from gi.repository import Gst, GObject, GLib
from gi.repository import GES
from gi.repository import GstPbutils

import os, sys
import argparse

class TextOverlayExample:
    def __init__ (self, args):
        self.__loop = GLib.MainLoop()
        self.__input = os.path.abspath(args.input)
        self.__output = os.path.abspath(args.output)
        self.__text = args.text
        self.__xpos = 0
        self.__ypos = 0

        self.__pipeline = GES.Pipeline()

        # setting up profile
        self.__container_profile = \
            GstPbutils.EncodingContainerProfile.new ("example-profile",
                                                     "Text Overlay Profile",
                                                     Gst.Caps.new_empty_simple ("video/quicktime"),
                                                     None)
        self.__video_profile = \
            GstPbutils.EncodingVideoProfile.new (Gst.Caps.new_empty_simple("video/x-h264"),
                                                 None,
                                                 Gst.Caps.new_empty_simple("video/x-raw"),
                                                 0)

        self.__container_profile.add_profile (self.__video_profile)

        # building timeline
        self.__timeline = GES.Timeline.new ()

        video_asset = GES.UriClipAsset.request_sync ("file://" + self.__input)
        layer = self.__timeline.append_layer ()
        layer.add_asset (video_asset, 0, 0, video_asset.get_duration(), GES.TrackType.VIDEO)

        self.__pipeline.set_timeline (self.__timeline)

        trackv = GES.VideoTrack.new()
        self.__timeline.add_track(trackv)


        # text overlay
        self.__textoverlayclip = GES.TextOverlayClip.new()
        self.__textoverlayclip.props.text = self.__text
        self.__textoverlayclip.props.xpos = self.__xpos
        self.__textoverlayclip.props.ypos = self.__ypos
        self.__textoverlayclip.props.font_desc = "Sans Italic 50"
        self.__textoverlayclip.props.start = 0
        #self.__textoverlayclip.props.in_point = 0
        self.__textoverlayclip.props.duration = video_asset.get_duration()

        layer.add_clip (self.__textoverlayclip)

        # setting render information
        self.__pipeline.set_render_settings ("file://" + self.__output, self.__container_profile)
        self.__pipeline.set_mode (GES.PipelineFlags.RENDER)

        # normal pipeline handling
        self.__bus = self.__pipeline.get_bus()
        self.__bus.connect ("message", self.__bus_message_cb)
        self.__bus.add_signal_watch()

    def run (self):
        self.__pipeline.set_state (Gst.State.PLAYING)
        self.__loop.run()

    def __bus_message_cb (self, bus, message):
        msg = message.get_structure()

        if message.type == Gst.MessageType.EOS:
            self.__loop.quit()

        if message.type == Gst.MessageType.ERROR:
            print msg.to_string ()
            self.__loop.quit()


if __name__ =="__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument ("-i", "--input", action="store", dest="input",
        help="the input video file to be overlayed")
    parser.add_argument ("-o", "--output", action="store", dest="output",
        help="the output video file")
    parser.add_argument ("-t", "--text", action="store", dest="text",
        help="the input text to be overlayed")

    args = parser.parse_args()

    Gst.init(None)
    GES.init()

    example = TextOverlayExample(args)
    example.run()