#!/usr/bin/env python

import argparse
import arvados
import daemon
import logging
import os
import signal
import subprocess

from arvados_fuse import *

logger = logging.getLogger('arvados.arv-mount')

if __name__ == '__main__':
    # Handle command line parameters
    parser = argparse.ArgumentParser(
        description='''Mount Keep data under the local filesystem.  Default mode is --home''',
        epilog="""
Note: When using the --exec feature, you must either specify the
mountpoint before --exec, or mark the end of your --exec arguments
with "--".
""")
    parser.add_argument('mountpoint', type=str, help="""Mount point.""")
    parser.add_argument('--allow-other', action='store_true',
                        help="""Let other users read the mount""")

    mount_mode = parser.add_mutually_exclusive_group()

    mount_mode.add_argument('--all', action='store_true', help="""Mount a subdirectory for each mode: home, shared, tags, portable data hash (default).""")
    mount_mode.add_argument('--home', action='store_true', help="""Mount only the user's home project.""")
    mount_mode.add_argument('--shared', action='store_true', help="""Mount only list of projects shared with the user.""")
    mount_mode.add_argument('--by-tag', action='store_true',
                            help="""Mount subdirectories listed by tag.""")
    mount_mode.add_argument('--by-hash', action='store_true',
                            help="""Mount subdirectories listed by portable data hash.""")
    mount_mode.add_argument('--project', type=str, help="""Mount a specific project.""")
    mount_mode.add_argument('--collection', type=str, help="""Mount only the specified collection.""")

    parser.add_argument('--debug', action='store_true', help="""Debug mode""")
    parser.add_argument('--logfile', help="""Write debug logs and errors to the specified file (default stderr).""")
    parser.add_argument('--foreground', action='store_true', help="""Run in foreground (default is to daemonize unless --exec specified)""", default=False)
    parser.add_argument('--exec', type=str, nargs=argparse.REMAINDER,
                        dest="exec_args", metavar=('command', 'args', '...', '--'),
                        help="""Mount, run a command, then unmount and exit""")

    args = parser.parse_args()
    args.mountpoint = os.path.realpath(args.mountpoint)
    if args.logfile:
        args.logfile = os.path.realpath(args.logfile)

    # Daemonize as early as possible, so we don't accidentally close
    # file descriptors we're using.
    if not (args.exec_args or args.foreground):
        os.chdir(args.mountpoint)
        daemon_ctx = daemon.DaemonContext(working_directory='.')
        daemon_ctx.open()
    else:
        daemon_ctx = None

    # Configure a logger based on command-line switches.
    # If we're using a contemporary Python SDK (mid-August 2014),
    # configure the arvados hierarchy logger.
    # Otherwise, configure the program root logger.
    base_logger = getattr(arvados, 'logger', None)

    if args.logfile:
        log_handler = logging.FileHandler(args.logfile)
    elif daemon_ctx:
        log_handler = logging.NullHandler()
    elif base_logger:
        log_handler = arvados.log_handler
    else:
        log_handler = logging.StreamHandler()

    if base_logger is None:
        base_logger = logging.getLogger()
    else:
        base_logger.removeHandler(arvados.log_handler)
    base_logger.addHandler(log_handler)

    if args.debug:
        base_logger.setLevel(logging.DEBUG)
        logger.debug("arv-mount debugging enabled")

    try:
        # Create the request handler
        operations = Operations(os.getuid(), os.getgid())
        api = arvados.api('v1')

        if args.by_hash:
            # Set up the request handler with the 'magic directory' at the root
            operations.inodes.add_entry(MagicDirectory(llfuse.ROOT_INODE, operations.inodes, api))
        elif args.by_tag:
            operations.inodes.add_entry(TagsDirectory(llfuse.ROOT_INODE, operations.inodes, api))
        elif args.shared:
            operations.inodes.add_entry(SharedDirectory(llfuse.ROOT_INODE, operations.inodes, api))
        elif args.collection != None:
            # Set up the request handler with the collection at the root
            operations.inodes.add_entry(CollectionDirectory(llfuse.ROOT_INODE, operations.inodes, args.collection))
        elif args.project != None:
            operations.inodes.add_entry(ProjectDirectory(llfuse.ROOT_INODE, operations.inodes, args.project))
        else:
            e = operations.inodes.add_entry(Directory(llfuse.ROOT_INODE))
            usr = api.users().current().execute()
            e._entries['home'] = operations.inodes.add_entry(ProjectDirectory(e.inode, operations.inodes, api, usr))
            e._entries['shared'] = operations.inodes.add_entry(SharedDirectory(e.inode, operations.inodes, api, usr))
            e._entries['by_tag'] = operations.inodes.add_entry(TagsDirectory(e.inode, operations.inodes, api))
            e._entries['by_hash'] = operations.inodes.add_entry(MagicDirectory(e.inode, operations.inodes, api))

    except Exception:
        logger.exception("arv-mount: exception during API setup")
        exit(1)

    # FUSE options, see mount.fuse(8)
    opts = [optname for optname in ['allow_other', 'debug']
            if getattr(args, optname)]

    if args.exec_args:
        # Initialize the fuse connection
        llfuse.init(operations, args.mountpoint, opts)

        t = threading.Thread(None, lambda: llfuse.main())
        t.start()

        # wait until the driver is finished initializing
        operations.initlock.wait()

        rc = 255
        try:
            sp = subprocess.Popen(args.exec_args, shell=False)

            # forward signals to the process.
            signal.signal(signal.SIGINT, lambda signum, frame: sp.send_signal(signum))
            signal.signal(signal.SIGTERM, lambda signum, frame: sp.send_signal(signum))
            signal.signal(signal.SIGQUIT, lambda signum, frame: sp.send_signal(signum))

            # wait for process to complete.
            rc = sp.wait()

            # restore default signal handlers.
            signal.signal(signal.SIGINT, signal.SIG_DFL)
            signal.signal(signal.SIGTERM, signal.SIG_DFL)
            signal.signal(signal.SIGQUIT, signal.SIG_DFL)
        except Exception as e:
            logger.exception('arv-mount: exception during exec %s',
                             args.exec_args)
            try:
                rc = e.errno
            except AttributeError:
                pass
        finally:
            subprocess.call(["fusermount", "-u", "-z", args.mountpoint])

        exit(rc)
    else:
        try:
            llfuse.init(operations, args.mountpoint, opts)
            llfuse.main()
        except Exception as e:
            logger.exception('arv-mount: exception during mount')
            exit(getattr(e, 'errno', 1))