#!/usr/bin/env ruby
# Tell the user to install the shared library if it's missing.
begin
  require 'gst'
rescue LoadError => le
  raise unless le.message =~ /libgst/

  # Multiple OS help
  help = <<~INSTALL

  Please install the GStreamer library for your system.
  INSTALL

  # Re-raise with install message
  raise $!, "#{help}\n#{$!}", $!.backtrace
end

require 'set'

require 'mime/types'

module Cooltrainer
  module DistorteD
    class Video

      MEDIA_TYPE = 'video'.freeze
      MIME_TYPES = MIME::Types[/^#{MEDIA_TYPE}/, :complete => true].to_set

      # Attributes for our <video>.
      # Automatically enabled as attrs for DD Liquid Tag.
      # https://developer.mozilla.org/en-US/docs/Web/HTML/Element/video#Attributes
      ATTRS = Set[:caption]

      # Defaults for HTML Element attributes.
      # Not every attr has to be listed here.
      # Many need no default and just won't render.
      ATTRS_DEFAULT = {}
      ATTRS_VALUES = {}

      attr_accessor :dest


      def initialize(src, dest, basename)
        @src = src
        @dest = dest
        @basename = basename
      end

      def rotate(angle=nil)
        false
      end

      def clean
        false
      end

      def generate
        self.generate_hls
        begin
          self.generate_dash
        rescue Gst::ParseError::NoSuchElement
          # This is going away once the new dashsink2 lands in Gst so :effort:
        end
      end

      def generate_dash
        orig_dest = @dest
        orig_path = @src

        FileUtils.mkdir_p(File.dirname(orig_dest))

        hls_dest = File.join(File.dirname(orig_dest), @basename + '.dash')
        FileUtils.mkdir_p(hls_dest)
        Jekyll.logger.debug(@tag_name, "Re-muxing #{orig_path} to #{hls_dest}.")

        #FileUtils.rm(orig_dest) if File.exist?(orig_dest)
        if not File.file?(orig_dest)
          FileUtils.cp(orig_path, orig_dest)
        end

        # https://gstreamer.freedesktop.org/documentation/tools/gst-launch.html?gi-language=c#pipeline-description
        # TODO: Convert this from parse_launch() pipeline notation to Element objects
        # TODO: Get source video duration/resolution/etc and use it to compute a
        #  value for `target-duration`.
        # TODO: Also support urldecodebin for remote media.
        pipeline, error = Gst.parse_launch("filesrc name=src ! decodebin name=demux ! videoconvert ! vaapih264enc ! queue2 ! h264parse ! queue2 ! mux.video dashsink name=mux max-files=0 playlist-length=0 target-duration=2 demux. ! audioconvert ! voaacenc ! queue2 ! mux.audio")

        if pipeline.nil?
          Jekyll.logger.error(@tag_name, "Parse error: #{error.message}")
          return false
        end

        filesrc = pipeline.get_by_name('src')
        filesrc.location = orig_path

        hls_playlist = "#{hls_dest}/#{@basename}.m3u8"
        hls = pipeline.get_by_name('mux')
        hls.location = "#{hls_dest}/#{@basename}%05d.ts"
        hls.playlist_location = hls_playlist

        # TODO: config option for absolute vs relative segment URIs in the playlist.
        #hls.playlist_root = @url

        # TODO: dashsink support once there is a stable GStreamer release including it:
        # https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/merge_requests/704

        pipeline.play

        # Play until End Of Stream
        event_loop(pipeline)

        pipeline.stop

      end

      def generate_hls
        orig_dest = @dest
        orig_path = @src

        FileUtils.mkdir_p(File.dirname(orig_dest))

        hls_dest = File.join(File.dirname(orig_dest), @basename + '.hls')
        FileUtils.mkdir_p(hls_dest)
        Jekyll.logger.debug(@tag_name, "Re-muxing #{orig_path} to #{hls_dest}.")

        #FileUtils.rm(orig_dest) if File.exist?(orig_dest)
        if not File.file?(orig_dest)
          FileUtils.cp(orig_path, orig_dest)
        end

        # https://gstreamer.freedesktop.org/documentation/tools/gst-launch.html?gi-language=c#pipeline-description
        # TODO: Convert this from parse_launch() pipeline notation to Element objects
        # TODO: Get source video duration/resolution/etc and use it to compute a
        #  value for `target-duration`.
        # TODO: Also support urldecodebin for remote media.
        pipeline, error = Gst.parse_launch("filesrc name=src ! decodebin name=demux ! videoconvert ! vaapih264enc ! queue2 ! h264parse ! queue2 ! mux.video hlssink2 name=mux max-files=0 playlist-length=0 target-duration=2 demux. ! audioconvert ! voaacenc ! queue2 ! mux.audio")

        if pipeline.nil?
          Jekyll.logger.error(@tag_name, "Parse error: #{error.message}")
          return false
        end

        filesrc = pipeline.get_by_name('src')
        filesrc.location = orig_path

        hls_playlist = "#{hls_dest}/#{@basename}.m3u8"
        hls = pipeline.get_by_name('mux')
        hls.location = "#{hls_dest}/#{@basename}%05d.ts"
        hls.playlist_location = hls_playlist

        # TODO: config option for absolute vs relative segment URIs in the playlist.
        #hls.playlist_root = @url

        # TODO: dashsink support once there is a stable GStreamer release including it:
        # https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/merge_requests/704

        pipeline.play

        # Play until End Of Stream
        event_loop(pipeline)

        pipeline.stop

        # HACK HACK HACK: Replace X-ALLOW-CACHE line in playlist with YES.
        # This property does not seem to be exposed to the outside of hlssink:
        # https://cgit.freedesktop.org/gstreamer/gst-plugins-bad/tree/ext/hls/gsthlssink.c
        text = File.read(hls_playlist)
        File.write(hls_playlist, text.gsub(/^#EXT-X-ALLOW-CACHE:NO$/, '#EXT-X-ALLOW-CACHE:YES'))
      end

      def event_loop(pipeline)
        running = true
        bus = pipeline.bus

        while running
          message = bus.poll(Gst::MessageType::ANY, -1)

          case message.type
          when Gst::MessageType::EOS
            running = false
          when Gst::MessageType::WARNING
            warning, _debug = message.parse_warning
            Jekyll.logger.warning(@tag_name, warning)
          when Gst::MessageType::ERROR
            error, _debug = message.parse_error
            Jekyll.logger.error(@tag_name, error)
            running = false
          end
        end
      end
    end  # Image
  end  # DistorteD
end  # Cooltrainer