# Source code for fsspec.implementations.dbfs

    from __future__ import annotations

    import base64
    import urllib

    import requests
    from requests.adapters import HTTPAdapter, Retry
    from typing_extensions import override

    from fsspec import AbstractFileSystem
    from fsspec.spec import AbstractBufferedFile

    class DatabricksException(Exception):
        """
        Helper class for exceptions raised in this module.
        """

        def __init__(self, error_code, message, details=None):
            """Create a new DatabricksException"""
            super().__init__(message)

            self.error_code = error_code
            self.message = message
            self.details = details

    class DatabricksFileSystem(AbstractFileSystem):
        """
        Get access to the Databricks filesystem implementation over HTTP.
        Can be used inside and outside of a databricks cluster.
        """

        def __init__(self, instance, token, **kwargs):
            """
            Create a new DatabricksFileSystem.

            Parameters
            ----------
            instance: str
                The instance URL of the databricks cluster.
                For example for an Azure databricks cluster, this
                has the form adb-<some-number>.<two digits>.azuredatabricks.net.
            token: str
                Your personal token. Find out more
                here: https://docs.databricks.com/dev-tools/api/latest/authentication.html
            """
            self.instance = instance
            self.token = token
            self.session = requests.Session()
            self.retries = Retry(
                total=10,
                backoff_factor=0.05,
                status_forcelist=[408, 429, 500, 502, 503, 504],
            )

            self.session.mount("https://", HTTPAdapter(max_retries=self.retries))
            self.session.headers.update({"Authorization": f"Bearer {self.token}"})

            super().__init__(**kwargs)

        @override
        def _ls_from_cache(self, path) -> list[dict[str, str | int]] | None:
            """Check cache for listing

            Returns listing, if found (may be empty list for a directory that
            exists but contains nothing), None if not in cache.
            """
            self.dircache.pop(path.rstrip("/"), None)

            parent = self._parent(path)
            if parent in self.dircache:
                for entry in self.dircache[parent]:
                    if entry["name"] == path.rstrip("/"):
                        if entry["type"] != "directory":
                            return [entry]
                        return []
                raise FileNotFoundError(path)

        def ls(self, path, detail=True, **kwargs):
            """
            List the contents of the given path.

            Parameters
            ----------
            path: str
                Absolute path
            detail: bool
                Return not only the list of filenames,
                but also additional information on file sizes
                and types.
            """
            try:
                out = self._ls_from_cache(path)
            except FileNotFoundError:
                # This happens if the `path`'s parent was cached, but `path` is not
                # there. This suggests that `path` is new since the parent was
                # cached. Attempt to invalidate parent's cache before continuing.
                self.dircache.pop(self._parent(path), None)
                out = None

            if not out:
                try:
                    r = self._send_to_api(
                        method="get", endpoint="list", json={"path": path}
                    )
                except DatabricksException as e:
                    if e.error_code == "RESOURCE_DOES_NOT_EXIST":
                        raise FileNotFoundError(e.message) from e

                    raise
                files = r.get("files", [])
                out = [
                    {
                        "name": o["path"],
                        "type": "directory" if o["is_dir"] else "file",
                        "size": o["file_size"],
                    }
                    for o in files
                ]
                self.dircache[path] = out

            if detail:
                return out
            return [o["name"] for o in out]

        def makedirs(self, path, exist_ok=True):
            """
            Create a given absolute path and all of its parents.

            Parameters
            ----------
            path: str
                Absolute path to create
            exist_ok: bool
                If false, checks if the folder
                exists before creating it (and raises an
                Exception if this is the case)
            """
            if not exist_ok:
                try:
                    # If the following succeeds, the path is already present
                    self._send_to_api(
                        method="get", endpoint="get-status", json={"path": path}
                    )
                    raise FileExistsError(f"Path {path} already exists")
                except DatabricksException as e:
                    if e.error_code == "RESOURCE_DOES_NOT_EXIST":
                        pass

            try:
                self._send_to_api(method="post", endpoint="mkdirs", json={"path": path})
            except DatabricksException as e:
                if e.error_code == "RESOURCE_ALREADY_EXISTS":
                    raise FileExistsError(e.message) from e

                raise
            self.invalidate_cache(self._parent(path))

        def mkdir(self, path, create_parents=True, **kwargs):
            """
            Create a given absolute path and all of its parents.

            Parameters
            ----------
            path: str
                Absolute path to create
            create_parents: bool
                Whether to create all parents or not.
                "False" is not implemented so far.
            """
            if not create_parents:
                raise NotImplementedError

            self.mkdirs(path, **kwargs)

        def rm(self, path, recursive=False, **kwargs):
            """
            Remove the file or folder at the given absolute path.

            Parameters
            ----------
            path: str
                Absolute path what to remove
            recursive: bool
                Recursively delete all files in a folder.
            """
            try:
                self._send_to_api(
                    method="post",
                    endpoint="delete",
                    json={"path": path, "recursive": recursive},
                )
            except DatabricksException as e:
                # This is not really an exception, it just means
                # not everything was deleted so far
                if e.error_code == "PARTIAL_DELETE":
                    self.rm(path=path, recursive=recursive)
                elif e.error_code == "IO_ERROR":
                    # Using the same exception as the os module would use here
                    raise OSError(e.message) from e

                raise
            self.invalidate_cache(self._parent(path))

        def mv(
            self, source_path, destination_path, recursive=False, maxdepth=None, **kwargs
        ):
            """
            Move a source to a destination path.

            A note from the original [databricks API manual]
            (https://docs.databricks.com/dev-tools/api/latest/dbfs.html#move).

            When moving a large number of files the API call will time out after
            approximately 60s, potentially resulting in partially moved data.
            Therefore, for operations that move more than 10k files, we strongly
            discourage using the DBFS REST API.

            Parameters
            ----------
            source_path: str
                From where to move (absolute path)
            destination_path: str
                To where to move (absolute path)
            recursive: bool
                Not implemented to far.
            maxdepth:
                Not implemented to far.
            """
            if recursive:
                raise NotImplementedError
            if maxdepth:
                raise NotImplementedError

            try:
                self._send_to_api(
                    method="post",
                    endpoint="move",
                    json={"source_path": source_path, "destination_path": destination_path},
                )
            except DatabricksException as e:
                if e.error_code == "RESOURCE_DOES_NOT_EXIST":
                    raise FileNotFoundError(e.message) from e
                elif e.error_code == "RESOURCE_ALREADY_EXISTS":
                    raise FileExistsError(e.message) from e

                raise
            self.invalidate_cache(self._parent(source_path))
            self.invalidate_cache(self._parent(destination_path))

        def _open(self, path, mode="rb", block_size="default", **kwargs):
            """
            Overwrite the base class method to make sure to create a DBFile.
            All arguments are copied from the base method.

            Only the default blocksize is allowed.
            """
            return DatabricksFile(self, path, mode=mode, block_size=block_size, **kwargs)

        def _send_to_api(self, method, endpoint, json):
            """
            Send the given json to the DBFS API
            using a get or post request (specified by the argument `method`).

            Parameters
            ----------
            method: str
                Which http method to use for communication; "get" or "post".
            endpoint: str
                Where to send the request to (last part of the API URL)
            json: dict
                Dictionary of information to send
            """
            if method == "post":
                session_call = self.session.post
            elif method == "get":
                session_call = self.session.get
            else:
                raise ValueError(f"Do not understand method {method}")

            url = urllib.parse.urljoin(f"https://{self.instance}/api/2.0/dbfs/", endpoint)

            r = session_call(url, json=json)

            # The DBFS API will return a json, also in case of an exception.
            # We want to preserve this information as good as possible.
            try:
                r.raise_for_status()
            except requests.HTTPError as e:
                # try to extract json error message
                # if that fails, fall back to the original exception
                try:
                    exception_json = e.response.json()
                except Exception:
                    raise e from None

                raise DatabricksException(**exception_json) from e

            return r.json()

        def _create_handle(self, path, overwrite=True):
            """
            Internal function to create a handle, which can be used to
            write blocks of a file to DBFS.
            A handle has a unique identifier which needs to be passed
            whenever written during this transaction.
            The handle is active for 10 minutes - after that a new
            write transaction needs to be created.
            Make sure to close the handle after you are finished.

            Parameters
            ----------
            path: str
                Absolute path for this file.
            overwrite: bool
                If a file already exist at this location, either overwrite
                it or raise an exception.
            """
            try:
                r = self._send_to_api(
                    method="post",
                    endpoint="create",
                    json={"path": path, "overwrite": overwrite},
                )
                return r["handle"]
            except DatabricksException as e:
                if e.error_code == "RESOURCE_ALREADY_EXISTS":
                    raise FileExistsError(e.message) from e

                raise

        def _close_handle(self, handle):
            """
            Close a handle, which was opened by :func:`_create_handle`.

            Parameters
            ----------
            handle: str
                Which handle to close.
            """
            try:
                self._send_to_api(method="post", endpoint="close", json={"handle": handle})
            except DatabricksException as e:
                if e.error_code == "RESOURCE_DOES_NOT_EXIST":
                    raise FileNotFoundError(e.message) from e

                raise

        def _add_data(self, handle, data):
            """
            Upload data to an already opened file handle
            (opened by :func:`_create_handle`).
            The maximal allowed data size is 1MB after
            conversion to base64.
            Remember to close the handle when you are finished.

            Parameters
            ----------
            handle: str
                Which handle to upload data to.
            data: bytes
                Block of data to add to the handle.
            """
            data = base64.b64encode(data).decode()
            try:
                self._send_to_api(
                    method="post",
                    endpoint="add-block",
                    json={"handle": handle, "data": data},
                )
            except DatabricksException as e:
                if e.error_code == "RESOURCE_DOES_NOT_EXIST":
                    raise FileNotFoundError(e.message) from e
                elif e.error_code == "MAX_BLOCK_SIZE_EXCEEDED":
                    raise ValueError(e.message) from e

                raise

        def _get_data(self, path, start, end):
            """
            Download data in bytes from a given absolute path in a block
            from [start, start+length].
            The maximum number of allowed bytes to read is 1MB.

            Parameters
            ----------
            path: str
                Absolute path to download data from
            start: int
                Start position of the block
            end: int
                End position of the block
            """
            try:
                r = self._send_to_api(
                    method="get",
                    endpoint="read",
                    json={"path": path, "offset": start, "length": end - start},
                )
                return base64.b64decode(r["data"])
            except DatabricksException as e:
                if e.error_code == "RESOURCE_DOES_NOT_EXIST":
                    raise FileNotFoundError(e.message) from e
                elif e.error_code in ["INVALID_PARAMETER_VALUE", "MAX_READ_SIZE_EXCEEDED"]:
                    raise ValueError(e.message) from e

                raise

        def invalidate_cache(self, path=None):
            if path is None:
                self.dircache.clear()
            else:
                self.dircache.pop(path, None)
            super().invalidate_cache(path)

    class DatabricksFile(AbstractBufferedFile):
        """
        Helper class for files referenced in the DatabricksFileSystem.
        """

        DEFAULT_BLOCK_SIZE = 1 * 2**20  # only allowed block size

        def __init__(
            self,
            fs,
            path,
            mode="rb",
            block_size="default",
            autocommit=True,
            cache_type="readahead",
            cache_options=None,
            **kwargs,
        ):
            """
            Create a new instance of the DatabricksFile.

            The blocksize needs to be the default one.
            """
            if block_size is None or block_size == "default":
                block_size = self.DEFAULT_BLOCK_SIZE

            assert block_size == self.DEFAULT_BLOCK_SIZE, (
                f"Only the default block size is allowed, not {block_size}"
            )

            super().__init__(
                fs,
                path,
                mode=mode,
                block_size=block_size,
                autocommit=autocommit,
                cache_type=cache_type,
                cache_options=cache_options or {},
                **kwargs,
            )

        def _initiate_upload(self):
            """Internal function to start a file upload"""
            self.handle = self.fs._create_handle(self.path)

        def _upload_chunk(self, final=False):
            """Internal function to add a chunk of data to a started upload"""
            self.buffer.seek(0)
            data = self.buffer.getvalue()

            data_chunks = [
                data[start:end] for start, end in self._to_sized_blocks(len(data))
            ]

            for data_chunk in data_chunks:
                self.fs._add_data(handle=self.handle, data=data_chunk)

            if final:
                self.fs._close_handle(handle=self.handle)
                return True

        def _fetch_range(self, start, end):
            """Internal function to download a block of data"""
            return_buffer = b""
            length = end - start
            for chunk_start, chunk_end in self._to_sized_blocks(length, start):
                return_buffer += self.fs._get_data(
                    path=self.path, start=chunk_start, end=chunk_end
                )

            return return_buffer

        def _to_sized_blocks(self, length, start=0):
            """Helper function to split a range from 0 to total_length into blocksizes"""
            end = start + length
            for data_chunk in range(start, end, self.blocksize):
                data_start = data_chunk
                data_end = min(end, data_chunk + self.blocksize)
                yield data_start, data_end