# Copyright (C) 2016-2023 RhodeCode GmbH
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License, version 3
# (only), as published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# This program is dual-licensed. If you wish to learn more about the
# RhodeCode Enterprise Edition, including its added features, Support services,
# and proprietary license terms, please see https://rhodecode.com/licenses/
import errno
import os
import hashlib
import functools
import time
import logging

from .. import config_keys
from ..exceptions import FileOverSizeException
from ..backends.base import BaseFileStoreBackend, fsspec, BaseShard, ShardFileReader

from ....lib.ext_json import json

log = logging.getLogger(__name__)


class LegacyFileSystemShard(BaseShard):
    # legacy ver
    METADATA_VER = 'v2'
    BACKEND_TYPE = config_keys.backend_legacy_filesystem
    storage_type: str = 'dir_struct'

    # legacy suffix
    metadata_suffix: str = '.meta'

    @classmethod
    def _sub_store_from_filename(cls, filename):
        return filename[:2]

    @classmethod
    def apply_counter(cls, counter, filename):
        name_counted = '%d-%s' % (counter, filename)
        return name_counted

    @classmethod
    def safe_make_dirs(cls, dir_path):
        if not os.path.exists(dir_path):
            try:
                os.makedirs(dir_path)
            except OSError as e:
                if e.errno != errno.EEXIST:
                    raise
                return

    @classmethod
    def resolve_name(cls, name, directory):
        """
        Resolves a unique name and the correct path. If a filename
        for that path already exists then a numeric prefix with values > 0 will be
        added, for example test.jpg -> 1-test.jpg etc. initially file would have 0 prefix.

        :param name: base name of file
        :param directory: absolute directory path
        """

        counter = 0
        while True:
            name_counted = cls.apply_counter(counter, name)

            # sub_store prefix to optimize disk usage, e.g some_path/ab/final_file
            sub_store: str = cls._sub_store_from_filename(name_counted)
            sub_store_path: str = os.path.join(directory, sub_store)
            cls.safe_make_dirs(sub_store_path)

            path = os.path.join(sub_store_path, name_counted)
            if not os.path.exists(path):
                return name_counted, path
            counter += 1

    def __init__(self, index, directory, directory_folder, fs, **settings):
        self._index: int = index
        self._directory: str = directory
        self._directory_folder: str = directory_folder
        self.fs = fs

    @property
    def dir_struct(self) -> str:
        """Cache directory final path."""
        return os.path.join(self._directory, '0-')

    def _write_file(self, full_path, iterator, max_filesize, mode='wb'):

        # ensure dir exists
        destination, _ = os.path.split(full_path)
        if not self.fs.exists(destination):
            self.fs.makedirs(destination)

        writer = self.fs.open(full_path, mode)

        digest = hashlib.sha256()
        oversize_cleanup = False
        with writer:
            size = 0
            for chunk in iterator:
                size += len(chunk)
                digest.update(chunk)
                writer.write(chunk)

                if max_filesize and size > max_filesize:
                    # free up the copied file, and raise exc
                    oversize_cleanup = True
                    break

            writer.flush()
            # Get the file descriptor
            fd = writer.fileno()

            # Sync the file descriptor to disk, helps with NFS cases...
            os.fsync(fd)

        if oversize_cleanup:
            self.fs.rm(full_path)
            raise FileOverSizeException(f'given file is over size limit ({max_filesize}): {full_path}')

        sha256 = digest.hexdigest()
        log.debug('written new artifact under %s, sha256: %s', full_path, sha256)
        return size, sha256

    def _store(self, key: str, uid_key, value_reader, max_filesize: int | None = None, metadata: dict | None = None, **kwargs):

        filename = key
        uid_filename = uid_key

        # NOTE:, also apply N- Counter...
        uid_filename, full_path = self.resolve_name(uid_filename, self._directory)

        # STORE METADATA
        # TODO: make it compatible, and backward proof
        _metadata = {
            "version": self.METADATA_VER,

            "filename": filename,
            "filename_uid_path": full_path,
            "filename_uid": uid_filename,
            "sha256": "",  # NOTE: filled in by reader iteration

            "store_time": time.time(),

            "size": 0
        }
        if metadata:
            _metadata.update(metadata)

        read_iterator = iter(functools.partial(value_reader.read, 2**22), b'')
        size, sha256 = self._write_file(full_path, read_iterator, max_filesize)
        _metadata['size'] = size
        _metadata['sha256'] = sha256

        # after storing the artifacts, we write the metadata present
        _metadata_file, metadata_file_path = self.get_metadata_filename(uid_filename)

        with self.fs.open(metadata_file_path, 'wb') as f:
            f.write(json.dumps(_metadata))

        return uid_filename, _metadata

    def store_path(self, uid_filename):
        """
        Returns absolute file path of the uid_filename
        """
        prefix_dir = ''
        if '/' in uid_filename:
            prefix_dir, filename = uid_filename.split('/')
            sub_store = self._sub_store_from_filename(filename)
        else:
            sub_store = self._sub_store_from_filename(uid_filename)

        return os.path.join(self._directory, prefix_dir, sub_store, uid_filename)

    def metadata_convert(self, uid_filename, metadata):
        # NOTE: backward compat mode here... this is for file created PRE 5.2 system
        if 'meta_ver' in metadata:
            full_path = self.store_path(uid_filename)
            metadata = {
                "_converted": True,
                "_org": metadata,
                "version": self.METADATA_VER,
                "store_type": self.BACKEND_TYPE,

                "filename": metadata['filename'],
                "filename_uid_path": full_path,
                "filename_uid": uid_filename,
                "sha256": metadata['sha256'],

                "store_time": metadata['time'],

                "size": metadata['size']
            }
        return metadata

    def _fetch(self, key, presigned_url_expires: int = 0):
        if key not in self:
            log.exception(f'requested key={key} not found in {self}')
            raise KeyError(key)

        metadata = self.get_metadata(key)

        file_path = metadata['filename_uid_path']
        if presigned_url_expires and presigned_url_expires > 0:
            metadata['url'] = self.fs.url(file_path, expires=presigned_url_expires)

        return ShardFileReader(self.fs.open(file_path, 'rb')), metadata

    def delete(self, key):
        return self._delete(key)

    def _delete(self, key):
        if key not in self:
            log.exception(f'requested key={key} not found in {self}')
            raise KeyError(key)

        metadata = self.get_metadata(key)
        metadata_file, metadata_file_path = self.get_metadata_filename(key)
        artifact_file_path = metadata['filename_uid_path']
        self.fs.rm(artifact_file_path)
        self.fs.rm(metadata_file_path)

    def get_metadata_filename(self, uid_filename) -> tuple[str, str]:

        metadata_file: str = f'{uid_filename}{self.metadata_suffix}'
        uid_path_in_store = self.store_path(uid_filename)

        metadata_file_path = f'{uid_path_in_store}{self.metadata_suffix}'
        return metadata_file, metadata_file_path


class LegacyFileSystemBackend(BaseFileStoreBackend):
    _shard_cls = LegacyFileSystemShard

    def __init__(self, settings):
        super().__init__(settings)

        store_dir = self.get_conf(config_keys.legacy_filesystem_storage_path)
        directory = os.path.expanduser(store_dir)

        self._directory = directory
        self._storage_path = directory  # common path for all from BaseCache

        log.debug('Initializing %s file_store instance', self)
        fs = fsspec.filesystem('file')

        if not fs.exists(self._directory):
            fs.makedirs(self._directory, exist_ok=True)

        # legacy system uses single shard
        self._shards = tuple(
            [
                self._shard_cls(
                    index=0,
                    directory=directory,
                    directory_folder='',
                    fs=fs,
                    **settings,
                )
            ]
        )

    @classmethod
    def get_shard_index(cls, filename: str, num_shards) -> int:
        # legacy filesystem doesn't use shards, and always uses single shard
        return 0