# -*- coding: utf-8 -*-

# Copyright (C) 2008 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, see <http://www.gnu.org/licenses/>.
#
# Based on bzr-fast-export
# Copyright (c) 2008 Adeodato Simó
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#
# vim: fileencoding=utf-8

"""Core engine for the fast-export command."""

# TODO: if a new_git_branch below gets merged repeatedly, the tip of the branch
# is not updated (because the parent of commit is already merged, so we don't
# set new_git_branch to the previously used name)

from email.Utils import parseaddr
import sys, time, re

import bzrlib.branch
import bzrlib.revision
from bzrlib import (
    builtins,
    errors as bazErrors,
    osutils,
    progress,
    trace,
    )

from bzrlib.plugins.fastimport import (
    helpers,
    marks_file,
    )

from fastimport import commands
from bzrlib.plugins.fastimport.helpers import (
    binary_stream,
    single_plural,
    )


def _get_output_stream(destination):
    if destination is None or destination == '-':
        return binary_stream(sys.stdout)
    elif destination.endswith('gz'):
        import gzip
        return gzip.open(destination, 'wb')
    else:
        return open(destination, 'wb')

# from dulwich.repo:
def check_ref_format(refname):
    """Check if a refname is correctly formatted.

    Implements all the same rules as git-check-ref-format[1].

    [1] http://www.kernel.org/pub/software/scm/git/docs/git-check-ref-format.html

    :param refname: The refname to check
    :return: True if refname is valid, False otherwise
    """
    # These could be combined into one big expression, but are listed separately
    # to parallel [1].
    if '/.' in refname or refname.startswith('.'):
        return False
    if '/' not in refname:
        return False
    if '..' in refname:
        return False
    for c in refname:
        if ord(c) < 040 or c in '\177 ~^:?*[':
            return False
    if refname[-1] in '/.':
        return False
    if refname.endswith('.lock'):
        return False
    if '@{' in refname:
        return False
    if '\\' in refname:
        return False
    return True


def sanitize_ref_name_for_git(refname):
    """Rewrite refname so that it will be accepted by git-fast-import.
    For the detailed rules see check_ref_format.

    By rewriting the refname we are breaking uniqueness guarantees provided by bzr
    so we have to manually
    verify that resulting ref names are unique.

    :param refname: refname to rewrite
    :return: new refname
    """
    new_refname = re.sub(
        # '/.' in refname or startswith '.'
        r"/\.|^\."
        # '..' in refname
        r"|\.\."
        # ord(c) < 040
        r"|[" + "".join([chr(x) for x in range(040)]) + r"]"
        # c in '\177 ~^:?*['
        r"|[\177 ~^:?*[]"
        # last char in "/."
        r"|[/.]$"
        # endswith '.lock'
        r"|.lock$"
        # "@{" in refname
        r"|@{"
        # "\\" in refname
        r"|\\",
        "_", refname)
    return new_refname


class BzrFastExporter(object):

    def __init__(self, source, outf, ref=None, checkpoint=-1,
        import_marks_file=None, export_marks_file=None, revision=None,
        verbose=False, plain_format=False, rewrite_tags=False,
        no_tags=False, baseline=False):
        """Export branch data in fast import format.

        :param plain_format: if True, 'classic' fast-import format is
            used without any extended features; if False, the generated
            data is richer and includes information like multiple
            authors, revision properties, etc.
        :param rewrite_tags: if True and if plain_format is set, tag names
            will be rewritten to be git-compatible.
            Otherwise tags which aren't valid for git will be skipped if
            plain_format is set.
        :param no_tags: if True tags won't be exported at all
        """
        self.branch = source
        self.outf = outf
        self.ref = ref
        self.checkpoint = checkpoint
        self.import_marks_file = import_marks_file
        self.export_marks_file = export_marks_file
        self.revision = revision
        self.excluded_revisions = set()
        self.plain_format = plain_format
        self.rewrite_tags = rewrite_tags
        self.no_tags = no_tags
        self.baseline = baseline
        self._multi_author_api_available = hasattr(bzrlib.revision.Revision,
            'get_apparent_authors')
        self.properties_to_exclude = ['authors', 'author']

        # Progress reporting stuff
        self.verbose = verbose
        if verbose:
            self.progress_every = 100
        else:
            self.progress_every = 1000
        self._start_time = time.time()
        self._commit_total = 0

        # Load the marks and initialise things accordingly
        self.revid_to_mark = {}
        self.branch_names = {}
        if self.import_marks_file:
            marks_info = marks_file.import_marks(self.import_marks_file)
            if marks_info is not None:
                self.revid_to_mark = dict((r, m) for m, r in
                    marks_info.items())
                # These are no longer included in the marks file
                #self.branch_names = marks_info[1]

    def interesting_history(self):
        if self.revision:
            rev1, rev2 = builtins._get_revision_range(self.revision,
                self.branch, "fast-export")
            start_rev_id = rev1.rev_id
            end_rev_id = rev2.rev_id
        else:
            start_rev_id = None
            end_rev_id = None
        self.note("Calculating the revisions to include ...")
        view_revisions = [rev_id for rev_id, _, _, _ in
            self.branch.iter_merge_sorted_revisions(end_rev_id, start_rev_id)]
        view_revisions.reverse()
        # If a starting point was given, we need to later check that we don't
        # start emitting revisions from before that point. Collect the
        # revisions to exclude now ...
        if start_rev_id is not None:
            self.note("Calculating the revisions to exclude ...")
            self.excluded_revisions = set([rev_id for rev_id, _, _, _ in
                self.branch.iter_merge_sorted_revisions(start_rev_id)])
            if self.baseline:
                # needed so the first relative commit knows its parent
                self.excluded_revisions.remove(start_rev_id)
                view_revisions.insert(0, start_rev_id)
        return list(view_revisions)

    def run(self):
        # Export the data
        self.branch.repository.lock_read()
        try:
            interesting = self.interesting_history()
            self._commit_total = len(interesting)
            self.note("Starting export of %d revisions ..." %
                self._commit_total)
            if not self.plain_format:
                self.emit_features()
            if self.baseline:
                self.emit_baseline(interesting.pop(0), self.ref)
            for revid in interesting:
                self.emit_commit(revid, self.ref)
            if self.branch.supports_tags() and not self.no_tags:
                self.emit_tags()
        finally:
            self.branch.repository.unlock()

        # Save the marks if requested
        self._save_marks()
        self.dump_stats()

    def note(self, msg, *args):
        """Output a note but timestamp it."""
        msg = "%s %s" % (self._time_of_day(), msg)
        trace.note(msg, *args)

    def warning(self, msg, *args):
        """Output a warning but timestamp it."""
        msg = "%s WARNING: %s" % (self._time_of_day(), msg)
        trace.warning(msg, *args)

    def _time_of_day(self):
        """Time of day as a string."""
        # Note: this is a separate method so tests can patch in a fixed value
        return time.strftime("%H:%M:%S")

    def report_progress(self, commit_count, details=''):
        if commit_count and commit_count % self.progress_every == 0:
            if self._commit_total:
                counts = "%d/%d" % (commit_count, self._commit_total)
            else:
                counts = "%d" % (commit_count,)
            minutes = (time.time() - self._start_time) / 60
            rate = commit_count * 1.0 / minutes
            if rate > 10:
                rate_str = "at %.0f/minute " % rate
            else:
                rate_str = "at %.1f/minute " % rate
            self.note("%s commits exported %s%s" % (counts, rate_str, details))

    def dump_stats(self):
        time_required = progress.str_tdelta(time.time() - self._start_time)
        rc = len(self.revid_to_mark)
        self.note("Exported %d %s in %s",
            rc, single_plural(rc, "revision", "revisions"),
            time_required)

    def print_cmd(self, cmd):
        self.outf.write("%r\n" % cmd)

    def _save_marks(self):
        if self.export_marks_file:
            revision_ids = dict((m, r) for r, m in self.revid_to_mark.items())
            marks_file.export_marks(self.export_marks_file, revision_ids)
 
    def is_empty_dir(self, tree, path):
        path_id = tree.path2id(path)
        if path_id is None:
            self.warning("Skipping empty_dir detection - no file_id for %s" %
                (path,))
            return False

        # Continue if path is not a directory
        if tree.kind(path_id) != 'directory':
            return False

        # Use treewalk to find the contents of our directory
        contents = list(tree.walkdirs(prefix=path))[0]
        if len(contents[1]) == 0:
            return True
        else:
            return False

    def emit_features(self):
        for feature in sorted(commands.FEATURE_NAMES):
            self.print_cmd(commands.FeatureCommand(feature))

    def emit_baseline(self, revid, ref):
        # Emit a full source tree of the first commit's parent
        revobj = self.branch.repository.get_revision(revid)
        mark = 1
        self.revid_to_mark[revid] = mark
        file_cmds = self._get_filecommands(bzrlib.revision.NULL_REVISION, revid)
        self.print_cmd(self._get_commit_command(ref, mark, revobj, file_cmds))

    def emit_commit(self, revid, ref):
        if revid in self.revid_to_mark or revid in self.excluded_revisions:
            return

        # Get the Revision object
        try:
            revobj = self.branch.repository.get_revision(revid)
        except bazErrors.NoSuchRevision:
            # This is a ghost revision. Mark it as not found and next!
            self.revid_to_mark[revid] = -1
            return
 
        # Get the primary parent
        # TODO: Consider the excluded revisions when deciding the parents.
        # Currently, a commit with parents that are excluded ought to be
        # triggering the ref calculation below (and it is not).
        # IGC 20090824
        ncommits = len(self.revid_to_mark)
        nparents = len(revobj.parent_ids)
        if nparents == 0:
            if ncommits:
                # This is a parentless commit but it's not the first one
                # output. We need to create a new temporary branch for it
                # otherwise git-fast-import will assume the previous commit
                # was this one's parent
                ref = self._next_tmp_ref()
            parent = bzrlib.revision.NULL_REVISION
        else:
            parent = revobj.parent_ids[0]

        # Print the commit
        mark = ncommits + 1
        self.revid_to_mark[revid] = mark
        file_cmds = self._get_filecommands(parent, revid)
        self.print_cmd(self._get_commit_command(ref, mark, revobj, file_cmds))

        # Report progress and checkpoint if it's time for that
        self.report_progress(ncommits)
        if (self.checkpoint > 0 and ncommits
            and ncommits % self.checkpoint == 0):
            self.note("Exported %i commits - adding checkpoint to output"
                % ncommits)
            self._save_marks()
            self.print_cmd(commands.CheckpointCommand())

    def _get_name_email(self, user):
        if user.find('<') == -1:
            # If the email isn't inside <>, we need to use it as the name
            # in order for things to round-trip correctly.
            # (note: parseaddr('a@b.com') => name:'', email: 'a@b.com')
            name = user
            email = ''
        else:
            name, email = parseaddr(user)
        return name.encode("utf-8"), email.encode("utf-8")

    def _get_commit_command(self, git_ref, mark, revobj, file_cmds):
        # Get the committer and author info
        committer = revobj.committer
        name, email = self._get_name_email(committer)
        committer_info = (name, email, revobj.timestamp, revobj.timezone)
        if self._multi_author_api_available:
            more_authors = revobj.get_apparent_authors()
            author = more_authors.pop(0)
        else:
            more_authors = []
            author = revobj.get_apparent_author()
        if not self.plain_format and more_authors:
            name, email = self._get_name_email(author)
            author_info = (name, email, revobj.timestamp, revobj.timezone)
            more_author_info = []
            for a in more_authors:
                name, email = self._get_name_email(a)
                more_author_info.append(
                    (name, email, revobj.timestamp, revobj.timezone))
        elif author != committer:
            name, email = self._get_name_email(author)
            author_info = (name, email, revobj.timestamp, revobj.timezone)
            more_author_info = None
        else:
            author_info = None
            more_author_info = None

        # Get the parents in terms of marks
        non_ghost_parents = []
        for p in revobj.parent_ids:
            if p in self.excluded_revisions:
                continue
            try:
                parent_mark = self.revid_to_mark[p]
                non_ghost_parents.append(":%s" % parent_mark)
            except KeyError:
                # ghost - ignore
                continue
        if non_ghost_parents:
            from_ = non_ghost_parents[0]
            merges = non_ghost_parents[1:]
        else:
            from_ = None
            merges = None

        # Filter the revision properties. Some metadata (like the
        # author information) is already exposed in other ways so
        # don't repeat it here.
        if self.plain_format:
            properties = None
        else:
            properties = revobj.properties
            for prop in self.properties_to_exclude:
                try:
                    del properties[prop]
                except KeyError:
                    pass

        # Build and return the result
        return commands.CommitCommand(git_ref, str(mark), author_info,
            committer_info, revobj.message.encode("utf-8"), from_, merges, iter(file_cmds),
            more_authors=more_author_info, properties=properties)

    def _get_revision_trees(self, parent, revision_id):
        try:
            tree_old = self.branch.repository.revision_tree(parent)
        except bazErrors.UnexpectedInventoryFormat:
            self.warning("Parent is malformed - diffing against previous parent")
            # We can't find the old parent. Let's diff against his parent
            pp = self.branch.repository.get_revision(parent)
            tree_old = self.branch.repository.revision_tree(pp.parent_ids[0])
        tree_new = None
        try:
            tree_new = self.branch.repository.revision_tree(revision_id)
        except bazErrors.UnexpectedInventoryFormat:
            # We can't really do anything anymore
            self.warning("Revision %s is malformed - skipping" % revision_id)
        return tree_old, tree_new

    def _get_filecommands(self, parent, revision_id):
        """Get the list of FileCommands for the changes between two revisions."""
        tree_old, tree_new = self._get_revision_trees(parent, revision_id)
        if not(tree_old and tree_new):
            # Something is wrong with this revision - ignore the filecommands
            return []

        changes = tree_new.changes_from(tree_old)

        # Make "modified" have 3-tuples, as added does
        my_modified = [ x[0:3] for x in changes.modified ]

        # The potential interaction between renames and deletes is messy.
        # Handle it here ...
        file_cmds, rd_modifies, renamed = self._process_renames_and_deletes(
            changes.renamed, changes.removed, revision_id, tree_old)

        # Map kind changes to a delete followed by an add
        for path, id_, kind1, kind2 in changes.kind_changed:
            path = self._adjust_path_for_renames(path, renamed, revision_id)
            # IGC: I don't understand why a delete is needed here.
            # In fact, it seems harmful? If you uncomment this line,
            # please file a bug explaining why you needed to.
            #file_cmds.append(commands.FileDeleteCommand(path))
            my_modified.append((path, id_, kind2))

        # Record modifications
        for path, id_, kind in changes.added + my_modified + rd_modifies:
            if kind == 'file':
                text = tree_new.get_file_text(id_)
                file_cmds.append(commands.FileModifyCommand(path.encode("utf-8"),
                    helpers.kind_to_mode('file', tree_new.is_executable(id_)),
                    None, text))
            elif kind == 'symlink':
                file_cmds.append(commands.FileModifyCommand(path.encode("utf-8"),
                    helpers.kind_to_mode('symlink', False),
                    None, tree_new.get_symlink_target(id_)))
            elif kind == 'directory':
                if not self.plain_format:
                    file_cmds.append(commands.FileModifyCommand(path.encode("utf-8"),
                        helpers.kind_to_mode('directory', False),
                        None, None))
            else:
                self.warning("cannot export '%s' of kind %s yet - ignoring" %
                    (path, kind))
        return file_cmds

    def _process_renames_and_deletes(self, renames, deletes,
        revision_id, tree_old):
        file_cmds = []
        modifies = []
        renamed = []

        # See https://bugs.edge.launchpad.net/bzr-fastimport/+bug/268933.
        # In a nutshell, there are several nasty cases:
        #
        # 1) bzr rm a; bzr mv b a; bzr commit
        # 2) bzr mv x/y z; bzr rm x; commmit
        #
        # The first must come out with the delete first like this:
        #
        # D a
        # R b a
        #
        # The second case must come out with the rename first like this:
        #
        # R x/y z
        # D x
        #
        # So outputting all deletes first or all renames first won't work.
        # Instead, we need to make multiple passes over the various lists to
        # get the ordering right.

        must_be_renamed = {}
        old_to_new = {}
        deleted_paths = set([p for p, _, _ in deletes])
        for (oldpath, newpath, id_, kind,
                text_modified, meta_modified) in renames:
            emit = kind != 'directory' or not self.plain_format
            if newpath in deleted_paths:
                if emit:
                    file_cmds.append(commands.FileDeleteCommand(newpath.encode("utf-8")))
                deleted_paths.remove(newpath)
            if (self.is_empty_dir(tree_old, oldpath)):
                self.note("Skipping empty dir %s in rev %s" % (oldpath,
                    revision_id))
                continue
            #oldpath = self._adjust_path_for_renames(oldpath, renamed,
            #    revision_id)
            renamed.append([oldpath, newpath])
            old_to_new[oldpath] = newpath
            if emit:
                file_cmds.append(
                    commands.FileRenameCommand(oldpath.encode("utf-8"), newpath.encode("utf-8")))
            if text_modified or meta_modified:
                modifies.append((newpath, id_, kind))

            # Renaming a directory implies all children must be renamed.
            # Note: changes_from() doesn't handle this
            if kind == 'directory' and tree_old.kind(id_) == 'directory':
                for p, e in tree_old.inventory.iter_entries_by_dir(from_dir=id_):
                    if e.kind == 'directory' and self.plain_format:
                        continue
                    old_child_path = osutils.pathjoin(oldpath, p)
                    new_child_path = osutils.pathjoin(newpath, p)
                    must_be_renamed[old_child_path] = new_child_path

        # Add children not already renamed
        if must_be_renamed:
            renamed_already = set(old_to_new.keys())
            still_to_be_renamed = set(must_be_renamed.keys()) - renamed_already
            for old_child_path in sorted(still_to_be_renamed):
                new_child_path = must_be_renamed[old_child_path]
                if self.verbose:
                    self.note("implicitly renaming %s => %s" % (old_child_path,
                        new_child_path))
                file_cmds.append(commands.FileRenameCommand(old_child_path.encode("utf-8"),
                    new_child_path.encode("utf-8")))

        # Record remaining deletes
        for path, id_, kind in deletes:
            if path not in deleted_paths:
                continue
            if kind == 'directory' and self.plain_format:
                continue
            #path = self._adjust_path_for_renames(path, renamed, revision_id)
            file_cmds.append(commands.FileDeleteCommand(path.encode("utf-8")))
        return file_cmds, modifies, renamed

    def _adjust_path_for_renames(self, path, renamed, revision_id):
        # If a previous rename is found, we should adjust the path
        for old, new in renamed:
            if path == old:
                self.note("Changing path %s given rename to %s in revision %s"
                    % (path, new, revision_id))
                path = new
            elif path.startswith(old + '/'):
                self.note(
                    "Adjusting path %s given rename of %s to %s in revision %s"
                    % (path, old, new, revision_id))
                path = path.replace(old + "/", new + "/")
        return path

    def emit_tags(self):
        for tag, revid in self.branch.tags.get_tag_dict().items():
            try:
                mark = self.revid_to_mark[revid]
            except KeyError:
                self.warning('not creating tag %r pointing to non-existent '
                    'revision %s' % (tag, revid))
            else:
                git_ref = 'refs/tags/%s' % tag.encode("utf-8")
                if self.plain_format and not check_ref_format(git_ref):
                    if self.rewrite_tags:
                        new_ref = sanitize_ref_name_for_git(git_ref)
                        self.warning('tag %r is exported as %r to be valid in git.',
                                     git_ref, new_ref)
                        git_ref = new_ref
                    else:
                        self.warning('not creating tag %r as its name would not be '
                                     'valid in git.', git_ref)
                        continue
                self.print_cmd(commands.ResetCommand(git_ref, ":" + str(mark)))

    def _next_tmp_ref(self):
        """Return a unique branch name. The name will start with "tmp"."""
        prefix = 'tmp'
        if prefix not in self.branch_names:
            self.branch_names[prefix] = 0
        else:
            self.branch_names[prefix] += 1
            prefix = '%s.%d' % (prefix, self.branch_names[prefix])
        return 'refs/heads/%s' % prefix