#!/usr/bin/env python
# coding: utf-8

# git-darcs-record, emulate "darcs record" interface on top of a git repository
#
# Usage:
# git-darcs-record first asks for any new file (previously
#    untracked) to be added to the index.
# git-darcs-record then asks for each hunk to be recorded in
#    the next commit. File deletion and binary blobs are supported
# git-darcs-record finally asks for a small commit message and
#    executes the 'git commit' command with the newly created
#    changeset in the index


# Copyright (C) 2007 Raphaël Slinckx <raphael@slinckx.net>
#
# 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.

import re, pprint, sys, os

BINARY = re.compile("GIT binary patch")
HEADER = re.compile("diff --git a/(.*) b/(.*)")
class Hunk:
	def __init__(self, lines, binary):
		self.diff = None
		self.lines = lines
		self.keep = False
		self.binary = binary
	
	def format(self):
		output = self.diff.header.modified + "\n"
		if self.diff.header.deleted:
			output = "Removed file: " + output
		if self.binary:
			output = "Binary file changed: " + output

		if not self.binary:
			output += "\n".join(self.lines) + "\n"

		return output

class Header:
	def __init__(self, lines):
		self.lines = lines
		self.modified = None
		self.deleted = False

		# Extract useful info from header from git
		for line in lines:
			if HEADER.match(line):
				match = HEADER.match(line)
				self.modified = match.group(1)
			if line.startswith("deleted "):
				self.deleted = True

		# Make sure we know what file we are modifying
		assert self.modified

class Diff:
	def __init__(self, header, hunks):
		self.header = header
		self.hunks = hunks
		# Put a reference to ourselves in the hunks
		for hunk in self.hunks:
			hunk.diff = self
		self.keep = False
	
	def filter(self):
		output = '\n'.join(self.header.lines) + "\n"
		for hunk in self.hunks:
			if not hunk.keep:
				continue
			output += '\n'.join(hunk.lines) + "\n"
		return output

	@classmethod
	def filter_diffs(kls, diffs):
		output = ""
		for diff in diffs:
			if not diff.keep:
				continue
			output += diff.filter()
		return output
	
	@classmethod
	def parse(kls, lines):
		in_header = True
		binary = False
		header = []
		hunks = []
		current_hunk = []
		for line in lines:
			if in_header and (line[0] not in (" ", "@", "\\") or line.startswith("+++ ") or line.startswith("--- ")) and not BINARY.match(line):
				header.append(line)
			elif BINARY.match(line):
				in_header = False
				binary = True
				header.append(line)
			elif len(line) >= 1 and line[0] == "@":
				in_header = False
				if current_hunk:
					hunks.append(Hunk(current_hunk, binary))
				current_hunk = []
				current_hunk.append(line)
			else:
				current_hunk.append(line)
		if current_hunk:
			hunks.append(Hunk(current_hunk, binary))
		return Diff(Header(header), hunks)

	@classmethod
	def split(kls, lines):
		diffs = []
		current_diff = []
		for line in lines:
			if line.startswith("diff --git "):
				if current_diff:
					diffs.append(current_diff)
				current_diff = []
				current_diff.append(line)
			else:
				current_diff.append(line)
		if current_diff:
			diffs.append(current_diff)
		return [Diff.parse(lines) for lines in diffs]

def read_answer(question, allowed_responses=["Y", "n", "d", "a"]):
	#Make sure there is alway a default selection
	assert [r for r in allowed_responses if r.isupper()]

	while True:
		resp = raw_input("%s [%s] : " % (question, "".join(allowed_responses)))
		if resp in [r.lower() for r in allowed_responses]:
			break
		elif resp == "":
			resp = [r for r in allowed_responses if r.isupper()][0].lower()
			break
		print 'Unexpected answer: %r' % resp
	return resp


def setup_git_dir():
	global GIT_DIR
	GIT_DIR = os.getcwd()
	while not os.path.exists(os.path.join(GIT_DIR, ".git")):
		GIT_DIR = os.path.dirname(GIT_DIR)
		if GIT_DIR == "/":
			return False
	os.chdir(GIT_DIR)
	return True

def git_get_untracked_files():
	return [f.strip() for f in os.popen("git ls-files --others --exclude-from='%s' --exclude-per-directory=.gitignore" % (os.path.join(GIT_DIR, ".git", "info", "exclude"))).readlines()]

def git_track_file(f):
	os.spawnvp(os.P_WAIT, "git", ["git", "add", f])

def git_diff():
	return os.popen("git diff -u --no-color --binary").readlines()

def git_apply(patch):
	stdin, stdout = os.popen2(["git", "apply", "--cached",  "-"])
	stdin.write(patch)
	stdin.close()
	output = stdout.read()
	stdout.close()
	os.wait()
	return output

def git_status():
	os.spawnvp(os.P_WAIT, "git", ["git", "status"])

def git_commit(msg):
	os.spawnvp(os.P_WAIT, "git", ["git", "commit", "-m", patch_name])

# Main loop ------------------------
if not setup_git_dir():
	print "Must be in a git (sub-)directory! Exiting..."
	sys.exit()

# Ask for new files ----------------
git_untracked_files = git_get_untracked_files()
git_track_files = []
all = False
done = False
for i, f in enumerate(git_untracked_files):
	if not all:
		print "Add file: ", f
		resp = read_answer("Shall I add this file? (%d/%d)" % (i+1, len(git_untracked_files)))
	else:
		resp = "y"

	if resp == "y":
		git_track_files.append(f)
	elif resp == "a":
		git_track_files.append(f)
		all = True
	elif resp == "d":
		done = True
		break

# Ask for each hunk of the diff
diffs = Diff.split([line[:-1] for line in git_diff()])
total_hunks = sum([len(diff.hunks) for diff in diffs])

n_hunk = 1
for diff in diffs:
	if done:
		break
	for hunk in diff.hunks:
		# Check if we are in override mode
		if not all:
			print
			print hunk.format()
			resp = read_answer('Shall I record this change? (%d/%d)' % (n_hunk, total_hunks))
		# Otherwise say 'y' to all remaining patches
		else:
			resp = "y"

		if resp == "y":
			diff.keep = True
			hunk.keep = True
		elif resp == "a":
			diff.keep = True
			hunk.keep = True
			all = True
		elif resp == "d":
			done = True
			break

		n_hunk += 1

# Add new files to track
for f in git_track_files:
	git_track_file(f)

# Generate a new patch to be used with git apply
new_patch = Diff.filter_diffs(diffs)
if new_patch:
	print git_apply(new_patch)

if new_patch or git_track_files:
	git_status()
	patch_name = raw_input("What is the patch name? ")
	git_commit(patch_name)
else:
	print "Ok, if you don't want to record anything, that's fine!"