# Copyright 2016-2019 Camptocamp SA
# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html)


import io
import logging
import os
from urllib.parse import urlsplit

from odoo import _, api, exceptions, models

from ..s3uri import S3Uri

_logger = logging.getLogger(__name__)

try:
    import boto3
    from botocore.exceptions import ClientError, EndpointConnectionError
except ImportError:
    boto3 = None  # noqa
    ClientError = None  # noqa
    EndpointConnectionError = None  # noqa
    _logger.debug("Cannot 'import boto3'.")


class IrAttachment(models.Model):
    _inherit = "ir.attachment"

    def _get_stores(self):
        return ["s3"] + super()._get_stores()

    @api.model
    def _get_s3_bucket(self, name=None):
        """Connect to S3 and return the bucket

        The following environment variables can be set:
        * ``AWS_HOST``
        * ``AWS_REGION``
        * ``AWS_ACCESS_KEY_ID``
        * ``AWS_SECRET_ACCESS_KEY``
        * ``AWS_BUCKETNAME``

        If a name is provided, we'll read this bucket, otherwise, the bucket
        from the environment variable ``AWS_BUCKETNAME`` will be read.

        """
        host = os.environ.get("AWS_HOST")

        # Ensure host is prefixed with a scheme (use https as default)
        if host and not urlsplit(host).scheme:
            host = "https://%s" % host

        region_name = os.environ.get("AWS_REGION")
        access_key = os.environ.get("AWS_ACCESS_KEY_ID")
        secret_key = os.environ.get("AWS_SECRET_ACCESS_KEY")
        bucket_name = name or os.environ.get("AWS_BUCKETNAME")
        # replaces {db} by the database name to handle multi-tenancy
        bucket_name = bucket_name.format(db=self.env.cr.dbname)

        params = {
            "aws_access_key_id": access_key,
            "aws_secret_access_key": secret_key,
        }
        if host:
            params["endpoint_url"] = host
        if region_name:
            params["region_name"] = region_name
        if not (access_key and secret_key and bucket_name):
            msg = _(
                "If you want to read from the %(bucket_name)s S3 bucket, the following "
                "environment variables must be set:\n"
                "* AWS_ACCESS_KEY_ID\n"
                "* AWS_SECRET_ACCESS_KEY\n"
                "If you want to write in the %(bucket_name)s S3 bucket, this variable "
                "must be set as well:\n"
                "* AWS_BUCKETNAME\n"
                "Optionally, the S3 host can be changed with:\n"
                "* AWS_HOST\n"
            ).format(bucket_name=bucket_name)

            raise exceptions.UserError(msg)
        # try:
        s3 = boto3.resource("s3", **params)
        bucket = s3.Bucket(bucket_name)
        exists = True
        try:
            s3.meta.client.head_bucket(Bucket=bucket_name)
        except ClientError as e:
            # If a client error is thrown, then check that it was a 404 error.
            # If it was a 404 error, then the bucket does not exist.
            error_code = e.response["Error"]["Code"]
            if error_code == "404":
                exists = False
        except EndpointConnectionError as error:
            # log verbose error from s3, return short message for user
            msg = _logger.exception("Error during connection on S3")
            raise exceptions.UserError(str(error)) from None

        if not exists:
            if not region_name:
                bucket = s3.create_bucket(Bucket=bucket_name)
            else:
                bucket = s3.create_bucket(
                    Bucket=bucket_name,
                    CreateBucketConfiguration={"LocationConstraint": region_name},
                )
        return bucket

    @api.model
    def _store_file_read(self, fname):
        if fname.startswith("s3://"):
            s3uri = S3Uri(fname)
            try:
                bucket = self._get_s3_bucket(name=s3uri.bucket())
            except exceptions.UserError:
                _logger.exception(
                    "error reading attachment '%s' from object storage", fname
                )
                return ""
            try:
                key = s3uri.item()
                bucket.meta.client.head_object(Bucket=bucket.name, Key=key)
                with io.BytesIO() as res:
                    bucket.download_fileobj(key, res)
                    res.seek(0)
                    read = res.read()
            except ClientError:
                read = ""
                _logger.info("attachment '%s' missing on object storage", fname)
            return read
        else:
            return super()._store_file_read(fname)

    @api.model
    def _store_file_write(self, key, bin_data):
        location = self.env.context.get("storage_location") or self._storage()
        if location == "s3":
            bucket = self._get_s3_bucket()
            obj = bucket.Object(key=key)
            with io.BytesIO() as file:
                file.write(bin_data)
                file.seek(0)
                filename = "s3://%s/%s" % (bucket.name, key)
                try:
                    obj.upload_fileobj(file)
                except ClientError as error:
                    # log verbose error from s3, return short message for user
                    _logger.exception("Error during storage of the file %s" % filename)
                    raise exceptions.UserError(
                        _("The file could not be stored: %s") % str(error)
                    ) from None
        else:
            _super = super()
            filename = _super._store_file_write(key, bin_data)
        return filename

    @api.model
    def _store_file_delete(self, fname):
        if fname.startswith("s3://"):
            s3uri = S3Uri(fname)
            bucket_name = s3uri.bucket()
            item_name = s3uri.item()
            # delete the file only if it is on the current configured bucket
            # otherwise, we might delete files used on a different environment
            if bucket_name == os.environ.get("AWS_BUCKETNAME"):
                bucket = self._get_s3_bucket()
                obj = bucket.Object(key=item_name)
                try:
                    bucket.meta.client.head_object(Bucket=bucket.name, Key=item_name)
                    obj.delete()
                    _logger.info("file %s deleted on the object storage" % (fname,))
                except ClientError:
                    # log verbose error from s3, return short message for
                    # user
                    _logger.exception("Error during deletion of the file %s" % fname)
        else:
            return super()._store_file_delete(fname)