hackernews

#!/usr/bin/env ruby
require 'curses'
require 'httparty'
require 'nokogiri'
require "optparse"
require 'launchy'

include Curses

ENTER_KEY = 10
BASE_URL = 'https://news.ycombinator.com/'
MAX_STORIES = 30 
STORY_RELOAD_INTERVAL_MILLIS = 60 * 1000
STORIES_PAGE_BOTTOM_BAR = '[q = Quit] [r = Refresh] [a = Launch Story In Browser] [Enter = View Comments]'
COMMENTS_PAGE_BOTTOM_BAR = '[q = Quit] [Left Arrow = Back] [Up Arrow = Scroll Up] [Down Arrow = Scroll Down]'

class HTTPartyProxy
  include HTTParty
end

opts_parser = OptionParser.new do |opts|
  opts.banner = "Usage: hackernews [--proxy-host <proxy_host>] [--proxy-port <proxy_port>]"
  opts.on("-h", "--proxy-host proxy_host", "The proxy host to use") do |proxy_host|
    @proxy_host = proxy_host
  end  
  opts.on("-p", "--proxy-port proxy_port", "The proxy port to use") do |proxy_port|
    @proxy_port = proxy_port
  end
  opts.on("-t", "--test", "Whether to run in test mode (with mocked assets)") do |test|
    @is_test_mode = true
  end
end
opts_parser.parse!

def get_stories_html
  return File.open("mockStories.html", "rb").read if @is_test_mode
  HTTPartyProxy.http_proxy(@proxy_host, @proxy_port.to_i) if @proxy_host
  return HTTPartyProxy.get(BASE_URL).body
end
def get_comments_html(url)
  return File.open("mockComments.html", "rb").read if @is_test_mode
  return HTTPartyProxy.get(url).body
end

def load_stories_from_server 
  return if (@last_load_time_millis ||= 0) > (Time.now.to_i - STORY_RELOAD_INTERVAL_MILLIS)
  @stories = []
  Nokogiri::HTML(get_stories_html).css("td.title a").each do |node|
    unless node.text == "More"
      comments_url = node.parent.parent.next_sibling.css("a")[1]['href']
      points = node.parent.parent.next_sibling.css("span").text.gsub(/ points/, '')
      url = node["href"].start_with?('item') ? BASE_URL + node["href"] : node["href"]
      @stories << OpenStruct.new(:points => points, :title => node.text, :url => url, :comments_url => BASE_URL + comments_url)
    end
    break if @stories.size == MAX_STORIES
  end 
  @last_load_time_millis = Time.now.to_i
end
def load_comments_from_server(url)
  comments = []
  Nokogiri::HTML(get_comments_html(url)).css('span.comment').each do |node|
    comments << OpenStruct.new(:comment => node.text, :indent => (node.parent.parent.css('img')[0]['width'].to_i / 40) + 1)
  end 
  @comment_lines = []
  comments.each do |comment|
    lines = split_comment_into_lines(comment.comment, @screen_width - comment.indent - 2) 
    @comment_lines << lines.map{ |line| " #{"|" * comment.indent}#{comment.indent > 0 ? " " : ""}#{line}" } << pad('')
  end
  @comment_lines.flatten!
end

def split_comment_into_lines(comment, line_length)
  lines = []
  comment.split("\n").each do |newline|
    current_line = ""
    newline.split(" ").each do |part|
      if (current_line + "#{part} ").length > line_length
        lines << current_line 
        current_line = "#{part }"
      else 
        current_line += "#{part} "
      end 
    end
    lines << current_line
  end
  lines
end

def init_screen
  Curses.noecho # do not show typed keys
  Curses.init_screen
  Curses.stdscr.keypad(true) # enable arrow keys
  Curses.start_color
  Curses.init_pair(COLOR_RED, COLOR_WHITE, COLOR_RED)
  Curses::timeout = 60 * 1000 # How often to fetch from the server if no keys have been pressed    
  @screen_height = Curses.lines
  @screen_width = Curses.cols
  @cursor_pos = 0
  begin
    yield
  ensure
    Curses.close_screen
  end
end

def draw_comments
  @comment_lines.each_with_index { |line, index|
    line_num = index + 2 + @comment_firstline
    write(line_num, 0, pad(line)) if line_num < @screen_height - 2 && line_num >= 2
  }
end
def draw_stories
  index = 2 
  @stories.each do |story|
    if (index - 2 == @cursor_pos) 
      Curses.attron(color_pair(COLOR_RED)|A_HORIZONTAL){
        write(index, 0, pad('  ' + story.title))
      }
    else 
      write(index, 0, pad('  ' + story.title))
    end
    index += 1
  end
end

def write(line, column, text)
  Curses.setpos(line, column)
  Curses.addstr(text);
end
def pad(message)
  message + " " * (@screen_width - message.length)
end

def draw_screen 
  @current_screen == 'comments' ? draw_comments : draw_stories 
  draw_title_bar
  draw_bottom_bar
end
def draw_title_bar
  Curses.attron(color_pair(COLOR_RED)|A_HORIZONTAL){ write(0, 0, pad(" Hacker News")) }
end
def draw_bottom_bar
  write(@screen_height - 1, 0, @current_screen == 'comments' ? COMMENTS_PAGE_BOTTOM_BAR : STORIES_PAGE_BOTTOM_BAR) 
end
def clear_screen
  Curses.clear
  Curses.refresh
end

init_screen do

  loop do
    load_stories_from_server
    draw_screen
    case Curses.getch
      when Curses::Key::UP then 
        if @current_screen == 'comments'
          @comment_firstline = @comment_firstline == 0 ? 0 : @comment_firstline + 1
        else
          @cursor_pos = @cursor_pos - 1 < 0 ? @stories.length - 1 : @cursor_pos - 1 
        end
      when Curses::Key::DOWN then 
        if @current_screen == 'comments'
          @comment_firstline = (@comment_lines.length + 3 - @screen_height + @comment_firstline) < 0 ? @comment_firstline : @comment_firstline - 1
        else
          @cursor_pos = (@cursor_pos + 1) % @stories.length 
        end
      when Curses::Key::LEFT then 
        @current_screen = 'stories' 
        clear_screen
      when ENTER_KEY, Curses::Key::RIGHT then 
        @current_screen = 'comments' 
        @comment_firstline = 0
        clear_screen
        load_comments_from_server(@stories[@cursor_pos].comments_url) 
      when ?a then
        Launchy.open(@stories[@cursor_pos].url)
      when ?r then load_stories_from_server 
      when ?q then break
    end
  end

end