#!/usr/bin/env python
"""
Downloads files to temp locations.  This script is invoked by the Transfer
Manager (galaxy.jobs.transfer_manager) and should not normally be invoked by
hand.
"""
import ConfigParser
import json
import logging
import optparse
import os
import random
import SocketServer
import sys
import tempfile
import threading
import time
import urllib2

try:
    import pexpect
except ImportError:
    pexpect = None

from daemon import DaemonContext
from sqlalchemy import create_engine, MetaData, Table
from sqlalchemy.orm import scoped_session, sessionmaker

galaxy_root = os.path.abspath(os.path.join(os.path.dirname(__file__), os.pardir))
sys.path.insert(1, os.path.join(galaxy_root, 'lib'))

import galaxy.model
from galaxy.util import bunch
from galaxy.util.json import jsonrpc_response, validate_jsonrpc_request

PEXPECT_IMPORT_MESSAGE = ('The Python pexpect package is required to use this '
                          'feature, please install it')

log = logging.getLogger(__name__)
log.setLevel(logging.DEBUG)
handler = logging.StreamHandler(sys.stdout)
log.addHandler(handler)

debug = False
slow = False


class ArgHandler(object):
    """
    Collect command line flags.
    """
    def __init__(self):
        self.parser = optparse.OptionParser()
        self.parser.add_option('-c', '--config', dest='config', help='Path to Galaxy config file (config/galaxy.ini)',
                               default=os.path.abspath(os.path.join(galaxy_root, 'config/galaxy.ini')))
        self.parser.add_option('-d', '--debug', action='store_true', dest='debug', help="Debug (don't detach)")
        self.parser.add_option('-s', '--slow', action='store_true', dest='slow', help="Transfer slowly (for debugging)")
        self.opts = None

    def parse(self):
        self.opts, args = self.parser.parse_args()
        if len(args) != 1:
            log.error('usage: transfer.py <transfer job id>')
            sys.exit(1)
        try:
            self.transfer_job_id = int(args[0])
        except TypeError:
            log.error('The provided transfer job ID is not an integer: %s' % args[0])
            sys.exit(1)
        if self.opts.debug:
            global debug
            debug = True
            log.setLevel(logging.DEBUG)
        if self.opts.slow:
            global slow
            slow = True


class GalaxyApp(object):
    """
    A shell Galaxy App to provide access to the Galaxy configuration and
    model/database.
    """
    def __init__(self, config_file):
        self.config = ConfigParser.ConfigParser(dict(database_file='database/universe.sqlite',
                                                     file_path='database/files',
                                                     transfer_worker_port_range='12275-12675',
                                                     transfer_worker_log=None))
        self.config.read(config_file)
        self.model = bunch.Bunch()
        self.connect_database()

    def connect_database(self):
        # Avoid loading the entire model since doing so is exceptionally slow
        default_dburl = 'sqlite:///%s?isolation_level=IMMEDIATE' % self.config.get('app:main', 'database_file')
        try:
            dburl = self.config.get('app:main', 'database_connection')
        except ConfigParser.NoOptionError:
            dburl = default_dburl
        engine = create_engine(dburl)
        metadata = MetaData(engine)
        self.sa_session = scoped_session(sessionmaker(bind=engine, autoflush=False, autocommit=True))
        self.model.TransferJob = galaxy.model.TransferJob
        self.model.TransferJob.table = Table("transfer_job", metadata, autoload=True)

    def get_transfer_job(self, id):
        return self.sa_session.query(self.model.TransferJob).get(int(id))


class ListenerServer(SocketServer.ThreadingTCPServer):
    """
    The listener will accept state requests and new transfers for as long as
    the manager is running.
    """
    def __init__(self, port_range, RequestHandlerClass, app, transfer_job, state_result):
        self.state_result = state_result
        # Try random ports until a free one is found
        while True:
            random_port = random.choice(port_range)
            try:
                SocketServer.ThreadingTCPServer.__init__(self, ('localhost', random_port), RequestHandlerClass)
                log.info('Listening on port %s' % random_port)
                break
            except Exception as e:
                log.warning('Tried binding port %s: %s' % (random_port, str(e)))
        transfer_job.socket = random_port
        app.sa_session.add(transfer_job)
        app.sa_session.flush()


class ListenerRequestHandler(SocketServer.BaseRequestHandler):
    """
    Handle state or transfer requests received on the socket.
    """
    def handle(self):
        request = self.request.recv(8192)
        response = {}
        valid, request, response = validate_jsonrpc_request(request, ('get_state', ), ())
        if valid:
            self.request.send(json.dumps(jsonrpc_response(request=request, result=self.server.state_result.result)))
        else:
            error_msg = 'Unable to serve request: %s' % response['error']['message']
            if 'data' in response['error']:
                error_msg += ': %s' % response['error']['data']
            log.error(error_msg)
            log.debug('Original request was: %s' % request)


class StateResult(object):
    """
    A mutable container for the 'result' portion of JSON-RPC responses to state requests.
    """
    def __init__(self, result=None):
        self.result = result


def transfer(app, transfer_job_id):
    transfer_job = app.get_transfer_job(transfer_job_id)
    if transfer_job is None:
        log.error('Invalid transfer job ID: %s' % transfer_job_id)
        return False
    port_range = app.config.get('app:main', 'transfer_worker_port_range')
    try:
        port_range = [int(p) for p in port_range.split('-')]
    except Exception as e:
        log.error('Invalid port range set in transfer_worker_port_range: %s: %s' % (port_range, str(e)))
        return False
    protocol = transfer_job.params['protocol']
    if protocol not in ('http', 'https', 'scp'):
        log.error('Unsupported protocol: %s' % protocol)
        return False
    state_result = StateResult(result=dict(state=transfer_job.states.RUNNING, info='Transfer process starting up.'))
    listener_server = ListenerServer(range(port_range[0], port_range[1] + 1), ListenerRequestHandler, app, transfer_job, state_result)
    # daemonize here (if desired)
    if not debug:
        daemon_context = DaemonContext(files_preserve=[listener_server.fileno()], working_directory=os.getcwd())
        daemon_context.open()
        # If this fails, it'll never be detected.  Hopefully it won't fail since it succeeded once.
        app.connect_database()  # daemon closed the database fd
        transfer_job = app.get_transfer_job(transfer_job_id)
    listener_thread = threading.Thread(target=listener_server.serve_forever)
    listener_thread.setDaemon(True)
    listener_thread.start()
    # Store this process' pid so unhandled deaths can be handled by the restarter
    transfer_job.pid = os.getpid()
    app.sa_session.add(transfer_job)
    app.sa_session.flush()
    terminal_state = None
    if protocol in ['http', 'https']:
        for transfer_result_dict in http_transfer(transfer_job):
            state_result.result = transfer_result_dict
            if transfer_result_dict['state'] in transfer_job.terminal_states:
                terminal_state = transfer_result_dict
    elif protocol in ['scp']:
        # Transfer the file using scp
        transfer_result_dict = scp_transfer(transfer_job)
        # Handle the state of the transfer
        state = transfer_result_dict['state']
        state_result.result = transfer_result_dict
        if state in transfer_job.terminal_states:
            terminal_state = transfer_result_dict
    if terminal_state is not None:
        transfer_job.state = terminal_state['state']
        for name in ['info', 'path']:
            if name in terminal_state:
                transfer_job.__setattr__(name, terminal_state[name])
    else:
        transfer_job.state = transfer_job.states.ERROR
        transfer_job.info = 'Unknown error encountered by transfer worker.'
    app.sa_session.add(transfer_job)
    app.sa_session.flush()
    return True


def http_transfer(transfer_job):
    """Plugin" for handling http(s) transfers."""
    url = transfer_job.params['url']
    assert url.startswith('http://') or url.startswith('https://')
    try:
        f = urllib2.urlopen(url)
    except urllib2.URLError as e:
        yield dict(state=transfer_job.states.ERROR, info='Unable to open URL: %s' % str(e))
        return
    size = f.info().getheader('Content-Length')
    if size is not None:
        size = int(size)
    chunksize = 1024 * 1024
    if slow:
        chunksize = 1024
    read = 0
    last = 0
    try:
        fh, fn = tempfile.mkstemp()
    except Exception as e:
        yield dict(state=transfer_job.states.ERROR, info='Unable to create temporary file for transfer: %s' % str(e))
        return
    log.debug('Writing %s to %s, size is %s' % (url, fn, size or 'unknown'))
    try:
        while True:
            chunk = f.read(chunksize)
            if not chunk:
                break
            os.write(fh, chunk)
            read += chunksize
            if size is not None and read < size:
                percent = int(float(read) / size * 100)
                if percent != last:
                    yield dict(state=transfer_job.states.PROGRESS, read=read, percent='%s' % percent)
                    last = percent
            elif size is None:
                yield dict(state=transfer_job.states.PROGRESS, read=read)
            if slow:
                time.sleep(1)
        os.close(fh)
        yield dict(state=transfer_job.states.DONE, path=fn)
    except Exception as e:
        yield dict(state=transfer_job.states.ERROR, info='Error during file transfer: %s' % str(e))
        return
    return


def scp_transfer(transfer_job):
    """Plugin" for handling scp transfers using pexpect"""
    def print_ticks(d):
        pass
    host = transfer_job.params['host']
    user_name = transfer_job.params['user_name']
    password = transfer_job.params['password']
    file_path = transfer_job.params['file_path']
    if pexpect is None:
        return dict(state=transfer_job.states.ERROR, info=PEXPECT_IMPORT_MESSAGE)
    try:
        fh, fn = tempfile.mkstemp()
    except Exception as e:
        return dict(state=transfer_job.states.ERROR, info='Unable to create temporary file for transfer: %s' % str(e))
    try:
        # TODO: add the ability to determine progress of the copy here like we do in the http_transfer above.
        cmd = "scp %s@%s:'%s' '%s'" % (user_name,
                                       host,
                                       file_path.replace(' ', '\ '),
                                       fn)
        pexpect.run(cmd, events={'.ssword:*': password + '\r\n',
                                 pexpect.TIMEOUT: print_ticks},
                    timeout=10)
        return dict(state=transfer_job.states.DONE, path=fn)
    except Exception as e:
        return dict(state=transfer_job.states.ERROR, info='Error during file transfer: %s' % str(e))


if __name__ == '__main__':
    arg_handler = ArgHandler()
    arg_handler.parse()
    app = GalaxyApp(arg_handler.opts.config)

    log.debug('Initiating transfer...')
    if transfer(app, arg_handler.transfer_job_id):
        log.debug('Finished')
    else:
        log.error('Error in transfer process...')
        sys.exit(1)
    sys.exit(0)