# commit.py
# Copyright (C) 2008, 2009 Michael Trier (mtrier@gmail.com) and contributors
#
# This module is part of GitPython and is released under
# the BSD License: http://www.opensource.org/licenses/bsd-license.php

from gitdb import IStream
from git.util import (
    hex_to_bin,
    Actor,
    Iterable,
    Stats,
    finalize_process
)
from git.diff import Diffable

from .tree import Tree
from . import base
from .util import (
    Traversable,
    Serializable,
    parse_date,
    altz_to_utctz_str,
    parse_actor_and_date,
    from_timestamp,
)
from git.compat import text_type

from time import (
    time,
    daylight,
    altzone,
    timezone,
    localtime
)
import os
from io import BytesIO
import logging

log = logging.getLogger('git.objects.commit')
log.addHandler(logging.NullHandler())

__all__ = ('Commit', )


class Commit(base.Object, Iterable, Diffable, Traversable, Serializable):

    """Wraps a git Commit object.

    This class will act lazily on some of its attributes and will query the
    value on demand only if it involves calling the git binary."""

    # ENVIRONMENT VARIABLES
    # read when creating new commits
    env_author_date = "GIT_AUTHOR_DATE"
    env_committer_date = "GIT_COMMITTER_DATE"

    # CONFIGURATION KEYS
    conf_encoding = 'i18n.commitencoding'

    # INVARIANTS
    default_encoding = "UTF-8"

    # object configuration
    type = "commit"
    __slots__ = ("tree",
                 "author", "authored_date", "author_tz_offset",
                 "committer", "committed_date", "committer_tz_offset",
                 "message", "parents", "encoding", "gpgsig")
    _id_attribute_ = "hexsha"

    def __init__(self, repo, binsha, tree=None, author=None, authored_date=None, author_tz_offset=None,
                 committer=None, committed_date=None, committer_tz_offset=None,
                 message=None, parents=None, encoding=None, gpgsig=None):
        """Instantiate a new Commit. All keyword arguments taking None as default will
        be implicitly set on first query.

        :param binsha: 20 byte sha1
        :param parents: tuple( Commit, ... )
            is a tuple of commit ids or actual Commits
        :param tree: Tree
            Tree object
        :param author: Actor
            is the author string ( will be implicitly converted into an Actor object )
        :param authored_date: int_seconds_since_epoch
            is the authored DateTime - use time.gmtime() to convert it into a
            different format
        :param author_tz_offset: int_seconds_west_of_utc
            is the timezone that the authored_date is in
        :param committer: Actor
            is the committer string
        :param committed_date: int_seconds_since_epoch
            is the committed DateTime - use time.gmtime() to convert it into a
            different format
        :param committer_tz_offset: int_seconds_west_of_utc
            is the timezone that the committed_date is in
        :param message: string
            is the commit message
        :param encoding: string
            encoding of the message, defaults to UTF-8
        :param parents:
            List or tuple of Commit objects which are our parent(s) in the commit
            dependency graph
        :return: git.Commit

        :note:
            Timezone information is in the same format and in the same sign
            as what time.altzone returns. The sign is inverted compared to git's
            UTC timezone."""
        super(Commit, self).__init__(repo, binsha)
        if tree is not None:
            assert isinstance(tree, Tree), "Tree needs to be a Tree instance, was %s" % type(tree)
        if tree is not None:
            self.tree = tree
        if author is not None:
            self.author = author
        if authored_date is not None:
            self.authored_date = authored_date
        if author_tz_offset is not None:
            self.author_tz_offset = author_tz_offset
        if committer is not None:
            self.committer = committer
        if committed_date is not None:
            self.committed_date = committed_date
        if committer_tz_offset is not None:
            self.committer_tz_offset = committer_tz_offset
        if message is not None:
            self.message = message
        if parents is not None:
            self.parents = parents
        if encoding is not None:
            self.encoding = encoding
        if gpgsig is not None:
            self.gpgsig = gpgsig

    @classmethod
    def _get_intermediate_items(cls, commit):
        return commit.parents

    def _set_cache_(self, attr):
        if attr in Commit.__slots__:
            # read the data in a chunk, its faster - then provide a file wrapper
            binsha, typename, self.size, stream = self.repo.odb.stream(self.binsha)  # @UnusedVariable
            self._deserialize(BytesIO(stream.read()))
        else:
            super(Commit, self)._set_cache_(attr)
        # END handle attrs

    @property
    def authored_datetime(self):
        return from_timestamp(self.authored_date, self.author_tz_offset)

    @property
    def committed_datetime(self):
        return from_timestamp(self.committed_date, self.committer_tz_offset)

    @property
    def summary(self):
        """:return: First line of the commit message"""
        return self.message.split('\n', 1)[0]

    def count(self, paths='', **kwargs):
        """Count the number of commits reachable from this commit

        :param paths:
            is an optional path or a list of paths restricting the return value
            to commits actually containing the paths

        :param kwargs:
            Additional options to be passed to git-rev-list. They must not alter
            the output style of the command, or parsing will yield incorrect results
        :return: int defining the number of reachable commits"""
        # yes, it makes a difference whether empty paths are given or not in our case
        # as the empty paths version will ignore merge commits for some reason.
        if paths:
            return len(self.repo.git.rev_list(self.hexsha, '--', paths, **kwargs).splitlines())
        else:
            return len(self.repo.git.rev_list(self.hexsha, **kwargs).splitlines())

    @property
    def name_rev(self):
        """
        :return:
            String describing the commits hex sha based on the closest Reference.
            Mostly useful for UI purposes"""
        return self.repo.git.name_rev(self)

    @classmethod
    def iter_items(cls, repo, rev, paths='', **kwargs):
        """Find all commits matching the given criteria.

        :param repo: is the Repo
        :param rev: revision specifier, see git-rev-parse for viable options
        :param paths:
            is an optional path or list of paths, if set only Commits that include the path
            or paths will be considered
        :param kwargs:
            optional keyword arguments to git rev-list where
            ``max_count`` is the maximum number of commits to fetch
            ``skip`` is the number of commits to skip
            ``since`` all commits since i.e. '1970-01-01'
        :return: iterator yielding Commit items"""
        if 'pretty' in kwargs:
            raise ValueError("--pretty cannot be used as parsing expects single sha's only")
        # END handle pretty

        # use -- in any case, to prevent possibility of ambiguous arguments
        # see https://github.com/gitpython-developers/GitPython/issues/264
        args = ['--']
        if paths:
            args.extend((paths, ))
        # END if paths

        proc = repo.git.rev_list(rev, args, as_process=True, **kwargs)
        return cls._iter_from_process_or_stream(repo, proc)

    def iter_parents(self, paths='', **kwargs):
        """Iterate _all_ parents of this commit.

        :param paths:
            Optional path or list of paths limiting the Commits to those that
            contain at least one of the paths
        :param kwargs: All arguments allowed by git-rev-list
        :return: Iterator yielding Commit objects which are parents of self """
        # skip ourselves
        skip = kwargs.get("skip", 1)
        if skip == 0:   # skip ourselves
            skip = 1
        kwargs['skip'] = skip

        return self.iter_items(self.repo, self, paths, **kwargs)

    @property
    def stats(self):
        """Create a git stat from changes between this commit and its first parent
        or from all changes done if this is the very first commit.

        :return: git.Stats"""
        if not self.parents:
            text = self.repo.git.diff_tree(self.hexsha, '--', numstat=True, root=True)
            text2 = ""
            for line in text.splitlines()[1:]:
                (insertions, deletions, filename) = line.split("\t")
                text2 += "%s\t%s\t%s\n" % (insertions, deletions, filename)
            text = text2
        else:
            text = self.repo.git.diff(self.parents[0].hexsha, self.hexsha, '--', numstat=True)
        return Stats._list_from_string(self.repo, text)

    @classmethod
    def _iter_from_process_or_stream(cls, repo, proc_or_stream):
        """Parse out commit information into a list of Commit objects
        We expect one-line per commit, and parse the actual commit information directly
        from our lighting fast object database

        :param proc: git-rev-list process instance - one sha per line
        :return: iterator returning Commit objects"""
        stream = proc_or_stream
        if not hasattr(stream, 'readline'):
            stream = proc_or_stream.stdout

        readline = stream.readline
        while True:
            line = readline()
            if not line:
                break
            hexsha = line.strip()
            if len(hexsha) > 40:
                # split additional information, as returned by bisect for instance
                hexsha, _ = line.split(None, 1)
            # END handle extra info

            assert len(hexsha) == 40, "Invalid line: %s" % hexsha
            yield Commit(repo, hex_to_bin(hexsha))
        # END for each line in stream
        # TODO: Review this - it seems process handling got a bit out of control
        # due to many developers trying to fix the open file handles issue
        if hasattr(proc_or_stream, 'wait'):
            finalize_process(proc_or_stream)

    @classmethod
    def create_from_tree(cls, repo, tree, message, parent_commits=None, head=False, author=None, committer=None,
                         author_date=None, commit_date=None):
        """Commit the given tree, creating a commit object.

        :param repo: Repo object the commit should be part of
        :param tree: Tree object or hex or bin sha
            the tree of the new commit
        :param message: Commit message. It may be an empty string if no message is provided.
            It will be converted to a string in any case.
        :param parent_commits:
            Optional Commit objects to use as parents for the new commit.
            If empty list, the commit will have no parents at all and become
            a root commit.
            If None , the current head commit will be the parent of the
            new commit object
        :param head:
            If True, the HEAD will be advanced to the new commit automatically.
            Else the HEAD will remain pointing on the previous commit. This could
            lead to undesired results when diffing files.
        :param author: The name of the author, optional. If unset, the repository
            configuration is used to obtain this value.
        :param committer: The name of the committer, optional. If unset, the
            repository configuration is used to obtain this value.
        :param author_date: The timestamp for the author field
        :param commit_date: The timestamp for the committer field

        :return: Commit object representing the new commit

        :note:
            Additional information about the committer and Author are taken from the
            environment or from the git configuration, see git-commit-tree for
            more information"""
        if parent_commits is None:
            try:
                parent_commits = [repo.head.commit]
            except ValueError:
                # empty repositories have no head commit
                parent_commits = []
            # END handle parent commits
        else:
            for p in parent_commits:
                if not isinstance(p, cls):
                    raise ValueError("Parent commit '%r' must be of type %s" % (p, cls))
            # end check parent commit types
        # END if parent commits are unset

        # retrieve all additional information, create a commit object, and
        # serialize it
        # Generally:
        # * Environment variables override configuration values
        # * Sensible defaults are set according to the git documentation

        # COMMITER AND AUTHOR INFO
        cr = repo.config_reader()
        env = os.environ

        committer = committer or Actor.committer(cr)
        author = author or Actor.author(cr)

        # PARSE THE DATES
        unix_time = int(time())
        is_dst = daylight and localtime().tm_isdst > 0
        offset = altzone if is_dst else timezone

        author_date_str = env.get(cls.env_author_date, '')
        if author_date:
            author_time, author_offset = parse_date(author_date)
        elif author_date_str:
            author_time, author_offset = parse_date(author_date_str)
        else:
            author_time, author_offset = unix_time, offset
        # END set author time

        committer_date_str = env.get(cls.env_committer_date, '')
        if commit_date:
            committer_time, committer_offset = parse_date(commit_date)
        elif committer_date_str:
            committer_time, committer_offset = parse_date(committer_date_str)
        else:
            committer_time, committer_offset = unix_time, offset
        # END set committer time

        # assume utf8 encoding
        enc_section, enc_option = cls.conf_encoding.split('.')
        conf_encoding = cr.get_value(enc_section, enc_option, cls.default_encoding)

        # if the tree is no object, make sure we create one - otherwise
        # the created commit object is invalid
        if isinstance(tree, str):
            tree = repo.tree(tree)
        # END tree conversion

        # CREATE NEW COMMIT
        new_commit = cls(repo, cls.NULL_BIN_SHA, tree,
                         author, author_time, author_offset,
                         committer, committer_time, committer_offset,
                         message, parent_commits, conf_encoding)

        stream = BytesIO()
        new_commit._serialize(stream)
        streamlen = stream.tell()
        stream.seek(0)

        istream = repo.odb.store(IStream(cls.type, streamlen, stream))
        new_commit.binsha = istream.binsha

        if head:
            # need late import here, importing git at the very beginning throws
            # as well ...
            import git.refs
            try:
                repo.head.set_commit(new_commit, logmsg=message)
            except ValueError:
                # head is not yet set to the ref our HEAD points to
                # Happens on first commit
                master = git.refs.Head.create(repo, repo.head.ref, new_commit, logmsg="commit (initial): %s" % message)
                repo.head.set_reference(master, logmsg='commit: Switching to %s' % master)
            # END handle empty repositories
        # END advance head handling

        return new_commit

    #{ Serializable Implementation

    def _serialize(self, stream):
        write = stream.write
        write(("tree %s\n" % self.tree).encode('ascii'))
        for p in self.parents:
            write(("parent %s\n" % p).encode('ascii'))

        a = self.author
        aname = a.name
        c = self.committer
        fmt = "%s %s <%s> %s %s\n"
        write((fmt % ("author", aname, a.email,
                      self.authored_date,
                      altz_to_utctz_str(self.author_tz_offset))).encode(self.encoding))

        # encode committer
        aname = c.name
        write((fmt % ("committer", aname, c.email,
                      self.committed_date,
                      altz_to_utctz_str(self.committer_tz_offset))).encode(self.encoding))

        if self.encoding != self.default_encoding:
            write(("encoding %s\n" % self.encoding).encode('ascii'))

        try:
            if self.__getattribute__('gpgsig') is not None:
                write(b"gpgsig")
                for sigline in self.gpgsig.rstrip("\n").split("\n"):
                    write((" " + sigline + "\n").encode('ascii'))
        except AttributeError:
            pass

        write(b"\n")

        # write plain bytes, be sure its encoded according to our encoding
        if isinstance(self.message, text_type):
            write(self.message.encode(self.encoding))
        else:
            write(self.message)
        # END handle encoding
        return self

    def _deserialize(self, stream):
        """:param from_rev_list: if true, the stream format is coming from the rev-list command
        Otherwise it is assumed to be a plain data stream from our object"""
        readline = stream.readline
        self.tree = Tree(self.repo, hex_to_bin(readline().split()[1]), Tree.tree_id << 12, '')

        self.parents = []
        next_line = None
        while True:
            parent_line = readline()
            if not parent_line.startswith(b'parent'):
                next_line = parent_line
                break
            # END abort reading parents
            self.parents.append(type(self)(self.repo, hex_to_bin(parent_line.split()[-1].decode('ascii'))))
        # END for each parent line
        self.parents = tuple(self.parents)

        # we don't know actual author encoding before we have parsed it, so keep the lines around
        author_line = next_line
        committer_line = readline()

        # we might run into one or more mergetag blocks, skip those for now
        next_line = readline()
        while next_line.startswith(b'mergetag '):
            next_line = readline()
            while next_line.startswith(b' '):
                next_line = readline()
        # end skip mergetags

        # now we can have the encoding line, or an empty line followed by the optional
        # message.
        self.encoding = self.default_encoding
        self.gpgsig = None

        # read headers
        enc = next_line
        buf = enc.strip()
        while buf:
            if buf[0:10] == b"encoding ":
                self.encoding = buf[buf.find(' ') + 1:].decode('ascii')
            elif buf[0:7] == b"gpgsig ":
                sig = buf[buf.find(b' ') + 1:] + b"\n"
                is_next_header = False
                while True:
                    sigbuf = readline()
                    if not sigbuf:
                        break
                    if sigbuf[0:1] != b" ":
                        buf = sigbuf.strip()
                        is_next_header = True
                        break
                    sig += sigbuf[1:]
                # end read all signature
                self.gpgsig = sig.rstrip(b"\n").decode('ascii')
                if is_next_header:
                    continue
            buf = readline().strip()
        # decode the authors name

        try:
            self.author, self.authored_date, self.author_tz_offset = \
                parse_actor_and_date(author_line.decode(self.encoding, 'replace'))
        except UnicodeDecodeError:
            log.error("Failed to decode author line '%s' using encoding %s", author_line, self.encoding,
                      exc_info=True)

        try:
            self.committer, self.committed_date, self.committer_tz_offset = \
                parse_actor_and_date(committer_line.decode(self.encoding, 'replace'))
        except UnicodeDecodeError:
            log.error("Failed to decode committer line '%s' using encoding %s", committer_line, self.encoding,
                      exc_info=True)
        # END handle author's encoding

        # a stream from our data simply gives us the plain message
        # The end of our message stream is marked with a newline that we strip
        self.message = stream.read()
        try:
            self.message = self.message.decode(self.encoding, 'replace')
        except UnicodeDecodeError:
            log.error("Failed to decode message '%s' using encoding %s", self.message, self.encoding, exc_info=True)
        # END exception handling

        return self

    #} END serializable implementation
