import logging
import os
import secrets
import urllib
from mimetypes import guess_type
from typing import IO, Any, Callable, Optional

import boto3
import botocore
from boto3.session import Session
from botocore.client import Config
from django.conf import settings
from mypy_boto3_s3.client import S3Client
from mypy_boto3_s3.service_resource import Bucket, Object

from zerver.lib.avatar_hash import user_avatar_path
from zerver.lib.upload.base import (
    INLINE_MIME_TYPES,
    MEDIUM_AVATAR_SIZE,
    ZulipUploadBackend,
    create_attachment,
    resize_avatar,
    resize_emoji,
    resize_logo,
    sanitize_name,
)
from zerver.models import Realm, RealmEmoji, UserProfile

# Duration that the signed upload URLs that we redirect to when
# accessing uploaded files are available for clients to fetch before
# they expire.
SIGNED_UPLOAD_URL_DURATION = 60

# 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.


# https://github.com/boto/botocore/issues/2644 means that the IMDS
# request _always_ pulls from the environment.  Monkey-patch the
# `should_bypass_proxies` function if we need to skip them, based
# on S3_SKIP_PROXY.
if settings.S3_SKIP_PROXY is True:  # nocoverage
    botocore.utils.should_bypass_proxies = lambda url: True


def get_bucket(bucket_name: str, session: Optional[Session] = None) -> Bucket:
    if session is None:
        session = Session(settings.S3_KEY, settings.S3_SECRET_KEY)
    bucket = session.resource(
        "s3", region_name=settings.S3_REGION, endpoint_url=settings.S3_ENDPOINT_URL
    ).Bucket(bucket_name)
    return bucket


def upload_image_to_s3(
    bucket: Bucket,
    file_name: str,
    content_type: Optional[str],
    user_profile: UserProfile,
    contents: bytes,
) -> None:
    key = bucket.Object(file_name)
    metadata = {
        "user_profile_id": str(user_profile.id),
        "realm_id": str(user_profile.realm_id),
    }

    content_disposition = ""
    if content_type is None:
        content_type = ""
    if content_type not in INLINE_MIME_TYPES:
        content_disposition = "attachment"

    key.put(
        Body=contents,
        Metadata=metadata,
        ContentType=content_type,
        ContentDisposition=content_disposition,
    )


def get_signed_upload_url(path: str, force_download: bool = False) -> str:
    client = boto3.client(
        "s3",
        aws_access_key_id=settings.S3_KEY,
        aws_secret_access_key=settings.S3_SECRET_KEY,
        region_name=settings.S3_REGION,
        endpoint_url=settings.S3_ENDPOINT_URL,
    )
    params = {
        "Bucket": settings.S3_AUTH_UPLOADS_BUCKET,
        "Key": path,
    }
    if force_download:
        params["ResponseContentDisposition"] = "attachment"

    return client.generate_presigned_url(
        ClientMethod="get_object",
        Params=params,
        ExpiresIn=SIGNED_UPLOAD_URL_DURATION,
        HttpMethod="GET",
    )


class S3UploadBackend(ZulipUploadBackend):
    def __init__(self) -> None:
        self.session = Session(settings.S3_KEY, settings.S3_SECRET_KEY)
        self.avatar_bucket = get_bucket(settings.S3_AVATAR_BUCKET, self.session)
        self.uploads_bucket = get_bucket(settings.S3_AUTH_UPLOADS_BUCKET, self.session)

        self._boto_client: Optional[S3Client] = None
        self.public_upload_url_base = self.construct_public_upload_url_base()

    def construct_public_upload_url_base(self) -> str:
        # Return the pattern for public URL for a key in the S3 Avatar bucket.
        # For Amazon S3 itself, this will return the following:
        #     f"https://{self.avatar_bucket.name}.{network_location}/{key}"
        #
        # However, we need this function to properly handle S3 style
        # file upload backends that Zulip supports, which can have a
        # different URL format. Configuring no signature and providing
        # no access key makes `generate_presigned_url` just return the
        # normal public URL for a key.
        #
        # It unfortunately takes 2ms per query to call
        # generate_presigned_url, even with our cached boto
        # client. Since we need to potentially compute hundreds of
        # avatar URLs in single `GET /messages` request, we instead
        # back-compute the URL pattern here.

        DUMMY_KEY = "dummy_key_ignored"
        foo_url = self.get_boto_client().generate_presigned_url(
            ClientMethod="get_object",
            Params={
                "Bucket": self.avatar_bucket.name,
                "Key": DUMMY_KEY,
            },
            ExpiresIn=0,
        )
        split_url = urllib.parse.urlsplit(foo_url)
        assert split_url.path.endswith(f"/{DUMMY_KEY}")

        return urllib.parse.urlunsplit(
            (split_url.scheme, split_url.netloc, split_url.path[: -len(DUMMY_KEY)], "", "")
        )

    def get_public_upload_url(
        self,
        key: str,
    ) -> str:
        assert not key.startswith("/")
        return urllib.parse.urljoin(self.public_upload_url_base, key)

    def get_boto_client(self) -> S3Client:
        """
        Creating the client takes a long time so we need to cache it.
        """
        if self._boto_client is None:
            config = Config(signature_version=botocore.UNSIGNED)
            self._boto_client = self.session.client(
                "s3",
                region_name=settings.S3_REGION,
                endpoint_url=settings.S3_ENDPOINT_URL,
                config=config,
            )
        return self._boto_client

    def delete_file_from_s3(self, path_id: str, bucket: Bucket) -> bool:
        key = bucket.Object(path_id)

        try:
            key.load()
        except botocore.exceptions.ClientError:
            file_name = path_id.split("/")[-1]
            logging.warning(
                "%s does not exist. Its entry in the database will be removed.", file_name
            )
            return False
        key.delete()
        return True

    def get_public_upload_root_url(self) -> str:
        return self.public_upload_url_base

    def generate_message_upload_path(self, realm_id: str, uploaded_file_name: str) -> str:
        return "/".join(
            [
                realm_id,
                secrets.token_urlsafe(18),
                sanitize_name(uploaded_file_name),
            ]
        )

    def upload_message_attachment(
        self,
        uploaded_file_name: str,
        uploaded_file_size: int,
        content_type: Optional[str],
        file_data: bytes,
        user_profile: UserProfile,
        target_realm: Optional[Realm] = None,
    ) -> str:
        if target_realm is None:
            target_realm = user_profile.realm
        s3_file_name = self.generate_message_upload_path(str(target_realm.id), uploaded_file_name)
        url = f"/user_uploads/{s3_file_name}"

        upload_image_to_s3(
            self.uploads_bucket,
            s3_file_name,
            content_type,
            user_profile,
            file_data,
        )

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

    def delete_message_attachment(self, path_id: str) -> bool:
        return self.delete_file_from_s3(path_id, self.uploads_bucket)

    def write_avatar_images(
        self,
        s3_file_name: str,
        target_user_profile: UserProfile,
        image_data: bytes,
        content_type: Optional[str],
    ) -> None:
        upload_image_to_s3(
            self.avatar_bucket,
            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(
            self.avatar_bucket,
            s3_file_name + "-medium.png",
            "image/png",
            target_user_profile,
            resized_medium,
        )

        resized_data = resize_avatar(image_data)
        upload_image_to_s3(
            self.avatar_bucket,
            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 upload_avatar_image(
        self,
        user_file: IO[bytes],
        acting_user_profile: UserProfile,
        target_user_profile: UserProfile,
        content_type: Optional[str] = None,
    ) -> None:
        if content_type is None:
            content_type = guess_type(user_file.name)[0]
        s3_file_name = user_avatar_path(target_user_profile)

        image_data = user_file.read()
        self.write_avatar_images(s3_file_name, target_user_profile, image_data, content_type)

    def delete_avatar_image(self, user: UserProfile) -> None:
        path_id = user_avatar_path(user)

        self.delete_file_from_s3(path_id + ".original", self.avatar_bucket)
        self.delete_file_from_s3(path_id + "-medium.png", self.avatar_bucket)
        self.delete_file_from_s3(path_id, self.avatar_bucket)

    def get_avatar_key(self, file_name: str) -> Object:
        key = self.avatar_bucket.Object(file_name)
        return key

    def copy_avatar(self, source_profile: UserProfile, target_profile: UserProfile) -> None:
        s3_source_file_name = user_avatar_path(source_profile)
        s3_target_file_name = user_avatar_path(target_profile)

        key = self.get_avatar_key(s3_source_file_name + ".original")
        image_data = key.get()["Body"].read()
        content_type = key.content_type

        self.write_avatar_images(s3_target_file_name, target_profile, image_data, content_type)

    def get_avatar_url(self, hash_key: str, medium: bool = False) -> str:
        medium_suffix = "-medium.png" if medium else ""
        return self.get_public_upload_url(f"{hash_key}{medium_suffix}")

    def get_export_tarball_url(self, realm: Realm, export_path: str) -> str:
        # export_path has a leading /
        return self.get_public_upload_url(export_path[1:])

    def upload_realm_icon_image(self, icon_file: IO[bytes], user_profile: UserProfile) -> None:
        content_type = guess_type(icon_file.name)[0]
        s3_file_name = os.path.join(self.realm_avatar_and_logo_path(user_profile.realm), "icon")

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

        resized_data = resize_avatar(image_data)
        upload_image_to_s3(
            self.avatar_bucket,
            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: int, version: int) -> str:
        public_url = self.get_public_upload_url(f"{realm_id}/realm/icon.png")
        return public_url + f"?version={version}"

    def upload_realm_logo_image(
        self, logo_file: IO[bytes], user_profile: UserProfile, night: bool
    ) -> None:
        content_type = guess_type(logo_file.name)[0]
        if night:
            basename = "night_logo"
        else:
            basename = "logo"
        s3_file_name = os.path.join(self.realm_avatar_and_logo_path(user_profile.realm), basename)

        image_data = logo_file.read()
        upload_image_to_s3(
            self.avatar_bucket,
            s3_file_name + ".original",
            content_type,
            user_profile,
            image_data,
        )

        resized_data = resize_logo(image_data)
        upload_image_to_s3(
            self.avatar_bucket,
            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_logo_url(self, realm_id: int, version: int, night: bool) -> str:
        if not night:
            file_name = "logo.png"
        else:
            file_name = "night_logo.png"
        public_url = self.get_public_upload_url(f"{realm_id}/realm/{file_name}")
        return public_url + f"?version={version}"

    def ensure_avatar_image(self, user_profile: UserProfile, is_medium: bool = False) -> None:
        # BUG: The else case should be user_avatar_path(user_profile) + ".png".
        # See #12852 for details on this bug and how to migrate it.
        file_extension = "-medium.png" if is_medium else ""
        file_path = user_avatar_path(user_profile)
        s3_file_name = file_path

        key = self.avatar_bucket.Object(file_path + ".original")
        image_data = key.get()["Body"].read()

        if is_medium:
            resized_avatar = resize_avatar(image_data, MEDIUM_AVATAR_SIZE)
        else:
            resized_avatar = resize_avatar(image_data)
        upload_image_to_s3(
            self.avatar_bucket,
            s3_file_name + file_extension,
            "image/png",
            user_profile,
            resized_avatar,
        )

    def upload_emoji_image(
        self, emoji_file: IO[bytes], emoji_file_name: str, user_profile: UserProfile
    ) -> bool:
        content_type = guess_type(emoji_file_name)[0]
        emoji_path = RealmEmoji.PATH_ID_TEMPLATE.format(
            realm_id=user_profile.realm_id,
            emoji_file_name=emoji_file_name,
        )

        image_data = emoji_file.read()
        upload_image_to_s3(
            self.avatar_bucket,
            ".".join((emoji_path, "original")),
            content_type,
            user_profile,
            image_data,
        )

        resized_image_data, is_animated, still_image_data = resize_emoji(image_data)
        upload_image_to_s3(
            self.avatar_bucket,
            emoji_path,
            content_type,
            user_profile,
            resized_image_data,
        )
        if is_animated:
            still_path = RealmEmoji.STILL_PATH_ID_TEMPLATE.format(
                realm_id=user_profile.realm_id,
                emoji_filename_without_extension=os.path.splitext(emoji_file_name)[0],
            )
            assert still_image_data is not None
            upload_image_to_s3(
                self.avatar_bucket,
                still_path,
                "image/png",
                user_profile,
                still_image_data,
            )

        return is_animated

    def get_emoji_url(self, emoji_file_name: str, realm_id: int, still: bool = False) -> str:
        if still:
            emoji_path = RealmEmoji.STILL_PATH_ID_TEMPLATE.format(
                realm_id=realm_id,
                emoji_filename_without_extension=os.path.splitext(emoji_file_name)[0],
            )
            return self.get_public_upload_url(emoji_path)
        else:
            emoji_path = RealmEmoji.PATH_ID_TEMPLATE.format(
                realm_id=realm_id, emoji_file_name=emoji_file_name
            )
            return self.get_public_upload_url(emoji_path)

    def upload_export_tarball(
        self,
        realm: Optional[Realm],
        tarball_path: str,
        percent_callback: Optional[Callable[[Any], None]] = None,
    ) -> str:
        # We use the avatar bucket, because it's world-readable.
        key = self.avatar_bucket.Object(
            os.path.join("exports", secrets.token_hex(16), os.path.basename(tarball_path))
        )

        if percent_callback is None:
            key.upload_file(Filename=tarball_path)
        else:
            key.upload_file(Filename=tarball_path, Callback=percent_callback)

        public_url = self.get_public_upload_url(key.key)
        return public_url

    def delete_export_tarball(self, export_path: str) -> Optional[str]:
        assert export_path.startswith("/")
        path_id = export_path[1:]
        if self.delete_file_from_s3(path_id, self.avatar_bucket):
            return export_path
        return None