"""
Data structures to interact with Discussions and Pull Requests on the Hub.

See [the Discussions and Pull Requests guide](https://huggingface.co/docs/hub/repositories-pull-requests-discussions)
for more information on Pull Requests, Discussions, and the community tab.
"""
from dataclasses import dataclass
from datetime import datetime
from typing import List, Literal, Optional, Union

from .constants import REPO_TYPE_MODEL
from .utils import parse_datetime


DiscussionStatus = Literal["open", "closed", "merged", "draft"]


@dataclass
class Discussion:
    """
    A Discussion or Pull Request on the Hub.

    This dataclass is not intended to be instantiated directly.

    Attributes:
        title (`str`):
            The title of the Discussion / Pull Request
        status (`str`):
            The status of the Discussion / Pull Request.
            It must be one of:
                * `"open"`
                * `"closed"`
                * `"merged"` (only for Pull Requests )
                * `"draft"` (only for Pull Requests )
        num (`int`):
            The number of the Discussion / Pull Request.
        repo_id (`str`):
            The id (`"{namespace}/{repo_name}"`) of the repo on which
            the Discussion / Pull Request was open.
        repo_type (`str`):
            The type of the repo on which the Discussion / Pull Request was open.
            Possible values are: `"model"`, `"dataset"`, `"space"`.
        author (`str`):
            The username of the Discussion / Pull Request author.
            Can be `"deleted"` if the user has been deleted since.
        is_pull_request (`bool`):
            Whether or not this is a Pull Request.
        created_at (`datetime`):
            The `datetime` of creation of the Discussion / Pull Request.
        endpoint (`str`):
            Endpoint of the Hub. Default is https://huggingface.co.
        git_reference (`str`, *optional*):
            (property) Git reference to which changes can be pushed if this is a Pull Request, `None` otherwise.
        url (`str`):
            (property) URL of the discussion on the Hub.
    """

    title: str
    status: DiscussionStatus
    num: int
    repo_id: str
    repo_type: str
    author: str
    is_pull_request: bool
    created_at: datetime
    endpoint: str

    @property
    def git_reference(self) -> Optional[str]:
        """
        If this is a Pull Request , returns the git reference to which changes can be pushed.
        Returns `None` otherwise.
        """
        if self.is_pull_request:
            return f"refs/pr/{self.num}"
        return None

    @property
    def url(self) -> str:
        """Returns the URL of the discussion on the Hub."""
        if self.repo_type is None or self.repo_type == REPO_TYPE_MODEL:
            return f"{self.endpoint}/{self.repo_id}/discussions/{self.num}"
        return f"{self.endpoint}/{self.repo_type}s/{self.repo_id}/discussions/{self.num}"


@dataclass
class DiscussionWithDetails(Discussion):
    """
    Subclass of [`Discussion`].

    Attributes:
        title (`str`):
            The title of the Discussion / Pull Request
        status (`str`):
            The status of the Discussion / Pull Request.
            It can be one of:
                * `"open"`
                * `"closed"`
                * `"merged"` (only for Pull Requests )
                * `"draft"` (only for Pull Requests )
        num (`int`):
            The number of the Discussion / Pull Request.
        repo_id (`str`):
            The id (`"{namespace}/{repo_name}"`) of the repo on which
            the Discussion / Pull Request was open.
        repo_type (`str`):
            The type of the repo on which the Discussion / Pull Request was open.
            Possible values are: `"model"`, `"dataset"`, `"space"`.
        author (`str`):
            The username of the Discussion / Pull Request author.
            Can be `"deleted"` if the user has been deleted since.
        is_pull_request (`bool`):
            Whether or not this is a Pull Request.
        created_at (`datetime`):
            The `datetime` of creation of the Discussion / Pull Request.
        events (`list` of [`DiscussionEvent`])
            The list of [`DiscussionEvents`] in this Discussion or Pull Request.
        conflicting_files (`Union[List[str], bool, None]`, *optional*):
            A list of conflicting files if this is a Pull Request.
            `None` if `self.is_pull_request` is `False`.
            `True` if there are conflicting files but the list can't be retrieved.
        target_branch (`str`, *optional*):
            The branch into which changes are to be merged if this is a
            Pull Request . `None`  if `self.is_pull_request` is `False`.
        merge_commit_oid (`str`, *optional*):
            If this is a merged Pull Request , this is set to the OID / SHA of
            the merge commit, `None` otherwise.
        diff (`str`, *optional*):
            The git diff if this is a Pull Request , `None` otherwise.
        endpoint (`str`):
            Endpoint of the Hub. Default is https://huggingface.co.
        git_reference (`str`, *optional*):
            (property) Git reference to which changes can be pushed if this is a Pull Request, `None` otherwise.
        url (`str`):
            (property) URL of the discussion on the Hub.
    """

    events: List["DiscussionEvent"]
    conflicting_files: Union[List[str], bool, None]
    target_branch: Optional[str]
    merge_commit_oid: Optional[str]
    diff: Optional[str]


@dataclass
class DiscussionEvent:
    """
    An event in a Discussion or Pull Request.

    Use concrete classes:
        * [`DiscussionComment`]
        * [`DiscussionStatusChange`]
        * [`DiscussionCommit`]
        * [`DiscussionTitleChange`]

    Attributes:
        id (`str`):
            The ID of the event. An hexadecimal string.
        type (`str`):
            The type of the event.
        created_at (`datetime`):
            A [`datetime`](https://docs.python.org/3/library/datetime.html?highlight=datetime#datetime.datetime)
            object holding the creation timestamp for the event.
        author (`str`):
            The username of the Discussion / Pull Request author.
            Can be `"deleted"` if the user has been deleted since.
    """

    id: str
    type: str
    created_at: datetime
    author: str

    _event: dict
    """Stores the original event data, in case we need to access it later."""


@dataclass
class DiscussionComment(DiscussionEvent):
    """A comment in a Discussion / Pull Request.

    Subclass of [`DiscussionEvent`].


    Attributes:
        id (`str`):
            The ID of the event. An hexadecimal string.
        type (`str`):
            The type of the event.
        created_at (`datetime`):
            A [`datetime`](https://docs.python.org/3/library/datetime.html?highlight=datetime#datetime.datetime)
            object holding the creation timestamp for the event.
        author (`str`):
            The username of the Discussion / Pull Request author.
            Can be `"deleted"` if the user has been deleted since.
        content (`str`):
            The raw markdown content of the comment. Mentions, links and images are not rendered.
        edited (`bool`):
            Whether or not this comment has been edited.
        hidden (`bool`):
            Whether or not this comment has been hidden.
    """

    content: str
    edited: bool
    hidden: bool

    @property
    def rendered(self) -> str:
        """The rendered comment, as a HTML string"""
        return self._event["data"]["latest"]["html"]

    @property
    def last_edited_at(self) -> datetime:
        """The last edit time, as a `datetime` object."""
        return parse_datetime(self._event["data"]["latest"]["updatedAt"])

    @property
    def last_edited_by(self) -> str:
        """The last edit time, as a `datetime` object."""
        return self._event["data"]["latest"].get("author", {}).get("name", "deleted")

    @property
    def edit_history(self) -> List[dict]:
        """The edit history of the comment"""
        return self._event["data"]["history"]

    @property
    def number_of_edits(self) -> int:
        return len(self.edit_history)


@dataclass
class DiscussionStatusChange(DiscussionEvent):
    """A change of status in a Discussion / Pull Request.

    Subclass of [`DiscussionEvent`].

    Attributes:
        id (`str`):
            The ID of the event. An hexadecimal string.
        type (`str`):
            The type of the event.
        created_at (`datetime`):
            A [`datetime`](https://docs.python.org/3/library/datetime.html?highlight=datetime#datetime.datetime)
            object holding the creation timestamp for the event.
        author (`str`):
            The username of the Discussion / Pull Request author.
            Can be `"deleted"` if the user has been deleted since.
        new_status (`str`):
            The status of the Discussion / Pull Request after the change.
            It can be one of:
                * `"open"`
                * `"closed"`
                * `"merged"` (only for Pull Requests )
    """

    new_status: str


@dataclass
class DiscussionCommit(DiscussionEvent):
    """A commit in a Pull Request.

    Subclass of [`DiscussionEvent`].

    Attributes:
        id (`str`):
            The ID of the event. An hexadecimal string.
        type (`str`):
            The type of the event.
        created_at (`datetime`):
            A [`datetime`](https://docs.python.org/3/library/datetime.html?highlight=datetime#datetime.datetime)
            object holding the creation timestamp for the event.
        author (`str`):
            The username of the Discussion / Pull Request author.
            Can be `"deleted"` if the user has been deleted since.
        summary (`str`):
            The summary of the commit.
        oid (`str`):
            The OID / SHA of the commit, as a hexadecimal string.
    """

    summary: str
    oid: str


@dataclass
class DiscussionTitleChange(DiscussionEvent):
    """A rename event in a Discussion / Pull Request.

    Subclass of [`DiscussionEvent`].

    Attributes:
        id (`str`):
            The ID of the event. An hexadecimal string.
        type (`str`):
            The type of the event.
        created_at (`datetime`):
            A [`datetime`](https://docs.python.org/3/library/datetime.html?highlight=datetime#datetime.datetime)
            object holding the creation timestamp for the event.
        author (`str`):
            The username of the Discussion / Pull Request author.
            Can be `"deleted"` if the user has been deleted since.
        old_title (`str`):
            The previous title for the Discussion / Pull Request.
        new_title (`str`):
            The new title.
    """

    old_title: str
    new_title: str


def deserialize_event(event: dict) -> DiscussionEvent:
    """Instantiates a [`DiscussionEvent`] from a dict"""
    event_id: str = event["id"]
    event_type: str = event["type"]
    created_at = parse_datetime(event["createdAt"])

    common_args = dict(
        id=event_id,
        type=event_type,
        created_at=created_at,
        author=event.get("author", {}).get("name", "deleted"),
        _event=event,
    )

    if event_type == "comment":
        return DiscussionComment(
            **common_args,
            edited=event["data"]["edited"],
            hidden=event["data"]["hidden"],
            content=event["data"]["latest"]["raw"],
        )
    if event_type == "status-change":
        return DiscussionStatusChange(
            **common_args,
            new_status=event["data"]["status"],
        )
    if event_type == "commit":
        return DiscussionCommit(
            **common_args,
            summary=event["data"]["subject"],
            oid=event["data"]["oid"],
        )
    if event_type == "title-change":
        return DiscussionTitleChange(
            **common_args,
            old_title=event["data"]["from"],
            new_title=event["data"]["to"],
        )

    return DiscussionEvent(**common_args)