import os
import sha

def gitsha(path):
	h = sha.sha()
	data = file(path).read()
	h.update("blob %d\0" % len(data))
	h.update(data)
	return h.hexdigest()

def git_info():
	commithash = os.popen('git-rev-parse --verify HEAD 2>/dev/null').read().strip()
	if not commithash:
		raise ValueError("Couldn't get hash")
	if os.getuid() == os.stat(".git/index").st_uid:
		os.system('git-update-index --refresh >/dev/null')
	else:
		print "NOT updating git cache, local changes might not be detected"
	changed = bool(os.popen('git-diff-index -r HEAD').read())
	return commithash, changed

def snapshot_info():
	info = file('commithash').read().split('\n')
	
	commithash = info[0]

	changed = False
	for line in [a for a in info[2:] if a]:
		[mode, tag, sha, path] = line.split(None, 4)
		if tag != 'blob':
			continue
		if gitsha(path) != sha:
			changed = True
			break
	return commithash, changed

def get_info():
	try:
		return git_info()
	except:
		try:
			return snapshot_info()
		except:
			return 'Unknown', False

def get_info_str():
	commithash, changed = get_info()
	if changed:
		changed = " + local changes"
	else:
		changed = ""

	return "%s%s" % (commithash, changed)