# Copyright (C) 2006-2012 Canonical Ltd
#
# 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

"""Full history branch formats."""

from __future__ import absolute_import

from .. import (
    debug,
    errors,
    revision as _mod_revision,
    )

from ..branch import (
    Branch,
    )
from .branch import (
    BzrBranch,
    BranchFormatMetadir,
    )

from ..trace import mutter_callsite


class FullHistoryBzrBranch(BzrBranch):
    """Bzr branch which contains the full revision history."""

    def set_last_revision_info(self, revno, revision_id):
        if not revision_id or not isinstance(revision_id, bytes):
            raise errors.InvalidRevisionId(
                revision_id=revision_id, branch=self)
        revision_id = _mod_revision.ensure_null(revision_id)
        with self.lock_write():
            # this old format stores the full history, but this api doesn't
            # provide it, so we must generate, and might as well check it's
            # correct
            history = self._lefthand_history(revision_id)
            if len(history) != revno:
                raise AssertionError('%d != %d' % (len(history), revno))
            self._set_revision_history(history)

    def _read_last_revision_info(self):
        rh = self._revision_history()
        revno = len(rh)
        if revno:
            return (revno, rh[-1])
        else:
            return (0, _mod_revision.NULL_REVISION)

    def _set_revision_history(self, rev_history):
        if 'evil' in debug.debug_flags:
            mutter_callsite(3, "set_revision_history scales with history.")
        check_not_reserved_id = _mod_revision.check_not_reserved_id
        for rev_id in rev_history:
            check_not_reserved_id(rev_id)
        if Branch.hooks['post_change_branch_tip']:
            # Don't calculate the last_revision_info() if there are no hooks
            # that will use it.
            old_revno, old_revid = self.last_revision_info()
        if len(rev_history) == 0:
            revid = _mod_revision.NULL_REVISION
        else:
            revid = rev_history[-1]
        self._run_pre_change_branch_tip_hooks(len(rev_history), revid)
        self._write_revision_history(rev_history)
        self._clear_cached_state()
        self._cache_revision_history(rev_history)
        if Branch.hooks['post_change_branch_tip']:
            self._run_post_change_branch_tip_hooks(old_revno, old_revid)

    def _write_revision_history(self, history):
        """Factored out of set_revision_history.

        This performs the actual writing to disk.
        It is intended to be called by set_revision_history."""
        self._transport.put_bytes(
            'revision-history', b'\n'.join(history),
            mode=self.controldir._get_file_mode())

    def _gen_revision_history(self):
        history = self._transport.get_bytes('revision-history').split(b'\n')
        if history[-1:] == [b'']:
            # There shouldn't be a trailing newline, but just in case.
            history.pop()
        return history

    def _synchronize_history(self, destination, revision_id):
        if not isinstance(destination, FullHistoryBzrBranch):
            super(BzrBranch, self)._synchronize_history(
                destination, revision_id)
            return
        if revision_id == _mod_revision.NULL_REVISION:
            new_history = []
        else:
            new_history = self._revision_history()
        if revision_id is not None and new_history != []:
            try:
                new_history = new_history[:new_history.index(revision_id) + 1]
            except ValueError:
                rev = self.repository.get_revision(revision_id)
                new_history = rev.get_history(self.repository)[1:]
        destination._set_revision_history(new_history)

    def generate_revision_history(self, revision_id, last_rev=None,
                                  other_branch=None):
        """Create a new revision history that will finish with revision_id.

        :param revision_id: the new tip to use.
        :param last_rev: The previous last_revision. If not None, then this
            must be a ancestory of revision_id, or DivergedBranches is raised.
        :param other_branch: The other branch that DivergedBranches should
            raise with respect to.
        """
        with self.lock_write():
            self._set_revision_history(self._lefthand_history(revision_id,
                                                              last_rev, other_branch))


class BzrBranch5(FullHistoryBzrBranch):
    """A format 5 branch. This supports new features over plain branches.

    It has support for a master_branch which is the data for bound branches.
    """


class BzrBranchFormat5(BranchFormatMetadir):
    """Bzr branch format 5.

    This format has:
     - a revision-history file.
     - a format string
     - a lock dir guarding the branch itself
     - all of this stored in a branch/ subdirectory
     - works with shared repositories.

    This format is new in bzr 0.8.
    """

    def _branch_class(self):
        return BzrBranch5

    @classmethod
    def get_format_string(cls):
        """See BranchFormat.get_format_string()."""
        return b"Bazaar-NG branch format 5\n"

    def get_format_description(self):
        """See BranchFormat.get_format_description()."""
        return "Branch format 5"

    def initialize(self, a_controldir, name=None, repository=None,
                   append_revisions_only=None):
        """Create a branch of this format in a_controldir."""
        if append_revisions_only:
            raise errors.UpgradeRequired(a_controldir.user_url)
        utf8_files = [('revision-history', b''),
                      ('branch-name', b''),
                      ]
        return self._initialize_helper(a_controldir, utf8_files, name, repository)

    def supports_tags(self):
        return False
