#!/usr/bin/env ruby

# Download imgur.com galleries easily
#
# Requirements:
#   gem install nokogiri
#
# Usage:
#   ruby imgur.rb [url of gallery] [directory to download into] [namespace for files]
#
# Example:
#   ruby imgur.rb http://imgur.com/a/npV94 battlefield3 scenery
#   All files will be downloaded into battlefield3 with filenames in the pattern of
#   scenery-[number].jpg


require 'nokogiri'
require 'open-uri'
require 'date'
require 'fileutils'
require 'optparse'
require 'pp'
require "shellwords"


def album_url origin_url
	url = URI.parse origin_url
	
	url.hostname = case url.hostname
				   when /(.*\.)?imgur.com/ then "imgur.com"
				   else raise "ERROR: unknown url hostname !"
				   end

	url.path = case url.path
			   when /^\/a\/(\S+).*?/ then
				   '/a/' + $1 + '/layout/blog'
			   else raise "ERROR: unknown url path !"
			   end

	puts "Fixed url #{url}"
	return url
end

def parse_cmdline args
	options = {}
	OptionParser.new do |opts|
  		opts.banner = "Usage: #{File.basename $0} [options]"

  		opts.on("-v", "--[no-]verbose", "Run verbosely") do |v|
    		options[:verbose] = v
  		end

  		opts.on("-z", "--[no-]zip", "Compress album to cbz (zip)") do |v|
    		options[:zip] = v
  		end

  		opts.on("-f", "--[no-]force", "Force overwrite in case file(s) exists") do |v|
    		options[:force] = v
  		end
	end.parse! args
	return options
end

options = parse_cmdline ARGV

#pp options
#pp ARGV
#exit 0

images = []
now = Time.now
url = album_url(ARGV[0])
directory = ( defined?(ARGV[1]) ? ARGV[1] : nil )
#namespace = ( defined?(ARGV[2]) ? ARGV[2] : "image" )
namespace = "image"

# filter url

page = Nokogiri::HTML(open url)
if directory.nil? then
	directory = page.title.strip.gsub(/\//,'-')
	directory = "#{directory} (#{url.path.split('/')[2]})"
end
directory = "#{now.year}#{sprintf("%02d", now.month)}/#{directory}"

page.search('.thumb-title').each do |image|
		uri = URI.parse(image.attributes['data-src'].value.gsub(/s.jpg/, '.jpg'))
	uri.scheme ||= "http"
  	images << uri.to_s
end

destination_exist = false
if options[:zip] and File.exist?(directory + ".cbz")
	destination_exist = true
elsif ( 
	   not options[:zip] and
	   FileTest.directory? directory and
	   FileTest.file? "#{directory}/.imguralbum" 
	  ) then
	  destination_exist = true
end

if destination_exist and not options[:force] then
	STDERR.puts "Destination already exists (use --force to overwrite)"
	exit 1
end
	
unless FileTest.directory? directory then
  	puts "Creating #{directory}"
  	FileUtils.mkdir_p directory
end

puts "Downloading images into #{directory}...\n\n"

images.each_with_index do |image, i|
	indexstr = sprintf("%04d", i)
  	puts "Downloading #{image} as #{namespace}-#{indexstr}.jpg..."
  	file = open(image)
  	File.open("#{directory}/#{namespace}-#{indexstr}.jpg", 'w') do |f| 
    	f.write file.read
  	end
end
FileUtils.touch "#{directory}/.imguralbum"

if options[:zip] then
	%x{zip -r #{directory.shellescape}.cbz #{directory.shellescape}}
	FileUtils.rm_rf directory
end

puts "\nDone."