###
# Copyright (c) 2011, Valentin Lorentz
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#   * Redistributions of source code must retain the above copyright notice,
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###

"""
An embedded and centralized HTTP server for Supybot's plugins.
"""

import os
import cgi
from threading import Event, Thread
from cStringIO import StringIO
from SocketServer import ThreadingMixIn
from BaseHTTPServer import HTTPServer, BaseHTTPRequestHandler
# For testing purposes
from SocketServer import StreamRequestHandler

import supybot.log as log
import supybot.conf as conf
import supybot.world as world
from supybot.i18n import PluginInternationalization
_ = PluginInternationalization()

configGroup = conf.supybot.servers.http

class RequestNotHandled(Exception):
    pass

class RealSupyHTTPServer(HTTPServer):
    # TODO: make this configurable
    timeout = 0.5
    callbacks = {}
    running = False
    def hook(self, subdir, callback):
        if subdir in self.callbacks:
            log.warning(('The HTTP subdirectory `%s` was already hooked but '
                    'has been claimed by another plugin (or maybe you '
                    'reloaded the plugin and it didn\'t properly unhook. '
                    'Forced unhook.') % subdir)
        self.callbacks[subdir] = callback
    def unhook(self, subdir):
        callback = self.callbacks.pop(subdir) # May raise a KeyError. We don't care.
        callback.doUnhook(self)
        return callback

class TestSupyHTTPServer(RealSupyHTTPServer):
    def __init__(self, *args, **kwargs):
        pass
    def serve_forever(self, *args, **kwargs):
        pass
    def shutdown(self, *args, **kwargs):
        pass

if world.testing:
    SupyHTTPServer = TestSupyHTTPServer
else:
    SupyHTTPServer = RealSupyHTTPServer

class SupyHTTPRequestHandler(BaseHTTPRequestHandler):
    def do_X(self, callbackMethod, *args, **kwargs):
        if self.path == '/':
            callback = SupyIndex()
        elif self.path == '/robots.txt':
            callback = RobotsTxt()
        elif self.path == '/favicon.ico':
            callback = Favicon()
        else:
            subdir = self.path.split('/')[1]
            try:
                callback = self.server.callbacks[subdir]
            except KeyError:
                callback = Supy404()

        # Some shortcuts
        for name in ('send_response', 'send_header', 'end_headers', 'rfile',
                'wfile', 'headers'):
            setattr(callback, name, getattr(self, name))
        # We call doX, because this is more supybotic than do_X.
        getattr(callback, callbackMethod)(self,
                '/' + '/'.join(self.path.split('/')[2:]),
                *args, **kwargs)

    def do_GET(self):
        self.do_X('doGet')

    def do_POST(self):
        if 'Content-Type' not in self.headers:
            self.headers['Content-Type'] = 'application/x-www-form-urlencoded'
        form = cgi.FieldStorage(
            fp=self.rfile,
            headers=self.headers,
            environ={'REQUEST_METHOD':'POST',
                     'CONTENT_TYPE':self.headers['Content-Type'],
                     })
        self.do_X('doPost', form=form)

    def do_HEAD(self):
        self.do_X('doHead')


    def log_message(self, format, *args):
        log.info('HTTP request: %s - %s' %
                (self.address_string(), format % args))

class SupyHTTPServerCallback:
    """This is a base class that should be overriden by any plugin that want
    to have a Web interface."""
    name = "Unnamed plugin"
    defaultResponse = _("""
    This is a default response of the Supybot HTTP server. If you see this
    message, it probably means you are developing a plugin, and you have
    neither overriden this message or defined an handler for this query.""")

    def doGet(self, handler, path, *args, **kwargs):
        handler.send_response(404)
        self.send_header('Content_type', 'text/plain; charset=utf-8')
        self.send_header('Content-Length', len(self.defaultResponse))
        self.end_headers()
        self.wfile.write(self.defaultResponse)

    doPost = doHead = doGet

    def doUnhook(self, handler):
        """Method called when unhooking this callback."""
        pass

class Supy404(SupyHTTPServerCallback):
    """A 404 Not Found error."""
    name = "Error 404"
    response = _("""
    I am a pretty clever IRC bot, but I suck at serving Web pages, particulary
    if I don't know what to serve.
    What I'm saying is you just triggered a 404 Not Found, and I am not
    trained to help you in such a case.""")
    def doGet(self, handler, path, *args, **kwargs):
        handler.send_response(404)
        self.send_header('Content_type', 'text/plain; charset=utf-8')
        self.send_header('Content-Length', len(self.response))
        self.end_headers()
        self.wfile.write(self.response)

    doPost = doHead = doGet

class SupyIndex(SupyHTTPServerCallback):
    """Displays the index of available plugins."""
    name = "index"
    defaultResponse = _("Request not handled.")
    template = """
    <html>
     <head>
      <title>""" + _('Supybot Web server index') + """</title>
     </head>
     <body>
      <p>""" + _('Here is a list of the plugins that have a Web interface:') +\
      """
      </p>
      %s
     </body>
    </html>"""
    def doGet(self, handler, path):
        plugins = [x for x in handler.server.callbacks.items()]
        if plugins == []:
            plugins = _('No plugins available.')
        else:
            plugins = '<ul><li>%s</li></ul>' % '</li><li>'.join(
                    ['<a href="/%s/">%s</a>' % (x,y.name) for x,y in plugins])
        response = self.template % plugins
        handler.send_response(200)
        self.send_header('Content_type', 'text/html')
        self.send_header('Content-Length', len(response))
        self.end_headers()
        self.wfile.write(response)

class RobotsTxt(SupyHTTPServerCallback):
    """Serves the robot.txt file to robots."""
    name = 'robotstxt'
    defaultResponse = _('Request not handled')
    def doGet(self, handler, path):
        response = conf.supybot.servers.http.robots().replace('\\n', '\n')
        handler.send_response(200)
        self.send_header('Content-type', 'text/plain')
        self.send_header('Content-Length', len(response))
        self.end_headers()
        self.wfile.write(response)

class Favicon(SupyHTTPServerCallback):
    """Services the favicon.ico file to browsers."""
    name = 'favicon'
    defaultResponse = _('Request not handled')
    def doGet(self, handler, path):
        file_path = conf.supybot.servers.http.favicon()
        found = False
        if file_path:
            try:
                icon = open(file_path, 'r')
                found = True
            except IOError:
                pass
        if found:
            response = icon.read()
            filename = file_path.rsplit(os.sep, 1)[1]
            if '.' in filename:
                ext = filename.rsplit('.', 1)[1]
            else:
                ext = 'ico'
            # I have no idea why, but this headers are already sent.
            # self.send_header('Content-Length', len(response))
            # self.send_header('Content-type', 'image/' + ext)
            # self.end_headers()
            self.wfile.write(response)
        else:
            response = _('No favicon set.')
            handler.send_response(404)
            self.send_header('Content-type', 'text/plain')
            self.send_header('Content-Length', len(response))
            self.end_headers()
            self.wfile.write(response)

httpServer = None

def startServer():
    """Starts the HTTP server. Shouldn't be called from other modules.
    The callback should be an instance of a child of SupyHTTPServerCallback."""
    global httpServer
    log.info('Starting HTTP server.')
    address = (configGroup.host(), configGroup.port())
    httpServer = SupyHTTPServer(address, SupyHTTPRequestHandler)
    Thread(target=httpServer.serve_forever, name='HTTP Server').start()

def stopServer():
    """Stops the HTTP server. Should be run only from this module or from
    when the bot is dying (ie. from supybot.world)"""
    global httpServer
    if httpServer is not None:
        log.info('Stopping HTTP server.')
        httpServer.shutdown()
        httpServer = None

if configGroup.keepAlive():
    startServer()

def hook(subdir, callback):
    """Sets a callback for a given subdir."""
    if httpServer is None:
        startServer()
    httpServer.hook(subdir, callback)

def unhook(subdir):
    """Unsets the callback assigned to the given subdir, and return it."""
    global httpServer
    assert httpServer is not None
    callback = httpServer.unhook(subdir)
    if len(httpServer.callbacks) <= 0 and not configGroup.keepAlive():
        stopServer()