Class: Gogdb::Engine

Inherits:
Object
  • Object
show all
Defined in:
lib/gogdb/engine.rb

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Engine

Returns a new instance of Engine.



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# File 'lib/gogdb/engine.rb', line 4

def initialize(options={})
  @logger = Logger.new(options)
  @utils = Utils.new(@logger)
end

Instance Method Details

#fetch(options) ⇒ Object

Downloads data from source and updates database with changes

Parameters:

  • options (Hash) —

    Additional options such as :limit and :type



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# File 'lib/gogdb/engine.rb', line 12

def fetch(options)
  # If user passed type parameter, we need to figure it out which urls we
  # need actually to fetch 
  sources = []
  sources.push(GOG_GAMES_URL) if options[:type] == "games"
  sources.push(GOG_MOVIES_URL) if options[:type] == "movies"
  sources = [GOG_GAMES_URL, GOG_MOVIES_URL] if options[:type] == "all" || options[:type] == nil

  sleep_time = 60 / options[:requestLimit]

  sources.each do |source|
    pages_number = get_pages_number(source)
    @logger.debug "Pages received: #{pages_number}"
    nil if pages_number < 1 # Do nothing if there are no pages

    # Loop through pages
    count = 0;
    catch :limitReached do
      for i in 0..pages_number do
        # Let's get products number and URL's for current page
        items_data = get_data(source)['products']
        items_number = items_data.length
        
        # Loop through products and get data of every one
        for i in 0..items_number do
          item_url = items_data[i]['url']
          item_data = get_data("#{GOG_URL}#{item_url}")['gameProductData']

          @logger.debug "Item received: #{item_data['title']}"

          count += 1
          # Break loop if limit is reached
          throw :limitReached if count >= options[:limit] && options[:limit] != 0
          
          sleep(sleep_time)
        end
      end
    end
  end
end

#get_data(url) ⇒ hash

Gets data from source and parses global javascript object.

Parameters:

  • url (string) —

    Page URL

Returns:

  • (hash) 


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# File 'lib/gogdb/engine.rb', line 71

def get_data(url)
  begin
    page = Net::HTTP.get(URI(url))
    JSON.parse(page[/(?<=var gogData = )(.*)(?=;)/,1])
  rescue => e
    @logger.warning "Cannot retrieve or parse data from gog.com"
    @logger.error e.message

    # In case crawler cannot access gog.com, let's check if gog.com is
    # actually online.
    ph = Net::Ping::HTTP.new(url)
    unless ph.ping?
      @logger.warning "Cannot establish connection to gog.com. Retrying..."
      
      # Retry connection until gog.com comes online. After that - retry
      # getting data.
      @utils.retryConnection(url)
      retry
    else
      @logger.warning "Connection to gog.com established successfully. Retrying..."
      sleep(15)
      retry
    end
  end
end

#get_pages_number(url) ⇒ integer

Gets pages number.

Parameters:

  • url (string) —

    Page URL

Returns:

  • (integer) —

    number of pages



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# File 'lib/gogdb/engine.rb', line 57

def get_pages_number(url)
  begin
    get_data(url)["totalPages"]
  rescue => e
    @logger.error "Cannot retrieve pages number."
    @logger.debug e.message
    0
  end
end