#!/usr/bin/env python

import sys
import json
import os
import hashlib
import io
from subprocess import call


###############
#
# Method for generating current state
#
###############
def get_state(model):
	state = {}
	state['path'] = model['path'] if 'path' in model else ''
	try:
		m = hashlib.md5()
		with open(state['path']) as f:
			buf = f.read(128)
			while len(buf) > 0:
				m.update(buf)
				buf = f.read(128)
		state['created'] = True
		state['content'] = '{md5}' + m.hexdigest()
	except IOError:
		state['created'] = False
		state['content'] = ''

	if state['created'] and 'content' in model:
		m = hashlib.md5()
		m.update(model['content'])
		state['created'] = (('{md5}' + m.hexdigest()) == state['content'])

	### dump current state
	print json.dumps(state)


###############
#
# Implementation of procedure 'del' (see pyfile.sfp)
#
###############
def delete(model):
	if 'path' in model:
		os.remove(model['path'])
	else:
		return False
	return True


###############
#
# Implementation of procedure 'create' (see pyfile.sfp)
#
###############
def create(model):
	if 'path' in model:
		content = model['content'] if 'content' in model else ''
		try:
			with open(model['path'], 'w') as f:
				f.write(content)
		except IOError, e:
			print str(e)
			return False
	else:
		return False

	if 'permission' in model:
		call(["chmod", model['permission'], model['path']])

	return True


###############
#
# Function to redirect procedure execution request by
# calling target function
#
###############
def execute(procedure, parameters, model):
	success = False
	description = ''
	if procedure == 'del':
		success = delete(model)
	elif procedure == 'create':
		success = create(model)
	else:
		description = 'unrecognized procedure ' + procedure
	status = 'ok' if success else 'failed'
	print json.dumps({'status': status, 'description': description})


###############
#
# Main logic for handling any request
#
###############
if len(sys.argv) <= 1:
	### invalid request
	print '{"status":"error","description":"invalid command line argument"}'
	exit(1)
else:
	### parse request data in JSON
	data = json.loads(sys.argv[1])

	if 'command' in data:
		try:
			if data['command'] == 'state' and 'model' in data:
				### request for current state
				get_state(data['model'])

			elif data['command'] == 'execute' and 'procedure' in data and 'parameters' in data and 'model' in data:
				### request for executing a procedure
				execute(data['procedure'], data['parameters'], data['model'])

			else:
				### invalid request
				print '{"status":"error","description":"invalid command"}'
				exit(1)

		except Exception, e:
			### dump exception
			print json.dumps({'status':'error','description': str(e)})

	else:
		### invalid request
		print '{"status":"error","description":"no command"}'
		exit(1)

exit(0)