from typing import Any, Dict, Mapping, Optional, Tuple, Text

from django.utils.translation import ugettext as _
from django.conf import settings
from django.template.defaultfilters import slugify
from django.core.files import File
from django.http import HttpRequest
from django.db.models import Sum
from jinja2 import Markup as mark_safe
import unicodedata

from zerver.lib.avatar_hash import user_avatar_path
from zerver.lib.exceptions import JsonableError, ErrorCode
from zerver.lib.str_utils import force_text, force_str, NonBinaryStr

from boto.s3.bucket import Bucket
from boto.s3.key import Key
from boto.s3.connection import S3Connection
from mimetypes import guess_type, guess_extension

from zerver.lib.str_utils import force_bytes, force_str
from zerver.models import get_user_profile_by_id, RealmEmoji
from zerver.models import Attachment
from zerver.models import Realm, RealmEmoji, UserProfile, Message

import urllib
import base64
import os
import re
from PIL import Image, ImageOps
import io
import random
import logging

DEFAULT_AVATAR_SIZE = 100
MEDIUM_AVATAR_SIZE = 500
DEFAULT_EMOJI_SIZE = 64

# Performance Note:
#
# For writing files to S3, the file could either be stored in RAM
# (if it is less than 2.5MiB or so) or an actual temporary file on disk.
#
# Because we set FILE_UPLOAD_MAX_MEMORY_SIZE to 0, only the latter case
# should occur in practice.
#
# This is great, because passing the pseudofile object that Django gives
# you to boto would be a pain.

# To come up with a s3 key we randomly generate a "directory". The
# "file name" is the original filename provided by the user run
# through a sanitization function.

attachment_url_re = re.compile('[/\-]user[\-_]uploads[/\.-].*?(?=[ )]|\Z)')

def attachment_url_to_path_id(attachment_url):
    # type: (Text) -> Text
    path_id_raw = re.sub('[/\-]user[\-_]uploads[/\.-]', '', attachment_url)
    # Remove any extra '.' after file extension. These are probably added by the user
    return re.sub('[.]+$', '', path_id_raw, re.M)

def sanitize_name(value):
    # type: (NonBinaryStr) -> Text
    """
    Sanitizes a value to be safe to store in a Linux filesystem, in
    S3, and in a URL.  So unicode is allowed, but not special
    characters other than ".", "-", and "_".

    This implementation is based on django.utils.text.slugify; it is
    modified by:
    * adding '.' and '_' to the list of allowed characters.
    * preserving the case of the value.
    """
    value = unicodedata.normalize('NFKC', value)
    value = re.sub('[^\w\s._-]', '', value, flags=re.U).strip()
    return mark_safe(re.sub('[-\s]+', '-', value, flags=re.U))

def random_name(bytes=60):
    # type: (int) -> Text
    return base64.urlsafe_b64encode(os.urandom(bytes)).decode('utf-8')

class BadImageError(JsonableError):
    code = ErrorCode.BAD_IMAGE

class ExceededQuotaError(JsonableError):
    code = ErrorCode.QUOTA_EXCEEDED

def resize_avatar(image_data, size=DEFAULT_AVATAR_SIZE):
    # type: (bytes, int) -> bytes
    try:
        im = Image.open(io.BytesIO(image_data))
        im = ImageOps.fit(im, (size, size), Image.ANTIALIAS)
    except IOError:
        raise BadImageError("Could not decode image; did you upload an image file?")
    out = io.BytesIO()
    im.save(out, format='png')
    return out.getvalue()


def resize_emoji(image_data, size=DEFAULT_EMOJI_SIZE):
    # type: (bytes, int) -> bytes
    try:
        im = Image.open(io.BytesIO(image_data))
        image_format = im.format
        if image_format == 'GIF' and im.is_animated:
            if im.size[0] != im.size[1]:
                raise JsonableError(
                    _("Animated emoji must be have same width and height."))
            elif im.size[0] > size:
                raise JsonableError(
                    _("Animated emoji can't be larger than 64px in width or height."))
            else:
                return image_data
        im = ImageOps.fit(im, (size, size), Image.ANTIALIAS)
    except IOError:
        raise BadImageError("Could not decode image; did you upload an image file?")
    out = io.BytesIO()
    im.save(out, format=image_format)
    return out.getvalue()


### Common

class ZulipUploadBackend:
    def upload_message_image(self, uploaded_file_name, uploaded_file_size,
                             content_type, file_data, user_profile, target_realm=None):
        # type: (Text, int, Optional[Text], bytes, UserProfile, Optional[Realm]) -> Text
        raise NotImplementedError()

    def upload_avatar_image(self, user_file, acting_user_profile, target_user_profile):
        # type: (File, UserProfile, UserProfile) -> None
        raise NotImplementedError()

    def delete_message_image(self, path_id):
        # type: (Text) -> bool
        raise NotImplementedError()

    def get_avatar_url(self, hash_key, medium=False):
        # type: (Text, bool) -> Text
        raise NotImplementedError()

    def ensure_medium_avatar_image(self, user_profile):
        # type: (UserProfile) -> None
        raise NotImplementedError()

    def upload_realm_icon_image(self, icon_file, user_profile):
        # type: (File, UserProfile) -> None
        raise NotImplementedError()

    def get_realm_icon_url(self, realm_id, version):
        # type: (int, int) -> Text
        raise NotImplementedError()

    def upload_emoji_image(self, emoji_file, emoji_file_name, user_profile):
        # type: (File, Text, UserProfile) -> None
        raise NotImplementedError()

    def get_emoji_url(self, emoji_file_name, realm_id):
        # type: (Text, int) -> Text
        raise NotImplementedError()


### S3

def get_bucket(conn, bucket_name):
    # type: (S3Connection, Text) -> Bucket
    # Calling get_bucket() with validate=True can apparently lead
    # to expensive S3 bills:
    #    http://www.appneta.com/blog/s3-list-get-bucket-default/
    # The benefits of validation aren't completely clear to us, and
    # we want to save on our bills, so we set the validate flag to False.
    # (We think setting validate to True would cause us to fail faster
    #  in situations where buckets don't exist, but that shouldn't be
    #  an issue for us.)
    bucket = conn.get_bucket(bucket_name, validate=False)
    return bucket

def upload_image_to_s3(
        bucket_name,
        file_name,
        content_type,
        user_profile,
        contents):
    # type: (NonBinaryStr, Text, Optional[Text], UserProfile, bytes) -> None

    conn = S3Connection(settings.S3_KEY, settings.S3_SECRET_KEY)
    bucket = get_bucket(conn, bucket_name)
    key = Key(bucket)
    key.key = force_str(file_name)
    key.set_metadata("user_profile_id", str(user_profile.id))
    key.set_metadata("realm_id", str(user_profile.realm_id))

    if content_type is not None:
        headers = {'Content-Type': content_type}  # type: Optional[Dict[Text, Text]]
    else:
        headers = None

    key.set_contents_from_string(contents, headers=headers)  # type: ignore # https://github.com/python/typeshed/issues/1552

def get_total_uploads_size_for_user(user):
    # type: (UserProfile) -> int
    uploads = Attachment.objects.filter(owner=user)
    total_quota = uploads.aggregate(Sum('size'))['size__sum']

    # In case user has no uploads
    if (total_quota is None):
        total_quota = 0
    return total_quota

def within_upload_quota(user, uploaded_file_size):
    # type: (UserProfile, int) -> bool
    total_quota = get_total_uploads_size_for_user(user)
    if (total_quota + uploaded_file_size > user.quota):
        return False
    else:
        return True

def get_file_info(request, user_file):
    # type: (HttpRequest, File) -> Tuple[Text, int, Optional[Text]]

    uploaded_file_name = user_file.name
    assert isinstance(uploaded_file_name, str)

    content_type = request.GET.get('mimetype')
    if content_type is None:
        guessed_type = guess_type(uploaded_file_name)[0]
        if guessed_type is not None:
            content_type = guessed_type
    else:
        extension = guess_extension(content_type)
        if extension is not None:
            uploaded_file_name = uploaded_file_name + extension

    uploaded_file_name = urllib.parse.unquote(uploaded_file_name)
    uploaded_file_size = user_file.size

    return uploaded_file_name, uploaded_file_size, content_type


def get_signed_upload_url(path):
    # type: (Text) -> Text
    conn = S3Connection(settings.S3_KEY, settings.S3_SECRET_KEY)
    return force_text(conn.generate_url(15, 'GET', bucket=settings.S3_AUTH_UPLOADS_BUCKET, key=force_str(path)))

def get_realm_for_filename(path):
    # type: (Text) -> Optional[int]
    conn = S3Connection(settings.S3_KEY, settings.S3_SECRET_KEY)
    key = get_bucket(conn, settings.S3_AUTH_UPLOADS_BUCKET).get_key(path)
    if key is None:
        # This happens if the key does not exist.
        return None
    return get_user_profile_by_id(key.metadata["user_profile_id"]).realm_id


class S3UploadBackend(ZulipUploadBackend):

    def upload_message_image(self, uploaded_file_name, uploaded_file_size,
                             content_type, file_data, user_profile, target_realm=None):
        # type: (Text, int, Optional[Text], bytes, UserProfile, Optional[Realm]) -> Text
        bucket_name = settings.S3_AUTH_UPLOADS_BUCKET
        if target_realm is None:
            target_realm = user_profile.realm
        s3_file_name = "/".join([
            str(target_realm.id),
            random_name(18),
            sanitize_name(uploaded_file_name)
        ])
        url = "/user_uploads/%s" % (s3_file_name,)

        upload_image_to_s3(
            bucket_name,
            s3_file_name,
            content_type,
            user_profile,
            file_data
        )

        create_attachment(uploaded_file_name, s3_file_name, user_profile, uploaded_file_size)
        return url

    def delete_message_image(self, path_id):
        # type: (Text) -> bool
        conn = S3Connection(settings.S3_KEY, settings.S3_SECRET_KEY)
        bucket = get_bucket(conn, settings.S3_AUTH_UPLOADS_BUCKET)

        # check if file exists
        key = bucket.get_key(path_id)
        if key is not None:
            bucket.delete_key(key)
            return True

        file_name = path_id.split("/")[-1]
        logging.warning("%s does not exist. Its entry in the database will be removed." % (file_name,))
        return False

    def upload_avatar_image(self, user_file, acting_user_profile, target_user_profile):
        # type: (File, UserProfile, UserProfile) -> None
        content_type = guess_type(user_file.name)[0]
        bucket_name = settings.S3_AVATAR_BUCKET
        s3_file_name = user_avatar_path(target_user_profile)

        image_data = user_file.read()
        upload_image_to_s3(
            bucket_name,
            s3_file_name + ".original",
            content_type,
            target_user_profile,
            image_data,
        )

        # custom 500px wide version
        resized_medium = resize_avatar(image_data, MEDIUM_AVATAR_SIZE)
        upload_image_to_s3(
            bucket_name,
            s3_file_name + "-medium.png",
            "image/png",
            target_user_profile,
            resized_medium
        )

        resized_data = resize_avatar(image_data)
        upload_image_to_s3(
            bucket_name,
            s3_file_name,
            'image/png',
            target_user_profile,
            resized_data,
        )
        # See avatar_url in avatar.py for URL.  (That code also handles the case
        # that users use gravatar.)

    def get_avatar_url(self, hash_key, medium=False):
        # type: (Text, bool) -> Text
        bucket = settings.S3_AVATAR_BUCKET
        medium_suffix = "-medium.png" if medium else ""
        # ?x=x allows templates to append additional parameters with &s
        return u"https://%s.s3.amazonaws.com/%s%s?x=x" % (bucket, hash_key, medium_suffix)

    def upload_realm_icon_image(self, icon_file, user_profile):
        # type: (File, UserProfile) -> None
        content_type = guess_type(icon_file.name)[0]
        bucket_name = settings.S3_AVATAR_BUCKET
        s3_file_name = os.path.join(str(user_profile.realm.id), 'realm', 'icon')

        image_data = icon_file.read()
        upload_image_to_s3(
            bucket_name,
            s3_file_name + ".original",
            content_type,
            user_profile,
            image_data,
        )

        resized_data = resize_avatar(image_data)
        upload_image_to_s3(
            bucket_name,
            s3_file_name + ".png",
            'image/png',
            user_profile,
            resized_data,
        )
        # See avatar_url in avatar.py for URL.  (That code also handles the case
        # that users use gravatar.)

    def get_realm_icon_url(self, realm_id, version):
        # type: (int, int) -> Text
        bucket = settings.S3_AVATAR_BUCKET
        # ?x=x allows templates to append additional parameters with &s
        return u"https://%s.s3.amazonaws.com/%s/realm/icon.png?version=%s" % (bucket, realm_id, version)

    def ensure_medium_avatar_image(self, user_profile):
        # type: (UserProfile) -> None
        file_path = user_avatar_path(user_profile)
        s3_file_name = file_path

        bucket_name = settings.S3_AVATAR_BUCKET
        conn = S3Connection(settings.S3_KEY, settings.S3_SECRET_KEY)
        bucket = get_bucket(conn, bucket_name)
        key = bucket.get_key(file_path)
        image_data = force_bytes(key.get_contents_as_string())

        resized_medium = resize_avatar(image_data, MEDIUM_AVATAR_SIZE)
        upload_image_to_s3(
            bucket_name,
            s3_file_name + "-medium.png",
            "image/png",
            user_profile,
            resized_medium
        )

    def upload_emoji_image(self, emoji_file, emoji_file_name, user_profile):
        # type: (File, Text, UserProfile) -> None
        content_type = guess_type(emoji_file.name)[0]
        bucket_name = settings.S3_AVATAR_BUCKET
        emoji_path = RealmEmoji.PATH_ID_TEMPLATE.format(
            realm_id=user_profile.realm_id,
            emoji_file_name=emoji_file_name
        )

        image_data = emoji_file.read()
        resized_image_data = resize_emoji(image_data)
        upload_image_to_s3(
            bucket_name,
            ".".join((emoji_path, "original")),
            content_type,
            user_profile,
            image_data,
        )
        upload_image_to_s3(
            bucket_name,
            emoji_path,
            content_type,
            user_profile,
            resized_image_data,
        )

    def get_emoji_url(self, emoji_file_name, realm_id):
        # type: (Text, int) -> Text
        bucket = settings.S3_AVATAR_BUCKET
        emoji_path = RealmEmoji.PATH_ID_TEMPLATE.format(realm_id=realm_id,
                                                        emoji_file_name=emoji_file_name)
        return u"https://%s.s3.amazonaws.com/%s" % (bucket, emoji_path)


### Local

def mkdirs(path):
    # type: (Text) -> None
    dirname = os.path.dirname(path)
    if not os.path.isdir(dirname):
        os.makedirs(dirname)

def write_local_file(type, path, file_data):
    # type: (Text, Text, bytes) -> None
    file_path = os.path.join(settings.LOCAL_UPLOADS_DIR, type, path)
    mkdirs(file_path)
    with open(file_path, 'wb') as f:
        f.write(file_data)

def get_local_file_path(path_id):
    # type: (Text) -> Optional[Text]
    local_path = os.path.join(settings.LOCAL_UPLOADS_DIR, 'files', path_id)
    if os.path.isfile(local_path):
        return local_path
    else:
        return None

class LocalUploadBackend(ZulipUploadBackend):
    def upload_message_image(self, uploaded_file_name, uploaded_file_size,
                             content_type, file_data, user_profile, target_realm=None):
        # type: (Text, int, Optional[Text], bytes, UserProfile, Optional[Realm]) -> Text
        # Split into 256 subdirectories to prevent directories from getting too big
        path = "/".join([
            str(user_profile.realm_id),
            format(random.randint(0, 255), 'x'),
            random_name(18),
            sanitize_name(uploaded_file_name)
        ])

        write_local_file('files', path, file_data)
        create_attachment(uploaded_file_name, path, user_profile, uploaded_file_size)
        return '/user_uploads/' + path

    def delete_message_image(self, path_id):
        # type: (Text) -> bool
        file_path = os.path.join(settings.LOCAL_UPLOADS_DIR, 'files', path_id)
        if os.path.isfile(file_path):
            # This removes the file but the empty folders still remain.
            os.remove(file_path)
            return True

        file_name = path_id.split("/")[-1]
        logging.warning("%s does not exist. Its entry in the database will be removed." % (file_name,))
        return False

    def upload_avatar_image(self, user_file, acting_user_profile, target_user_profile):
        # type: (File, UserProfile, UserProfile) -> None
        file_path = user_avatar_path(target_user_profile)

        image_data = user_file.read()
        write_local_file('avatars', file_path + '.original', image_data)

        resized_data = resize_avatar(image_data)
        write_local_file('avatars', file_path + '.png', resized_data)

        resized_medium = resize_avatar(image_data, MEDIUM_AVATAR_SIZE)
        write_local_file('avatars', file_path + '-medium.png', resized_medium)

    def get_avatar_url(self, hash_key, medium=False):
        # type: (Text, bool) -> Text
        # ?x=x allows templates to append additional parameters with &s
        medium_suffix = "-medium" if medium else ""
        return u"/user_avatars/%s%s.png?x=x" % (hash_key, medium_suffix)

    def upload_realm_icon_image(self, icon_file, user_profile):
        # type: (File, UserProfile) -> None
        upload_path = os.path.join('avatars', str(user_profile.realm.id), 'realm')

        image_data = icon_file.read()
        write_local_file(
            upload_path,
            'icon.original',
            image_data)

        resized_data = resize_avatar(image_data)
        write_local_file(upload_path, 'icon.png', resized_data)

    def get_realm_icon_url(self, realm_id, version):
        # type: (int, int) -> Text
        # ?x=x allows templates to append additional parameters with &s
        return u"/user_avatars/%s/realm/icon.png?version=%s" % (realm_id, version)

    def ensure_medium_avatar_image(self, user_profile):
        # type: (UserProfile) -> None
        file_path = user_avatar_path(user_profile)

        output_path = os.path.join(settings.LOCAL_UPLOADS_DIR, "avatars", file_path + "-medium.png")
        if os.path.isfile(output_path):
            return

        image_path = os.path.join(settings.LOCAL_UPLOADS_DIR, "avatars", file_path + ".original")
        image_data = open(image_path, "rb").read()
        resized_medium = resize_avatar(image_data, MEDIUM_AVATAR_SIZE)
        write_local_file('avatars', file_path + '-medium.png', resized_medium)

    def upload_emoji_image(self, emoji_file, emoji_file_name, user_profile):
        # type: (File, Text, UserProfile) -> None
        emoji_path = RealmEmoji.PATH_ID_TEMPLATE.format(
            realm_id= user_profile.realm_id,
            emoji_file_name=emoji_file_name
        )

        image_data = emoji_file.read()
        resized_image_data = resize_emoji(image_data)
        write_local_file(
            'avatars',
            ".".join((emoji_path, "original")),
            image_data)
        write_local_file(
            'avatars',
            emoji_path,
            resized_image_data)

    def get_emoji_url(self, emoji_file_name, realm_id):
        # type: (Text, int) -> Text
        return os.path.join(
            u"/user_avatars",
            RealmEmoji.PATH_ID_TEMPLATE.format(realm_id=realm_id, emoji_file_name=emoji_file_name))

# Common and wrappers
if settings.LOCAL_UPLOADS_DIR is not None:
    upload_backend = LocalUploadBackend()  # type: ZulipUploadBackend
else:
    upload_backend = S3UploadBackend()

def delete_message_image(path_id):
    # type: (Text) -> bool
    return upload_backend.delete_message_image(path_id)

def upload_avatar_image(user_file, acting_user_profile, target_user_profile):
    # type: (File, UserProfile, UserProfile) -> None
    upload_backend.upload_avatar_image(user_file, acting_user_profile, target_user_profile)

def upload_icon_image(user_file, user_profile):
    # type: (File, UserProfile) -> None
    upload_backend.upload_realm_icon_image(user_file, user_profile)

def upload_emoji_image(emoji_file, emoji_file_name, user_profile):
    # type: (File, Text, UserProfile) -> None
    upload_backend.upload_emoji_image(emoji_file, emoji_file_name, user_profile)

def upload_message_image(uploaded_file_name, uploaded_file_size,
                         content_type, file_data, user_profile, target_realm=None):
    # type: (Text, int, Optional[Text], bytes, UserProfile, Optional[Realm]) -> Text
    return upload_backend.upload_message_image(uploaded_file_name, uploaded_file_size,
                                               content_type, file_data, user_profile, target_realm=target_realm)

def claim_attachment(user_profile, path_id, message, is_message_realm_public):
    # type: (UserProfile, Text, Message, bool) -> None
    attachment = Attachment.objects.get(path_id=path_id)
    attachment.messages.add(message)
    attachment.is_realm_public = attachment.is_realm_public or is_message_realm_public
    attachment.save()

def create_attachment(file_name, path_id, user_profile, file_size):
    # type: (Text, Text, UserProfile, int) -> bool
    Attachment.objects.create(file_name=file_name, path_id=path_id, owner=user_profile,
                              realm=user_profile.realm, size=file_size)
    return True

def upload_message_image_from_request(request, user_file, user_profile):
    # type: (HttpRequest, File, UserProfile) -> Text
    uploaded_file_name, uploaded_file_size, content_type = get_file_info(request, user_file)
    return upload_message_image(uploaded_file_name, uploaded_file_size,
                                content_type, user_file.read(), user_profile)