#!/usr/bin/python
# dul-daemon - Simple git-daemon a like
# Copyright (C) 2008 John Carr <john.carr@unrouted.co.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; version 2
# of the License.
# 
# 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.

import os, sys, tempfile, struct
from dulwich.server import Backend, TCPGitServer
from dulwich.repo import Repo
from dulwich.pack import PackData, Pack

import sha
from dulwich.pack import write_pack_object
class PackWriteWrapper(object):

    def __init__(self, write):
        self.writefn = write
        self.sha = sha.sha()

    def write(self, blob):
        self.sha.update(blob)
        self.writefn(blob)

    def tell(self):
        pass

    @property
    def digest(self):
        return self.sha.digest()

class GitBackend(Backend):

    def __init__(self, gitdir=None):
        self.gitdir = gitdir

        if not self.gitdir:
            self.gitdir = tempfile.mkdtemp()
            Repo.create(self.gitdir)

        self.repo = Repo(self.gitdir)

    def get_refs(self):
        refs = []
        if self.repo.head():
            refs.append(('HEAD', self.repo.head()))
        for ref, sha in self.repo.heads().items():
            refs.append(('refs/heads/'+ref,sha))
        return refs

    def has_revision(self, sha):
        return self.repo.get_object(sha) != None

    def apply_pack(self, refs, read):
        # store the incoming pack in the repository
        fd, name = tempfile.mkstemp(suffix='.pack', prefix='', dir=self.repo.pack_dir())
        os.write(fd, read())
        os.close(fd)

        # strip '.pack' off our filename
        basename = name[:-5]

        # generate an index for it
        pd = PackData(name)
        pd.create_index_v2(basename+".idx")

        for oldsha, sha, ref in refs:
            if ref == "0" * 40:
                self.repo.remove_ref(ref)
            else:
                self.repo.set_ref(ref, sha)

        print "pack applied"

    def generate_pack(self, want, have, write, progress):
        progress("dul-daemon says what\n")

        sha_queue = []

        commits_to_send = want[:]
        for sha in commits_to_send:
            sha_queue.append((1,sha))

            c = self.repo.commit(sha)
            for p in c.parents():
                commits_to_send.append(p)

            progress("counting objects: %d\r" % len(sha_queue))

        progress("counting objects: %d, done.\n" % len(sha_queue))

        w = PackWriteWrapper(write)
        w.write("PACK")
        w.write(struct.pack(">L", 2))
        w.write(struct.pack(">L", len(sha_queue)))

        for type, sha in sha_queue:
            obj = self.repo.get_object(sha)
            write_pack_object(w, type, object)

        # send sha1 of pack
        write(w.digest())
        

if __name__ == "__main__":
    gitdir = None
    if len(sys.argv) > 1:
        gitdir = sys.argv[1]

    backend = GitBackend(gitdir)
    server = TCPGitServer(backend, ('localhost', 9418))
    server.serve_forever()