# coding: utf-8
"""A tornado based IPython notebook server.

Authors:

* Brian Granger
"""
#-----------------------------------------------------------------------------
#  Copyright (C) 2008-2011  The IPython Development Team
#
#  Distributed under the terms of the BSD License.  The full license is in
#  the file COPYING, distributed as part of this software.
#-----------------------------------------------------------------------------

#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------

# stdlib
import errno
import logging
import os
import random
import re
import select
import signal
import socket
import sys
import threading
import time
import webbrowser

# Third party
import zmq

# Install the pyzmq ioloop. This has to be done before anything else from
# tornado is imported.
from zmq.eventloop import ioloop
ioloop.install()

from tornado import httpserver
from tornado import web

# Our own libraries
from .kernelmanager import MappingKernelManager
from .handlers import (LoginHandler, LogoutHandler,
    ProjectDashboardHandler, NewHandler, NamedNotebookHandler,
    MainKernelHandler, KernelHandler, KernelActionHandler, IOPubHandler,
    ShellHandler, NotebookRootHandler, NotebookHandler, NotebookCopyHandler,
    RSTHandler, AuthenticatedFileHandler, PrintNotebookHandler,
    MainClusterHandler, ClusterProfileHandler, ClusterActionHandler
)
from .notebookmanager import NotebookManager
from .clustermanager import ClusterManager

from IPython.config.application import catch_config_error, boolean_flag
from IPython.core.application import BaseIPythonApplication
from IPython.core.profiledir import ProfileDir
from IPython.frontend.consoleapp import IPythonConsoleApp
from IPython.lib.kernel import swallow_argv
from IPython.zmq.session import Session, default_secure
from IPython.zmq.zmqshell import ZMQInteractiveShell
from IPython.zmq.ipkernel import (
    flags as ipkernel_flags,
    aliases as ipkernel_aliases,
    IPKernelApp
)
from IPython.utils.traitlets import Dict, Unicode, Integer, List, Enum, Bool
from IPython.utils import py3compat

#-----------------------------------------------------------------------------
# Module globals
#-----------------------------------------------------------------------------

_kernel_id_regex = r"(?P<kernel_id>\w+-\w+-\w+-\w+-\w+)"
_kernel_action_regex = r"(?P<action>restart|interrupt)"
_notebook_id_regex = r"(?P<notebook_id>\w+-\w+-\w+-\w+-\w+)"
_profile_regex = r"(?P<profile>[^\/]+)" # there is almost no text that is invalid
_cluster_action_regex = r"(?P<action>start|stop)"


LOCALHOST = '127.0.0.1'

_examples = """
ipython notebook                       # start the notebook
ipython notebook --profile=sympy       # use the sympy profile
ipython notebook --pylab=inline        # pylab in inline plotting mode
ipython notebook --certfile=mycert.pem # use SSL/TLS certificate
ipython notebook --port=5555 --ip=*    # Listen on port 5555, all interfaces
"""

#-----------------------------------------------------------------------------
# Helper functions
#-----------------------------------------------------------------------------

def url_path_join(a,b):
    if a.endswith('/') and b.startswith('/'):
        return a[:-1]+b
    else:
        return a+b

def random_ports(port, n):
    """Generate a list of n random ports near the given port.

    The first 5 ports will be sequential, and the remaining n-5 will be
    randomly selected in the range [port-2*n, port+2*n].
    """
    for i in range(min(5, n)):
        yield port + i
    for i in range(n-5):
        yield port + random.randint(-2*n, 2*n)

#-----------------------------------------------------------------------------
# The Tornado web application
#-----------------------------------------------------------------------------

class NotebookWebApplication(web.Application):

    def __init__(self, ipython_app, kernel_manager, notebook_manager, 
                 cluster_manager, log,
                 base_project_url, settings_overrides):
        handlers = [
            (r"/", ProjectDashboardHandler),
            (r"/login", LoginHandler),
            (r"/logout", LogoutHandler),
            (r"/new", NewHandler),
            (r"/%s" % _notebook_id_regex, NamedNotebookHandler),
            (r"/%s/copy" % _notebook_id_regex, NotebookCopyHandler),
            (r"/%s/print" % _notebook_id_regex, PrintNotebookHandler),
            (r"/kernels", MainKernelHandler),
            (r"/kernels/%s" % _kernel_id_regex, KernelHandler),
            (r"/kernels/%s/%s" % (_kernel_id_regex, _kernel_action_regex), KernelActionHandler),
            (r"/kernels/%s/iopub" % _kernel_id_regex, IOPubHandler),
            (r"/kernels/%s/shell" % _kernel_id_regex, ShellHandler),
            (r"/notebooks", NotebookRootHandler),
            (r"/notebooks/%s" % _notebook_id_regex, NotebookHandler),
            (r"/rstservice/render", RSTHandler),
            (r"/files/(.*)", AuthenticatedFileHandler, {'path' : notebook_manager.notebook_dir}),
            (r"/clusters", MainClusterHandler),
            (r"/clusters/%s/%s" % (_profile_regex, _cluster_action_regex), ClusterActionHandler),
            (r"/clusters/%s" % _profile_regex, ClusterProfileHandler),
        ]

        # Python < 2.6.5 doesn't accept unicode keys in f(**kwargs), and
        # base_project_url will always be unicode, which will in turn
        # make the patterns unicode, and ultimately result in unicode
        # keys in kwargs to handler._execute(**kwargs) in tornado.
        # This enforces that base_project_url be ascii in that situation.
        # 
        # Note that the URLs these patterns check against are escaped,
        # and thus guaranteed to be ASCII: 'héllo' is really 'h%C3%A9llo'.
        base_project_url = py3compat.unicode_to_str(base_project_url, 'ascii')
        
        settings = dict(
            template_path=os.path.join(os.path.dirname(__file__), "templates"),
            static_path=os.path.join(os.path.dirname(__file__), "static"),
            cookie_secret=os.urandom(1024),
            login_url="%s/login"%(base_project_url.rstrip('/')),
        )

        # allow custom overrides for the tornado web app.
        settings.update(settings_overrides)

        # prepend base_project_url onto the patterns that we match
        new_handlers = []
        for handler in handlers:
            pattern = url_path_join(base_project_url, handler[0])
            new_handler = tuple([pattern]+list(handler[1:]))
            new_handlers.append( new_handler )

        super(NotebookWebApplication, self).__init__(new_handlers, **settings)

        self.kernel_manager = kernel_manager
        self.notebook_manager = notebook_manager
        self.cluster_manager = cluster_manager
        self.ipython_app = ipython_app
        self.read_only = self.ipython_app.read_only
        self.log = log


#-----------------------------------------------------------------------------
# Aliases and Flags
#-----------------------------------------------------------------------------

flags = dict(ipkernel_flags)
flags['no-browser']=(
    {'NotebookApp' : {'open_browser' : False}},
    "Don't open the notebook in a browser after startup."
)
flags['no-mathjax']=(
    {'NotebookApp' : {'enable_mathjax' : False}},
    """Disable MathJax
    
    MathJax is the javascript library IPython uses to render math/LaTeX. It is
    very large, so you may want to disable it if you have a slow internet
    connection, or for offline use of the notebook.
    
    When disabled, equations etc. will appear as their untransformed TeX source.
    """
)
flags['read-only'] = (
    {'NotebookApp' : {'read_only' : True}},
    """Allow read-only access to notebooks.
    
    When using a password to protect the notebook server, this flag
    allows unauthenticated clients to view the notebook list, and
    individual notebooks, but not edit them, start kernels, or run
    code.
    
    If no password is set, the server will be entirely read-only.
    """
)

# Add notebook manager flags
flags.update(boolean_flag('script', 'NotebookManager.save_script',
               'Auto-save a .py script everytime the .ipynb notebook is saved',
               'Do not auto-save .py scripts for every notebook'))

# the flags that are specific to the frontend
# these must be scrubbed before being passed to the kernel,
# or it will raise an error on unrecognized flags
notebook_flags = ['no-browser', 'no-mathjax', 'read-only', 'script', 'no-script']

aliases = dict(ipkernel_aliases)

aliases.update({
    'ip': 'NotebookApp.ip',
    'port': 'NotebookApp.port',
    'port-retries': 'NotebookApp.port_retries',
    'keyfile': 'NotebookApp.keyfile',
    'certfile': 'NotebookApp.certfile',
    'notebook-dir': 'NotebookManager.notebook_dir',
    'browser': 'NotebookApp.browser',
})

# remove ipkernel flags that are singletons, and don't make sense in
# multi-kernel evironment:
aliases.pop('f', None)

notebook_aliases = ['port', 'port-retries', 'ip', 'keyfile', 'certfile',
                    'notebook-dir']

#-----------------------------------------------------------------------------
# NotebookApp
#-----------------------------------------------------------------------------

class NotebookApp(BaseIPythonApplication):

    name = 'ipython-notebook'
    default_config_file_name='ipython_notebook_config.py'
    
    description = """
        The IPython HTML Notebook.
        
        This launches a Tornado based HTML Notebook Server that serves up an
        HTML5/Javascript Notebook client.
    """
    examples = _examples
    
    classes = IPythonConsoleApp.classes + [MappingKernelManager, NotebookManager]
    flags = Dict(flags)
    aliases = Dict(aliases)

    kernel_argv = List(Unicode)

    log_level = Enum((0,10,20,30,40,50,'DEBUG','INFO','WARN','ERROR','CRITICAL'),
                    default_value=logging.INFO,
                    config=True,
                    help="Set the log level by value or name.")

    # create requested profiles by default, if they don't exist:
    auto_create = Bool(True)

    # file to be opened in the notebook server
    file_to_run = Unicode('')

    # Network related information.

    ip = Unicode(LOCALHOST, config=True,
        help="The IP address the notebook server will listen on."
    )

    def _ip_changed(self, name, old, new):
        if new == '*': self.ip = ''

    port = Integer(8888, config=True,
        help="The port the notebook server will listen on."
    )
    port_retries = Integer(50, config=True,
        help="The number of additional ports to try if the specified port is not available."
    )

    certfile = Unicode('', config=True, 
        help="""The full path to an SSL/TLS certificate file."""
    )
    
    keyfile = Unicode('', config=True, 
        help="""The full path to a private key file for usage with SSL/TLS."""
    )

    password = Unicode('', config=True,
                      help="""Hashed password to use for web authentication.

                      To generate, type in a python/IPython shell:

                        from IPython.lib import passwd; passwd()

                      The string should be of the form type:salt:hashed-password.
                      """
    )

    open_browser = Bool(True, config=True,
                        help="""Whether to open in a browser after starting.
                        The specific browser used is platform dependent and
                        determined by the python standard library `webbrowser`
                        module, unless it is overridden using the --browser
                        (NotebookApp.browser) configuration option.
                        """)

    browser = Unicode('', config=True,
                      help="""Specify what command to use to invoke a web
                      browser when opening the notebook. If not specified, the
                      default browser will be determined by the `webbrowser`
                      standard library module, which allows setting of the
                      BROWSER environment variable to override it.
                      """)
    
    read_only = Bool(False, config=True,
        help="Whether to prevent editing/execution of notebooks."
    )
    
    webapp_settings = Dict(config=True,
            help="Supply overrides for the tornado.web.Application that the "
                 "IPython notebook uses.")
    
    enable_mathjax = Bool(True, config=True,
        help="""Whether to enable MathJax for typesetting math/TeX

        MathJax is the javascript library IPython uses to render math/LaTeX. It is
        very large, so you may want to disable it if you have a slow internet
        connection, or for offline use of the notebook.

        When disabled, equations etc. will appear as their untransformed TeX source.
        """
    )
    def _enable_mathjax_changed(self, name, old, new):
        """set mathjax url to empty if mathjax is disabled"""
        if not new:
            self.mathjax_url = ''

    base_project_url = Unicode('/', config=True,
                               help='''The base URL for the notebook server''')
    base_kernel_url = Unicode('/', config=True,
                               help='''The base URL for the kernel server''')
    websocket_host = Unicode("", config=True,
        help="""The hostname for the websocket server."""
    )

    mathjax_url = Unicode("", config=True,
        help="""The url for MathJax.js."""
    )
    def _mathjax_url_default(self):
        if not self.enable_mathjax:
            return ''
        static_path = self.webapp_settings.get("static_path", os.path.join(os.path.dirname(__file__), "static"))
        static_url_prefix = self.webapp_settings.get("static_url_prefix",
                                                     "/static/")
        if os.path.exists(os.path.join(static_path, 'mathjax', "MathJax.js")):
            self.log.info("Using local MathJax")
            return static_url_prefix+"mathjax/MathJax.js"
        else:
            if self.certfile:
                # HTTPS: load from Rackspace CDN, because SSL certificate requires it
                base = "https://c328740.ssl.cf1.rackcdn.com"
            else:
                base = "http://cdn.mathjax.org"
            
            url = base + "/mathjax/latest/MathJax.js"
            self.log.info("Using MathJax from CDN: %s", url)
            return url
    
    def _mathjax_url_changed(self, name, old, new):
        if new and not self.enable_mathjax:
            # enable_mathjax=False overrides mathjax_url
            self.mathjax_url = ''
        else:
            self.log.info("Using MathJax: %s", new)

    def parse_command_line(self, argv=None):
        super(NotebookApp, self).parse_command_line(argv)
        if argv is None:
            argv = sys.argv[1:]

        # Scrub frontend-specific flags
        self.kernel_argv = swallow_argv(argv, notebook_aliases, notebook_flags)
        # Kernel should inherit default config file from frontend
        self.kernel_argv.append("--KernelApp.parent_appname='%s'"%self.name)

        if self.extra_args:
            f = os.path.abspath(self.extra_args[0])
            if os.path.isdir(f):
                nbdir = f
            else:
                self.file_to_run = f
                nbdir = os.path.dirname(f)
            self.config.NotebookManager.notebook_dir = nbdir

    def init_configurables(self):
        # force Session default to be secure
        default_secure(self.config)
        self.kernel_manager = MappingKernelManager(
            config=self.config, log=self.log, kernel_argv=self.kernel_argv,
            connection_dir = self.profile_dir.security_dir,
        )
        self.notebook_manager = NotebookManager(config=self.config, log=self.log)
        self.log.info("Serving notebooks from %s", self.notebook_manager.notebook_dir)
        self.notebook_manager.list_notebooks()
        self.cluster_manager = ClusterManager(config=self.config, log=self.log)
        self.cluster_manager.update_profiles()

    def init_logging(self):
        # This prevents double log messages because tornado use a root logger that
        # self.log is a child of. The logging module dipatches log messages to a log
        # and all of its ancenstors until propagate is set to False.
        self.log.propagate = False
    
    def init_webapp(self):
        """initialize tornado webapp and httpserver"""
        self.web_app = NotebookWebApplication(
            self, self.kernel_manager, self.notebook_manager, 
            self.cluster_manager, self.log,
            self.base_project_url, self.webapp_settings
        )
        if self.certfile:
            ssl_options = dict(certfile=self.certfile)
            if self.keyfile:
                ssl_options['keyfile'] = self.keyfile
        else:
            ssl_options = None
        self.web_app.password = self.password
        self.http_server = httpserver.HTTPServer(self.web_app, ssl_options=ssl_options)
        if ssl_options is None and not self.ip and not (self.read_only and not self.password):
            self.log.critical('WARNING: the notebook server is listening on all IP addresses '
                              'but not using any encryption or authentication. This is highly '
                              'insecure and not recommended.')

        success = None
        for port in random_ports(self.port, self.port_retries+1):
            try:
                self.http_server.listen(port, self.ip)
            except socket.error as e:
                if e.errno != errno.EADDRINUSE:
                    raise
                self.log.info('The port %i is already in use, trying another random port.' % port)
            else:
                self.port = port
                success = True
                break
        if not success:
            self.log.critical('ERROR: the notebook server could not be started because '
                              'no available port could be found.')
            self.exit(1)
    
    def init_signal(self):
        # FIXME: remove this check when pyzmq dependency is >= 2.1.11
        # safely extract zmq version info:
        try:
            zmq_v = zmq.pyzmq_version_info()
        except AttributeError:
            zmq_v = [ int(n) for n in re.findall(r'\d+', zmq.__version__) ]
            if 'dev' in zmq.__version__:
                zmq_v.append(999)
            zmq_v = tuple(zmq_v)
        if zmq_v >= (2,1,9) and not sys.platform.startswith('win'):
            # This won't work with 2.1.7 and
            # 2.1.9-10 will log ugly 'Interrupted system call' messages,
            # but it will work
            signal.signal(signal.SIGINT, self._handle_sigint)
        signal.signal(signal.SIGTERM, self._signal_stop)
    
    def _handle_sigint(self, sig, frame):
        """SIGINT handler spawns confirmation dialog"""
        # register more forceful signal handler for ^C^C case
        signal.signal(signal.SIGINT, self._signal_stop)
        # request confirmation dialog in bg thread, to avoid
        # blocking the App
        thread = threading.Thread(target=self._confirm_exit)
        thread.daemon = True
        thread.start()
    
    def _restore_sigint_handler(self):
        """callback for restoring original SIGINT handler"""
        signal.signal(signal.SIGINT, self._handle_sigint)
    
    def _confirm_exit(self):
        """confirm shutdown on ^C
        
        A second ^C, or answering 'y' within 5s will cause shutdown,
        otherwise original SIGINT handler will be restored.
        
        This doesn't work on Windows.
        """
        # FIXME: remove this delay when pyzmq dependency is >= 2.1.11
        time.sleep(0.1)
        sys.stdout.write("Shutdown Notebook Server (y/[n])? ")
        sys.stdout.flush()
        r,w,x = select.select([sys.stdin], [], [], 5)
        if r:
            line = sys.stdin.readline()
            if line.lower().startswith('y'):
                self.log.critical("Shutdown confirmed")
                ioloop.IOLoop.instance().stop()
                return
        else:
            print("No answer for 5s:", end=' ')
        print("resuming operation...")
        # no answer, or answer is no:
        # set it back to original SIGINT handler
        # use IOLoop.add_callback because signal.signal must be called
        # from main thread
        ioloop.IOLoop.instance().add_callback(self._restore_sigint_handler)
    
    def _signal_stop(self, sig, frame):
        self.log.critical("received signal %s, stopping", sig)
        ioloop.IOLoop.instance().stop()
    
    @catch_config_error
    def initialize(self, argv=None):
        self.init_logging()
        super(NotebookApp, self).initialize(argv)
        self.init_configurables()
        self.init_webapp()
        self.init_signal()

    def cleanup_kernels(self):
        """shutdown all kernels
        
        The kernels will shutdown themselves when this process no longer exists,
        but explicit shutdown allows the KernelManagers to cleanup the connection files.
        """
        self.log.info('Shutting down kernels')
        km = self.kernel_manager
        # copy list, since shutdown_kernel deletes keys
        for kid in list(km.kernel_ids):
            km.shutdown_kernel(kid)

    def start(self):
        ip = self.ip if self.ip else '[all ip addresses on your system]'
        proto = 'https' if self.certfile else 'http'
        info = self.log.info
        info("The IPython Notebook is running at: %s://%s:%i%s" %
             (proto, ip, self.port,self.base_project_url) )
        info("Use Control-C to stop this server and shut down all kernels.")

        if self.open_browser or self.file_to_run:
            ip = self.ip or '127.0.0.1'
            try:
                browser = webbrowser.get(self.browser or None)
            except webbrowser.Error as e:
                self.log.warn('No web browser found: %s.' % e)
                browser = None

            if self.file_to_run:
                filename, _ = os.path.splitext(os.path.basename(self.file_to_run))
                for nb in self.notebook_manager.list_notebooks():
                    if filename == nb['name']:
                        url = nb['notebook_id']
                        break
                else:
                    url = ''
            else:
                url = ''
            if browser:
                b = lambda : browser.open("%s://%s:%i%s%s" % (proto, ip,
                    self.port, self.base_project_url, url), new=2)
                threading.Thread(target=b).start()
        try:
            ioloop.IOLoop.instance().start()
        except KeyboardInterrupt:
            info("Interrupted...")
        finally:
            self.cleanup_kernels()
    

#-----------------------------------------------------------------------------
# Main entry point
#-----------------------------------------------------------------------------

def launch_new_instance():
    app = NotebookApp.instance()
    app.initialize()
    app.start()

