from contextlib import contextmanager
from cStringIO import StringIO
import logging
import datetime
import time
from textwrap import dedent
import os
from StringIO import StringIO
from teuthology.orchestra import run
from teuthology.orchestra.run import CommandFailedError, ConnectionLostError

log = logging.getLogger(__name__)


class CephFSMount(object):
    def __init__(self, test_dir, client_id, client_remote):
        """
        :param test_dir: Global teuthology test dir
        :param client_id: Client ID, the 'foo' in client.foo
        :param client_remote: Remote instance for the host where client will run
        """

        self.test_dir = test_dir
        self.client_id = client_id
        self.client_remote = client_remote

        self.mountpoint = os.path.join(self.test_dir, 'mnt.{id}'.format(id=self.client_id))
        self.test_files = ['a', 'b', 'c']

        self.background_procs = []

    def is_mounted(self):
        raise NotImplementedError()

    def mount(self):
        raise NotImplementedError()

    def umount(self):
        raise NotImplementedError()

    def umount_wait(self, force=False):
        raise NotImplementedError()

    def kill_cleanup(self):
        raise NotImplementedError()

    def kill(self):
        raise NotImplementedError()

    def cleanup(self):
        raise NotImplementedError()

    def wait_until_mounted(self):
        raise NotImplementedError()

    @contextmanager
    def mounted(self):
        """
        A context manager, from an initially unmounted state, to mount
        this, yield, and then unmount and clean up.
        """
        self.mount()
        self.wait_until_mounted()
        try:
            yield
        finally:
            self.umount_wait()

    def create_files(self):
        assert(self.is_mounted())

        for suffix in self.test_files:
            log.info("Creating file {0}".format(suffix))
            self.client_remote.run(args=[
                'sudo', 'touch', os.path.join(self.mountpoint, suffix)
            ])

    def check_files(self):
        assert(self.is_mounted())

        for suffix in self.test_files:
            log.info("Checking file {0}".format(suffix))
            r = self.client_remote.run(args=[
                'sudo', 'ls', os.path.join(self.mountpoint, suffix)
            ], check_status=False)
            if r.exitstatus != 0:
                raise RuntimeError("Expected file {0} not found".format(suffix))

    def create_destroy(self):
        assert(self.is_mounted())

        filename = "{0} {1}".format(datetime.datetime.now(), self.client_id)
        log.debug("Creating test file {0}".format(filename))
        self.client_remote.run(args=[
            'sudo', 'touch', os.path.join(self.mountpoint, filename)
        ])
        log.debug("Deleting test file {0}".format(filename))
        self.client_remote.run(args=[
            'sudo', 'rm', '-f', os.path.join(self.mountpoint, filename)
        ])

    def _run_python(self, pyscript):
        return self.client_remote.run(args=[
            'sudo', 'adjust-ulimits', 'daemon-helper', 'kill', 'python', '-c', pyscript
        ], wait=False, stdin=run.PIPE, stdout=StringIO())

    def run_python(self, pyscript):
        p = self._run_python(pyscript)
        p.wait()

    def run_shell(self, args):
        args = ["cd", self.mountpoint, run.Raw('&&')] + args
        return self.client_remote.run(args=args, stdout=StringIO())

    def open_no_data(self, basename):
        """
        A pure metadata operation
        """
        assert(self.is_mounted())

        path = os.path.join(self.mountpoint, basename)

        p = self._run_python(dedent(
            """
            f = open("{path}", 'w')
            """.format(path=path)
        ))
        p.wait()

    def open_background(self, basename="background_file"):
        """
        Open a file for writing, then block such that the client
        will hold a capability
        """
        assert(self.is_mounted())

        path = os.path.join(self.mountpoint, basename)

        pyscript = dedent("""
            import time

            f = open("{path}", 'w')
            f.write('content')
            f.flush()
            f.write('content2')
            while True:
                time.sleep(1)
            """).format(path=path)

        rproc = self._run_python(pyscript)
        self.background_procs.append(rproc)
        return rproc

    def wait_for_visible(self, basename="background_file", timeout=30):
        i = 0
        while i < timeout:
            r = self.client_remote.run(args=[
                'sudo', 'ls', os.path.join(self.mountpoint, basename)
            ], check_status=False)
            if r.exitstatus == 0:
                log.debug("File {0} became visible from {1} after {2}s".format(
                    basename, self.client_id, i))
                return
            else:
                time.sleep(1)
                i += 1

        raise RuntimeError("Timed out after {0}s waiting for {1} to become visible from {2}".format(
            i, basename, self.client_id))

    def lock_background(self, basename="background_file"):
        """
        Open and lock a files for writing, hold the lock in a background process
        """
        assert(self.is_mounted())

        path = os.path.join(self.mountpoint, basename)

        pyscript = dedent("""
            import time
            import fcntl
            import struct

            f1 = open("{path}-1", 'w')
            fcntl.flock(f1, fcntl.LOCK_EX | fcntl.LOCK_NB)

            f2 = open("{path}-2", 'w')
            lockdata = struct.pack('hhllhh', fcntl.F_WRLCK, 0, 0, 0, 0, 0)
            fcntl.fcntl(f2, fcntl.F_SETLK, lockdata)
            while True:
                time.sleep(1)
            """).format(path=path)

        log.info("lock file {0}".format(basename))
        rproc = self._run_python(pyscript)
        self.background_procs.append(rproc)
        return rproc

    def check_filelock(self, basename="background_file"):
        assert(self.is_mounted())

        path = os.path.join(self.mountpoint, basename)

        pyscript = dedent("""
            import fcntl
            import errno
            import struct

            f1 = open("{path}-1", 'r')
            try:
                fcntl.flock(f1, fcntl.LOCK_EX | fcntl.LOCK_NB)
            except IOError, e:
                if e.errno == errno.EAGAIN:
                    pass
            else:
                raise RuntimeError("flock on file {path}-1 not found")

            f2 = open("{path}-2", 'r')
            try:
                lockdata = struct.pack('hhllhh', fcntl.F_WRLCK, 0, 0, 0, 0, 0)
                fcntl.fcntl(f2, fcntl.F_SETLK, lockdata)
            except IOError, e:
                if e.errno == errno.EAGAIN:
                    pass
            else:
                raise RuntimeError("posix lock on file {path}-2 not found")
            """).format(path=path)

        log.info("check lock on file {0}".format(basename))
        r = self.client_remote.run(args=[
            'sudo', 'python', '-c', pyscript
        ])

    def write_background(self, basename="background_file", loop=False):
        """
        Open a file for writing, complete as soon as you can
        :param basename:
        :return:
        """
        assert(self.is_mounted())

        path = os.path.join(self.mountpoint, basename)

        pyscript = dedent("""
            import os
            import time

            fd = os.open("{path}", os.O_RDWR | os.O_CREAT, 0644)
            try:
                while True:
                    os.write(fd, 'content')
                    time.sleep(1)
                    if not {loop}:
                        break
            except IOError, e:
                pass
            os.close(fd)
            """).format(path=path, loop=str(loop))

        rproc = self._run_python(pyscript)
        self.background_procs.append(rproc)
        return rproc

    def write_n_mb(self, filename, n_mb, seek=0):
        """
        Write the requested number of megabytes to a file
        """
        assert(self.is_mounted())

        self.run_shell(["dd", "if=/dev/urandom", "of={0}".format(filename),
                        "bs=1M",
                        "count={0}".format(n_mb),
                        "seek={0}".format(seek)
        ])

    def open_n_background(self, fs_path, count):
        """
        Open N files for writing, hold them open in a background process

        :param fs_path: Path relative to CephFS root, e.g. "foo/bar"
        :return: a RemoteProcess
        """
        assert(self.is_mounted())

        abs_path = os.path.join(self.mountpoint, fs_path)

        pyscript = dedent("""
            import sys
            import time
            import os

            n = {count}
            abs_path = "{abs_path}"

            if not os.path.exists(os.path.dirname(abs_path)):
                os.makedirs(os.path.dirname(abs_path))

            handles = []
            for i in range(0, n):
                fname = "{{0}}_{{1}}".format(abs_path, i)
                handles.append(open(fname, 'w'))

            while True:
                time.sleep(1)
            """).format(abs_path=abs_path, count=count)

        rproc = self._run_python(pyscript)
        self.background_procs.append(rproc)
        return rproc

    def teardown(self):
        for p in self.background_procs:
            log.info("Terminating background process")
            if p.stdin:
                p.stdin.close()
                try:
                    p.wait()
                except (CommandFailedError, ConnectionLostError):
                    pass

    def get_global_id(self):
        raise NotImplementedError()

    def get_osd_epoch(self):
        raise NotImplementedError()

    def path_to_ino(self, fs_path):
        abs_path = os.path.join(self.mountpoint, fs_path)

        pyscript = dedent("""
            import os
            import stat

            print os.stat("{path}").st_ino
            """).format(path=abs_path)
        proc = self._run_python(pyscript)
        proc.wait()
        return int(proc.stdout.getvalue().strip())