""" Defines a KernelManager that provides signals and slots.
"""
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------

import os
import re
import time
from string import Template

#Basic http manipulation imports
import cgi
import json
import mimetypes

#HTTPserver imports
from BaseHTTPServer import HTTPServer, BaseHTTPRequestHandler
from SocketServer import ThreadingMixIn

#Cometmanager import
from CometManager import Manager

# IPython imports.
from IPython.utils.traitlets import Type
from IPython.zmq.kernelmanager import KernelManager, SubSocketChannel, \
    XReqSocketChannel, RepSocketChannel, HBSocketChannel

#-----------------------------------------------------------------------------
# Constants
#-----------------------------------------------------------------------------
#Base path to serve js and css files from
basepath = os.path.split(__file__)[0]+"/" 
manager = Manager()

## HTTP server and handlers
class IPyHttpHandler(BaseHTTPRequestHandler):
    """Derives from BaseHTTPRequestHandler to handle requests from HTTP server
    """
    def do_GET(self):
        """Handles GET requests from the client
        """
        #Path is either a real path, or the client_id
        path = self.path.strip("/")
        if path in manager:
            self.send_response(200)
            self.send_header("Content-type", "application/json")
            self.end_headers()
            
            #Manager.get blocks until a message is available
            json.dump(manager[path].get(), self.wfile)
        elif path == "notebook":
            self.send_response(200)
            self.send_header("Content-type", "application/xhtml+xml")
            self.end_headers()
            
            #This is a good spot to add login mechanics
            client_id = str(time.time())
            manager.register(client_id)
            page_text = Template(open(basepath + "notebook.html").read())
            
            self.wfile.write(page_text.safe_substitute(client_id = client_id))
        elif os.path.exists(basepath+path):
            self.send_response(200)
            mime = mimetypes.guess_type(path)[0]
            self.send_header("Content-type", mime)
            self.end_headers()
            
            self.wfile.write(open(basepath + path).read())
        else:
            self.send_response(404)
            self.end_headers()
    
    def do_POST(self):
        """Handles GET requests from the client
        """
        self.send_response(200)
        self.send_header("Content-type", "application/json")
        self.end_headers()
        
        client_id = self.path.strip("/")
        data = cgi.FieldStorage(fp=self.rfile, 
            headers=self.headers,
            environ={'REQUEST_METHOD':'POST',
                     'CONTENT_TYPE':self.headers['Content-Type'],
                     })
                     
        msg_type = data["type"].value
        if msg_type == "heartbeat":
            manager.heartbeat(client_id)
        else:
            if msg_type == "execute":
                resp = manager.execute(data["code"].value)
            elif msg_type == "complete":
                resp = manager.complete(data["code"].value, data["pos"].value)
            elif msg_type == "inspect":
                resp = manager.inspect(data['name'].value)
            elif msg_type == "connect":
                resp = manager.connect()
            elif msg_type == "history":
                resp = manager.history(data['index'].value)
            json.dump(resp, self.wfile)
    
    def do_PUT(self):
        '''Placeholder for future REP channel, need to figure out how it works'''
        pass

class IPyHttpServer(ThreadingMixIn, HTTPServer):
    pass


## IPython kernel sockets
class HttpXReqSocketChannel(XReqSocketChannel):
    #---------------------------------------------------------------------------
    # 'XReqSocketChannel' interface
    #---------------------------------------------------------------------------
    def call_handlers(self, msg):
        """ Reimplemented to emit signals instead of making callbacks.
        """
        if msg["msg_type"] == "execute_reply":
            manager.append(msg)
        else:
            manager.addreq(msg)
    """
        Useful for filtering namespace:
        filter( lambda x: not x.startswith('_') and x not in startns, 
                globals())
    """

class HttpSubSocketChannel(SubSocketChannel):
    #---------------------------------------------------------------------------
    # 'SubSocketChannel' interface
    #---------------------------------------------------------------------------
    
    def call_handlers(self, msg):
        """ Reimplemented to emit signals instead of making callbacks.
        """
        manager.append(msg)

class HttpRepSocketChannel(RepSocketChannel):
    #---------------------------------------------------------------------------
    # 'RepSocketChannel' interface
    #---------------------------------------------------------------------------

    def call_handlers(self, msg):
        """ Reimplemented to emit signals instead of making callbacks.
        """
        #FIXME: Need to find a sane way to implement REP socket
        pass

class HttpHBSocketChannel(HBSocketChannel):
    #---------------------------------------------------------------------------
    # 'HBSocketChannel' interface
    #---------------------------------------------------------------------------

    def call_handlers(self, since_last_heartbeat):
        """ Reimplemented to emit signals instead of making callbacks.
        """
        # Emit the generic signal.
        #FIXME: What to do with a dead kernel on client side?
        pass

## IPython Kernel
class HttpKernelManager(KernelManager):
    """ A KernelManager that provides signals and slots.
    """
    
    # Use Http-specific channel classes that emit signals.
    sub_channel_class = Type(HttpSubSocketChannel)
    xreq_channel_class = Type(HttpXReqSocketChannel)
    rep_channel_class = Type(HttpRepSocketChannel)
    hb_channel_class = Type(HttpHBSocketChannel)
    
    def __init__(self, *args, **kwargs):
        super(HttpKernelManager, self).__init__(*args, **kwargs)
        #Give kernel manager access to the CometManager
        manager.kernel_manager = self