# This module is part of GitPython and is released under the
# 3-Clause BSD License: https://opensource.org/license/bsd-3-clause/

__all__ = ["RefLog", "RefLogEntry"]

from mmap import mmap
import os.path as osp
import re
import time as _time

from git.compat import defenc
from git.objects.util import (
    Serializable,
    altz_to_utctz_str,
    parse_date,
)
from git.util import (
    Actor,
    LockedFD,
    LockFile,
    assure_directory_exists,
    bin_to_hex,
    file_contents_ro_filepath,
    to_native_path,
)

# typing ------------------------------------------------------------------

from typing import Iterator, List, Tuple, TYPE_CHECKING, Union

from git.types import PathLike

if TYPE_CHECKING:
    from io import BytesIO

    from git.config import GitConfigParser, SectionConstraint
    from git.refs import SymbolicReference

# ------------------------------------------------------------------------------


class RefLogEntry(Tuple[str, str, Actor, Tuple[int, int], str]):
    """Named tuple allowing easy access to the revlog data fields."""

    _re_hexsha_only = re.compile(r"^[0-9A-Fa-f]{40}$")

    __slots__ = ()

    def __repr__(self) -> str:
        """Representation of ourselves in git reflog format."""
        return self.format()

    def format(self) -> str:
        """:return: A string suitable to be placed in a reflog file."""
        act = self.actor
        time = self.time
        return "{} {} {} <{}> {!s} {}\t{}\n".format(
            self.oldhexsha,
            self.newhexsha,
            act.name,
            act.email,
            time[0],
            altz_to_utctz_str(time[1]),
            self.message,
        )

    @property
    def oldhexsha(self) -> str:
        """The hexsha to the commit the ref pointed to before the change."""
        return self[0]

    @property
    def newhexsha(self) -> str:
        """The hexsha to the commit the ref now points to, after the change."""
        return self[1]

    @property
    def actor(self) -> Actor:
        """Actor instance, providing access."""
        return self[2]

    @property
    def time(self) -> Tuple[int, int]:
        """Time as tuple:

        * [0] = ``int(time)``
        * [1] = ``int(timezone_offset)`` in :attr:`time.altzone` format
        """
        return self[3]

    @property
    def message(self) -> str:
        """Message describing the operation that acted on the reference."""
        return self[4]

    @classmethod
    def new(
        cls,
        oldhexsha: str,
        newhexsha: str,
        actor: Actor,
        time: int,
        tz_offset: int,
        message: str,
    ) -> "RefLogEntry":  # skipcq: PYL-W0621
        """:return: New instance of a :class:`RefLogEntry`"""
        if not isinstance(actor, Actor):
            raise ValueError("Need actor instance, got %s" % actor)
        # END check types
        return RefLogEntry((oldhexsha, newhexsha, actor, (time, tz_offset), message))

    @classmethod
    def from_line(cls, line: bytes) -> "RefLogEntry":
        """:return: New :class:`RefLogEntry` instance from the given revlog line.

        :param line:
            Line bytes without trailing newline

        :raise ValueError:
            If `line` could not be parsed.
        """
        line_str = line.decode(defenc)
        fields = line_str.split("\t", 1)
        if len(fields) == 1:
            info, msg = fields[0], None
        elif len(fields) == 2:
            info, msg = fields
        else:
            raise ValueError("Line must have up to two TAB-separated fields. Got %s" % repr(line_str))
        # END handle first split

        oldhexsha = info[:40]
        newhexsha = info[41:81]
        for hexsha in (oldhexsha, newhexsha):
            if not cls._re_hexsha_only.match(hexsha):
                raise ValueError("Invalid hexsha: %r" % (hexsha,))
            # END if hexsha re doesn't match
        # END for each hexsha

        email_end = info.find(">", 82)
        if email_end == -1:
            raise ValueError("Missing token: >")
        # END handle missing end brace

        actor = Actor._from_string(info[82 : email_end + 1])
        time, tz_offset = parse_date(info[email_end + 2 :])  # skipcq: PYL-W0621

        return RefLogEntry((oldhexsha, newhexsha, actor, (time, tz_offset), msg))


class RefLog(List[RefLogEntry], Serializable):
    R"""A reflog contains :class:`RefLogEntry`\s, each of which defines a certain state
    of the head in question. Custom query methods allow to retrieve log entries by date
    or by other criteria.

    Reflog entries are ordered. The first added entry is first in the list. The last
    entry, i.e. the last change of the head or reference, is last in the list.
    """

    __slots__ = ("_path",)

    def __new__(cls, filepath: Union[PathLike, None] = None) -> "RefLog":
        inst = super().__new__(cls)
        return inst

    def __init__(self, filepath: Union[PathLike, None] = None) -> None:
        """Initialize this instance with an optional filepath, from which we will
        initialize our data. The path is also used to write changes back using the
        :meth:`write` method."""
        self._path = filepath
        if filepath is not None:
            self._read_from_file()
        # END handle filepath

    def _read_from_file(self) -> None:
        try:
            fmap = file_contents_ro_filepath(self._path, stream=True, allow_mmap=True)
        except OSError:
            # It is possible and allowed that the file doesn't exist!
            return
        # END handle invalid log

        try:
            self._deserialize(fmap)
        finally:
            fmap.close()
        # END handle closing of handle

    # { Interface

    @classmethod
    def from_file(cls, filepath: PathLike) -> "RefLog":
        """
        :return:
            A new :class:`RefLog` instance containing all entries from the reflog at the
            given `filepath`.

        :param filepath:
            Path to reflog.

        :raise ValueError:
            If the file could not be read or was corrupted in some way.
        """
        return cls(filepath)

    @classmethod
    def path(cls, ref: "SymbolicReference") -> str:
        """
        :return:
            String to absolute path at which the reflog of the given ref instance would
            be found. The path is not guaranteed to point to a valid file though.

        :param ref:
            :class:`~git.refs.symbolic.SymbolicReference` instance
        """
        return osp.join(ref.repo.git_dir, "logs", to_native_path(ref.path))

    @classmethod
    def iter_entries(cls, stream: Union[str, "BytesIO", mmap]) -> Iterator[RefLogEntry]:
        """
        :return:
            Iterator yielding :class:`RefLogEntry` instances, one for each line read
            from the given stream.

        :param stream:
            File-like object containing the revlog in its native format or string
            instance pointing to a file to read.
        """
        new_entry = RefLogEntry.from_line
        if isinstance(stream, str):
            # Default args return mmap since Python 3.
            _stream = file_contents_ro_filepath(stream)
            assert isinstance(_stream, mmap)
        else:
            _stream = stream
        # END handle stream type
        while True:
            line = _stream.readline()
            if not line:
                return
            yield new_entry(line.strip())
        # END endless loop

    @classmethod
    def entry_at(cls, filepath: PathLike, index: int) -> "RefLogEntry":
        """
        :return:
            :class:`RefLogEntry` at the given index.

        :param filepath:
            Full path to the index file from which to read the entry.

        :param index:
            Python list compatible index, i.e. it may be negative to specify an entry
            counted from the end of the list.

        :raise IndexError:
            If the entry didn't exist.

        :note:
            This method is faster as it only parses the entry at index, skipping all
            other lines. Nonetheless, the whole file has to be read if the index is
            negative.
        """
        with open(filepath, "rb") as fp:
            if index < 0:
                return RefLogEntry.from_line(fp.readlines()[index].strip())
            # Read until index is reached.

            for i in range(index + 1):
                line = fp.readline()
                if not line:
                    raise IndexError(f"Index file ended at line {i + 1}, before given index was reached")
                # END abort on eof
            # END handle runup

            return RefLogEntry.from_line(line.strip())
        # END handle index

    def to_file(self, filepath: PathLike) -> None:
        """Write the contents of the reflog instance to a file at the given filepath.

        :param filepath:
            Path to file. Parent directories are assumed to exist.
        """
        lfd = LockedFD(filepath)
        assure_directory_exists(filepath, is_file=True)

        fp = lfd.open(write=True, stream=True)
        try:
            self._serialize(fp)
            lfd.commit()
        except BaseException:
            lfd.rollback()
            raise
        # END handle change

    @classmethod
    def append_entry(
        cls,
        config_reader: Union[Actor, "GitConfigParser", "SectionConstraint", None],
        filepath: PathLike,
        oldbinsha: bytes,
        newbinsha: bytes,
        message: str,
        write: bool = True,
    ) -> "RefLogEntry":
        """Append a new log entry to the revlog at filepath.

        :param config_reader:
            Configuration reader of the repository - used to obtain user information.
            May also be an :class:`~git.util.Actor` instance identifying the committer
            directly or ``None``.

        :param filepath:
            Full path to the log file.

        :param oldbinsha:
            Binary sha of the previous commit.

        :param newbinsha:
            Binary sha of the current commit.

        :param message:
            Message describing the change to the reference.

        :param write:
            If ``True``, the changes will be written right away.
            Otherwise the change will not be written.

        :return:
            :class:`RefLogEntry` objects which was appended to the log.

        :note:
            As we are append-only, concurrent access is not a problem as we do not
            interfere with readers.
        """

        if len(oldbinsha) != 20 or len(newbinsha) != 20:
            raise ValueError("Shas need to be given in binary format")
        # END handle sha type
        assure_directory_exists(filepath, is_file=True)
        first_line = message.split("\n")[0]
        if isinstance(config_reader, Actor):
            committer = config_reader  # mypy thinks this is Actor | Gitconfigparser, but why?
        else:
            committer = Actor.committer(config_reader)
        entry = RefLogEntry(
            (
                bin_to_hex(oldbinsha).decode("ascii"),
                bin_to_hex(newbinsha).decode("ascii"),
                committer,
                (int(_time.time()), _time.altzone),
                first_line,
            )
        )

        if write:
            lf = LockFile(filepath)
            lf._obtain_lock_or_raise()
            fd = open(filepath, "ab")
            try:
                fd.write(entry.format().encode(defenc))
            finally:
                fd.close()
                lf._release_lock()
            # END handle write operation
        return entry

    def write(self) -> "RefLog":
        """Write this instance's data to the file we are originating from.

        :return:
            self
        """
        if self._path is None:
            raise ValueError("Instance was not initialized with a path, use to_file(...) instead")
        # END assert path
        self.to_file(self._path)
        return self

    # } END interface

    # { Serializable Interface

    def _serialize(self, stream: "BytesIO") -> "RefLog":
        write = stream.write

        # Write all entries.
        for e in self:
            write(e.format().encode(defenc))
        # END for each entry
        return self

    def _deserialize(self, stream: "BytesIO") -> "RefLog":
        self.extend(self.iter_entries(stream))
        return self

    # } END serializable interface
