#!/usr/bin/env python

# Encoding: iso-8859-1

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

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

# Project   : Basic Darcs to Mercurial conversion script

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

# Authors   : Sebastien Pierre                           <sebastien@xprima.com>

#             TK Soh                                      <teekaysoh@gmail.com>

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

# Creation  : 24-May-2006

# Last mod  : 05-Jun-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 [SKIP]

    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.

    In case an error occurs within the process, you can resume the process by

    giving the last successfuly applied change number.

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

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

#

# Utilities

#

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

def cmd(text, path=None, silent=False):

	"""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)

	if not silent: print "> ", text

	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()

def error( *args ):

	sys.stderr.write("ERROR: ")

	for a in args: sys.stderr.write(str(a))

	sys.stderr.write("\n")

	sys.stderr.write("You can make manual fixes if necessary and then resume by"

	" giving the last changeset number")

	sys.exit(-1)

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

#

# 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")

		chash  = os.path.splitext(patch_node.getAttribute("hash"))[0]

		yield author, date, name, chash, comm

def darcs_tip(darcs_repo):

	changes = cmd("darcs changes",darcs_repo,silent=True)

	changes = filter(lambda l:l.strip().startswith("* "), changes.split("\n"))

	return len(changes)

def darcs_pull(hg_repo, darcs_repo, chash):

	old_tip = darcs_tip(darcs_repo)

	print res

	new_tip = darcs_tip(darcs_repo)

	if not new_tip != old_tip + 1:

		error("Darcs pull did not work as expected: " + res)

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

#

# Mercurial interface

#

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

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

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

	writefile(tmpfile, text)

	old_tip = hg_tip(hg_repo)

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

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

	os.unlink(tmpfile)

	new_tip = hg_tip(hg_repo)

	if not new_tip == old_tip + 1:

		# Sometimes we may have empty commits, we simply skip them

		if res.strip().lower().find("nothing changed") != -1:

			pass

		else:

			error("Mercurial commit did not work as expected: " + res)

def hg_tip( hg_repo ):

	"""Returns the latest local revision number in the given repository."""

	tip = cmd("hg tip", hg_repo, silent=True)

	tip = tip.split("\n")[0].split(":")[1].strip()

	return int(tip)

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

#

# 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])

		skip       = None

	elif len(args) == 3:

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

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

		skip       = int(args[2])

	else:

		print USAGE

		sys.exit(-1)

	# Initializes the target repo

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

		print "No darcs directory found at: " + darcs_repo

		sys.exit(-1)

	if not os.path.isdir(hg_repo):

		os.mkdir(hg_repo)

	elif skip == None:

		print "Given HG repository must not exist when no SKIP is specified."

		sys.exit(-1)

	if skip == None:

		cmd("darcs initialize", hg_repo)

	# Get the changes from the Darcs repository

	change_number = 0

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

		print "== changeset", change_number,

		if skip != None and change_number <= skip:

			print "(skipping)"

		else:

			text = summary + "\n" + description

			darcs_pull(hg_repo, darcs_repo, chash)

			# The commit hash has a date like 20021020201112

			# --------------------------------YYYYMMDDHHMMSS

			date = chash.split("-")[0]

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

			hg_commit(hg_repo, text, author, epoch)

		change_number += 1

	print "Darcs repository (_darcs) was not deleted. You can keep or remove it."

# EOF