#!/usr/bin/env ruby
# encoding: utf-8

if ARGV.length < 1
	puts "usage: #{$0} <filenames>"
	exit 1
end

require 'gst'
Gst.init

#TODO define Exceptions
class Pipeline < Gst::Pipeline
	@@new_pipe_per_file=true
	@@new_pipe_per_file=false

	def self.pipeline
		if @@new_pipe_per_file
			new("pipeline")
		else
			@pipeline||=new("pipeline")
		end
	end

	attr_reader :location

	def initialize(name)
		pipeline=super
		@source=Gst::ElementFactory.make("filesrc", "source")
		raise "'filesrc' gstreamer plugin missing" if @source.nil?
		decodebin=Gst::ElementFactory.make("decodebin", "decode")
		raise "'decodebin' gstreamer plugin missing" if decodebin.nil?
		pipeline << @source << decodebin
		@source >> decodebin
		pipeline
	end

	def location=(file)
		@location=file
		@source.location=@location
	end

	def stop
		super
		check_state_returned(super)
	end

	def pause
		check_state_returned(super)
	end

	def bus
		(@bus||=super) || raise("Bus not found")
	end

	def tags
		tags=Gst::TagList.new
		while message=bus.pop
			#case message#Not working
			case message.type
			when Gst::MessageType::ERROR
				puts message.parse_error
			when Gst::MessageType::EOS
				puts "EOS"
				break
			when Gst::MessageType::TAG
p "TAG"
				tags=tags.merge(message.parse_tag, Gst::TagMergeMode::KEEP)
			end
		end
		tags
	end

private

	def check_state_returned(sret)
		return if sret==Gst::StateChangeReturn::SUCCESS
		if sret==Gst::StateChangeReturn::ASYNC
			return if get_state(5*Gst::SECOND).first==Gst::StateChangeReturn::SUCCESS
		end
		raise "State failed to changed"
	end
end

ARGV.each do |filename|
	pipeline=Pipeline.pipeline
	pipeline.stop
	pipeline.location=filename
	begin
# Decodebin will only commit to PAUSED if it actually finds a type
# otherwise the state change fails
		pipeline.pause
		tags=pipeline.tags
		if tags.empty?
			puts "No metadata found for #{filename}"
		else
			tags.each do |taglist, tag|
				if taglist.get_tag_size(tag)==1
					puts "%-15s: %s" % [Gst.tag_get_nick(tag), taglist.get_value_index(tag, 0).value]
				else
					puts "#{tag}"
				end
			end
		end
	rescue => error
		puts "#{error.message} (#{filename})"
		next
	end
end