#!/usr/bin/env python

# Encoding: iso-8859-1

# vim: tw=80 ts=4 sw=4 noet

# -----------------------------------------------------------------------------

# Project   : Basic Darcs to Mercurial conversion script

# -----------------------------------------------------------------------------

# Creation  : 24-May-2006

# -----------------------------------------------------------------------------

import os, sys

import tempfile

import xml.dom.minidom as xml_dom

from time import strptime, mktime

DARCS_REPO = None

HG_REPO    = None

USAGE = """\

%s DARCSREPO HGREPO

    Converts the given Darcs repository to a new Mercurial repository. The given

    HGREPO must not exist, as it will be created and filled up (this will avoid

    overwriting valuable data.

""" % (os.path.basename(sys.argv[0]))

# ------------------------------------------------------------------------------

#

# Utilities

#

# ------------------------------------------------------------------------------

	"""Executes a command, in the given directory (if any), and returns the

	command result as a string."""

	cwd = None

	if path:

		path = os.path.abspath(path)

		cwd  = os.getcwd()

		os.chdir(path)

	res = os.popen(text).read()

	if path:

		os.chdir(cwd)

	return res

def writefile(path, data):

	"""Writes the given data into the given file."""

	f = file(path, "w") ; f.write(data)  ; f.close()

# ------------------------------------------------------------------------------

#

# Darcs interface

#

# ------------------------------------------------------------------------------

def darcs_changes(darcsRepo):

	"""Gets the changes list from the given darcs repository. This returns the

	chronological list of changes as (change name, change summary)."""

	changes    = cmd("darcs changes --reverse --xml-output", darcsRepo)

	doc        = xml_dom.parseString(changes)

	for patch_node in doc.childNodes[0].childNodes:

		name = filter(lambda n:n.nodeName == "name", patch_node.childNodes)

		comm = filter(lambda n:n.nodeName == "comment", patch_node.childNodes)

		if not name:continue

		else: name = name[0].childNodes[0].data

		if not comm: comm = ""

		else: comm = comm[0].childNodes[0].data

		author = patch_node.getAttribute("author")

		date = patch_node.getAttribute("date")

        hash = patch_node.getAttribute("hash")

        yield hash, author, date, name, comm

def darcs_pull(hg_repo, darcs_repo, change):

	cmd("darcs pull '%s' --all --patches='%s'" % (darcs_repo, change), hg_repo)

# ------------------------------------------------------------------------------

#

# Mercurial interface

#

# ------------------------------------------------------------------------------

def hg_commit( hg_repo, text, author, date ):

	fd, tmpfile = tempfile.mkstemp(prefix="darcs2hg_")

	writefile(tmpfile, text)

	cmd("hg add -X _darcs", hg_repo)

	cmd("hg remove -X _darcs --after", hg_repo)

	cmd("hg commit -l %s -u '%s' -d '%s 0'"  % (tmpfile, author, date), hg_repo)

	os.unlink(tmpfile)

# ------------------------------------------------------------------------------

#

# Main

#

# ------------------------------------------------------------------------------

if __name__ == "__main__":

	args = sys.argv[1:]

	# We parse the arguments

	if len(args)   == 2:

		darcs_repo = os.path.abspath(args[0])

		hg_repo    = os.path.abspath(args[1])

	else:

		print USAGE

		sys.exit(-1)

	# Initializes the target repo

	if not os.path.isdir(darcs_repo + "/_darcs"):

		sys.exit(-1)

	if not os.path.isdir(hg_repo):

		os.mkdir(hg_repo)

	else:

		print "Given HG repository must not exist. It will be created"

		sys.exit(-1)

	cmd("hg init '%s'" % (hg_repo))

	cmd("darcs initialize", hg_repo)

	# Get the changes from the Darcs repository

	for hash, author, date, summary, description in darcs_changes(darcs_repo):

		text = summary + "\n" + description

		darcs_pull(hg_repo, darcs_repo, hash)

		epoch = int(mktime(strptime(date, '%Y%m%d%H%M%S')))

		hg_commit(hg_repo, text, author, epoch)

# EOF