require "socialcrawler/version"
require "csv"
require "open-uri"
require "nokogiri"
require 'logger'

# Copyright (C) 2015 Ivica Ceraj
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

module SocialCrawler

  class SocialCrawler

    def initialize
      @map = {
          twitter: 'twitter.com/',
          facebook: 'facebook.com/',
          google_plus: 'plus.google.com/'
      }
    end

    def _put(hash, symbol, value, log=nil)
      log = Logger.new(STDOUT) if log.nil?
      if not hash.has_key?(symbol)
        hash[symbol] = value
      else
        hash[symbol] = "#{hash[symbol]} #{value}"
        log.info("Multiple values for #{symbol} value #{hash[symbol]}")
      end
    end

    def page_to_result(page, result, log)
      links = page.css('a[href]')
      links.each do |link|
        link_url = link['href']
        @map.each do |k, prefix|
          if not link_url.index(prefix).nil?
            _put(result, k, link_url, log)
          end
        end
      end
    end

    def crawl_url(url, log=nil)
      log = Logger.new(STDOUT) if log.nil?
      log.info("Crawling #{url}")
      result = Hash.new('NOT FOUND')
      begin
        page = Nokogiri::HTML(open(url))
        title = page.css('title')
        if not title.nil?
          result[:title] = title.text.strip
        end
        page_to_result(page, result, log)
        result[:url] = url
        result[:success] = true
        result[:message] = ''
      rescue Exception => e
        result[:url] = url
        result[:success] = false
        result[:message] = "#{e}"
      end
      return result
    end

    def load_status_cache(status_filename, log=nil)
      status = Hash.new
      if not status_filename.nil? and File.exists?(status_filename)
        log.info("Loading previous status from #{status_filename}")
        CSV.foreach(status_filename) do |row|
          if row.count >= 3
            status[row[0]] = {
                :url => row[0],
                :result => row[1],
                :message => row[2]
            }
          end
        end
        log.info("Loading previous status from #{status_filename} finished, #{status.keys.length} loaded.")
      end
      return status
    end

    def load_output_cache(output_list_filename, log=nil)
      data = Hash.new()
      log.info("Loading previous status from #{output_list_filename}")
      if not File.exist?(output_list_filename)
        return data
      end
      CSV.foreach(output_list_filename) do |row|
        log.info("Loading #{row} #{row.count}")
        if row.count >= 5
          data[row[0]] = {
              :url => row[0],
              :title => row[1],
              :twitter => row[2],
              :facebook => row[3],
              :google_plus => row[4]
          }
        end
        log.info("Loading previous status from #{output_list_filename} finished, #{data.keys.length} loaded.")
      end
      return data
    end

    def crawl(domain_list_filename, output_list_filename, status_filename=nil, log=nil)
      log = Logger.new(STDOUT) if log.nil?
      log.info("Crawler started")

      status = load_status_cache(status_filename, log)

      data = load_output_cache(output_list_filename, log)

      CSV.open(output_list_filename, "wb") do |output|
        data.each do |k, v|
          output << [k, v[:title], v[:twitter], v[:facebook], v[:google_plus]]
        end
        CSV.open(status_filename, "wb") do |status_line|
          status.each do |k, v|
            status_line << [k, v[:success], v[:message]]
          end
          crawl_loop(data, domain_list_filename, log, output, status, status_line)
        end
      end
    end

    def crawl_loop(data, domain_list_filename, log, output, status, status_line)
      CSV.foreach(domain_list_filename) do |row|
        url = row[0]
        if status.has_key?(url)
          next
        end
        result = crawl_url(url, log)
        set_data(result, url, data, output)
        set_status(result, url, status, status_line)
      end
    end

    private

    def set_data(result, url, data, output)
      if result[:success] == true
        data[url] = result
        output << [url, result[:title], result[:twitter], result[:facebook], result[:google_plus]]
      end
    end

    def set_status(result, url, status, status_line)
      status[url] = {
          :url => url,
          :result => result[:success],
          :message => result[:message]
      }
      status_line << [url, result[:success], result[:message]]
    end
  end
end

if __FILE__ == $0
  # :nocov:
  SocialCrawler::SocialCrawler.new.crawl(ARGV[0], ARGV[1], ARGV[2])
  # :nocov:
end