listTopics.rb

require 'net/http'
require 'rubygems'
require 'json'
require 'uri'

topicId='DOubanTA'
maxCount = 50

# get topic count
#response = Net::HTTP.get_response('www.baidu.com', "/index.html");
response = Net::HTTP.get_response('api.douban.com', "/v2/group/#{topicId}/topics");
# puts response.body

topics = JSON.parse(response.body);
total = topics['total'];
puts "total topic count: #{total}" 

topicHash = {}
topicList = []
start = 0;
count = 100;


while start < total do
	#url = URI.parse("http://api.douban.com/v2/group/#{topicId}/topics?start=#{start}&count=#{count}");
	#http = Net::HTTP.new(url.host, url.port)
	#http.read_timeout = 50
	#http.open_timeout = 50
	#response = http.start() {|http|
	#    http.get(url.path)
	#}
	begin
	    response = Net::HTTP.get_response('api.douban.com', "/v2/group/#{topicId}/topics?start=#{start}&count=#{count}");
		start += count
	rescue Exception => e
	    puts e
		next
	end
    # response = Net::HTTP.get_response('api.douban.com', "/v2/group/#{topicId}/topics?start=#{start}&count=#{count}");
	puts "topics: #{start} - #{start + count} fetched."
	topics = JSON.parse(response.body)['topics']
	topics.each do |topic| 
	    id = topic['id']
		title = topic['title']
		created = topic['created']
		commentsCount = topic['comments_count']
		t = { :id => id, :title => title, :created => created, :commentsCount => commentsCount}
		if topicList.size < maxCount
		    topicList.push(t)
		else
		    topicList.sort! { |x, y| x[:commentsCount] <=> y[:commentsCount]}
			if not topicList.include?(t) and commentsCount > topicList[0][:commentsCount]
			    topicList.delete_at(0)
				topicList.insert(0, t)
			end
		end    
	end
end

topicList.sort! { |x, y| x[:commentsCount] <=> y[:commentsCount]}
topicList.reverse!
topicList.each do |v|
    puts "#{v[:title]}\##{v[:id]}(#{v[:commentsCount]})"
end