# $Id: server.py,v 1.8 2011/05/26 19:34:19 edwlan Exp $

#
#  Copyright (c) 2011 Edward Langley
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import cgi
import copy
import time
import itertools
import jsonrpc.jsonutil
import json

# Twisted imports
from twisted.web import server
from twisted.internet import threads
from twisted.web.resource import Resource


import UserDict, collections
collections.Mapping.register(UserDict.DictMixin)

class ServerEvents(object):
	'''Subclass this and pass to :py:meth:`jsonrpc.customize` to customize the jsonrpc server'''

	def __init__(self, jsonrpc):
		#: A link to the JSON-RPC server instance
		self.server = jsonrpc

	def callmethod(self, request, method, kwargs, args, **kw):
		'''Finds the method and calls it with the specified args'''
		method = self.findmethod(method)
		if method is None: raise MethodNotFound

		return method(*args, **kwargs)

	def findmethod(self, method):
		'''Override to allow server to define methods'''
		return lambda *a, **kw: 'Test Data'

	def processrequest(self, result, args):
		'''Override to implement custom handling of the method result and request'''
		return result

	def log(self, result, request):
		'''Override to implement custom error handling'''
		pass

	def processcontent(self, content, request):
		'''Given the freshly decoded content of the request, return what content should be used'''
		return content


class ServerError(Exception):
	code = 0
	msg = ""
	id = None

	def json_equivalent(self):
		return dict(jsonrpc="2.0", error=dict(code=self.code, message=self.msg), id=self.id)
	def __str__(self):
		return jsonrpc.jsonutil.encode(self)

class InvalidRequest(ServerError):
	code = -32600
	msg = "Invalid Request."

class MethodNotFound(ServerError):
	code = -32601
	msg = "Procedure not found."

class ParseError(ServerError):
	code = -32700
	msg = "Parse error."

## Base class providing a JSON-RPC 2.0 implementation with 2 customizable hooks
class JSON_RPC(Resource):
	'''This class implements a JSON-RPC 2.0 server as a Twisted Resource'''
	isLeaf = True

	#: set by :py:meth:`customize` used to change the behavior of the server
	eventhandler = ServerEvents

	def customize(self, eventhandler):
		'''customize the behavior of the server'''
		self.eventhandler = eventhandler(self)
		return self


	def __init__(self, *args, **kwargs):
		self.customize(self.eventhandler)
		Resource.__init__(self,*args, **kwargs)


	def render(self, request):
		#move to emen2 event handler
		#ctxid = request.getCookie("ctxid") or request.args.get("ctxid", [None])[0]
		#host = request.getClientIP()

		request.content.seek(0, 0)
		try:
			try:
				content = jsonrpc.jsonutil.decode(request.content.read())
			except ValueError: raise ParseError
			content = self.eventhandler.processcontent(content, request)
			d = threads.deferToThread(self._action, request, content)
			d.addCallback(self._cbRender, request)
			d.addErrback(self._ebRender, request, content.get('id') if hasattr(content, 'get') else None)
		except BaseException, e:
			self._ebRender(e, request, None)

		return server.NOT_DONE_YET


	def _cbRender(self, result, request):
		if result is not None:
			request.setHeader("content-type", 'application/json')
			request.setResponseCode(200)
			result = jsonrpc.jsonutil.encode(result).encode('utf-8')
			request.setHeader("content-length", len(result))
			request.write(result)
		request.finish()

	def _ebRender(self, result, request, id, finish=True):
		self.eventhandler.log(result, request)

		err = None
		if not isinstance(result, BaseException):
			try: result.raiseException()
			except BaseException, e:
				err = e
		else: err = result
		err = self.render_error(err, id)

		request.setHeader("content-type", 'application/json')
		request.setResponseCode(200)
		result = jsonrpc.jsonutil.encode(err).encode('utf-8')
		request.setHeader("content-length", len(result))
		request.write(result)
		if finish: request.finish()

	def _parse_data(self, content):
		if content.get('jsonrpc') != '2.0': raise InvalidRequest

		method = content.get('method')
		if not isinstance(method, (str, unicode)): raise InvalidRequest

		kwargs = content.get('params', {})
		args = ()
		if not isinstance(kwargs, dict):
			args = tuple(kwargs)
			kwargs = {}
		else:
			args = kwargs.pop('__args', args)
		kwargs = dict( (str(k), v) for k,v in kwargs.items() )

		return method, kwargs, args



	def render_error(self, e, id):
		if isinstance(e, ServerError):
			e.id = id
			err = e.json_equivalent()
		else:
			err = dict(
				jsonrpc='2.0',
				id = id,
				error= dict(
					code=0,
					message=str(e),
					data = e.args
			))

		return err



	def _action(self, request, contents):
		result = []
		ol = (True if isinstance(contents, list) else False)
		if not ol: contents = [contents]

		if contents == []: raise InvalidRequest

		for content in contents:
			try:
				res = dict(jsonrpc='2.0', id=content.get('id'), result=self.eventhandler.callmethod(request, *self._parse_data(content)))

				res = self.eventhandler.processrequest(res, request.args)

				if res['id'] is not None: result.append(res)
			except Exception, e:
				err = self.render_error(e, content.get('id'))
				if err['id'] is not None: result.append(err)



		self.eventhandler.log(result, request)

		if result != []:
			if not ol: result = result[0]
		else: result = None

		return result