import sys,os

import libxml2
# allow to run sfa2wsdl if this is missing (for mac)
try:import libxslt
except: print("WARNING, could not import libxslt", file=sys.stderr)

from sfatables.globals import sfatables_config

class XMLRule:
    def apply_processor(self, type, doc, output_xpath_filter=None):
        processor = self.processors[type]

        # XXX TO CLEAN UP
        filepath = os.path.join(sfatables_config, 'processors', processor)
        # XXX

        styledoc = libxml2.parseFile(filepath)
        style = libxslt.parseStylesheetDoc(styledoc)
        result = style.applyStylesheet(doc, None)
        if (output_xpath_filter):
            p = result.xpathNewContext()
            xpath_result = p.xpathEval(output_xpath_filter)
            if (xpath_result == []):
                raise Exception("Could not apply processor %s."%processor)

            stylesheet_result = xpath_result
            p.xpathFreeContext()
        else:
            stylesheet_result = result #style.saveResultToString(result)

        style.freeStylesheet()
        #doc.freeDoc()
        #result.freeDoc()

        return stylesheet_result

    def wrap_up(self, doc):
        filepath = os.path.join(sfatables_config, 'processors', self.final_processor)

        if not os.path.exists(filepath):
            raise Exception('Could not find final rule filter')

        styledoc = libxml2.parseFile(filepath)
        style = libxslt.parseStylesheetDoc(styledoc)
        result = style.applyStylesheet(doc, None)
        stylesheet_result = result#style.saveResultToString(result)
        style.freeStylesheet()
        #doc.freeDoc()
        #result.freeDoc()

        return stylesheet_result

    def match(self, rspec):
        match_result = self.apply_processor('match',rspec,"//result/@verdict") 
        return (match_result[0].content=='True')

    def target(self, rspec):
        target_result = self.apply_processor('target',rspec,None)
        return target_result

    def add_rule_context_to_rspec(self, doc):
        p = doc.xpathNewContext()
        context = p.xpathEval("//*")
        if not context or context[0].name not in ['RSpec', 'rspec']:
            raise Exception('Request is not an rspec')
        else:
            # Add the request context
            matchNode = libxml2.newNode('match-context')
            for match_argument in self.arguments['match']:
                matchNode.addChild(match_argument)

            targetNode = libxml2.newNode('target-context')
            for target_argument in self.arguments['target']:
                targetNode.addChild(target_argument)

            context[0].addChild(matchNode)
            context[0].addChild(targetNode)
        p.xpathFreeContext()

        return doc

    def apply_interpreted(self, rspec):
        rspec = self.add_rule_context_to_rspec(rspec)
        # Interpreted
        #
        # output =
        #    if (match(match_args, rspec)
        #       then target(target_args, rspec)
        #       else rspec
        
        if (self.match(rspec)):
            return (True,self.wrap_up(self.target(rspec)))
        else:
            return (False,self.wrap_up(rspec))


    def apply_compiled(self, rspec):
        # Not supported yet
        return None

    def load_xml_extension (self, type, chain, rule_number):
        filename = sfatables_config+"/"+chain+"/"+"sfatables-%d-%s"%(rule_number,type)

        self.xmldoc = libxml2.parseFile(filename)
        p = self.xmldoc.xpathNewContext()

        context = p.xpathEval('//context/@select')
        self.context[type] = context[0].content

        processor = p.xpathEval('//processor/@filename')

        context = p.xpathEval('//attributes/attribute[@terminal="yes"]')
        if (context != []):
            self.terminal = 1
        
        self.processors[type] = processor[0].content
        self.arguments[type] = p.xpathEval('//rule//argument[value!=""]')

        p.xpathFreeContext()


    def __init__(self, chain=None, rule_number=None):
        self.rule_number = None
        self.chain = None
        self.xmldoc = None
        self.terminal = 0
        self.final_processor = '__sfatables_rule_wrap_up__.xsl'

        self.arguments = {'match':None,'target':None}
        self.processors = {'match':None,'target':None}
        self.context = {'match':None,'target':None}

        if (chain and rule_number):
            self.load_xml_extension('match', chain, rule_number)
            self.load_xml_extension('target',chain, rule_number)
            self.rule_number = rule_number
            self.chain = chain
        return
        
    def free(self):
        self.xmldoc.freeDoc()