# Copyright (C) 2009-2018 Jelmer Vernooij <jelmer@jelmer.uk>

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

"""Custom revision specifier for Subversion."""

from __future__ import absolute_import

# Please note that imports are delayed as much as possible here since
# if DWIM revspecs are supported this module is imported by __init__.py.

from ..errors import (
    InvalidRevisionId,
    InvalidRevisionSpec,
    )
from ..revision import (
    NULL_REVISION,
)
from ..revisionspec import (
    RevisionInfo,
    RevisionSpec,
    )


def valid_git_sha1(hex):
    """Check if `hex` is a validly formatted Git SHA1.

    :param hex: Hex string to validate
    :return: Boolean
    """
    try:
        int(hex, 16)
    except ValueError:
        return False
    else:
        return True


class RevisionSpec_git(RevisionSpec):
    """Selects a revision using a Subversion revision number."""

    help_txt = """Selects a revision using a Git revision sha1.
    """

    prefix = 'git:'
    wants_revision_history = False

    def _lookup_git_sha1(self, branch, sha1):
        from .errors import (
            GitSmartRemoteNotSupported,
            )
        from .mapping import (
            default_mapping,
            )

        bzr_revid = getattr(branch.repository, "lookup_foreign_revision_id",
                            default_mapping.revision_id_foreign_to_bzr)(sha1)
        try:
            if branch.repository.has_revision(bzr_revid):
                return RevisionInfo.from_revision_id(branch, bzr_revid)
        except GitSmartRemoteNotSupported:
            return RevisionInfo(branch, None, bzr_revid)
        raise InvalidRevisionSpec(self.user_spec, branch)

    def __nonzero__(self):
        # The default implementation uses branch.repository.has_revision()
        if self.rev_id is None:
            return False
        if self.rev_id == NULL_REVISION:
            return False
        return True

    def _find_short_git_sha1(self, branch, sha1):
        from .mapping import (
            ForeignGit,
            mapping_registry,
            )
        parse_revid = getattr(branch.repository, "lookup_bzr_revision_id",
                              mapping_registry.parse_revision_id)
        with branch.repository.lock_read():
            graph = branch.repository.get_graph()
            for revid, _ in graph.iter_ancestry([branch.last_revision()]):
                if revid == NULL_REVISION:
                    continue
                try:
                    foreign_revid, mapping = parse_revid(revid)
                except InvalidRevisionId:
                    continue
                if not isinstance(mapping.vcs, ForeignGit):
                    continue
                if foreign_revid.startswith(sha1):
                    return RevisionInfo.from_revision_id(branch, revid)
            raise InvalidRevisionSpec(self.user_spec, branch)

    def _match_on(self, branch, revs):
        loc = self.spec.find(':')
        git_sha1 = self.spec[loc + 1:].encode("utf-8")
        if (len(git_sha1) > 40 or len(git_sha1) < 4 or
                not valid_git_sha1(git_sha1)):
            raise InvalidRevisionSpec(self.user_spec, branch)
        from . import (
            lazy_check_versions,
            )
        lazy_check_versions()
        if len(git_sha1) == 40:
            return self._lookup_git_sha1(branch, git_sha1)
        else:
            return self._find_short_git_sha1(branch, git_sha1)

    def needs_branch(self):
        return True

    def get_branch(self):
        return None
