from functools import wraps
from django.contrib.auth.models import User, Group
from piston.utils import rc
from main.models import Plugin, PluginPermission

def manglePluginPerms(apiFunc):
	""" Changes to a given user when the authenticated user is an plugin.
	
	When the user which called the apifunc is a plugin this function
	goes through the following steps:
	
		- searches the user it should change to
		- checks if this user allowed the plugin to "speak for him"
		- change the request so it looks like the user called himself
		- add an plugin_user entry containing the previous request user
	
	This decorator is intended to be used with django piston, so on error
	it will return the appropriate rc.* values.
	"""
	
	@wraps(apiFunc)
	def wrapper(self, request, *args, **kwargs):
		if request.method != 'GET':
			if not request.content_type:
				request.data = request.POST
		else:
			request.data = request.GET
		
		# 0. is user a plugin? 
		try:
			group = request.user.groups.get(name="Plugin")
		except Group.DoesNotExist:
			# user is not a plugin, exec the apiFunc
			return apiFunc(self, request, *args, **kwargs)
		
		# get the plugin for the user
		# FIXME: Could throw exception when we have no plugin for the
		#        user - where should we report this?
		plugin = Plugin.objects.get(user=request.user)
		
		# 1. find user!
		user = None
		try:
			user = User.objects.get(username=request.data.get('user', ''))
		except User.DoesNotExist:
			ret = rc.NOT_HERE
			ret.write("\nThe user you requested could not be found\n")
			return ret
		
		# 2. does the plugin has permission for this user?
		perms = None
		try:
			perms = PluginPermission.objects.get(user=user, plugin=plugin)
		except PluginPermission.DoesNotExist:
			ret = rc.FORBIDDEN
			ret.write("\nThe user did not grant you permission to act on his behalf\n")
			return ret
		
		# 3. put stuff into the request
		request.user = user 
		request.plugin = plugin
		request.pluginperms = perms
		return apiFunc(self, request, *args, **kwargs)
	return wrapper

def requirePlugin(apiFunc):
	"""Check if user is a plugin.
	
	Checks if the user is a member of the "Plugin" Group. Returns a rc.FORBIDDEN 
	if not.
	"""
	
	@wraps(apiFunc)
	def wrapper(self, request, *args, **kwargs):
		try:
			if request.user:
				group = request.user.groups.get(name="Plugin")
				# no exception, exec apiFunc!
				request.plugin = Plugin.objects.get(user=request.user)
				return apiFunc(self, request, *args, **kwargs)
		except Group.DoesNotExist:
			pass
		ret = rc.FORBIDDEN
		ret.write("\nA plugin is required for this api function\n")
		return ret
	return wrapper

def fix_mime(mime_func):
	""" Fix mimetype by truncating everything behind a ';'. 
	
	This is used to fix pistons ``piston.utils.Mimer.content_type``."""
	@wraps(mime_func)
	def wrapper(self):
		ctype = self.request.META.get('CONTENT_TYPE', None)
		if ctype and ctype.find(";") >= 0:
			ctype = self.request.META['CONTENT_TYPE'] = ctype.split(";")[0]
		return mime_func(self)
	return wrapper