:
            wallet = self.wallet_by_hid_id(client.hid_id())
            if wallet:
                wallet.disconnected()
            self.close_client(client)

        # Now see if any new devices are present.
        for hid_id, (create_client, path) in devices.items():
            try:
                client = create_client(path, handler, hid_id)
            except BaseException as e:
                self.print_error("could not create client", str(e))
                client = None
            if client:
                self.print_error("client created for", path)
                with self.lock:
                    self.clients.append(client)
                # Inform re-paired wallet
                wallet = self.wallet_by_hid_id(hid_id)
                if wallet:
                    self.pair_wallet(wallet, client)

    def get_client(self, wallet, force_pair=True):
        '''Returns a client for the wallet, or None if one could not be found.
        If force_pair is False then if an already paired client cannot
        be found None is returned rather than requiring user
        interaction.'''
        # We must scan devices to get an up-to-date idea of which
        # devices are present.  Operating on a client when its device
        # has been removed can cause the process to hang.
        # Unfortunately there is no plugged / unplugged notification
        # system.
        self.scan_devices(wallet.handler)

        # Previously paired wallets only need look for matching HID IDs
        hid_id = self.wallet_hid_id(wallet)
        if hid_id:
            return self.client_by_hid_id(hid_id)

        first_address, derivation = wallet.first_address()
        # Wallets don't have a first address in the install wizard
        # until account creation
        if not first_address:
            self.print_error("no first address for ", wallet)
            return None

        with self.lock:
            # The wallet has not been previously paired, so get the
            # first address of all unpaired clients and compare.
            for client in self.clients:
                # If already paired skip it
                if self.wallet_by_hid_id(client.hid_id()):
                    continue
                # This will trigger a PIN/passphrase entry request
                if client.first_address(derivation) == first_address:
                    self.pair_wallet(wallet, client)
                    return client

            # Not found
            return None