import mimetypes
from datetime import datetime
from datetime import timedelta
from tempfile import SpooledTemporaryFile

from azure.core.exceptions import ResourceNotFoundError
from azure.storage.blob import BlobClient
from azure.storage.blob import BlobSasPermissions
from azure.storage.blob import BlobServiceClient
from azure.storage.blob import ContentSettings
from azure.storage.blob import generate_blob_sas
from django.core.exceptions import SuspiciousOperation
from django.core.files.base import File
from django.utils import timezone
from django.utils.deconstruct import deconstructible

from storages.base import BaseStorage
from storages.utils import clean_name
from storages.utils import get_available_overwrite_name
from storages.utils import safe_join
from storages.utils import setting
from storages.utils import to_bytes


@deconstructible
class AzureStorageFile(File):

    def __init__(self, name, mode, storage):
        self.name = name
        self._mode = mode
        self._storage = storage
        self._is_dirty = False
        self._file = None
        self._path = storage._get_valid_path(name)

    def _get_file(self):
        if self._file is not None:
            return self._file

        file = SpooledTemporaryFile(
            max_size=self._storage.max_memory_size,
            suffix=".AzureStorageFile",
            dir=setting("FILE_UPLOAD_TEMP_DIR", None))

        if 'r' in self._mode or 'a' in self._mode:
            download_stream = self._storage.client.download_blob(
                self._path, timeout=self._storage.timeout)
            download_stream.readinto(file)
        if 'r' in self._mode:
            file.seek(0)

        self._file = file
        return self._file

    def _set_file(self, value):
        self._file = value

    file = property(_get_file, _set_file)

    def read(self, *args, **kwargs):
        if 'r' not in self._mode and 'a' not in self._mode:
            raise AttributeError("File was not opened in read mode.")
        return super().read(*args, **kwargs)

    def write(self, content):
        if ('w' not in self._mode and
                '+' not in self._mode and
                'a' not in self._mode):
            raise AttributeError("File was not opened in write mode.")
        self._is_dirty = True
        return super().write(to_bytes(content))

    def close(self):
        if self._file is None:
            return
        if self._is_dirty:
            self._file.seek(0)
            self._storage._save(self.name, self._file)
            self._is_dirty = False
        self._file.close()
        self._file = None


def _content_type(content):
    try:
        return content.file.content_type
    except AttributeError:
        pass
    try:
        return content.content_type
    except AttributeError:
        pass
    return None


def _get_valid_path(s):
    # A blob name:
    #   * must not end with dot or slash
    #   * can contain any character
    #   * must escape URL reserved characters
    #     (not needed here since the azure client will do that)
    s = s.strip('./')
    if len(s) > _AZURE_NAME_MAX_LEN:
        raise ValueError(
            "File name max len is %d" % _AZURE_NAME_MAX_LEN)
    if not len(s):
        raise ValueError(
            "File name must contain one or more "
            "printable characters")
    if s.count('/') > 256:
        raise ValueError(
            "File name must not contain "
            "more than 256 slashes")
    return s


# Max len according to azure's docs
_AZURE_NAME_MAX_LEN = 1024


@deconstructible
class AzureStorage(BaseStorage):
    def __init__(self, **settings):
        super().__init__(**settings)
        self._service_client = None
        self._custom_service_client = None
        self._client = None
        self._custom_client = None
        self._user_delegation_key = None
        self._user_delegation_key_expiry = datetime.utcnow()

    def get_default_settings(self):
        return {
            "account_name": setting("AZURE_ACCOUNT_NAME"),
            "account_key": setting("AZURE_ACCOUNT_KEY"),
            "object_parameters": setting("AZURE_OBJECT_PARAMETERS", {}),
            "azure_container": setting("AZURE_CONTAINER"),
            "azure_ssl": setting("AZURE_SSL", True),
            "upload_max_conn": setting("AZURE_UPLOAD_MAX_CONN", 2),
            "timeout": setting('AZURE_CONNECTION_TIMEOUT_SECS', 20),
            "max_memory_size": setting('AZURE_BLOB_MAX_MEMORY_SIZE', 2*1024*1024),
            "expiration_secs": setting('AZURE_URL_EXPIRATION_SECS'),
            "overwrite_files": setting('AZURE_OVERWRITE_FILES', False),
            "location": setting('AZURE_LOCATION', ''),
            "default_content_type": 'application/octet-stream',
            "cache_control": setting("AZURE_CACHE_CONTROL"),
            "sas_token": setting('AZURE_SAS_TOKEN'),
            "endpoint_suffix": setting('AZURE_ENDPOINT_SUFFIX', 'core.windows.net'),
            "custom_domain": setting('AZURE_CUSTOM_DOMAIN'),
            "connection_string": setting('AZURE_CONNECTION_STRING'),
            "token_credential": setting('AZURE_TOKEN_CREDENTIAL'),
            "api_version": setting('AZURE_API_VERSION', None),
        }

    def _get_service_client(self, use_custom_domain):
        if self.connection_string is not None:
            return BlobServiceClient.from_connection_string(self.connection_string)

        account_domain = self.custom_domain if self.custom_domain and use_custom_domain else "{}.blob.{}".format(
            self.account_name,
            self.endpoint_suffix,
        )
        account_url = "{}://{}".format(self.azure_protocol, account_domain)

        credential = None
        if self.account_key:
            credential = {
                "account_name": self.account_name,
                "account_key": self.account_key,
            }
        elif self.sas_token:
            credential = self.sas_token
        elif self.token_credential:
            credential = self.token_credential
        options = {}
        if self.api_version:
            options["api_version"] = self.api_version
        return BlobServiceClient(account_url, credential=credential, **options)

    @property
    def service_client(self):
        if self._service_client is None:
            self._service_client = self._get_service_client(use_custom_domain=False)
        return self._service_client

    @property
    def custom_service_client(self):
        if self._custom_service_client is None:
            self._custom_service_client = self._get_service_client(use_custom_domain=True)
        return self._custom_service_client

    @property
    def client(self):
        if self._client is None:
            self._client = self.service_client.get_container_client(
                self.azure_container
            )
        return self._client

    @property
    def custom_client(self):
        if self._custom_client is None:
            self._custom_client = self.custom_service_client.get_container_client(
                self.azure_container
            )
        return self._custom_client

    def get_user_delegation_key(self, expiry):
        # We'll only be able to get a user delegation key if we've authenticated with a
        # token credential.
        if self.token_credential is None:
            return None

        # Get a new key if we don't already have one, or if the one we have expires too
        # soon.
        if (
            self._user_delegation_key is None
            or expiry > self._user_delegation_key_expiry
        ):
            now = datetime.utcnow()
            key_expiry_time = now + timedelta(days=7)
            self._user_delegation_key = self.custom_service_client.get_user_delegation_key(
                key_start_time=now, key_expiry_time=key_expiry_time
            )
            self._user_delegation_key_expiry = key_expiry_time

        return self._user_delegation_key

    @property
    def azure_protocol(self):
        if self.azure_ssl:
            return 'https'
        else:
            return 'http'

    def _normalize_name(self, name):
        try:
            return safe_join(self.location, name)
        except ValueError:
            raise SuspiciousOperation("Attempted access to '%s' denied." % name)

    def _get_valid_path(self, name):
        # Must be idempotent
        return _get_valid_path(
            self._normalize_name(
                clean_name(name)))

    def _open(self, name, mode="rb"):
        return AzureStorageFile(name, mode, self)

    def get_available_name(self, name, max_length=_AZURE_NAME_MAX_LEN):
        """
        Returns a filename that's free on the target storage system, and
        available for new content to be written to.
        """
        name = clean_name(name)
        if self.overwrite_files:
            return get_available_overwrite_name(name, max_length)
        return super().get_available_name(name, max_length)

    def exists(self, name):
        blob_client = self.client.get_blob_client(self._get_valid_path(name))
        return blob_client.exists()

    def delete(self, name):
        try:
            self.client.delete_blob(
                self._get_valid_path(name),
                timeout=self.timeout)
        except ResourceNotFoundError:
            pass

    def size(self, name):
        blob_client = self.client.get_blob_client(self._get_valid_path(name))
        properties = blob_client.get_blob_properties(timeout=self.timeout)
        return properties.size

    def _save(self, name, content):
        cleaned_name = clean_name(name)
        name = self._get_valid_path(name)
        params = self._get_content_settings_parameters(name, content)

        # Unwrap django file (wrapped by parent's save call)
        if isinstance(content, File):
            content = content.file

        content.seek(0)
        self.client.upload_blob(
            name,
            content,
            content_settings=ContentSettings(**params),
            max_concurrency=self.upload_max_conn,
            timeout=self.timeout,
            overwrite=self.overwrite_files)
        return cleaned_name

    def _expire_at(self, expire):
        # azure expects time in UTC
        return datetime.utcnow() + timedelta(seconds=expire)

    def url(self, name, expire=None, parameters=None):
        name = self._get_valid_path(name)
        params = parameters or {}

        if expire is None:
            expire = self.expiration_secs

        credential = None
        if expire:
            expiry = self._expire_at(expire)
            user_delegation_key = self.get_user_delegation_key(expiry)
            sas_token = generate_blob_sas(
                self.account_name,
                self.azure_container,
                name,
                account_key=self.account_key,
                user_delegation_key=user_delegation_key,
                permission=BlobSasPermissions(read=True),
                expiry=expiry,
                **params
            )
            credential = sas_token

        container_blob_url = self.custom_client.get_blob_client(name).url
        return BlobClient.from_blob_url(container_blob_url, credential=credential).url

    def _get_content_settings_parameters(self, name, content=None):
        params = {}

        guessed_type, content_encoding = mimetypes.guess_type(name)
        content_type = (
            _content_type(content) or
            guessed_type or
            self.default_content_type)

        params['cache_control'] = self.cache_control
        params['content_type'] = content_type
        params['content_encoding'] = content_encoding

        params.update(self.get_object_parameters(name))
        return params

    def get_object_parameters(self, name):
        """
        Returns a dictionary that is passed to content settings. Override this
        method to adjust this on a per-object basis to set e.g ContentDisposition.

        By default, returns the value of AZURE_OBJECT_PARAMETERS.
        """
        return self.object_parameters.copy()

    def get_modified_time(self, name):
        """
        Returns an (aware) datetime object containing the last modified time if
        USE_TZ is True, otherwise returns a naive datetime in the local timezone.
        """
        blob_client = self.client.get_blob_client(self._get_valid_path(name))
        properties = blob_client.get_blob_properties(timeout=self.timeout)
        if not setting('USE_TZ', False):
            return timezone.make_naive(properties.last_modified)

        tz = timezone.get_current_timezone()
        if timezone.is_naive(properties.last_modified):
            return timezone.make_aware(properties.last_modified, tz)

        # `last_modified` is in UTC time_zone, we
        # must convert it to settings time_zone
        return properties.last_modified.astimezone(tz)

    def modified_time(self, name):
        """Returns a naive datetime object containing the last modified time."""
        mtime = self.get_modified_time(name)
        if timezone.is_naive(mtime):
            return mtime
        return timezone.make_naive(mtime)

    def list_all(self, path=''):
        """Return all files for a given path"""
        if path:
            path = self._get_valid_path(path)
        if path and not path.endswith('/'):
            path += '/'
        # XXX make generator, add start, end
        return [
            blob.name
            for blob in self.client.list_blobs(
                name_starts_with=path,
                timeout=self.timeout)]

    def listdir(self, path=''):
        """
        Return directories and files for a given path.
        Leave the path empty to list the root.
        Order of dirs and files is undefined.
        """
        files = []
        dirs = set()
        for name in self.list_all(path):
            n = name[len(path):]
            if '/' in n:
                dirs.add(n.split('/', 1)[0])
            else:
                files.append(n)
        return list(dirs), files

    def get_name_max_len(self):
        max_len = _AZURE_NAME_MAX_LEN - len(self._get_valid_path('foo')) - len('foo')
        if not self.overwrite_files:
            max_len -= len('_1234567')
        return max_len