Class: TideScraper::Scraper

Inherits:
Object
  • Object
show all
Defined in:
lib/tide_scraper/ports.rb,
lib/tide_scraper/scraper.rb,
lib/tide_scraper/predictions.rb

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Scraper

Returns a new instance of Scraper.



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# File 'lib/tide_scraper/scraper.rb', line 6

def initialize
  @site = 'http://www.ukho.gov.uk/easytide/EasyTide'
  @clnt = HTTPClient.new
  return true
end

Instance Method Details

#get_port_info(port_id) ⇒ Object 



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# File 'lib/tide_scraper/ports.rb', line 3

def get_port_info(port_id)
  endpoint = '/SelectPrediction.aspx?PortID='
  url = @site+endpoint+port_id.to_s
  response = @clnt.get(url)
  return nil unless response.code == 200
  doc = Nokogiri::HTML response.content
  error = doc.xpath('//h1[contains(.,"An error has occurred")]').size
  return nil if error > 0
  port_info = Hash.new
  port_info[:id] = port_id.to_s
  port_info[:name] = doc.xpath('//span[@class="PortName"]').text
  port_info[:country] = doc.xpath('//span[@class="CountryPredSummary"]').text
  return port_info
end

#get_prediction(port, length = 7) ⇒ Object

Returns tidal prediction



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# File 'lib/tide_scraper/predictions.rb', line 5

def get_prediction(port,length=7)
  endpoint = '/ShowPrediction.aspx'
  url = @site+endpoint+"?PortID=#{port}&PredictionLength=#{length}"
  response = @clnt.get(url, follow_redirect: true)
#return nil if response.code != '200'
  doc = Nokogiri::HTML response.content
  tables = doc.xpath('//table[starts-with(@class,"HWLWTable")]')
  tides = []
  tables.each do |table|
    tides.concat(parse_tide_table(table))
  end
  tides.sort_by {|hsh| hsh[:time]}
end

#parse_tide_table(table) ⇒ Object

Will parse a table from a predictions page on UKHO’s EasyTide TODO: Timezones



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# File 'lib/tide_scraper/predictions.rb', line 21

def parse_tide_table(table)
  year = Time.now.year
  date = table.xpath('tr/th[@class="HWLWTableHeaderCell"]').text
# Populate highs and lows
  hilow = []
  table.xpath('tr[2]/th').each do |hilowth|
    hilow.push hilowth.text
  end
# Populate times
  times = []
  table.xpath('tr[3]/td').each do |timetd|
    times.push Time.parse(timetd.text + " " + year.to_s + " " + date)
  end
  heights = []
  table.xpath('tr[4]/td').each do |heighttd|
    heights.push heighttd.text.gsub("\u00A0"," ")
  end
  tides = []
  hilow.each_index do |i|
    tide = Hash.new
    tide[:stage] = hilow[i]
    tide[:time] = times[i]
    tide[:height] = heights[i]
    tides.push tide
  end
  return tides
end