#!/usr/bin/env python3
#
# gst-playbin-switch - an example of switching file inputs with playbin
#
# Copyright (C) 2016  Antonio Ospite <ao2@ao2.it>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import sys

import gi
gi.require_version('Gst', '1.0')
from gi.repository import Gst
Gst.init(None)

from gi.repository import GLib


class Player:
    def __init__(self):
        self.loop = GLib.MainLoop()
        self.pipeline = Gst.ElementFactory.make("playbin3", "player")

        files = ["sample_440hz.webm", "sample_880hz.webm"]
        self.uris = [Gst.filename_to_uri(f) for f in files]
        self.uri_index = 0
        self.pipeline.set_property("uri", self.uris[self.uri_index])
        self.pipeline.connect("about-to-finish", self.on_about_to_finish)

        bus = self.pipeline.get_bus()
        bus.add_signal_watch()
        bus.connect('message::eos', self.on_eos)
        bus.connect('message::error', self.on_error)
        bus.connect('message::state-changed', self.on_state_changed)

    def on_about_to_finish(self, playbin):
        sys.stderr.write(".")
        sys.stderr.flush()
        playbin.set_property("uri", self.uris[self.uri_index])

    def run(self):
        self.pipeline.set_state(Gst.State.PLAYING)
        self.loop.run()

    def quit(self):
        self.pipeline.set_state(Gst.State.NULL)
        self.loop.quit()

    def on_switch(self):
        self.uri_index ^= 1
        print("Next: %s" % self.uris[self.uri_index])

        # Seek to the end of the stream, this will trigger the about-to-finish
        # signal
        seek_event = Gst.Event.new_seek(1.0,
                                        Gst.Format.TIME,
                                        Gst.SeekFlags.FLUSH,
                                        Gst.SeekType.END, -1,
                                        Gst.SeekType.NONE, 0)

        self.pipeline.send_event(seek_event)

    def on_eos(self, bus, msg):
        self.quit()

    def on_error(self, bus, msg):
        (err, debug) = msg.parse_error()
        print("Error: %s" % err)
        print("Error: %s" % debug)
        self.quit()

    def on_state_changed(self, bus, msg):
        if msg.src != self.pipeline:
            return

        old_state, new_state, pending = msg.parse_state_changed()
        print("%s from %s to %s" % (msg.src.get_name(), old_state, new_state))


def main():
    player = Player()

    def stdin_cb(source, condition):
        source.readline()
        player.on_switch()
        return True

    GLib.io_add_watch(sys.stdin, GLib.IO_IN, stdin_cb)

    print("\nPress Enter to switch the source\n")
    player.run()


if __name__ == '__main__':
    sys.exit(main())