from __future__ import absolute_import
from __future__ import print_function
import os
import io
import tempfile
import contextlib
import shutil
import hashlib
import base64
import logging
import math
import socket
import inspect
import threading
import random
import datetime
import json
import sys
import irods.client_configuration as config
from irods.session import iRODSSession
from irods.message import (iRODSMessage, IRODS_VERSION)
from irods.password_obfuscation import encode
from six.moves import range

class iRODSUserLogins(object):
    """A class which creates users and set passwords from a given dict or list of tuples of
       (username,password).  

       The utility method self.login(username) is then used to generate a session object
       for one of those users.

       This class may be used standalone or as a mixin.
    """
    def session_for_user(self, username):
        session_parameters = dict(port = self.admin.port,
                                  zone = self.admin.zone,
                                  host = self.admin.host,
                                  user = username)
        password = self._pw.get(username, None)
        if password is not None:
            session_parameters['password'] = password
        return iRODSSession(**session_parameters)
    
    def create_user(self, username, password = None, usertype = 'rodsuser', auto_remove = True):
        u = self.admin.users.create(username, usertype)
        if password is not None:
            u.modify('password',password)
            self._pw[username] = password
        if auto_remove:
            self._users_to_remove[username] = True

    def __init__(self,admin_session):
        self.admin = admin_session
        self._users_to_remove = {}
        self._pw = {}

    def __del__(self):
        for username in self._users_to_remove:
            self.admin.users.remove(username)


def configuration_file_exists():
    try:
        config.load(failure_modes = (config.NoConfigError,), logging_level = logging.DEBUG)
    except config.NoConfigError:
        return False
    return True


class StopTestsException(Exception):

    def __init__(self,*args,**kwargs):
        super(StopTestsException,self).__init__(*args,**kwargs)
        if 'unittest' in sys.modules.keys():
            print("Aborting tests [ Got : %r ]" % self, file = sys.stderr)
            os.abort()


class iRODS_Server_Too_Recent(StopTestsException):
    pass


def my_function_name():
    """Returns the name of the calling function or method"""
    return inspect.getframeinfo(inspect.currentframe().f_back).function


_thrlocal = threading.local()

def unique_name(*seed_tuple):
    '''For deterministic pseudo-random identifiers based on function/method name
       to prevent e.g.  ICAT collisions within and between tests.  Example use:

           def f(session):
             seq_num = 1
             a_name = unique_name( my_function_name(), seq_num # [, *optional_further_args]
                                  )
             seq_num += 1
             session.resources.create( a_name, 'unixfilesystem', session.host, '/tmp/' + a_name )
    '''
    if not getattr(_thrlocal,"rand_gen",None) : _thrlocal.rand_gen = random.Random()
    _thrlocal.rand_gen.seed(seed_tuple)
    return '%016X' % _thrlocal.rand_gen.randint(0,(1<<64)-1)


IRODS_SHARED_DIR = os.path.join( os.path.sep, 'irods_shared' )
IRODS_SHARED_TMP_DIR = os.path.join(IRODS_SHARED_DIR,'tmp')
IRODS_SHARED_REG_RESC_VAULT = os.path.join(IRODS_SHARED_DIR,'reg_resc')

IRODS_REG_RESC = 'MyRegResc'

def irods_shared_tmp_dir():
    pth = IRODS_SHARED_TMP_DIR
    can_write = False
    if os.path.exists(pth):
        try:     tempfile.NamedTemporaryFile(dir = pth)
        except:  pass
        else:    can_write = True 
    return pth if can_write else ''

def irods_shared_reg_resc_vault() :
    vault = IRODS_SHARED_REG_RESC_VAULT
    if os.path.exists(vault):
        return vault
    else:
        return None

def get_register_resource(session):
    vault_path = irods_shared_reg_resc_vault()
    Reg_Resc_Name = ''
    if vault_path:
        session.resources.create(IRODS_REG_RESC, 'unixfilesystem', session.host, vault_path)
        Reg_Resc_Name = IRODS_REG_RESC
    return Reg_Resc_Name


def make_environment_and_auth_files( dir_, **params ):
    if not os.path.exists(dir_): os.mkdir(dir_)
    def recast(k):
        return 'irods_' + k + ('_name' if k in ('user','zone') else '')
    config = os.path.join(dir_,'irods_environment.json')
    with open(config,'w') as f1:
        json.dump({recast(k):v for k,v in params.items() if k != 'password'},f1,indent=4)
    auth = os.path.join(dir_,'.irodsA')
    with open(auth,'w') as f2:
        f2.write(encode(params['password']))
    os.chmod(auth,0o600)
    return (config, auth)


# Create a connection for test, based on ~/.irods environment by default.

def make_session(test_server_version = True, **kwargs):
    try:
        env_file = kwargs.pop('irods_env_file')
    except KeyError:
        try:
            env_file = os.environ['IRODS_ENVIRONMENT_FILE']
        except KeyError:
            env_file = os.path.expanduser('~/.irods/irods_environment.json')
    session = iRODSSession( irods_env_file = env_file, **kwargs )

    if test_server_version:
        connected_version = session.server_version[:3]
        advertised_version = IRODS_VERSION[:3]
        if connected_version > advertised_version:
            msg = ("Connected server is {connected_version}, "
                   "but this python-irodsclient advertises compatibility up to {advertised_version}.").format(**locals())
            raise iRODS_Server_Too_Recent(msg)

    return session


def home_collection(session):
    return "/{0.zone}/home/{0.username}".format(session)


def make_object(session, path, content=None, **options):
    if content is None:
        content = u'blah'

    content = iRODSMessage.encode_unicode(content)

    if session.server_version <= (4,1,4):
        # 2 step open-create necessary for iRODS 4.1.4 or older
        obj = session.data_objects.create(path)
        with obj.open('w', **options) as obj_desc:
            obj_desc.write(content)
    else:
        with session.data_objects.open(path, 'w', **options) as obj_desc:
            obj_desc.write(content)

    # refresh object after write
    return session.data_objects.get(path)


def make_collection(session, path, object_names=None, object_content=None):
    # create collection
    coll = session.collections.create(path)

    # create objects
    if object_names:
        for name in object_names:
            obj_path = os.path.join(path, name)
            make_object(session, obj_path, content=object_content)

    return coll


def make_test_collection(session, path, obj_count):
    coll = session.collections.create(path)

    for n in range(obj_count):
        obj_path = path + "/test" + str(n).zfill(6) + ".txt"
        make_object(session, obj_path)

    return coll


def make_deep_collection(session, root_path, depth=10, objects_per_level=50, object_content=None):
    # start at root path
    current_coll_path = root_path

    # make collections recursively
    for d in range(depth):
        # make list of object names
        obj_names = ['obj' + str(i).zfill(len(str(objects_per_level)))
                     for i in range(objects_per_level)]

        # make subcollection and objects
        if d == 0:
            root_coll = make_collection(
                session, current_coll_path, obj_names, object_content)
        else:
            make_collection(
                session, current_coll_path, obj_names, object_content)

        # next level down
        current_coll_path = os.path.join(
            current_coll_path, 'subcoll' + str(d).zfill(len(str(d))))

    return root_coll


def make_flat_test_dir(dir_path, file_count=10, file_size=1024):
    if file_count < 1:
        raise ValueError

    os.mkdir(dir_path)

    for i in range(file_count):
        # pad file name suffix with zeroes
        suffix_width = int(math.log10(file_count))+1
        file_path = '{dir_path}/test_{i:0>{suffix_width}}.txt'.format(**locals())

        # make random binary file
        with open(file_path, 'wb') as f:
            f.write(os.urandom(file_size))

@contextlib.contextmanager
def create_simple_resc (self, rescName = None, vault_path = '', hostname = ''):
    if not rescName: 
        rescName =  'simple_resc_' + unique_name (my_function_name() + '_simple_resc', datetime.datetime.now())
    created = False
    try:
        self.sess.resources.create(rescName,
                                   'unixfilesystem',
                                   host = self.sess.host if not hostname else hostname,
                                   path = vault_path or '/tmp/' + rescName)
        created = True
        yield rescName
    finally:
        if created:
            self.sess.resources.remove(rescName)

@contextlib.contextmanager
def create_simple_resc_hierarchy (self, Root, Leaf):
    d = tempfile.mkdtemp()
    self.sess.resources.create(Leaf,'unixfilesystem',
                           host = self.sess.host,
                           path=d)
    self.sess.resources.create(Root,'passthru')
    self.sess.resources.add_child(Root,Leaf)
    try:
        yield ';'.join([Root,Leaf])
    finally:
        self.sess.resources.remove_child(Root,Leaf)
        self.sess.resources.remove(Leaf)
        self.sess.resources.remove(Root)
        shutil.rmtree(d)


def chunks(f, chunksize=io.DEFAULT_BUFFER_SIZE):
    return iter(lambda: f.read(chunksize), b'')


def compute_sha256_digest(file_path):
    hasher = hashlib.sha256()

    with open(file_path, 'rb') as f:
        for chunk in chunks(f):
            hasher.update(chunk)

    return base64.b64encode(hasher.digest()).decode()


def remove_unused_metadata(session):
    from irods.message import GeneralAdminRequest
    from irods.api_number import api_number
    message_body = GeneralAdminRequest( 'rm', 'unusedAVUs', '','','','')
    req = iRODSMessage("RODS_API_REQ", msg = message_body,int_info=api_number['GENERAL_ADMIN_AN'])
    with session.pool.get_connection() as conn:
        conn.send(req)
        response=conn.recv()
        if (response.int_info != 0): raise RuntimeError("Error removing unused AVUs")


@contextlib.contextmanager
def file_backed_up(filename, require_that_file_exists = True):
    _basename = os.path.basename(filename) if os.path.exists(filename) else None
    if _basename is None and require_that_file_exists:
        err = RuntimeError("Attempted to back up a file which doesn't exist: %r" % (filename,))
        raise err
    with tempfile.NamedTemporaryFile(prefix=('tmp' if not _basename else _basename)) as f:
        try:
            if _basename is not None:
                shutil.copyfile(filename, f.name)
            yield filename
        finally:
            if _basename is None:
                # Restore the condition of the file being absent.
                if os.path.exists(filename):
                    os.unlink(filename)
            else:
                # Restore the file's contents as they were originally.
                shutil.copyfile(f.name, filename)

@contextlib.contextmanager
def environment_variable_backed_up(var):
    old_value = os.environ.get(var)
    try:
        yield var
    finally:
        os.environ.pop(var,None)
        if old_value is not None:
            os.environ[var] = old_value

def irods_session_host_local (sess):
    return socket.gethostbyname(sess.host) == \
           socket.gethostbyname(socket.gethostname())


@contextlib.contextmanager
def enableLogging(logger, handlerType, args, level_ = logging.INFO):
    """Context manager for temporarily enabling a logger. For debug or test.

    Usage Example
    -------------
    Dump INFO and higher priority logging messages from irods.parallel
    module to a temporary log file:

    with irods.test.helpers.enableLogging(logging.getLogger('irods.parallel'),
                                          logging.FileHandler,(tempfile.gettempdir()+'/logfile.txt',)):
        # parallel put/get test call here
    """
    h = None
    saveLevel = logger.level
    try:
        logger.setLevel(level_)
        h = handlerType(*args)
        h.setLevel( level_ )
        logger.addHandler(h)
        yield
    finally:
        logger.setLevel(saveLevel)
        if h in logger.handlers:
            logger.removeHandler(h)