# -*- test-case-name: twisted.web.test.test_web -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.


"""
This is a web-server which integrates with the twisted.internet
infrastructure.
"""

# System Imports

import warnings
import string
import types
import copy
import os
from urllib import quote

from zope.interface import implements

from urllib import unquote

#some useful constants
NOT_DONE_YET = 1

# Twisted Imports
from twisted.spread import pb
from twisted.internet import address, task
from twisted.web import iweb, http
from twisted.python import log, reflect, failure, components
from twisted import copyright
from twisted.web import util as webutil, resource
from twisted.web.error import UnsupportedMethod
from twisted.web.microdom import escape

# backwards compatability
date_time_string = http.datetimeToString
string_date_time = http.stringToDatetime

# Support for other methods may be implemented on a per-resource basis.
supportedMethods = ('GET', 'HEAD', 'POST')


def _addressToTuple(addr):
    if isinstance(addr, address.IPv4Address):
        return ('INET', addr.host, addr.port)
    elif isinstance(addr, address.UNIXAddress):
        return ('UNIX', addr.name)
    else:
        return tuple(addr)

class Request(pb.Copyable, http.Request, components.Componentized):
    """
    An HTTP request.
    """
    implements(iweb.IRequest)

    site = None
    appRootURL = None
    __pychecker__ = 'unusednames=issuer'
    _inFakeHead = False

    def __init__(self, *args, **kw):
        http.Request.__init__(self, *args, **kw)
        components.Componentized.__init__(self)

    def getStateToCopyFor(self, issuer):
        x = self.__dict__.copy()
        del x['transport']
        # XXX refactor this attribute out; it's from protocol
        # del x['server']
        del x['channel']
        del x['content']
        del x['site']
        self.content.seek(0, 0)
        x['content_data'] = self.content.read()
        x['remote'] = pb.ViewPoint(issuer, self)

        # Address objects aren't jellyable
        x['host'] = _addressToTuple(x['host'])
        x['client'] = _addressToTuple(x['client'])

        # Header objects also aren't jellyable.
        x['requestHeaders'] = list(x['requestHeaders'].getAllRawHeaders())

        return x

    # HTML generation helpers

    def sibLink(self, name):
        "Return the text that links to a sibling of the requested resource."
        if self.postpath:
            return (len(self.postpath)*"../") + name
        else:
            return name

    def childLink(self, name):
        "Return the text that links to a child of the requested resource."
        lpp = len(self.postpath)
        if lpp > 1:
            return ((lpp-1)*"../") + name
        elif lpp == 1:
            return name
        else: # lpp == 0
            if len(self.prepath) and self.prepath[-1]:
                return self.prepath[-1] + '/' + name
            else:
                return name

    def process(self):
        "Process a request."

        # get site from channel
        self.site = self.channel.site

        # set various default headers
        self.setHeader('server', version)
        self.setHeader('date', http.datetimeToString())
        self.setHeader('content-type', "text/html")

        # Resource Identification
        self.prepath = []
        self.postpath = map(unquote, string.split(self.path[1:], '/'))
        try:
            resrc = self.site.getResourceFor(self)
            self.render(resrc)
        except:
            self.processingFailed(failure.Failure())

    def write(self, data):
        """
        Write data to the transport (if not responding to a HEAD request).

        @param data: A string to write to the response.
        """
        if not self._inFakeHead:
            http.Request.write(self, data)

    def render(self, resrc):
        """
        Ask a resource to render itself.

        @param resrc: a L{twisted.web.resource.IResource}.
        """
        try:
            body = resrc.render(self)
        except UnsupportedMethod, e:
            allowedMethods = e.allowedMethods
            if (self.method == "HEAD") and ("GET" in allowedMethods):
                # We must support HEAD (RFC 2616, 5.1.1).  If the
                # resource doesn't, fake it by giving the resource
                # a 'GET' request and then return only the headers,
                # not the body.
                log.msg("Using GET to fake a HEAD request for %s" %
                        (resrc,))
                self.method = "GET"
                self._inFakeHead = True
                body = resrc.render(self)

                if body is NOT_DONE_YET:
                    log.msg("Tried to fake a HEAD request for %s, but "
                            "it got away from me." % resrc)
                    # Oh well, I guess we won't include the content length.
                else:
                    self.setHeader('content-length', str(len(body)))

                self._inFakeHead = False
                self.method = "HEAD"
                self.write('')
                self.finish()
                return

            if self.method in (supportedMethods):
                # We MUST include an Allow header
                # (RFC 2616, 10.4.6 and 14.7)
                self.setHeader('Allow', ', '.join(allowedMethods))
                s = ('''Your browser approached me (at %(URI)s) with'''
                     ''' the method "%(method)s".  I only allow'''
                     ''' the method%(plural)s %(allowed)s here.''' % {
                    'URI': escape(self.uri),
                    'method': self.method,
                    'plural': ((len(allowedMethods) > 1) and 's') or '',
                    'allowed': string.join(allowedMethods, ', ')
                    })
                epage = resource.ErrorPage(http.NOT_ALLOWED,
                                           "Method Not Allowed", s)
                body = epage.render(self)
            else:
                epage = resource.ErrorPage(
                    http.NOT_IMPLEMENTED, "Huh?",
                    "I don't know how to treat a %s request." %
                    (escape(self.method),))
                body = epage.render(self)
        # end except UnsupportedMethod

        if body == NOT_DONE_YET:
            return
        if type(body) is not types.StringType:
            body = resource.ErrorPage(
                http.INTERNAL_SERVER_ERROR,
                "Request did not return a string",
                "Request: " + html.PRE(reflect.safe_repr(self)) + "<br />" +
                "Resource: " + html.PRE(reflect.safe_repr(resrc)) + "<br />" +
                "Value: " + html.PRE(reflect.safe_repr(body))).render(self)

        if self.method == "HEAD":
            if len(body) > 0:
                # This is a Bad Thing (RFC 2616, 9.4)
                log.msg("Warning: HEAD request %s for resource %s is"
                        " returning a message body."
                        "  I think I'll eat it."
                        % (self, resrc))
                self.setHeader('content-length', str(len(body)))
            self.write('')
        else:
            self.setHeader('content-length', str(len(body)))
            self.write(body)
        self.finish()

    def processingFailed(self, reason):
        log.err(reason)
        if self.site.displayTracebacks:
            body = ("<html><head><title>web.Server Traceback (most recent call last)</title></head>"
                    "<body><b>web.Server Traceback (most recent call last):</b>\n\n"
                    "%s\n\n</body></html>\n"
                    % webutil.formatFailure(reason))
        else:
            body = ("<html><head><title>Processing Failed</title></head><body>"
                  "<b>Processing Failed</b></body></html>")

        self.setResponseCode(http.INTERNAL_SERVER_ERROR)
        self.setHeader('content-type',"text/html")
        self.setHeader('content-length', str(len(body)))
        self.write(body)
        self.finish()
        return reason

    def view_write(self, issuer, data):
        """Remote version of write; same interface.
        """
        self.write(data)

    def view_finish(self, issuer):
        """Remote version of finish; same interface.
        """
        self.finish()

    def view_addCookie(self, issuer, k, v, **kwargs):
        """Remote version of addCookie; same interface.
        """
        self.addCookie(k, v, **kwargs)

    def view_setHeader(self, issuer, k, v):
        """Remote version of setHeader; same interface.
        """
        self.setHeader(k, v)

    def view_setLastModified(self, issuer, when):
        """Remote version of setLastModified; same interface.
        """
        self.setLastModified(when)

    def view_setETag(self, issuer, tag):
        """Remote version of setETag; same interface.
        """
        self.setETag(tag)

    def view_setResponseCode(self, issuer, code):
        """Remote version of setResponseCode; same interface.
        """
        self.setResponseCode(code)

    def view_registerProducer(self, issuer, producer, streaming):
        """Remote version of registerProducer; same interface.
        (requires a remote producer.)
        """
        self.registerProducer(_RemoteProducerWrapper(producer), streaming)

    def view_unregisterProducer(self, issuer):
        self.unregisterProducer()

    ### these calls remain local

    session = None

    def getSession(self, sessionInterface = None):
        # Session management
        if not self.session:
            cookiename = string.join(['TWISTED_SESSION'] + self.sitepath, "_")
            sessionCookie = self.getCookie(cookiename)
            if sessionCookie:
                try:
                    self.session = self.site.getSession(sessionCookie)
                except KeyError:
                    pass
            # if it still hasn't been set, fix it up.
            if not self.session:
                self.session = self.site.makeSession()
                self.addCookie(cookiename, self.session.uid, path='/')
        self.session.touch()
        if sessionInterface:
            return self.session.getComponent(sessionInterface)
        return self.session

    def _prePathURL(self, prepath):
        port = self.getHost().port
        if self.isSecure():
            default = 443
        else:
            default = 80
        if port == default:
            hostport = ''
        else:
            hostport = ':%d' % port
        return 'http%s://%s%s/%s' % (
            self.isSecure() and 's' or '',
            self.getRequestHostname(),
            hostport,
            '/'.join([quote(segment, safe='') for segment in prepath]))

    def prePathURL(self):
        return self._prePathURL(self.prepath)

    def URLPath(self):
        from twisted.python import urlpath
        return urlpath.URLPath.fromRequest(self)

    def rememberRootURL(self):
        """
        Remember the currently-processed part of the URL for later
        recalling.
        """
        url = self._prePathURL(self.prepath[:-1])
        self.appRootURL = url

    def getRootURL(self):
        """
        Get a previously-remembered URL.
        """
        return self.appRootURL


class _RemoteProducerWrapper:
    def __init__(self, remote):
        self.resumeProducing = remote.remoteMethod("resumeProducing")
        self.pauseProducing = remote.remoteMethod("pauseProducing")
        self.stopProducing = remote.remoteMethod("stopProducing")


class Session(components.Componentized):
    """
    A user's session with a system.

    This utility class contains no functionality, but is used to
    represent a session.

    @ivar _reactor: An object providing L{IReactorTime} to use for scheduling
        expiration.
    @ivar sessionTimeout: timeout of a session, in seconds.
    @ivar loopFactory: Deprecated in Twisted 9.0.  Does nothing.  Do not use.
    """
    sessionTimeout = 900
    loopFactory = task.LoopingCall

    _expireCall = None

    def __init__(self, site, uid, reactor=None):
        """
        Initialize a session with a unique ID for that session.
        """
        components.Componentized.__init__(self)

        if reactor is None:
            from twisted.internet import reactor
        self._reactor = reactor

        self.site = site
        self.uid = uid
        self.expireCallbacks = []
        self.touch()
        self.sessionNamespaces = {}


    def startCheckingExpiration(self, lifetime=None):
        """
        Start expiration tracking.

        @param lifetime: Ignored; deprecated.

        @return: C{None}
        """
        if lifetime is not None:
            warnings.warn(
                "The lifetime parameter to startCheckingExpiration is "
                "deprecated since Twisted 9.0.  See Session.sessionTimeout "
                "instead.", DeprecationWarning, stacklevel=2)
        self._expireCall = self._reactor.callLater(
            self.sessionTimeout, self.expire)


    def notifyOnExpire(self, callback):
        """
        Call this callback when the session expires or logs out.
        """
        self.expireCallbacks.append(callback)


    def expire(self):
        """
        Expire/logout of the session.
        """
        del self.site.sessions[self.uid]
        for c in self.expireCallbacks:
            c()
        self.expireCallbacks = []
        if self._expireCall and self._expireCall.active():
            self._expireCall.cancel()
            # Break reference cycle.
            self._expireCall = None


    def touch(self):
        """
        Notify session modification.
        """
        self.lastModified = self._reactor.seconds()
        if self._expireCall is not None:
            self._expireCall.reset(self.sessionTimeout)


    def checkExpired(self):
        """
        Deprecated; does nothing.
        """
        warnings.warn(
            "Session.checkExpired is deprecated since Twisted 9.0; sessions "
            "check themselves now, you don't need to.",
            stacklevel=2, category=DeprecationWarning)


version = "TwistedWeb/%s" % copyright.version


class Site(http.HTTPFactory):
    """
    A web site: manage log, sessions, and resources.

    @ivar counter: increment value used for generating unique sessions ID.
    @ivar requestFactory: factory creating requests objects. Default to
        L{Request}.
    @ivar displayTracebacks: if set, Twisted internal errors are displayed on
        rendered pages. Default to C{True}.
    @ivar sessionFactory: factory for sessions objects. Default to L{Session}.
    @ivar sessionCheckTime: Deprecated.  See L{Session.sessionTimeout} instead.
    """
    counter = 0
    requestFactory = Request
    displayTracebacks = True
    sessionFactory = Session
    sessionCheckTime = 1800

    def __init__(self, resource, logPath=None, timeout=60*60*12):
        """
        Initialize.
        """
        http.HTTPFactory.__init__(self, logPath=logPath, timeout=timeout)
        self.sessions = {}
        self.resource = resource

    def _openLogFile(self, path):
        from twisted.python import logfile
        return logfile.LogFile(os.path.basename(path), os.path.dirname(path))

    def __getstate__(self):
        d = self.__dict__.copy()
        d['sessions'] = {}
        return d

    def _mkuid(self):
        """
        (internal) Generate an opaque, unique ID for a user's session.
        """
        from twisted.python.hashlib import md5
        import random
        self.counter = self.counter + 1
        return md5("%s_%s" % (str(random.random()) , str(self.counter))).hexdigest()

    def makeSession(self):
        """
        Generate a new Session instance, and store it for future reference.
        """
        uid = self._mkuid()
        session = self.sessions[uid] = self.sessionFactory(self, uid)
        session.startCheckingExpiration()
        return session

    def getSession(self, uid):
        """
        Get a previously generated session, by its unique ID.
        This raises a KeyError if the session is not found.
        """
        return self.sessions[uid]

    def buildProtocol(self, addr):
        """
        Generate a channel attached to this site.
        """
        channel = http.HTTPFactory.buildProtocol(self, addr)
        channel.requestFactory = self.requestFactory
        channel.site = self
        return channel

    isLeaf = 0

    def render(self, request):
        """
        Redirect because a Site is always a directory.
        """
        request.redirect(request.prePathURL() + '/')
        request.finish()

    def getChildWithDefault(self, pathEl, request):
        """
        Emulate a resource's getChild method.
        """
        request.site = self
        return self.resource.getChildWithDefault(pathEl, request)

    def getResourceFor(self, request):
        """
        Get a resource for a request.

        This iterates through the resource heirarchy, calling
        getChildWithDefault on each resource it finds for a path element,
        stopping when it hits an element where isLeaf is true.
        """
        request.site = self
        # Sitepath is used to determine cookie names between distributed
        # servers and disconnected sites.
        request.sitepath = copy.copy(request.prepath)
        return resource.getChildForRequest(self.resource, request)


import html

