"""
Type definitions and utilities for the `create_commit` API
"""

import base64
import io
import os
import warnings
from collections import defaultdict
from contextlib import contextmanager
from dataclasses import dataclass, field
from itertools import groupby
from pathlib import Path, PurePosixPath
from typing import TYPE_CHECKING, Any, BinaryIO, Dict, Iterable, Iterator, List, Literal, Optional, Tuple, Union

from tqdm.contrib.concurrent import thread_map

from . import constants
from .errors import EntryNotFoundError
from .file_download import hf_hub_url
from .lfs import UploadInfo, lfs_upload, post_lfs_batch_info
from .utils import (
    FORBIDDEN_FOLDERS,
    chunk_iterable,
    get_session,
    hf_raise_for_status,
    logging,
    sha,
    tqdm_stream_file,
    validate_hf_hub_args,
)
from .utils import tqdm as hf_tqdm


if TYPE_CHECKING:
    from .hf_api import RepoFile


logger = logging.get_logger(__name__)


UploadMode = Literal["lfs", "regular"]

# Max is 1,000 per request on the Hub for HfApi.get_paths_info
# Otherwise we get:
# HfHubHTTPError: 413 Client Error: Payload Too Large for url: https://huggingface.co/api/datasets/xxx (Request ID: xxx)\n\ntoo many parameters
# See https://github.com/huggingface/huggingface_hub/issues/1503
FETCH_LFS_BATCH_SIZE = 500


@dataclass
class CommitOperationDelete:
    """
    Data structure holding necessary info to delete a file or a folder from a repository
    on the Hub.

    Args:
        path_in_repo (`str`):
            Relative filepath in the repo, for example: `"checkpoints/1fec34a/weights.bin"`
            for a file or `"checkpoints/1fec34a/"` for a folder.
        is_folder (`bool` or `Literal["auto"]`, *optional*)
            Whether the Delete Operation applies to a folder or not. If "auto", the path
            type (file or folder) is guessed automatically by looking if path ends with
            a "/" (folder) or not (file). To explicitly set the path type, you can set
            `is_folder=True` or `is_folder=False`.
    """

    path_in_repo: str
    is_folder: Union[bool, Literal["auto"]] = "auto"

    def __post_init__(self):
        self.path_in_repo = _validate_path_in_repo(self.path_in_repo)

        if self.is_folder == "auto":
            self.is_folder = self.path_in_repo.endswith("/")
        if not isinstance(self.is_folder, bool):
            raise ValueError(
                f"Wrong value for `is_folder`. Must be one of [`True`, `False`, `'auto'`]. Got '{self.is_folder}'."
            )


@dataclass
class CommitOperationCopy:
    """
    Data structure holding necessary info to copy a file in a repository on the Hub.

    Limitations:
      - Only LFS files can be copied. To copy a regular file, you need to download it locally and re-upload it
      - Cross-repository copies are not supported.

    Note: you can combine a [`CommitOperationCopy`] and a [`CommitOperationDelete`] to rename an LFS file on the Hub.

    Args:
        src_path_in_repo (`str`):
            Relative filepath in the repo of the file to be copied, e.g. `"checkpoints/1fec34a/weights.bin"`.
        path_in_repo (`str`):
            Relative filepath in the repo where to copy the file, e.g. `"checkpoints/1fec34a/weights_copy.bin"`.
        src_revision (`str`, *optional*):
            The git revision of the file to be copied. Can be any valid git revision.
            Default to the target commit revision.
    """

    src_path_in_repo: str
    path_in_repo: str
    src_revision: Optional[str] = None
    # set to the OID of the file to be copied if it has already been uploaded
    # useful to determine if a commit will be empty or not.
    _src_oid: Optional[str] = None
    # set to the OID of the file to copy to if it has already been uploaded
    # useful to determine if a commit will be empty or not.
    _dest_oid: Optional[str] = None

    def __post_init__(self):
        self.src_path_in_repo = _validate_path_in_repo(self.src_path_in_repo)
        self.path_in_repo = _validate_path_in_repo(self.path_in_repo)


@dataclass
class CommitOperationAdd:
    """
    Data structure holding necessary info to upload a file to a repository on the Hub.

    Args:
        path_in_repo (`str`):
            Relative filepath in the repo, for example: `"checkpoints/1fec34a/weights.bin"`
        path_or_fileobj (`str`, `Path`, `bytes`, or `BinaryIO`):
            Either:
            - a path to a local file (as `str` or `pathlib.Path`) to upload
            - a buffer of bytes (`bytes`) holding the content of the file to upload
            - a "file object" (subclass of `io.BufferedIOBase`), typically obtained
                with `open(path, "rb")`. It must support `seek()` and `tell()` methods.

    Raises:
        [`ValueError`](https://docs.python.org/3/library/exceptions.html#ValueError)
            If `path_or_fileobj` is not one of `str`, `Path`, `bytes` or `io.BufferedIOBase`.
        [`ValueError`](https://docs.python.org/3/library/exceptions.html#ValueError)
            If `path_or_fileobj` is a `str` or `Path` but not a path to an existing file.
        [`ValueError`](https://docs.python.org/3/library/exceptions.html#ValueError)
            If `path_or_fileobj` is a `io.BufferedIOBase` but it doesn't support both
            `seek()` and `tell()`.
    """

    path_in_repo: str
    path_or_fileobj: Union[str, Path, bytes, BinaryIO]
    upload_info: UploadInfo = field(init=False, repr=False)

    # Internal attributes

    # set to "lfs" or "regular" once known
    _upload_mode: Optional[UploadMode] = field(init=False, repr=False, default=None)

    # set to True if .gitignore rules prevent the file from being uploaded as LFS
    # (server-side check)
    _should_ignore: Optional[bool] = field(init=False, repr=False, default=None)

    # set to the remote OID of the file if it has already been uploaded
    # useful to determine if a commit will be empty or not
    _remote_oid: Optional[str] = field(init=False, repr=False, default=None)

    # set to True once the file has been uploaded as LFS
    _is_uploaded: bool = field(init=False, repr=False, default=False)

    # set to True once the file has been committed
    _is_committed: bool = field(init=False, repr=False, default=False)

    def __post_init__(self) -> None:
        """Validates `path_or_fileobj` and compute `upload_info`."""
        self.path_in_repo = _validate_path_in_repo(self.path_in_repo)

        # Validate `path_or_fileobj` value
        if isinstance(self.path_or_fileobj, Path):
            self.path_or_fileobj = str(self.path_or_fileobj)
        if isinstance(self.path_or_fileobj, str):
            path_or_fileobj = os.path.normpath(os.path.expanduser(self.path_or_fileobj))
            if not os.path.isfile(path_or_fileobj):
                raise ValueError(f"Provided path: '{path_or_fileobj}' is not a file on the local file system")
        elif not isinstance(self.path_or_fileobj, (io.BufferedIOBase, bytes)):
            # ^^ Inspired from: https://stackoverflow.com/questions/44584829/how-to-determine-if-file-is-opened-in-binary-or-text-mode
            raise ValueError(
                "path_or_fileobj must be either an instance of str, bytes or"
                " io.BufferedIOBase. If you passed a file-like object, make sure it is"
                " in binary mode."
            )
        if isinstance(self.path_or_fileobj, io.BufferedIOBase):
            try:
                self.path_or_fileobj.tell()
                self.path_or_fileobj.seek(0, os.SEEK_CUR)
            except (OSError, AttributeError) as exc:
                raise ValueError(
                    "path_or_fileobj is a file-like object but does not implement seek() and tell()"
                ) from exc

        # Compute "upload_info" attribute
        if isinstance(self.path_or_fileobj, str):
            self.upload_info = UploadInfo.from_path(self.path_or_fileobj)
        elif isinstance(self.path_or_fileobj, bytes):
            self.upload_info = UploadInfo.from_bytes(self.path_or_fileobj)
        else:
            self.upload_info = UploadInfo.from_fileobj(self.path_or_fileobj)

    @contextmanager
    def as_file(self, with_tqdm: bool = False) -> Iterator[BinaryIO]:
        """
        A context manager that yields a file-like object allowing to read the underlying
        data behind `path_or_fileobj`.

        Args:
            with_tqdm (`bool`, *optional*, defaults to `False`):
                If True, iterating over the file object will display a progress bar. Only
                works if the file-like object is a path to a file. Pure bytes and buffers
                are not supported.

        Example:

        ```python
        >>> operation = CommitOperationAdd(
        ...        path_in_repo="remote/dir/weights.h5",
        ...        path_or_fileobj="./local/weights.h5",
        ... )
        CommitOperationAdd(path_in_repo='remote/dir/weights.h5', path_or_fileobj='./local/weights.h5')

        >>> with operation.as_file() as file:
        ...     content = file.read()

        >>> with operation.as_file(with_tqdm=True) as file:
        ...     while True:
        ...         data = file.read(1024)
        ...         if not data:
        ...              break
        config.json: 100%|█████████████████████████| 8.19k/8.19k [00:02<00:00, 3.72kB/s]

        >>> with operation.as_file(with_tqdm=True) as file:
        ...     requests.put(..., data=file)
        config.json: 100%|█████████████████████████| 8.19k/8.19k [00:02<00:00, 3.72kB/s]
        ```
        """
        if isinstance(self.path_or_fileobj, str) or isinstance(self.path_or_fileobj, Path):
            if with_tqdm:
                with tqdm_stream_file(self.path_or_fileobj) as file:
                    yield file
            else:
                with open(self.path_or_fileobj, "rb") as file:
                    yield file
        elif isinstance(self.path_or_fileobj, bytes):
            yield io.BytesIO(self.path_or_fileobj)
        elif isinstance(self.path_or_fileobj, io.BufferedIOBase):
            prev_pos = self.path_or_fileobj.tell()
            yield self.path_or_fileobj
            self.path_or_fileobj.seek(prev_pos, io.SEEK_SET)

    def b64content(self) -> bytes:
        """
        The base64-encoded content of `path_or_fileobj`

        Returns: `bytes`
        """
        with self.as_file() as file:
            return base64.b64encode(file.read())

    @property
    def _local_oid(self) -> Optional[str]:
        """Return the OID of the local file.

        This OID is then compared to `self._remote_oid` to check if the file has changed compared to the remote one.
        If the file did not change, we won't upload it again to prevent empty commits.

        For LFS files, the OID corresponds to the SHA256 of the file content (used a LFS ref).
        For regular files, the OID corresponds to the SHA1 of the file content.
        Note: this is slightly different to git OID computation since the oid of an LFS file is usually the git-SHA1 of the
              pointer file content (not the actual file content). However, using the SHA256 is enough to detect changes
              and more convenient client-side.
        """
        if self._upload_mode is None:
            return None
        elif self._upload_mode == "lfs":
            return self.upload_info.sha256.hex()
        else:
            # Regular file => compute sha1
            # => no need to read by chunk since the file is guaranteed to be <=5MB.
            with self.as_file() as file:
                return sha.git_hash(file.read())


def _validate_path_in_repo(path_in_repo: str) -> str:
    # Validate `path_in_repo` value to prevent a server-side issue
    if path_in_repo.startswith("/"):
        path_in_repo = path_in_repo[1:]
    if path_in_repo == "." or path_in_repo == ".." or path_in_repo.startswith("../"):
        raise ValueError(f"Invalid `path_in_repo` in CommitOperation: '{path_in_repo}'")
    if path_in_repo.startswith("./"):
        path_in_repo = path_in_repo[2:]
    for forbidden in FORBIDDEN_FOLDERS:
        if any(part == forbidden for part in path_in_repo.split("/")):
            raise ValueError(
                f"Invalid `path_in_repo` in CommitOperation: cannot update files under a '{forbidden}/' folder (path:"
                f" '{path_in_repo}')."
            )
    return path_in_repo


CommitOperation = Union[CommitOperationAdd, CommitOperationCopy, CommitOperationDelete]


def _warn_on_overwriting_operations(operations: List[CommitOperation]) -> None:
    """
    Warn user when a list of operations is expected to overwrite itself in a single
    commit.

    Rules:
    - If a filepath is updated by multiple `CommitOperationAdd` operations, a warning
      message is triggered.
    - If a filepath is updated at least once by a `CommitOperationAdd` and then deleted
      by a `CommitOperationDelete`, a warning is triggered.
    - If a `CommitOperationDelete` deletes a filepath that is then updated by a
      `CommitOperationAdd`, no warning is triggered. This is usually useless (no need to
      delete before upload) but can happen if a user deletes an entire folder and then
      add new files to it.
    """
    nb_additions_per_path: Dict[str, int] = defaultdict(int)
    for operation in operations:
        path_in_repo = operation.path_in_repo
        if isinstance(operation, CommitOperationAdd):
            if nb_additions_per_path[path_in_repo] > 0:
                warnings.warn(
                    "About to update multiple times the same file in the same commit:"
                    f" '{path_in_repo}'. This can cause undesired inconsistencies in"
                    " your repo."
                )
            nb_additions_per_path[path_in_repo] += 1
            for parent in PurePosixPath(path_in_repo).parents:
                # Also keep track of number of updated files per folder
                # => warns if deleting a folder overwrite some contained files
                nb_additions_per_path[str(parent)] += 1
        if isinstance(operation, CommitOperationDelete):
            if nb_additions_per_path[str(PurePosixPath(path_in_repo))] > 0:
                if operation.is_folder:
                    warnings.warn(
                        "About to delete a folder containing files that have just been"
                        f" updated within the same commit: '{path_in_repo}'. This can"
                        " cause undesired inconsistencies in your repo."
                    )
                else:
                    warnings.warn(
                        "About to delete a file that have just been updated within the"
                        f" same commit: '{path_in_repo}'. This can cause undesired"
                        " inconsistencies in your repo."
                    )


@validate_hf_hub_args
def _upload_lfs_files(
    *,
    additions: List[CommitOperationAdd],
    repo_type: str,
    repo_id: str,
    headers: Dict[str, str],
    endpoint: Optional[str] = None,
    num_threads: int = 5,
    revision: Optional[str] = None,
):
    """
    Uploads the content of `additions` to the Hub using the large file storage protocol.

    Relevant external documentation:
        - LFS Batch API: https://github.com/git-lfs/git-lfs/blob/main/docs/api/batch.md

    Args:
        additions (`List` of `CommitOperationAdd`):
            The files to be uploaded
        repo_type (`str`):
            Type of the repo to upload to: `"model"`, `"dataset"` or `"space"`.
        repo_id (`str`):
            A namespace (user or an organization) and a repo name separated
            by a `/`.
        headers (`Dict[str, str]`):
            Headers to use for the request, including authorization headers and user agent.
        num_threads (`int`, *optional*):
            The number of concurrent threads to use when uploading. Defaults to 5.
        revision (`str`, *optional*):
            The git revision to upload to.

    Raises:
        [`EnvironmentError`](https://docs.python.org/3/library/exceptions.html#EnvironmentError)
            If an upload failed for any reason
        [`ValueError`](https://docs.python.org/3/library/exceptions.html#ValueError)
            If the server returns malformed responses
        [`HTTPError`](https://requests.readthedocs.io/en/latest/api/#requests.HTTPError)
            If the LFS batch endpoint returned an HTTP error.
    """
    # Step 1: retrieve upload instructions from the LFS batch endpoint.
    #         Upload instructions are retrieved by chunk of 256 files to avoid reaching
    #         the payload limit.
    batch_actions: List[Dict] = []
    for chunk in chunk_iterable(additions, chunk_size=256):
        batch_actions_chunk, batch_errors_chunk = post_lfs_batch_info(
            upload_infos=[op.upload_info for op in chunk],
            repo_id=repo_id,
            repo_type=repo_type,
            revision=revision,
            endpoint=endpoint,
            headers=headers,
            token=None,  # already passed in 'headers'
        )

        # If at least 1 error, we do not retrieve information for other chunks
        if batch_errors_chunk:
            message = "\n".join(
                [
                    f"Encountered error for file with OID {err.get('oid')}: `{err.get('error', {}).get('message')}"
                    for err in batch_errors_chunk
                ]
            )
            raise ValueError(f"LFS batch endpoint returned errors:\n{message}")

        batch_actions += batch_actions_chunk
    oid2addop = {add_op.upload_info.sha256.hex(): add_op for add_op in additions}

    # Step 2: ignore files that have already been uploaded
    filtered_actions = []
    for action in batch_actions:
        if action.get("actions") is None:
            logger.debug(
                f"Content of file {oid2addop[action['oid']].path_in_repo} is already"
                " present upstream - skipping upload."
            )
        else:
            filtered_actions.append(action)

    if len(filtered_actions) == 0:
        logger.debug("No LFS files to upload.")
        return

    # Step 3: upload files concurrently according to these instructions
    def _wrapped_lfs_upload(batch_action) -> None:
        try:
            operation = oid2addop[batch_action["oid"]]
            lfs_upload(operation=operation, lfs_batch_action=batch_action, headers=headers, endpoint=endpoint)
        except Exception as exc:
            raise RuntimeError(f"Error while uploading '{operation.path_in_repo}' to the Hub.") from exc

    if constants.HF_HUB_ENABLE_HF_TRANSFER:
        logger.debug(f"Uploading {len(filtered_actions)} LFS files to the Hub using `hf_transfer`.")
        for action in hf_tqdm(filtered_actions, name="huggingface_hub.lfs_upload"):
            _wrapped_lfs_upload(action)
    elif len(filtered_actions) == 1:
        logger.debug("Uploading 1 LFS file to the Hub")
        _wrapped_lfs_upload(filtered_actions[0])
    else:
        logger.debug(
            f"Uploading {len(filtered_actions)} LFS files to the Hub using up to {num_threads} threads concurrently"
        )
        thread_map(
            _wrapped_lfs_upload,
            filtered_actions,
            desc=f"Upload {len(filtered_actions)} LFS files",
            max_workers=num_threads,
            tqdm_class=hf_tqdm,
        )


def _validate_preupload_info(preupload_info: dict):
    files = preupload_info.get("files")
    if not isinstance(files, list):
        raise ValueError("preupload_info is improperly formatted")
    for file_info in files:
        if not (
            isinstance(file_info, dict)
            and isinstance(file_info.get("path"), str)
            and isinstance(file_info.get("uploadMode"), str)
            and (file_info["uploadMode"] in ("lfs", "regular"))
        ):
            raise ValueError("preupload_info is improperly formatted:")
    return preupload_info


@validate_hf_hub_args
def _fetch_upload_modes(
    additions: Iterable[CommitOperationAdd],
    repo_type: str,
    repo_id: str,
    headers: Dict[str, str],
    revision: str,
    endpoint: Optional[str] = None,
    create_pr: bool = False,
    gitignore_content: Optional[str] = None,
) -> None:
    """
    Requests the Hub "preupload" endpoint to determine whether each input file should be uploaded as a regular git blob
    or as git LFS blob. Input `additions` are mutated in-place with the upload mode.

    Args:
        additions (`Iterable` of :class:`CommitOperationAdd`):
            Iterable of :class:`CommitOperationAdd` describing the files to
            upload to the Hub.
        repo_type (`str`):
            Type of the repo to upload to: `"model"`, `"dataset"` or `"space"`.
        repo_id (`str`):
            A namespace (user or an organization) and a repo name separated
            by a `/`.
        headers (`Dict[str, str]`):
            Headers to use for the request, including authorization headers and user agent.
        revision (`str`):
            The git revision to upload the files to. Can be any valid git revision.
        gitignore_content (`str`, *optional*):
            The content of the `.gitignore` file to know which files should be ignored. The order of priority
            is to first check if `gitignore_content` is passed, then check if the `.gitignore` file is present
            in the list of files to commit and finally default to the `.gitignore` file already hosted on the Hub
            (if any).
    Raises:
        [`~utils.HfHubHTTPError`]
            If the Hub API returned an error.
        [`ValueError`](https://docs.python.org/3/library/exceptions.html#ValueError)
            If the Hub API response is improperly formatted.
    """
    endpoint = endpoint if endpoint is not None else constants.ENDPOINT

    # Fetch upload mode (LFS or regular) chunk by chunk.
    upload_modes: Dict[str, UploadMode] = {}
    should_ignore_info: Dict[str, bool] = {}
    oid_info: Dict[str, Optional[str]] = {}

    for chunk in chunk_iterable(additions, 256):
        payload: Dict = {
            "files": [
                {
                    "path": op.path_in_repo,
                    "sample": base64.b64encode(op.upload_info.sample).decode("ascii"),
                    "size": op.upload_info.size,
                }
                for op in chunk
            ]
        }
        if gitignore_content is not None:
            payload["gitIgnore"] = gitignore_content

        resp = get_session().post(
            f"{endpoint}/api/{repo_type}s/{repo_id}/preupload/{revision}",
            json=payload,
            headers=headers,
            params={"create_pr": "1"} if create_pr else None,
        )
        hf_raise_for_status(resp)
        preupload_info = _validate_preupload_info(resp.json())
        upload_modes.update(**{file["path"]: file["uploadMode"] for file in preupload_info["files"]})
        should_ignore_info.update(**{file["path"]: file["shouldIgnore"] for file in preupload_info["files"]})
        oid_info.update(**{file["path"]: file.get("oid") for file in preupload_info["files"]})

    # Set upload mode for each addition operation
    for addition in additions:
        addition._upload_mode = upload_modes[addition.path_in_repo]
        addition._should_ignore = should_ignore_info[addition.path_in_repo]
        addition._remote_oid = oid_info[addition.path_in_repo]

    # Empty files cannot be uploaded as LFS (S3 would fail with a 501 Not Implemented)
    # => empty files are uploaded as "regular" to still allow users to commit them.
    for addition in additions:
        if addition.upload_info.size == 0:
            addition._upload_mode = "regular"


@validate_hf_hub_args
def _fetch_files_to_copy(
    copies: Iterable[CommitOperationCopy],
    repo_type: str,
    repo_id: str,
    headers: Dict[str, str],
    revision: str,
    endpoint: Optional[str] = None,
) -> Dict[Tuple[str, Optional[str]], Union["RepoFile", bytes]]:
    """
    Fetch information about the files to copy.

    For LFS files, we only need their metadata (file size and sha256) while for regular files
    we need to download the raw content from the Hub.

    Args:
        copies (`Iterable` of :class:`CommitOperationCopy`):
            Iterable of :class:`CommitOperationCopy` describing the files to
            copy on the Hub.
        repo_type (`str`):
            Type of the repo to upload to: `"model"`, `"dataset"` or `"space"`.
        repo_id (`str`):
            A namespace (user or an organization) and a repo name separated
            by a `/`.
        headers (`Dict[str, str]`):
            Headers to use for the request, including authorization headers and user agent.
        revision (`str`):
            The git revision to upload the files to. Can be any valid git revision.

    Returns: `Dict[Tuple[str, Optional[str]], Union[RepoFile, bytes]]]`
        Key is the file path and revision of the file to copy.
        Value is the raw content as bytes (for regular files) or the file information as a RepoFile (for LFS files).

    Raises:
        [`~utils.HfHubHTTPError`]
            If the Hub API returned an error.
        [`ValueError`](https://docs.python.org/3/library/exceptions.html#ValueError)
            If the Hub API response is improperly formatted.
    """
    from .hf_api import HfApi, RepoFolder

    hf_api = HfApi(endpoint=endpoint, headers=headers)
    files_to_copy: Dict[Tuple[str, Optional[str]], Union["RepoFile", bytes]] = {}
    # Store (path, revision) -> oid mapping
    oid_info: Dict[Tuple[str, Optional[str]], Optional[str]] = {}
    # 1. Fetch OIDs for destination paths in batches.
    dest_paths = [op.path_in_repo for op in copies]
    for offset in range(0, len(dest_paths), FETCH_LFS_BATCH_SIZE):
        dest_repo_files = hf_api.get_paths_info(
            repo_id=repo_id,
            paths=dest_paths[offset : offset + FETCH_LFS_BATCH_SIZE],
            revision=revision,
            repo_type=repo_type,
        )
        for file in dest_repo_files:
            if not isinstance(file, RepoFolder):
                oid_info[(file.path, revision)] = file.blob_id

    # 2. Group by source revision and fetch source file info in batches.
    for src_revision, operations in groupby(copies, key=lambda op: op.src_revision):
        operations = list(operations)  # type: ignore
        src_paths = [op.src_path_in_repo for op in operations]
        for offset in range(0, len(src_paths), FETCH_LFS_BATCH_SIZE):
            src_repo_files = hf_api.get_paths_info(
                repo_id=repo_id,
                paths=src_paths[offset : offset + FETCH_LFS_BATCH_SIZE],
                revision=src_revision or revision,
                repo_type=repo_type,
            )

            for src_repo_file in src_repo_files:
                if isinstance(src_repo_file, RepoFolder):
                    raise NotImplementedError("Copying a folder is not implemented.")
                oid_info[(src_repo_file.path, src_revision)] = src_repo_file.blob_id
                # If it's an LFS file, store the RepoFile object. Otherwise, download raw bytes.
                if src_repo_file.lfs:
                    files_to_copy[(src_repo_file.path, src_revision)] = src_repo_file
                else:
                    # TODO: (optimization) download regular files to copy concurrently
                    url = hf_hub_url(
                        endpoint=endpoint,
                        repo_type=repo_type,
                        repo_id=repo_id,
                        revision=src_revision or revision,
                        filename=src_repo_file.path,
                    )
                    response = get_session().get(url, headers=headers)
                    hf_raise_for_status(response)
                    files_to_copy[(src_repo_file.path, src_revision)] = response.content
        # 3. Ensure all operations found a corresponding file in the Hub
        #  and track src/dest OIDs for each operation.
        for operation in operations:
            if (operation.src_path_in_repo, src_revision) not in files_to_copy:
                raise EntryNotFoundError(
                    f"Cannot copy {operation.src_path_in_repo} at revision "
                    f"{src_revision or revision}: file is missing on repo."
                )
            operation._src_oid = oid_info.get((operation.src_path_in_repo, operation.src_revision))
            operation._dest_oid = oid_info.get((operation.path_in_repo, revision))
    return files_to_copy


def _prepare_commit_payload(
    operations: Iterable[CommitOperation],
    files_to_copy: Dict[Tuple[str, Optional[str]], Union["RepoFile", bytes]],
    commit_message: str,
    commit_description: Optional[str] = None,
    parent_commit: Optional[str] = None,
) -> Iterable[Dict[str, Any]]:
    """
    Builds the payload to POST to the `/commit` API of the Hub.

    Payload is returned as an iterator so that it can be streamed as a ndjson in the
    POST request.

    For more information, see:
        - https://github.com/huggingface/huggingface_hub/issues/1085#issuecomment-1265208073
        - http://ndjson.org/
    """
    commit_description = commit_description if commit_description is not None else ""

    # 1. Send a header item with the commit metadata
    header_value = {"summary": commit_message, "description": commit_description}
    if parent_commit is not None:
        header_value["parentCommit"] = parent_commit
    yield {"key": "header", "value": header_value}

    nb_ignored_files = 0

    # 2. Send operations, one per line
    for operation in operations:
        # Skip ignored files
        if isinstance(operation, CommitOperationAdd) and operation._should_ignore:
            logger.debug(f"Skipping file '{operation.path_in_repo}' in commit (ignored by gitignore file).")
            nb_ignored_files += 1
            continue

        # 2.a. Case adding a regular file
        if isinstance(operation, CommitOperationAdd) and operation._upload_mode == "regular":
            yield {
                "key": "file",
                "value": {
                    "content": operation.b64content().decode(),
                    "path": operation.path_in_repo,
                    "encoding": "base64",
                },
            }
        # 2.b. Case adding an LFS file
        elif isinstance(operation, CommitOperationAdd) and operation._upload_mode == "lfs":
            yield {
                "key": "lfsFile",
                "value": {
                    "path": operation.path_in_repo,
                    "algo": "sha256",
                    "oid": operation.upload_info.sha256.hex(),
                    "size": operation.upload_info.size,
                },
            }
        # 2.c. Case deleting a file or folder
        elif isinstance(operation, CommitOperationDelete):
            yield {
                "key": "deletedFolder" if operation.is_folder else "deletedFile",
                "value": {"path": operation.path_in_repo},
            }
        # 2.d. Case copying a file or folder
        elif isinstance(operation, CommitOperationCopy):
            file_to_copy = files_to_copy[(operation.src_path_in_repo, operation.src_revision)]
            if isinstance(file_to_copy, bytes):
                yield {
                    "key": "file",
                    "value": {
                        "content": base64.b64encode(file_to_copy).decode(),
                        "path": operation.path_in_repo,
                        "encoding": "base64",
                    },
                }
            elif file_to_copy.lfs:
                yield {
                    "key": "lfsFile",
                    "value": {
                        "path": operation.path_in_repo,
                        "algo": "sha256",
                        "oid": file_to_copy.lfs.sha256,
                    },
                }
            else:
                raise ValueError(
                    "Malformed files_to_copy (should be raw file content as bytes or RepoFile objects with LFS info."
                )
        # 2.e. Never expected to happen
        else:
            raise ValueError(
                f"Unknown operation to commit. Operation: {operation}. Upload mode:"
                f" {getattr(operation, '_upload_mode', None)}"
            )

    if nb_ignored_files > 0:
        logger.info(f"Skipped {nb_ignored_files} file(s) in commit (ignored by gitignore file).")
