"""
Displays Agg images in the browser, with interactivity
"""
from __future__ import (absolute_import, division, print_function,
                        unicode_literals)

# The WebAgg backend is divided into two modules:
#
# - `backend_webagg_core.py` contains code necessary to embed a WebAgg
#   plot inside of a web application, and communicate in an abstract
#   way over a web socket.
#
# - `backend_webagg.py` contains a concrete implementation of a basic
#   application, implemented with tornado.

from matplotlib.externals import six

import datetime
import errno
import json
import os
import random
import sys
import socket
import threading

try:
    import tornado
except ImportError:
    raise RuntimeError("The WebAgg backend requires Tornado.")

import tornado.web
import tornado.ioloop
import tornado.websocket

import matplotlib
from matplotlib import rcParams
from matplotlib import backend_bases
from matplotlib.figure import Figure
from matplotlib._pylab_helpers import Gcf
from . import backend_webagg_core as core
from .backend_webagg_core import TimerTornado


def new_figure_manager(num, *args, **kwargs):
    """
    Create a new figure manager instance
    """
    FigureClass = kwargs.pop('FigureClass', Figure)
    thisFig = FigureClass(*args, **kwargs)
    return new_figure_manager_given_figure(num, thisFig)


def new_figure_manager_given_figure(num, figure):
    """
    Create a new figure manager instance for the given figure.
    """
    canvas = FigureCanvasWebAgg(figure)
    manager = core.FigureManagerWebAgg(canvas, num)
    return manager


def draw_if_interactive():
    """
    Is called after every pylab drawing command
    """
    if matplotlib.is_interactive():
        figManager = Gcf.get_active()
        if figManager is not None:
            figManager.canvas.draw_idle()


class Show(backend_bases.ShowBase):
    def mainloop(self):
        WebAggApplication.initialize()

        url = "http://127.0.0.1:{port}{prefix}".format(
            port=WebAggApplication.port,
            prefix=WebAggApplication.url_prefix)

        if rcParams['webagg.open_in_browser']:
            import webbrowser
            webbrowser.open(url)
        else:
            print("To view figure, visit {0}".format(url))

        WebAggApplication.start()


show = Show().mainloop


class ServerThread(threading.Thread):
    def run(self):
        tornado.ioloop.IOLoop.instance().start()

webagg_server_thread = ServerThread()


class FigureCanvasWebAgg(core.FigureCanvasWebAggCore):
    def show(self):
        # show the figure window
        show()

    def new_timer(self, *args, **kwargs):
        return TimerTornado(*args, **kwargs)

    def start_event_loop(self, timeout):
        backend_bases.FigureCanvasBase.start_event_loop_default(
            self, timeout)
    start_event_loop.__doc__ = \
        backend_bases.FigureCanvasBase.start_event_loop_default.__doc__

    def stop_event_loop(self):
        backend_bases.FigureCanvasBase.stop_event_loop_default(self)
    stop_event_loop.__doc__ = \
        backend_bases.FigureCanvasBase.stop_event_loop_default.__doc__


class WebAggApplication(tornado.web.Application):
    initialized = False
    started = False

    class FavIcon(tornado.web.RequestHandler):
        def get(self):
            image_path = os.path.join(
                os.path.dirname(os.path.dirname(__file__)),
                'mpl-data', 'images')

            self.set_header('Content-Type', 'image/png')
            with open(os.path.join(image_path,
                                   'matplotlib.png'), 'rb') as fd:
                self.write(fd.read())

    class SingleFigurePage(tornado.web.RequestHandler):
        def __init__(self, application, request, **kwargs):
            self.url_prefix = kwargs.pop('url_prefix', '')
            return tornado.web.RequestHandler.__init__(self, application,
                                                       request, **kwargs)

        def get(self, fignum):
            fignum = int(fignum)
            manager = Gcf.get_fig_manager(fignum)

            ws_uri = 'ws://{req.host}{prefix}/'.format(req=self.request,
                                                       prefix=self.url_prefix)
            self.render(
                "single_figure.html",
                prefix=self.url_prefix,
                ws_uri=ws_uri,
                fig_id=fignum,
                toolitems=core.NavigationToolbar2WebAgg.toolitems,
                canvas=manager.canvas)

    class AllFiguresPage(tornado.web.RequestHandler):
        def __init__(self, application, request, **kwargs):
            self.url_prefix = kwargs.pop('url_prefix', '')
            return tornado.web.RequestHandler.__init__(self, application,
                                                       request, **kwargs)

        def get(self):
            ws_uri = 'ws://{req.host}{prefix}/'.format(req=self.request,
                                                       prefix=self.url_prefix)
            self.render(
                "all_figures.html",
                prefix=self.url_prefix,
                ws_uri=ws_uri,
                figures=sorted(
                    list(Gcf.figs.items()), key=lambda item: item[0]),
                toolitems=core.NavigationToolbar2WebAgg.toolitems)

    class MplJs(tornado.web.RequestHandler):
        def get(self):
            self.set_header('Content-Type', 'application/javascript')

            js_content = core.FigureManagerWebAgg.get_javascript()

            self.write(js_content)

    class Download(tornado.web.RequestHandler):
        def get(self, fignum, fmt):
            fignum = int(fignum)
            manager = Gcf.get_fig_manager(fignum)

            # TODO: Move this to a central location
            mimetypes = {
                'ps': 'application/postscript',
                'eps': 'application/postscript',
                'pdf': 'application/pdf',
                'svg': 'image/svg+xml',
                'png': 'image/png',
                'jpeg': 'image/jpeg',
                'tif': 'image/tiff',
                'emf': 'application/emf'
            }

            self.set_header('Content-Type', mimetypes.get(fmt, 'binary'))

            buff = six.BytesIO()
            manager.canvas.print_figure(buff, format=fmt)
            self.write(buff.getvalue())

    class WebSocket(tornado.websocket.WebSocketHandler):
        supports_binary = True

        def open(self, fignum):
            self.fignum = int(fignum)
            self.manager = Gcf.get_fig_manager(self.fignum)
            self.manager.add_web_socket(self)
            if hasattr(self, 'set_nodelay'):
                self.set_nodelay(True)

        def on_close(self):
            self.manager.remove_web_socket(self)

        def on_message(self, message):
            message = json.loads(message)
            # The 'supports_binary' message is on a client-by-client
            # basis.  The others affect the (shared) canvas as a
            # whole.
            if message['type'] == 'supports_binary':
                self.supports_binary = message['value']
            else:
                manager = Gcf.get_fig_manager(self.fignum)
                # It is possible for a figure to be closed,
                # but a stale figure UI is still sending messages
                # from the browser.
                if manager is not None:
                    manager.handle_json(message)

        def send_json(self, content):
            self.write_message(json.dumps(content))

        def send_binary(self, blob):
            if self.supports_binary:
                self.write_message(blob, binary=True)
            else:
                data_uri = "data:image/png;base64,{0}".format(
                    blob.encode('base64').replace('\n', ''))
                self.write_message(data_uri)

    def __init__(self, url_prefix=''):
        if url_prefix:
            assert url_prefix[0] == '/' and url_prefix[-1] != '/', \
                'url_prefix must start with a "/" and not end with one.'

        super(WebAggApplication, self).__init__(
            [
                # Static files for the CSS and JS
                (url_prefix + r'/_static/(.*)',
                 tornado.web.StaticFileHandler,
                 {'path': core.FigureManagerWebAgg.get_static_file_path()}),

                # An MPL favicon
                (url_prefix + r'/favicon.ico', self.FavIcon),

                # The page that contains all of the pieces
                (url_prefix + r'/([0-9]+)', self.SingleFigurePage,
                 {'url_prefix': url_prefix}),

                # The page that contains all of the figures
                (url_prefix + r'/?', self.AllFiguresPage,
                 {'url_prefix': url_prefix}),

                (url_prefix + r'/mpl.js', self.MplJs),

                # Sends images and events to the browser, and receives
                # events from the browser
                (url_prefix + r'/([0-9]+)/ws', self.WebSocket),

                # Handles the downloading (i.e., saving) of static images
                (url_prefix + r'/([0-9]+)/download.([a-z0-9.]+)',
                 self.Download),
            ],
            template_path=core.FigureManagerWebAgg.get_static_file_path())

    @classmethod
    def initialize(cls, url_prefix='', port=None):
        if cls.initialized:
            return

        # Create the class instance
        app = cls(url_prefix=url_prefix)

        cls.url_prefix = url_prefix

        # This port selection algorithm is borrowed, more or less
        # verbatim, from IPython.
        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)

        success = None
        cls.port = rcParams['webagg.port']
        for port in random_ports(cls.port, rcParams['webagg.port_retries']):
            try:
                app.listen(port)
            except socket.error as e:
                if e.errno != errno.EADDRINUSE:
                    raise
            else:
                cls.port = port
                success = True
                break

        if not success:
            raise SystemExit(
                "The webagg server could not be started because an available "
                "port could not be found")

        cls.initialized = True

    @classmethod
    def start(cls):
        if cls.started:
            return

        # Set the flag to True *before* blocking on IOLoop.instance().start()
        cls.started = True

        """
        IOLoop.running() was removed as of Tornado 2.4; see for example
        https://groups.google.com/forum/#!topic/python-tornado/QLMzkpQBGOY
        Thus there is no correct way to check if the loop has already been
        launched. We may end up with two concurrently running loops in that
        unlucky case with all the expected consequences.
        """
        print("Press Ctrl+C to stop WebAgg server")
        sys.stdout.flush()
        try:
            tornado.ioloop.IOLoop.instance().start()
        except KeyboardInterrupt:
            print("Server is stopped")
            sys.stdout.flush()
        finally:
            cls.started = False


def ipython_inline_display(figure):
    import tornado.template

    WebAggApplication.initialize()
    if not webagg_server_thread.is_alive():
        webagg_server_thread.start()

    with open(os.path.join(
            core.FigureManagerWebAgg.get_static_file_path(),
            'ipython_inline_figure.html')) as fd:
        tpl = fd.read()

    fignum = figure.number

    t = tornado.template.Template(tpl)
    return t.generate(
        prefix=WebAggApplication.url_prefix,
        fig_id=fignum,
        toolitems=core.NavigationToolbar2WebAgg.toolitems,
        canvas=figure.canvas,
        port=WebAggApplication.port).decode('utf-8')


FigureCanvas = FigureCanvasWebAgg